Some charts.py fixes (sugarpycha)

11 files changed, 2821 insertions, 0 deletions

diff --git a/sugarpycha/__init__.py b/sugarpycha/__init__.py
new file mode 100644
index 0000000..35bba09
--- /dev/null
+++ b/sugarpycha/__init__.py
@@ -0,0 +1,18 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+version = "0.6.1dev"
diff --git a/sugarpycha/bar.py b/sugarpycha/bar.py
new file mode 100644
index 0000000..ab0eeec
--- /dev/null
+++ b/sugarpycha/bar.py
@@ -0,0 +1,318 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+from pycha.chart import Chart, uniqueIndices
+from pycha.color import hex2rgb
+from pycha.utils import safe_unicode
+
+
+class BarChart(Chart):
+
+    def __init__(self, surface=None, options={}, debug=False):
+        super(BarChart, self).__init__(surface, options, debug)
+        self.bars = []
+        self.minxdelta = 0.0
+        self.barWidthForSet = 0.0
+        self.barMargin = 0.0
+
+    def _updateXY(self):
+        super(BarChart, self)._updateXY()
+        # each dataset is centered around a line segment. that's why we
+        # need n + 1 divisions on the x axis
+        self.xscale = 1 / (self.xrange + 1.0)
+
+    def _updateChart(self):
+        """Evaluates measures for vertical bars"""
+        stores = self._getDatasetsValues()
+        uniqx = uniqueIndices(stores)
+
+        if len(uniqx) == 1:
+            self.minxdelta = 1.0
+        else:
+            self.minxdelta = min([abs(uniqx[j] - uniqx[j - 1])
+                                  for j in range(1, len(uniqx))])
+
+        k = self.minxdelta * self.xscale
+        barWidth = k * self.options.barWidthFillFraction
+        self.barWidthForSet = barWidth / len(stores)
+        self.barMargin = k * (1.0 - self.options.barWidthFillFraction) / 2
+
+        self.bars = []
+
+    def _renderChart(self, cx):
+        """Renders a horizontal/vertical bar chart"""
+
+        def drawBar(bar):
+            stroke_width = self.options.stroke.width
+            ux, uy = cx.device_to_user_distance(stroke_width, stroke_width)
+            if ux < uy:
+                ux = uy
+            cx.set_line_width(ux)
+
+            # gather bar proportions
+            x = self.layout.chart.x + self.layout.chart.w * bar.x
+            y = self.layout.chart.y + self.layout.chart.h * bar.y
+            w = self.layout.chart.w * bar.w
+            h = self.layout.chart.h * bar.h
+
+            if (w < 1 or h < 1) and self.options.yvals.skipSmallValues:
+                return  # don't draw when the bar is too small
+
+            if self.options.stroke.shadow:
+                cx.set_source_rgba(0, 0, 0, 0.15)
+                rectangle = self._getShadowRectangle(x, y, w, h)
+                cx.rectangle(*rectangle)
+                cx.fill()
+
+            if self.options.shouldFill or (not self.options.stroke.hide):
+
+                if self.options.shouldFill:
+                    cx.set_source_rgb(*self.colorScheme[bar.name])
+                    cx.rectangle(x, y, w, h)
+                    cx.fill()
+
+                if not self.options.stroke.hide:
+                    cx.set_source_rgb(*hex2rgb(self.options.stroke.color))
+                    cx.rectangle(x, y, w, h)
+                    cx.stroke()
+
+            if bar.yerr:
+                self._renderError(cx, x, y, w, h, bar.yval, bar.yerr)
+
+            # render yvals above/beside bars
+            if self.options.yvals.show:
+                cx.save()
+                cx.set_font_size(self.options.yvals.fontSize)
+                cx.set_source_rgb(*hex2rgb(self.options.yvals.fontColor))
+
+                if callable(self.options.yvals.renderer):
+                    label = safe_unicode(self.options.yvals.renderer(bar),
+                                         self.options.encoding)
+                else:
+                    label = safe_unicode(bar.yval, self.options.encoding)
+                extents = cx.text_extents(label)
+                labelW = extents[2]
+                labelH = extents[3]
+
+                self._renderYVal(cx, label, labelW, labelH, x, y, w, h)
+
+                cx.restore()
+
+        cx.save()
+        for bar in self.bars:
+            drawBar(bar)
+        cx.restore()
+
+    def _renderYVal(self, cx, label, width, height, x, y, w, h):
+        raise NotImplementedError
+
+
+class VerticalBarChart(BarChart):
+
+    def _updateChart(self):
+        """Evaluates measures for vertical bars"""
+        super(VerticalBarChart, self)._updateChart()
+        for i, (name, store) in enumerate(self.datasets):
+            for item in store:
+                if len(item) == 3:
+                    xval, yval, yerr = item
+                else:
+                    xval, yval = item
+
+                x = (((xval - self.minxval) * self.xscale)
+                    + self.barMargin + (i * self.barWidthForSet))
+                w = self.barWidthForSet
+                h = abs(yval) * self.yscale
+                if yval > 0:
+                    y = (1.0 - h) - self.origin
+                else:
+                    y = 1 - self.origin
+                rect = Rect(x, y, w, h, xval, yval, name)
+
+                if (0.0 <= rect.x <= 1.0) and (0.0 <= rect.y <= 1.0):
+                    self.bars.append(rect)
+
+    def _updateTicks(self):
+        """Evaluates bar ticks"""
+        super(BarChart, self)._updateTicks()
+        offset = (self.minxdelta * self.xscale) / 2
+        self.xticks = [(tick[0] + offset, tick[1]) for tick in self.xticks]
+
+    def _getShadowRectangle(self, x, y, w, h):
+        return (x - 2, y - 2, w + 4, h + 2)
+
+    def _renderYVal(self, cx, label, labelW, labelH, barX, barY, barW, barH):
+        x = barX + (barW / 2.0) - (labelW / 2.0)
+        if self.options.yvals.snapToOrigin:
+            y = barY + barH - 0.5 * labelH
+        elif self.options.yvals.inside:
+            y = barY + (1.5 * labelH)
+        else:
+            y = barY - 0.5 * labelH
+
+        # if the label doesn't fit below the bar, put it above the bar
+        if y > (barY + barH):
+            y = barY - 0.5 * labelH
+
+        cx.move_to(x, y)
+        cx.show_text(label)
+
+    def _renderError(self, cx, barX, barY, barW, barH, value, error):
+        center = barX + (barW / 2.0)
+        errorWidth = max(barW * 0.1, 5.0)
+        left = center - errorWidth
+        right = center + errorWidth
+        errorSize = barH * error / value
+        top = barY + errorSize
+        bottom = barY - errorSize
+
+        cx.set_source_rgb(0, 0, 0)
+        cx.move_to(left, top)
+        cx.line_to(right, top)
+        cx.stroke()
+        cx.move_to(center, top)
+        cx.line_to(center, bottom)
+        cx.stroke()
+        cx.move_to(left, bottom)
+        cx.line_to(right, bottom)
+        cx.stroke()
+
+
+class HorizontalBarChart(BarChart):
+
+    def _updateChart(self):
+        """Evaluates measures for horizontal bars"""
+        super(HorizontalBarChart, self)._updateChart()
+
+        for i, (name, store) in enumerate(self.datasets):
+            for item in store:
+                if len(item) == 3:
+                    xval, yval, yerr = item
+                else:
+                    xval, yval = item
+                    yerr = 0.0
+
+                y = (((xval - self.minxval) * self.xscale)
+                     + self.barMargin + (i * self.barWidthForSet))
+                h = self.barWidthForSet
+                w = abs(yval) * self.yscale
+                if yval > 0:
+                    x = self.origin
+                else:
+                    x = self.origin - w
+                rect = Rect(x, y, w, h, xval, yval, name, yerr)
+
+                if (0.0 <= rect.x <= 1.0) and (0.0 <= rect.y <= 1.0):
+                    self.bars.append(rect)
+
+    def _updateTicks(self):
+        """Evaluates bar ticks"""
+        super(BarChart, self)._updateTicks()
+        offset = (self.minxdelta * self.xscale) / 2
+        tmp = self.xticks
+        self.xticks = [(1.0 - tick[0], tick[1]) for tick in self.yticks]
+        self.yticks = [(tick[0] + offset, tick[1]) for tick in tmp]
+
+    def _renderLines(self, cx):
+        """Aux function for _renderBackground"""
+        if self.options.axis.y.showLines and self.yticks:
+            for tick in self.xticks:
+                self._renderLine(cx, tick, True)
+        if self.options.axis.x.showLines and self.xticks:
+            for tick in self.yticks:
+                self._renderLine(cx, tick, False)
+
+    def _getShadowRectangle(self, x, y, w, h):
+        return (x, y - 2, w + 2, h + 4)
+
+    def _renderXAxisLabel(self, cx, labelText):
+        labelText = self.options.axis.x.label
+        super(HorizontalBarChart, self)._renderYAxisLabel(cx, labelText)
+
+    def _renderXAxis(self, cx):
+        """Draws the horizontal line representing the X axis"""
+        cx.new_path()
+        cx.move_to(self.layout.chart.x,
+                   self.layout.chart.y + self.layout.chart.h)
+        cx.line_to(self.layout.chart.x + self.layout.chart.w,
+                   self.layout.chart.y + self.layout.chart.h)
+        cx.close_path()
+        cx.stroke()
+
+    def _renderYAxisLabel(self, cx, labelText):
+        labelText = self.options.axis.y.label
+        super(HorizontalBarChart, self)._renderXAxisLabel(cx, labelText)
+
+    def _renderYAxis(self, cx):
+        # draws the vertical line representing the Y axis
+        cx.new_path()
+        cx.move_to(self.layout.chart.x + self.origin * self.layout.chart.w,
+                   self.layout.chart.y)
+        cx.line_to(self.layout.chart.x + self.origin * self.layout.chart.w,
+                   self.layout.chart.y + self.layout.chart.h)
+        cx.close_path()
+        cx.stroke()
+
+    def _renderYVal(self, cx, label, labelW, labelH, barX, barY, barW, barH):
+        y = barY + (barH / 2.0) + (labelH / 2.0)
+        if self.options.yvals.snapToOrigin:
+            x = barX + 2
+        elif self.options.yvals.inside:
+            x = barX + barW - (1.2 * labelW)
+        else:
+            x = barX + barW + 0.2 * labelW
+
+        # if the label doesn't fit to the left of the bar, put it to the right
+        if x < barX:
+            x = barX + barW + 0.2 * labelW
+
+        cx.move_to(x, y)
+        cx.show_text(label)
+
+    def _renderError(self, cx, barX, barY, barW, barH, value, error):
+        center = barY + (barH / 2.0)
+        errorHeight = max(barH * 0.1, 5.0)
+        top = center + errorHeight
+        bottom = center - errorHeight
+        errorSize = barW * error / value
+        right = barX + barW + errorSize
+        left = barX + barW - errorSize
+
+        cx.set_source_rgb(0, 0, 0)
+        cx.move_to(left, top)
+        cx.line_to(left, bottom)
+        cx.stroke()
+        cx.move_to(left, center)
+        cx.line_to(right, center)
+        cx.stroke()
+        cx.move_to(right, top)
+        cx.line_to(right, bottom)
+        cx.stroke()
+
+
+class Rect(object):
+
+    def __init__(self, x, y, w, h, xval, yval, name, yerr=0.0):
+        self.x, self.y, self.w, self.h = x, y, w, h
+        self.xval, self.yval, self.yerr = xval, yval, yerr
+        self.name = name
+
+    def __str__(self):
+        return ("<pycha.bar.Rect@(%.2f, %.2f) %.2fx%.2f (%.2f, %.2f, %.2f) %s>"
+                % (self.x, self.y, self.w, self.h,
+                   self.xval, self.yval, self.yerr,
+                   self.name))
diff --git a/sugarpycha/chart.py b/sugarpycha/chart.py
new file mode 100644
index 0000000..c6a1c34
--- /dev/null
+++ b/sugarpycha/chart.py
@@ -0,0 +1,883 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+import copy
+import inspect
+import math
+
+import cairo
+
+from pycha.color import ColorScheme, hex2rgb, DEFAULT_COLOR
+from pycha.utils import safe_unicode
+
+
+class Chart(object):
+
+    def __init__(self, surface, options={}, debug=False):
+        # this flag is useful to reuse this chart for drawing different data
+        # or use different options
+        self.resetFlag = False
+
+        # initialize storage
+        self.datasets = []
+
+        # computed values used in several methods
+        self.layout = Layout()
+        self.minxval = None
+        self.maxxval = None
+        self.minyval = None
+        self.maxyval = None
+        self.xscale = 1.0
+        self.yscale = 1.0
+        self.xrange = None
+        self.yrange = None
+        self.origin = 0.0
+
+        self.xticks = []
+        self.yticks = []
+
+        # set the default options
+        self.options = copy.deepcopy(DEFAULT_OPTIONS)
+        if options:
+            self.options.merge(options)
+
+        # initialize the surface
+        self._initSurface(surface)
+
+        self.colorScheme = None
+
+        # debug mode to draw aditional hints
+        self.debug = debug
+
+    def addDataset(self, dataset):
+        """Adds an object containing chart data to the storage hash"""
+        self.datasets += dataset
+
+    def _getDatasetsKeys(self):
+        """Return the name of each data set"""
+        return [d[0] for d in self.datasets]
+
+    def _getDatasetsValues(self):
+        """Return the data (value) of each data set"""
+        return [d[1] for d in self.datasets]
+
+    def setOptions(self, options={}):
+        """Sets options of this chart"""
+        self.options.merge(options)
+
+    def getSurfaceSize(self):
+        cx = cairo.Context(self.surface)
+        x, y, w, h = cx.clip_extents()
+        return w, h
+
+    def reset(self):
+        """Resets options and datasets.
+
+        In the next render the surface will be cleaned before any drawing.
+        """
+        self.resetFlag = True
+        self.options = copy.deepcopy(DEFAULT_OPTIONS)
+        self.datasets = []
+
+    def render(self, surface=None, options={}):
+        """Renders the chart with the specified options.
+
+        The optional parameters can be used to render a chart in a different
+        surface with new options.
+        """
+        self._update(options)
+        if surface:
+            self._initSurface(surface)
+
+        cx = cairo.Context(self.surface)
+
+        # calculate area data
+        surface_width, surface_height = self.getSurfaceSize()
+        self.layout.update(cx, self.options, surface_width, surface_height,
+                           self.xticks, self.yticks)
+
+        self._renderBackground(cx)
+        if self.debug:
+            self.layout.render(cx)
+        self._renderChart(cx)
+        self._renderAxis(cx)
+        self._renderTitle(cx)
+        self._renderLegend(cx)
+
+    def clean(self):
+        """Clears the surface with a white background."""
+        cx = cairo.Context(self.surface)
+        cx.save()
+        cx.set_source_rgb(1, 1, 1)
+        cx.paint()
+        cx.restore()
+
+    def _setColorscheme(self):
+        """Sets the colorScheme used for the chart using the
+        options.colorScheme option
+        """
+        name = self.options.colorScheme.name
+        keys = self._getDatasetsKeys()
+        colorSchemeClass = ColorScheme.getColorScheme(name, None)
+        if colorSchemeClass is None:
+            raise ValueError('Color scheme "%s" is invalid!' % name)
+
+        # Remove invalid args before calling the constructor
+        kwargs = dict(self.options.colorScheme.args)
+        validArgs = inspect.getargspec(colorSchemeClass.__init__)[0]
+        kwargs = dict([(k, v) for k, v in kwargs.items() if k in validArgs])
+        self.colorScheme = colorSchemeClass(keys, **kwargs)
+
+    def _initSurface(self, surface):
+        self.surface = surface
+
+        if self.resetFlag:
+            self.resetFlag = False
+            self.clean()
+
+    def _update(self, options={}):
+        """Update all the information needed to render the chart"""
+        self.setOptions(options)
+        self._setColorscheme()
+        self._updateXY()
+        self._updateChart()
+        self._updateTicks()
+
+    def _updateXY(self):
+        """Calculates all kinds of metrics for the x and y axis"""
+        x_range_is_defined = self.options.axis.x.range is not None
+        y_range_is_defined = self.options.axis.y.range is not None
+
+        if not x_range_is_defined or not y_range_is_defined:
+            stores = self._getDatasetsValues()
+
+        # gather data for the x axis
+        if x_range_is_defined:
+            self.minxval, self.maxxval = self.options.axis.x.range
+        else:
+            xdata = [pair[0] for pair in reduce(lambda a, b: a + b, stores)]
+            self.minxval = float(min(xdata))
+            self.maxxval = float(max(xdata))
+            if self.minxval * self.maxxval > 0 and self.minxval > 0:
+                self.minxval = 0.0
+
+        self.xrange = self.maxxval - self.minxval
+        if self.xrange == 0:
+            self.xscale = 1.0
+        else:
+            self.xscale = 1.0 / self.xrange
+
+        # gather data for the y axis
+        if y_range_is_defined:
+            self.minyval, self.maxyval = self.options.axis.y.range
+        else:
+            ydata = [pair[1] for pair in reduce(lambda a, b: a + b, stores)]
+            self.minyval = float(min(ydata))
+            self.maxyval = float(max(ydata))
+            if self.minyval * self.maxyval > 0 and self.minyval > 0:
+                self.minyval = 0.0
+
+        self.yrange = self.maxyval - self.minyval
+        if self.yrange == 0:
+            self.yscale = 1.0
+        else:
+            self.yscale = 1.0 / self.yrange
+
+        if self.minyval * self.maxyval < 0:  # different signs
+            self.origin = abs(self.minyval) * self.yscale
+        else:
+            self.origin = 0.0
+
+    def _updateChart(self):
+        raise NotImplementedError
+
+    def _updateTicks(self):
+        """Evaluates ticks for x and y axis.
+
+        You should call _updateXY before because that method computes the
+        values of xscale, minxval, yscale, and other attributes needed for
+        this method.
+        """
+        stores = self._getDatasetsValues()
+
+        # evaluate xTicks
+        self.xticks = []
+        if self.options.axis.x.ticks:
+            for tick in self.options.axis.x.ticks:
+                if not isinstance(tick, Option):
+                    tick = Option(tick)
+                if tick.label is None:
+                    label = str(tick.v)
+                else:
+                    label = tick.label
+                pos = self.xscale * (tick.v - self.minxval)
+                if 0.0 <= pos <= 1.0:
+                    self.xticks.append((pos, label))
+
+        elif self.options.axis.x.interval > 0:
+            interval = self.options.axis.x.interval
+            label = (divmod(self.minxval, interval)[0] + 1) * interval
+            pos = self.xscale * (label - self.minxval)
+            prec = self.options.axis.x.tickPrecision
+            while 0.0 <= pos <= 1.0:
+                pretty_label = round(label, prec)
+                if prec == 0:
+                    pretty_label = int(pretty_label)
+                self.xticks.append((pos, pretty_label))
+                label += interval
+                pos = self.xscale * (label - self.minxval)
+
+        elif self.options.axis.x.tickCount > 0:
+            uniqx = range(len(uniqueIndices(stores)) + 1)
+            roughSeparation = self.xrange / self.options.axis.x.tickCount
+            i = j = 0
+            while i < len(uniqx) and j < self.options.axis.x.tickCount:
+                if (uniqx[i] - self.minxval) >= (j * roughSeparation):
+                    pos = self.xscale * (uniqx[i] - self.minxval)
+                    if 0.0 <= pos <= 1.0:
+                        self.xticks.append((pos, uniqx[i]))
+                        j += 1
+                i += 1
+
+        # evaluate yTicks
+        self.yticks = []
+        if self.options.axis.y.ticks:
+            for tick in self.options.axis.y.ticks:
+                if not isinstance(tick, Option):
+                    tick = Option(tick)
+                if tick.label is None:
+                    label = str(tick.v)
+                else:
+                    label = tick.label
+                pos = 1.0 - (self.yscale * (tick.v - self.minyval))
+                if 0.0 <= pos <= 1.0:
+                    self.yticks.append((pos, label))
+
+        elif self.options.axis.y.interval > 0:
+            interval = self.options.axis.y.interval
+            label = (divmod(self.minyval, interval)[0] + 1) * interval
+            pos = 1.0 - (self.yscale * (label - self.minyval))
+            prec = self.options.axis.y.tickPrecision
+            while 0.0 <= pos <= 1.0:
+                pretty_label = round(label, prec)
+                if prec == 0:
+                    pretty_label = int(pretty_label)
+                self.yticks.append((pos, pretty_label))
+                label += interval
+                pos = 1.0 - (self.yscale * (label - self.minyval))
+
+        elif self.options.axis.y.tickCount > 0:
+            prec = self.options.axis.y.tickPrecision
+            num = self.yrange / self.options.axis.y.tickCount
+            if (num < 1 and prec == 0):
+                roughSeparation = 1
+            else:
+                roughSeparation = round(num, prec)
+
+            for i in range(self.options.axis.y.tickCount + 1):
+                yval = self.minyval + (i * roughSeparation)
+                pos = 1.0 - ((yval - self.minyval) * self.yscale)
+                if 0.0 <= pos <= 1.0:
+                    pretty_label = round(yval, prec)
+                    if prec == 0:
+                        pretty_label = int(pretty_label)
+                    self.yticks.append((pos, pretty_label))
+
+    def _renderBackground(self, cx):
+        """Renders the background area of the chart"""
+        if self.options.background.hide:
+            return
+
+        cx.save()
+
+        if self.options.background.baseColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.baseColor))
+            cx.paint()
+
+        if self.options.background.chartColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.chartColor))
+            surface_width, surface_height = self.getSurfaceSize()
+            cx.rectangle(self.options.padding.left, self.options.padding.top,
+                         surface_width - (self.options.padding.left
+                                          + self.options.padding.right),
+                         surface_height - (self.options.padding.top
+                                           + self.options.padding.bottom))
+            cx.fill()
+
+        if self.options.background.lineColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.lineColor))
+            cx.set_line_width(self.options.axis.lineWidth)
+            self._renderLines(cx)
+
+        cx.restore()
+
+    def _renderLines(self, cx):
+        """Aux function for _renderBackground"""
+        if self.options.axis.y.showLines and self.yticks:
+            for tick in self.yticks:
+                self._renderLine(cx, tick, False)
+        if self.options.axis.x.showLines and self.xticks:
+            for tick in self.xticks:
+                self._renderLine(cx, tick, True)
+
+    def _renderLine(self, cx, tick, horiz):
+        """Aux function for _renderLines"""
+        x1, x2, y1, y2 = (0, 0, 0, 0)
+        if horiz:
+            x1 = x2 = tick[0] * self.layout.chart.w + self.layout.chart.x
+            y1 = self.layout.chart.y
+            y2 = y1 + self.layout.chart.h
+        else:
+            x1 = self.layout.chart.x
+            x2 = x1 + self.layout.chart.w
+            y1 = y2 = tick[0] * self.layout.chart.h + self.layout.chart.y
+
+        cx.new_path()
+        cx.move_to(x1, y1)
+        cx.line_to(x2, y2)
+        cx.close_path()
+        cx.stroke()
+
+    def _renderChart(self, cx):
+        raise NotImplementedError
+
+    def _renderTick(self, cx, tick, x, y, x2, y2, rotate, text_position):
+        """Aux method for _renderXTick and _renderYTick"""
+        if callable(tick):
+            return
+
+        cx.new_path()
+        cx.move_to(x, y)
+        cx.line_to(x2, y2)
+        cx.close_path()
+        cx.stroke()
+
+        cx.select_font_face(self.options.axis.tickFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(self.options.axis.tickFontSize)
+
+        label = safe_unicode(tick[1], self.options.encoding)
+        xb, yb, width, height, xa, ya = cx.text_extents(label)
+
+        x, y = text_position
+
+        if rotate:
+            cx.save()
+            cx.translate(x, y)
+            cx.rotate(math.radians(rotate))
+            x = -width / 2.0
+            y = -height / 2.0
+            cx.move_to(x - xb, y - yb)
+            cx.show_text(label)
+            if self.debug:
+                cx.rectangle(x, y, width, height)
+                cx.stroke()
+            cx.restore()
+        else:
+            x -= width / 2.0
+            y -= height / 2.0
+            cx.move_to(x - xb, y - yb)
+            cx.show_text(label)
+            if self.debug:
+                cx.rectangle(x, y, width, height)
+                cx.stroke()
+
+        return label
+
+    def _renderYTick(self, cx, tick):
+        """Aux method for _renderAxis"""
+        x = self.layout.y_ticks.x + self.layout.y_ticks.w
+        y = self.layout.y_ticks.y + tick[0] * self.layout.y_ticks.h
+
+        text_position = ((self.layout.y_tick_labels.x
+                          + self.layout.y_tick_labels.w / 2.0), y)
+
+        return self._renderTick(cx, tick,
+                                x, y,
+                                x - self.options.axis.tickSize, y,
+                                self.options.axis.y.rotate,
+                                text_position)
+
+    def _renderXTick(self, cx, tick):
+        """Aux method for _renderAxis"""
+
+        x = self.layout.x_ticks.x + tick[0] * self.layout.x_ticks.w
+        y = self.layout.x_ticks.y
+
+        text_position = (x, (self.layout.x_tick_labels.y
+                             + self.layout.x_tick_labels.h / 2.0))
+
+        return self._renderTick(cx, tick,
+                                x, y,
+                                x, y + self.options.axis.tickSize,
+                                self.options.axis.x.rotate,
+                                text_position)
+
+    def _renderAxisLabel(self, cx, label, x, y, vertical=False):
+        cx.save()
+        cx.select_font_face(self.options.axis.labelFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_BOLD)
+        cx.set_font_size(self.options.axis.labelFontSize)
+        cx.set_source_rgb(*hex2rgb(self.options.axis.labelColor))
+
+        xb, yb, width, height, xa, ya = cx.text_extents(label)
+
+        if vertical:
+            y = y + width / 2.0
+            cx.move_to(x - xb, y - yb)
+            cx.translate(x, y)
+            cx.rotate(-math.radians(90))
+            cx.move_to(-xb, -yb)
+            cx.show_text(label)
+            if self.debug:
+                cx.rectangle(0, 0, width, height)
+                cx.stroke()
+        else:
+            x = x - width / 2.0
+            cx.move_to(x - xb, y - yb)
+            cx.show_text(label)
+            if self.debug:
+                cx.rectangle(x, y, width, height)
+                cx.stroke()
+        cx.restore()
+
+    def _renderYAxisLabel(self, cx, label_text):
+        label = safe_unicode(label_text, self.options.encoding)
+        x = self.layout.y_label.x
+        y = self.layout.y_label.y + self.layout.y_label.h / 2.0
+        self._renderAxisLabel(cx, label, x, y, True)
+
+    def _renderYAxis(self, cx):
+        """Draws the vertical line represeting the Y axis"""
+        cx.new_path()
+        cx.move_to(self.layout.chart.x, self.layout.chart.y)
+        cx.line_to(self.layout.chart.x,
+                   self.layout.chart.y + self.layout.chart.h)
+        cx.close_path()
+        cx.stroke()
+
+    def _renderXAxisLabel(self, cx, label_text):
+        label = safe_unicode(label_text, self.options.encoding)
+        x = self.layout.x_label.x + self.layout.x_label.w / 2.0
+        y = self.layout.x_label.y
+        self._renderAxisLabel(cx, label, x, y, False)
+
+    def _renderXAxis(self, cx):
+        """Draws the horizontal line representing the X axis"""
+        cx.new_path()
+        y = self.layout.chart.y + (1.0 - self.origin) * self.layout.chart.h
+        cx.move_to(self.layout.chart.x, y)
+        cx.line_to(self.layout.chart.x + self.layout.chart.w, y)
+        cx.close_path()
+        cx.stroke()
+
+    def _renderAxis(self, cx):
+        """Renders axis"""
+        if self.options.axis.x.hide and self.options.axis.y.hide:
+            return
+
+        cx.save()
+        cx.set_source_rgb(*hex2rgb(self.options.axis.lineColor))
+        cx.set_line_width(self.options.axis.lineWidth)
+
+        if not self.options.axis.y.hide:
+            if self.yticks:
+                for tick in self.yticks:
+                    self._renderYTick(cx, tick)
+
+            if self.options.axis.y.label:
+                self._renderYAxisLabel(cx, self.options.axis.y.label)
+
+            self._renderYAxis(cx)
+
+        if not self.options.axis.x.hide:
+            if self.xticks:
+                for tick in self.xticks:
+                    self._renderXTick(cx, tick)
+
+            if self.options.axis.x.label:
+                self._renderXAxisLabel(cx, self.options.axis.x.label)
+
+            self._renderXAxis(cx)
+
+        cx.restore()
+
+    def _renderTitle(self, cx):
+        if self.options.title:
+            cx.save()
+            cx.select_font_face(self.options.titleFont,
+                                cairo.FONT_SLANT_NORMAL,
+                                cairo.FONT_WEIGHT_BOLD)
+            cx.set_font_size(self.options.titleFontSize)
+            cx.set_source_rgb(*hex2rgb(self.options.titleColor))
+
+            title = safe_unicode(self.options.title, self.options.encoding)
+            extents = cx.text_extents(title)
+            title_width = extents[2]
+
+            x = (self.layout.title.x
+                 + self.layout.title.w / 2.0
+                 - title_width / 2.0)
+            y = self.layout.title.y - extents[1]
+
+            cx.move_to(x, y)
+            cx.show_text(title)
+
+            cx.restore()
+
+    def _renderLegend(self, cx):
+        """This function adds a legend to the chart"""
+        if self.options.legend.hide:
+            return
+
+        surface_width, surface_height = self.getSurfaceSize()
+
+        # Compute legend dimensions
+        padding = 4
+        bullet = 15
+        width = 0
+        height = padding
+        keys = self._getDatasetsKeys()
+        cx.select_font_face(self.options.legend.legendFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(self.options.legend.legendFontSize)
+        for key in keys:
+            key = safe_unicode(key, self.options.encoding)
+            extents = cx.text_extents(key)
+            width = max(extents[2], width)
+            height += max(extents[3], bullet) + padding
+        width = padding + bullet + padding + width + padding
+
+        # Compute legend position
+        legend = self.options.legend
+        if legend.position.right is not None:
+            legend.position.left = (surface_width
+                                    - legend.position.right
+                                    - width)
+        if legend.position.bottom is not None:
+            legend.position.top = (surface_height
+                                   - legend.position.bottom
+                                   - height)
+
+        # Draw the legend
+        cx.save()
+        cx.rectangle(self.options.legend.position.left,
+                     self.options.legend.position.top,
+                     width, height)
+        cx.set_source_rgba(1, 1, 1, self.options.legend.opacity)
+        cx.fill_preserve()
+        cx.set_line_width(self.options.legend.borderWidth)
+        cx.set_source_rgb(*hex2rgb(self.options.legend.borderColor))
+        cx.stroke()
+
+        def drawKey(key, x, y, text_height):
+            cx.rectangle(x, y, bullet, bullet)
+            cx.set_source_rgb(*self.colorScheme[key])
+            cx.fill_preserve()
+            cx.set_source_rgb(0, 0, 0)
+            cx.stroke()
+            cx.move_to(x + bullet + padding,
+                       y + bullet / 2.0 + text_height / 2.0)
+            cx.show_text(key)
+
+        cx.set_line_width(1)
+        x = self.options.legend.position.left + padding
+        y = self.options.legend.position.top + padding
+        for key in keys:
+            extents = cx.text_extents(key)
+            drawKey(key, x, y, extents[3])
+            y += max(extents[3], bullet) + padding
+
+        cx.restore()
+
+
+def uniqueIndices(arr):
+    """Return a list with the indexes of the biggest element of arr"""
+    return range(max([len(a) for a in arr]))
+
+
+class Area(object):
+    """Simple rectangle to hold an area coordinates and dimensions"""
+
+    def __init__(self, x=0.0, y=0.0, w=0.0, h=0.0):
+        self.x, self.y, self.w, self.h = x, y, w, h
+
+    def __str__(self):
+        msg = "<pycha.chart.Area@(%.2f, %.2f) %.2f x %.2f>"
+        return  msg % (self.x, self.y, self.w, self.h)
+
+
+def get_text_extents(cx, text, font, font_size, encoding):
+    if text:
+        cx.save()
+        cx.select_font_face(font,
+                            cairo.FONT_SLANT_NORMAL, cairo.FONT_WEIGHT_BOLD)
+        cx.set_font_size(font_size)
+        safe_text = safe_unicode(text, encoding)
+        extents = cx.text_extents(safe_text)
+        cx.restore()
+        return extents[2:4]
+    return (0.0, 0.0)
+
+
+class Layout(object):
+    """Set of chart areas"""
+
+    def __init__(self):
+        self.title = Area()
+        self.x_label = Area()
+        self.y_label = Area()
+        self.x_tick_labels = Area()
+        self.y_tick_labels = Area()
+        self.x_ticks = Area()
+        self.y_ticks = Area()
+        self.chart = Area()
+
+        self._areas = (
+            (self.title, (1, 126 / 255.0, 0)),  # orange
+            (self.y_label, (41 / 255.0, 91 / 255.0, 41 / 255.0)),  # grey
+            (self.x_label, (41 / 255.0, 91 / 255.0, 41 / 255.0)),  # grey
+            (self.y_tick_labels, (0, 115 / 255.0, 0)),  # green
+            (self.x_tick_labels, (0, 115 / 255.0, 0)),  # green
+            (self.y_ticks, (229 / 255.0, 241 / 255.0, 18 / 255.0)),  # yellow
+            (self.x_ticks, (229 / 255.0, 241 / 255.0, 18 / 255.0)),  # yellow
+            (self.chart, (75 / 255.0, 75 / 255.0, 1.0)),  # blue
+            )
+
+    def update(self, cx, options, width, height, xticks, yticks):
+        self.title.x = options.padding.left
+        self.title.y = options.padding.top
+        self.title.w = width - (options.padding.left + options.padding.right)
+        self.title.h = get_text_extents(cx,
+                                        options.title,
+                                        options.titleFont,
+                                        options.titleFontSize,
+                                        options.encoding)[1]
+        x_axis_label_height = get_text_extents(cx,
+                                               options.axis.x.label,
+                                               options.axis.labelFont,
+                                               options.axis.labelFontSize,
+                                               options.encoding)[1]
+        y_axis_label_width = get_text_extents(cx,
+                                              options.axis.y.label,
+                                              options.axis.labelFont,
+                                              options.axis.labelFontSize,
+                                              options.encoding)[1]
+
+        x_axis_tick_labels_height = self._getAxisTickLabelsSize(cx, options,
+                                                                options.axis.x,
+                                                                xticks)[1]
+        y_axis_tick_labels_width = self._getAxisTickLabelsSize(cx, options,
+                                                               options.axis.y,
+                                                               yticks)[0]
+
+        self.y_label.x = options.padding.left
+        self.y_label.y = options.padding.top + self.title.h
+        self.y_label.w = y_axis_label_width
+        self.y_label.h = height - (options.padding.bottom
+                                   + options.padding.top
+                                   + x_axis_label_height
+                                   + x_axis_tick_labels_height
+                                   + options.axis.tickSize
+                                   + self.title.h)
+        self.x_label.x = (options.padding.left
+                          + y_axis_label_width
+                          + y_axis_tick_labels_width
+                          + options.axis.tickSize)
+        self.x_label.y = height - (options.padding.bottom
+                                   + x_axis_label_height)
+        self.x_label.w = width - (options.padding.left
+                                  + options.padding.right
+                                  + options.axis.tickSize
+                                  + y_axis_label_width
+                                  + y_axis_tick_labels_width)
+        self.x_label.h = x_axis_label_height
+
+        self.y_tick_labels.x = self.y_label.x + self.y_label.w
+        self.y_tick_labels.y = self.y_label.y
+        self.y_tick_labels.w = y_axis_tick_labels_width
+        self.y_tick_labels.h = self.y_label.h
+
+        self.x_tick_labels.x = self.x_label.x
+        self.x_tick_labels.y = self.x_label.y - x_axis_tick_labels_height
+        self.x_tick_labels.w = self.x_label.w
+        self.x_tick_labels.h = x_axis_tick_labels_height
+
+        self.y_ticks.x = self.y_tick_labels.x + self.y_tick_labels.w
+        self.y_ticks.y = self.y_tick_labels.y
+        self.y_ticks.w = options.axis.tickSize
+        self.y_ticks.h = self.y_label.h
+
+        self.x_ticks.x = self.x_tick_labels.x
+        self.x_ticks.y = self.x_tick_labels.y - options.axis.tickSize
+        self.x_ticks.w = self.x_label.w
+        self.x_ticks.h = options.axis.tickSize
+
+        self.chart.x = self.y_ticks.x + self.y_ticks.w
+        self.chart.y = self.title.y + self.title.h
+        self.chart.w = self.x_ticks.w
+        self.chart.h = self.y_ticks.h
+
+    def render(self, cx):
+
+        def draw_area(area, r, g, b):
+            cx.rectangle(area.x, area.y, area.w, area.h)
+            cx.set_source_rgba(r, g, b, 0.5)
+            cx.fill()
+
+        cx.save()
+        for area, color in self._areas:
+            draw_area(area, *color)
+        cx.restore()
+
+    def _getAxisTickLabelsSize(self, cx, options, axis, ticks):
+        cx.save()
+        cx.select_font_face(options.axis.tickFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(options.axis.tickFontSize)
+
+        max_width = max_height = 0.0
+        if not axis.hide:
+            extents = [cx.text_extents(safe_unicode(
+                        tick[1], options.encoding,
+                        ))[2:4]  # get width and height as a tuple
+                       for tick in ticks]
+            if extents:
+                widths, heights = zip(*extents)
+                max_width, max_height = max(widths), max(heights)
+                if axis.rotate:
+                    radians = math.radians(axis.rotate)
+                    sin = math.sin(radians)
+                    cos = math.cos(radians)
+                    max_width, max_height = (
+                        max_width * cos + max_height * sin,
+                        max_width * sin + max_height * cos,
+                        )
+        cx.restore()
+        return max_width, max_height
+
+
+class Option(dict):
+    """Useful dict that allow attribute-like access to its keys"""
+
+    def __getattr__(self, name):
+        if name in self.keys():
+            return self[name]
+        else:
+            raise AttributeError(name)
+
+    def merge(self, other):
+        """Recursive merge with other Option or dict object"""
+        for key, value in other.items():
+            if key in self:
+                if isinstance(self[key], Option):
+                    self[key].merge(other[key])
+                else:
+                    self[key] = other[key]
+
+
+DEFAULT_OPTIONS = Option(
+    axis=Option(
+        lineWidth=1.0,
+        lineColor='#0f0000',
+        tickSize=3.0,
+        labelColor='#666666',
+        labelFont='Tahoma',
+        labelFontSize=9,
+        tickFont='Tahoma',
+        tickFontSize=9,
+        x=Option(
+            hide=False,
+            ticks=None,
+            tickCount=10,
+            tickPrecision=1,
+            range=None,
+            rotate=None,
+            label=None,
+            interval=0,
+            showLines=False,
+        ),
+        y=Option(
+            hide=False,
+            ticks=None,
+            tickCount=10,
+            tickPrecision=1,
+            range=None,
+            rotate=None,
+            label=None,
+            interval=0,
+            showLines=True,
+        ),
+    ),
+    background=Option(
+        hide=False,
+        baseColor=None,
+        chartColor='#f5f5f5',
+        lineColor='#ffffff',
+        lineWidth=1.5,
+    ),
+    legend=Option(
+        opacity=0.8,
+        borderColor='#000000',
+        borderWidth=2,
+        hide=False,
+        legendFont='Tahoma',
+        legendFontSize=9,
+        position=Option(top=20, left=40, bottom=None, right=None),
+    ),
+    padding=Option(
+        left=10,
+        right=10,
+        top=10,
+        bottom=10,
+    ),
+    stroke=Option(
+        color='#ffffff',
+        hide=False,
+        shadow=True,
+        width=2
+    ),
+    yvals=Option(
+        show=False,
+        inside=False,
+        fontSize=11,
+        fontColor='#000000',
+        skipSmallValues=True,
+        snapToOrigin=False,
+        renderer=None
+    ),
+    fillOpacity=1.0,
+    shouldFill=True,
+    barWidthFillFraction=0.75,
+    pieRadius=0.4,
+    colorScheme=Option(
+        name='gradient',
+        args=Option(
+            initialColor=DEFAULT_COLOR,
+            colors=None,
+            ),
+    ),
+    title=None,
+    titleColor='#000000',
+    titleFont='Tahoma',
+    titleFontSize=12,
+    encoding='utf-8',
+)
diff --git a/sugarpycha/color.py b/sugarpycha/color.py
new file mode 100644
index 0000000..82b436f
--- /dev/null
+++ b/sugarpycha/color.py
@@ -0,0 +1,204 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#              2009 by Yaco S.L. <lgs@yaco.es>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+import math
+
+from pycha.utils import clamp
+
+
+DEFAULT_COLOR = '#3c581a'
+
+
+def hex2rgb(hexstring, digits=2):
+    """Converts a hexstring color to a rgb tuple.
+
+    Example: #ff0000 -> (1.0, 0.0, 0.0)
+
+    digits is an integer number telling how many characters should be
+    interpreted for each component in the hexstring.
+    """
+    if isinstance(hexstring, (tuple, list)):
+        return hexstring
+
+    top = float(int(digits * 'f', 16))
+    r = int(hexstring[1:digits + 1], 16)
+    g = int(hexstring[digits + 1:digits * 2 + 1], 16)
+    b = int(hexstring[digits * 2 + 1:digits * 3 + 1], 16)
+    return r / top, g / top, b / top
+
+
+def rgb2hsv(r, g, b):
+    """Converts a RGB color into a HSV one
+
+    See http://en.wikipedia.org/wiki/HSV_color_space
+    """
+    maximum = max(r, g, b)
+    minimum = min(r, g, b)
+    if maximum == minimum:
+        h = 0.0
+    elif maximum == r:
+        h = 60.0 * ((g - b) / (maximum - minimum)) + 360.0
+        if h >= 360.0:
+            h -= 360.0
+    elif maximum == g:
+        h = 60.0 * ((b - r) / (maximum - minimum)) + 120.0
+    elif maximum == b:
+        h = 60.0 * ((r - g) / (maximum - minimum)) + 240.0
+
+    if maximum == 0.0:
+        s = 0.0
+    else:
+        s = 1.0 - (minimum / maximum)
+
+    v = maximum
+
+    return h, s, v
+
+
+def hsv2rgb(h, s, v):
+    """Converts a HSV color into a RGB one
+
+    See http://en.wikipedia.org/wiki/HSV_color_space
+    """
+    hi = int(math.floor(h / 60.0)) % 6
+    f = (h / 60.0) - hi
+    p = v * (1 - s)
+    q = v * (1 - f * s)
+    t = v * (1 - (1 - f) * s)
+
+    if hi == 0:
+        r, g, b = v, t, p
+    elif hi == 1:
+        r, g, b = q, v, p
+    elif hi == 2:
+        r, g, b = p, v, t
+    elif hi == 3:
+        r, g, b = p, q, v
+    elif hi == 4:
+        r, g, b = t, p, v
+    elif hi == 5:
+        r, g, b = v, p, q
+
+    return r, g, b
+
+
+def lighten(r, g, b, amount):
+    """Return a lighter version of the color (r, g, b)"""
+    return (clamp(0.0, 1.0, r + amount),
+            clamp(0.0, 1.0, g + amount),
+            clamp(0.0, 1.0, b + amount))
+
+
+basicColors = dict(
+    red='#6d1d1d',
+    green=DEFAULT_COLOR,
+    blue='#224565',
+    grey='#444444',
+    black='#000000',
+    darkcyan='#305755',
+    )
+
+
+class ColorSchemeMetaclass(type):
+    """This metaclass is used to autoregister all ColorScheme classes"""
+
+    def __new__(mcs, name, bases, dict):
+        klass = type.__new__(mcs, name, bases, dict)
+        klass.registerColorScheme()
+        return klass
+
+
+class ColorScheme(dict):
+    """A color scheme is a dictionary where the keys match the keys
+    constructor argument and the values are colors"""
+
+    __metaclass__ = ColorSchemeMetaclass
+    __registry__ = {}
+
+    def __init__(self, keys):
+        super(ColorScheme, self).__init__()
+
+    @classmethod
+    def registerColorScheme(cls):
+        key = cls.__name__.replace('ColorScheme', '').lower()
+        if key:
+            cls.__registry__[key] = cls
+
+    @classmethod
+    def getColorScheme(cls, name, default=None):
+        return cls.__registry__.get(name, default)
+
+
+class GradientColorScheme(ColorScheme):
+    """In this color scheme each color is a lighter version of initialColor.
+
+    This difference is computed based on the number of keys.
+
+    The initialColor is given in a hex string format.
+    """
+
+    def __init__(self, keys, initialColor=DEFAULT_COLOR):
+        super(GradientColorScheme, self).__init__(keys)
+        if initialColor in basicColors:
+            initialColor = basicColors[initialColor]
+
+        r, g, b = hex2rgb(initialColor)
+        light = 1.0 / (len(keys) * 2)
+
+        for i, key in enumerate(keys):
+            self[key] = lighten(r, g, b, light * i)
+
+
+class FixedColorScheme(ColorScheme):
+    """In this color scheme fixed colors are used.
+
+    These colors are provided as a list argument in the constructor.
+    """
+
+    def __init__(self, keys, colors=[]):
+        super(FixedColorScheme, self).__init__(keys)
+
+        if len(keys) != len(colors):
+            raise ValueError("You must provide as many colors as datasets "
+                             "for the fixed color scheme")
+
+        for i, key in enumerate(keys):
+            self[key] = hex2rgb(colors[i])
+
+
+class RainbowColorScheme(ColorScheme):
+    """In this color scheme the rainbow is divided in N pieces
+    where N is the number of datasets.
+
+    So each dataset gets a color of the rainbow.
+    """
+
+    def __init__(self, keys, initialColor=DEFAULT_COLOR):
+        super(RainbowColorScheme, self).__init__(keys)
+        if initialColor in basicColors:
+            initialColor = basicColors[initialColor]
+
+        r, g, b = hex2rgb(initialColor)
+        h, s, v = rgb2hsv(r, g, b)
+
+        angleDelta = 360.0 / (len(keys) + 1)
+        for key in keys:
+            self[key] = hsv2rgb(h, s, v)
+            h += angleDelta
+            if h >= 360.0:
+                h -= 360.0
diff --git a/sugarpycha/line.py b/sugarpycha/line.py
new file mode 100644
index 0000000..9b12152
--- /dev/null
+++ b/sugarpycha/line.py
@@ -0,0 +1,129 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+from pycha.chart import Chart
+from pycha.color import hex2rgb
+
+
+class LineChart(Chart):
+
+    def __init__(self, surface=None, options={}, debug=False):
+        super(LineChart, self).__init__(surface, options, debug)
+        self.points = []
+
+    def _updateChart(self):
+        """Evaluates measures for line charts"""
+        self.points = []
+
+        for i, (name, store) in enumerate(self.datasets):
+            for item in store:
+                xval, yval = item
+                x = (xval - self.minxval) * self.xscale
+                y = 1.0 - (yval - self.minyval) * self.yscale
+                point = Point(x, y, xval, yval, name)
+
+                if 0.0 <= point.x <= 1.0 and 0.0 <= point.y <= 1.0:
+                    self.points.append(point)
+
+    def _renderChart(self, cx):
+        """Renders a line chart"""
+
+        def preparePath(storeName):
+            cx.new_path()
+            firstPoint = True
+            lastX = None
+            if self.options.shouldFill:
+                # Go to the (0,0) coordinate to start drawing the area
+                #cx.move_to(self.layout.chart.x,
+                #           self.layout.chart.y + self.layout.chart.h)
+                offset = (1.0 - self.origin) * self.layout.chart.h
+                cx.move_to(self.layout.chart.x, self.layout.chart.y + offset)
+
+            for point in self.points:
+                if point.name == storeName:
+                    if not self.options.shouldFill and firstPoint:
+                        # starts the first point of the line
+                        cx.move_to(point.x * self.layout.chart.w
+                                   + self.layout.chart.x,
+                                   point.y * self.layout.chart.h
+                                   + self.layout.chart.y)
+                        firstPoint = False
+                        continue
+                    cx.line_to(point.x * self.layout.chart.w
+                               + self.layout.chart.x,
+                               point.y * self.layout.chart.h
+                               + self.layout.chart.y)
+                    # we remember the last X coordinate to close the area
+                    # properly. See bug #4
+                    lastX = point.x
+
+            if self.options.shouldFill:
+                # Close the path to the start point
+                y = ((1.0 - self.origin) * self.layout.chart.h
+                     + self.layout.chart.y)
+                cx.line_to(lastX * self.layout.chart.w
+                           + self.layout.chart.x, y)
+                cx.line_to(self.layout.chart.x, y)
+                cx.close_path()
+            else:
+                cx.set_source_rgb(*self.colorScheme[storeName])
+                cx.stroke()
+
+        cx.save()
+        cx.set_line_width(self.options.stroke.width)
+        if self.options.shouldFill:
+
+            def drawLine(storeName):
+                if self.options.stroke.shadow:
+                    # draw shadow
+                    cx.save()
+                    cx.set_source_rgba(0, 0, 0, 0.15)
+                    cx.translate(2, -2)
+                    preparePath(storeName)
+                    cx.fill()
+                    cx.restore()
+
+                # fill the line
+                cx.set_source_rgb(*self.colorScheme[storeName])
+                preparePath(storeName)
+                cx.fill()
+
+                if not self.options.stroke.hide:
+                    # draw stroke
+                    cx.set_source_rgb(*hex2rgb(self.options.stroke.color))
+                    preparePath(storeName)
+                    cx.stroke()
+
+            # draw the lines
+            for key in self._getDatasetsKeys():
+                drawLine(key)
+        else:
+            for key in self._getDatasetsKeys():
+                preparePath(key)
+
+        cx.restore()
+
+
+class Point(object):
+
+    def __init__(self, x, y, xval, yval, name):
+        self.x, self.y = x, y
+        self.xval, self.yval = xval, yval
+        self.name = name
+
+    def __str__(self):
+        return "<pycha.line.Point@(%.2f, %.2f)>" % (self.x, self.y)
diff --git a/sugarpycha/pie.py b/sugarpycha/pie.py
new file mode 100644
index 0000000..d7b3df2
--- /dev/null
+++ b/sugarpycha/pie.py
@@ -0,0 +1,352 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+import math
+
+import cairo
+
+from pycha.chart import Chart, Option, Layout, Area, get_text_extents
+from pycha.color import hex2rgb
+
+
+class PieChart(Chart):
+
+    def __init__(self, surface=None, options={}, debug=False):
+        super(PieChart, self).__init__(surface, options, debug)
+        self.slices = []
+        self.centerx = 0
+        self.centery = 0
+        self.layout = PieLayout(self.slices)
+
+    def _updateChart(self):
+        """Evaluates measures for pie charts"""
+        slices = [dict(name=key,
+                       value=(i, value[0][1]))
+                  for i, (key, value) in enumerate(self.datasets)]
+
+        s = float(sum([slice['value'][1] for slice in slices]))
+
+        fraction = angle = 0.0
+
+        del self.slices[:]
+        for slice in slices:
+            if slice['value'][1] > 0:
+                angle += fraction
+                fraction = slice['value'][1] / s
+                self.slices.append(Slice(slice['name'], fraction,
+                                         slice['value'][0], slice['value'][1],
+                                         angle))
+
+    def _updateTicks(self):
+        """Evaluates pie ticks"""
+        self.xticks = []
+        if self.options.axis.x.ticks:
+            lookup = dict([(_slice.xval, _slice) for _slice in self.slices])
+            for tick in self.options.axis.x.ticks:
+                if not isinstance(tick, Option):
+                    tick = Option(tick)
+                _slice = lookup.get(tick.v, None)
+                label = tick.label or str(tick.v)
+                if _slice is not None:
+                    label += ' (%.1f%%)' % (_slice.fraction * 100)
+                    self.xticks.append((tick.v, label))
+        else:
+            for _slice in self.slices:
+                label = '%s (%.1f%%)' % (_slice.name, _slice.fraction * 100)
+                self.xticks.append((_slice.xval, label))
+
+    def _renderLines(self, cx):
+        """Aux function for _renderBackground"""
+        # there are no lines in a Pie Chart
+
+    def _renderChart(self, cx):
+        """Renders a pie chart"""
+        self.centerx = self.layout.chart.x + self.layout.chart.w * 0.5
+        self.centery = self.layout.chart.y + self.layout.chart.h * 0.5
+
+        cx.set_line_join(cairo.LINE_JOIN_ROUND)
+
+        if self.options.stroke.shadow and False:
+            cx.save()
+            cx.set_source_rgba(0, 0, 0, 0.15)
+
+            cx.new_path()
+            cx.move_to(self.centerx, self.centery)
+            cx.arc(self.centerx + 1, self.centery + 2,
+                   self.layout.radius + 1, 0, math.pi * 2)
+            cx.line_to(self.centerx, self.centery)
+            cx.close_path()
+            cx.fill()
+            cx.restore()
+
+        cx.save()
+        for slice in self.slices:
+            if slice.isBigEnough():
+                cx.set_source_rgb(*self.colorScheme[slice.name])
+                if self.options.shouldFill:
+                    slice.draw(cx, self.centerx, self.centery,
+                               self.layout.radius)
+                    cx.fill()
+
+                if not self.options.stroke.hide:
+                    slice.draw(cx, self.centerx, self.centery,
+                               self.layout.radius)
+                    cx.set_line_width(self.options.stroke.width)
+                    cx.set_source_rgb(*hex2rgb(self.options.stroke.color))
+                    cx.stroke()
+
+        cx.restore()
+
+        if self.debug:
+            cx.set_source_rgba(1, 0, 0, 0.5)
+            px = max(cx.device_to_user_distance(1, 1))
+            for x, y in self.layout._lines:
+                cx.arc(x, y, 5 * px, 0, 2 * math.pi)
+                cx.fill()
+                cx.new_path()
+                cx.move_to(self.centerx, self.centery)
+                cx.line_to(x, y)
+                cx.stroke()
+
+    def _renderAxis(self, cx):
+        """Renders the axis for pie charts"""
+        if self.options.axis.x.hide or not self.xticks:
+            return
+
+        self.xlabels = []
+
+        if self.debug:
+            px = max(cx.device_to_user_distance(1, 1))
+            cx.set_source_rgba(0, 0, 1, 0.5)
+            for x, y, w, h in self.layout.ticks:
+                cx.rectangle(x, y, w, h)
+                cx.stroke()
+                cx.arc(x + w / 2.0, y + h / 2.0, 5 * px, 0, 2 * math.pi)
+                cx.fill()
+                cx.arc(x, y, 2 * px, 0, 2 * math.pi)
+                cx.fill()
+
+        cx.select_font_face(self.options.axis.tickFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(self.options.axis.tickFontSize)
+
+        cx.set_source_rgb(*hex2rgb(self.options.axis.labelColor))
+
+        for i, tick in enumerate(self.xticks):
+            label = tick[1]
+            x, y, w, h = self.layout.ticks[i]
+
+            xb, yb, width, height, xa, ya = cx.text_extents(label)
+
+            # draw label with text tick[1]
+            cx.move_to(x - xb, y - yb)
+            cx.show_text(label)
+            self.xlabels.append(label)
+
+
+class Slice(object):
+
+    def __init__(self, name, fraction, xval, yval, angle):
+        self.name = name
+        self.fraction = fraction
+        self.xval = xval
+        self.yval = yval
+        self.startAngle = 2 * angle * math.pi
+        self.endAngle = 2 * (angle + fraction) * math.pi
+
+    def __str__(self):
+        return ("<pycha.pie.Slice from %.2f to %.2f (%.2f%%)>" %
+                (self.startAngle, self.endAngle, self.fraction))
+
+    def isBigEnough(self):
+        return abs(self.startAngle - self.endAngle) > 0.001
+
+    def draw(self, cx, centerx, centery, radius):
+        cx.new_path()
+        cx.move_to(centerx, centery)
+        cx.arc(centerx, centery, radius, -self.endAngle, -self.startAngle)
+        cx.close_path()
+
+    def getNormalisedAngle(self):
+        normalisedAngle = (self.startAngle + self.endAngle) / 2
+
+        if normalisedAngle > math.pi * 2:
+            normalisedAngle -= math.pi * 2
+        elif normalisedAngle < 0:
+            normalisedAngle += math.pi * 2
+
+        return normalisedAngle
+
+
+class PieLayout(Layout):
+    """Set of chart areas for pie charts"""
+
+    def __init__(self, slices):
+        self.slices = slices
+
+        self.title = Area()
+        self.chart = Area()
+
+        self.ticks = []
+        self.radius = 0
+
+        self._areas = (
+            (self.title, (1, 126 / 255.0, 0)),  # orange
+            (self.chart, (75 / 255.0, 75 / 255.0, 1.0)),  # blue
+            )
+
+        self._lines = []
+
+    def update(self, cx, options, width, height, xticks, yticks):
+        self.title.x = options.padding.left
+        self.title.y = options.padding.top
+        self.title.w = width - (options.padding.left + options.padding.right)
+        self.title.h = get_text_extents(cx,
+                                        options.title,
+                                        options.titleFont,
+                                        options.titleFontSize,
+                                        options.encoding)[1]
+
+        lookup = dict([(slice.xval, slice) for slice in self.slices])
+
+        self.chart.x = self.title.x
+        self.chart.y = self.title.y + self.title.h
+        self.chart.w = self.title.w
+        self.chart.h = height - self.title.h - (options.padding.top
+                                                + options.padding.bottom)
+
+        centerx = self.chart.x + self.chart.w * 0.5
+        centery = self.chart.y + self.chart.h * 0.5
+
+        self.radius = min(self.chart.w / 2.0, self.chart.h / 2.0)
+        for tick in xticks:
+            _slice = lookup.get(tick[0], None)
+            width, height = get_text_extents(cx, tick[1],
+                                             options.axis.tickFont,
+                                             options.axis.tickFontSize,
+                                             options.encoding)
+            angle = _slice.getNormalisedAngle()
+            radius = self._get_min_radius(angle, centerx, centery,
+                                          width, height)
+            self.radius = min(self.radius, radius)
+
+        # Now that we now the radius we move the ticks as close as we can
+        # to the circle
+        for i, tick in enumerate(xticks):
+            _slice = lookup.get(tick[0], None)
+            angle = _slice.getNormalisedAngle()
+            self.ticks[i] = self._get_tick_position(self.radius, angle,
+                                                    self.ticks[i],
+                                                    centerx, centery)
+
+    def _get_min_radius(self, angle, centerx, centery, width, height):
+        min_radius = None
+
+        # precompute some common values
+        tan = math.tan(angle)
+        half_width = width / 2.0
+        half_height = height / 2.0
+        offset_x = half_width * tan
+        offset_y = half_height / tan
+
+        def intersect_horizontal_line(y):
+            return centerx + (centery - y) / tan
+
+        def intersect_vertical_line(x):
+            return centery - tan * (x - centerx)
+
+        # computes the intersection between the rect that has
+        # that angle with the X axis and the bounding chart box
+        if 0.25 * math.pi <= angle < 0.75 * math.pi:
+            # intersects with the top rect
+            y = self.chart.y
+            x = intersect_horizontal_line(y)
+            self._lines.append((x, y))
+
+            x1 = x - half_width - offset_y
+            self.ticks.append((x1, self.chart.y, width, height))
+
+            min_radius = abs((y + height) - centery)
+        elif 0.75 * math.pi <= angle < 1.25 * math.pi:
+            # intersects with the left rect
+            x = self.chart.x
+            y = intersect_vertical_line(x)
+            self._lines.append((x, y))
+
+            y1 = y - half_height - offset_x
+            self.ticks.append((x, y1, width, height))
+
+            min_radius = abs(centerx - (x + width))
+        elif 1.25 * math.pi <= angle < 1.75 * math.pi:
+            # intersects with the bottom rect
+            y = self.chart.y + self.chart.h
+            x = intersect_horizontal_line(y)
+            self._lines.append((x, y))
+
+            x1 = x - half_width + offset_y
+            self.ticks.append((x1, y - height, width, height))
+
+            min_radius = abs((y - height) - centery)
+        else:
+            # intersects with the right rect
+            x = self.chart.x + self.chart.w
+            y = intersect_vertical_line(x)
+            self._lines.append((x, y))
+
+            y1 = y - half_height + offset_x
+            self.ticks.append((x - width, y1, width, height))
+
+            min_radius = abs((x - width) - centerx)
+
+        return min_radius
+
+    def _get_tick_position(self, radius, angle, tick, centerx, centery):
+        text_width, text_height = tick[2:4]
+        half_width = text_width / 2.0
+        half_height = text_height / 2.0
+
+        if 0 <= angle < 0.5 * math.pi:
+            # first quadrant
+            k1 = j1 = k2 = 1
+            j2 = -1
+        elif 0.5 * math.pi <= angle < math.pi:
+            # second quadrant
+            k1 = k2 = -1
+            j1 = j2 = 1
+        elif math.pi <= angle < 1.5 * math.pi:
+            # third quadrant
+            k1 = j1 = k2 = -1
+            j2 = 1
+        elif 1.5 * math.pi <= angle < 2 * math.pi:
+            # fourth quadrant
+            k1 = k2 = 1
+            j1 = j2 = -1
+
+        cx = radius * math.cos(angle) + k1 * half_width
+        cy = radius * math.sin(angle) + j1 * half_height
+
+        radius2 = math.sqrt(cx * cx + cy * cy)
+
+        tan = math.tan(angle)
+        x = math.sqrt((radius2 * radius2) / (1 + tan * tan))
+        y = tan * x
+
+        x = centerx + k2 * x
+        y = centery + j2 * y
+
+        return x - half_width, y - half_height, text_width, text_height
diff --git a/sugarpycha/polygonal.py b/sugarpycha/polygonal.py
new file mode 100644
index 0000000..b470c87
--- /dev/null
+++ b/sugarpycha/polygonal.py
@@ -0,0 +1,372 @@
+# Copyright(c) 2011 by Roberto Garcia Carvajal <roberpot@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+import math
+
+import cairo
+
+from pycha.chart import Chart
+from pycha.line import Point
+from pycha.color import hex2rgb
+from pycha.utils import safe_unicode
+
+
+class PolygonalChart(Chart):
+
+    def __init__(self, surface=None, options={}):
+        super(PolygonalChart, self).__init__(surface, options)
+        self.points = []
+
+    def _updateChart(self):
+        """Evaluates measures for polygonal charts"""
+        self.points = []
+
+        for i, (name, store) in enumerate(self.datasets):
+            for item in store:
+                xval, yval = item
+                x = (xval - self.minxval) * self.xscale
+                y = 1.0 - (yval - self.minyval) * self.yscale
+                point = Point(x, y, xval, yval, name)
+
+                if 0.0 <= point.x <= 1.0 and 0.0 <= point.y <= 1.0:
+                    self.points.append(point)
+
+    def _renderBackground(self, cx):
+        """Renders the background area of the chart"""
+        if self.options.background.hide:
+            return
+
+        cx.save()
+
+        if self.options.background.baseColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.baseColor))
+            cx.paint()
+
+        if self.options.background.chartColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.chartColor))
+            cx.set_line_width(10.0)
+            cx.new_path()
+            init = None
+            count = len(self.xticks)
+            for index, tick in enumerate(self.xticks):
+                ang = math.pi / 2 - index * 2 * math.pi / count
+                x = (self.layout.chart.x + self.layout.chart.w / 2
+                     - math.cos(ang)
+                     * min(self.layout.chart.w / 2, self.layout.chart.h / 2))
+                y = (self.layout.chart.y + self.layout.chart.h / 2
+                     - math.sin(ang)
+                     * min(self.layout.chart.w / 2, self.layout.chart.h / 2))
+                if init is None:
+                    cx.move_to(x, y)
+                    init = (x, y)
+                else:
+                    cx.line_to(x, y)
+            cx.line_to(init[0], init[1])
+            cx.close_path()
+            cx.fill()
+
+        if self.options.background.lineColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.lineColor))
+            cx.set_line_width(self.options.axis.lineWidth)
+            self._renderLines(cx)
+
+        cx.restore()
+
+    def _renderLine(self, cx, tick, horiz):
+        """Aux function for _renderLines"""
+
+        rad = (self.layout.chart.h / 2) * (1 - tick[0])
+        cx.new_path()
+        init = None
+        count = len(self.xticks)
+        for index, tick in enumerate(self.xticks):
+            ang = math.pi / 2 - index * 2 * math.pi / count
+            x = (self.layout.chart.x + self.layout.chart.w / 2
+                 - math.cos(ang) * rad)
+            y = (self.layout.chart.y + self.layout.chart.h / 2
+                 - math.sin(ang) * rad)
+            if init is None:
+                cx.move_to(x, y)
+                init = (x, y)
+            else:
+                cx.line_to(x, y)
+        cx.line_to(init[0], init[1])
+        cx.close_path()
+        cx.stroke()
+
+    def _renderXAxis(self, cx):
+        """Draws the horizontal line representing the X axis"""
+
+        count = len(self.xticks)
+
+        centerx = self.layout.chart.x + self.layout.chart.w / 2
+        centery = self.layout.chart.y + self.layout.chart.h / 2
+
+        for i in range(0, count):
+            offset1 = i * 2 * math.pi / count
+            offset = math.pi / 2 - offset1
+
+            rad = self.layout.chart.h / 2
+            (r1, r2) = (0, rad + 5)
+
+            x1 = centerx - math.cos(offset) * r1
+            x2 = centerx - math.cos(offset) * r2
+            y1 = centery - math.sin(offset) * r1
+            y2 = centery - math.sin(offset) * r2
+
+            cx.new_path()
+            cx.move_to(x1, y1)
+            cx.line_to(x2, y2)
+            cx.close_path()
+            cx.stroke()
+
+    def _renderYTick(self, cx, tick, center):
+        """Aux method for _renderAxis"""
+
+        i = tick
+        tick = self.yticks[i]
+
+        count = len(self.yticks)
+
+        if callable(tick):
+            return
+
+        x = center[0]
+        y = center[1] - i * (self.layout.chart.h / 2) / count
+
+        cx.new_path()
+        cx.move_to(x, y)
+        cx.line_to(x - self.options.axis.tickSize, y)
+        cx.close_path()
+        cx.stroke()
+
+        cx.select_font_face(self.options.axis.tickFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(self.options.axis.tickFontSize)
+
+        label = safe_unicode(tick[1], self.options.encoding)
+        extents = cx.text_extents(label)
+        labelWidth = extents[2]
+        labelHeight = extents[3]
+
+        if self.options.axis.y.rotate:
+            radians = math.radians(self.options.axis.y.rotate)
+            cx.move_to(x - self.options.axis.tickSize
+                       - (labelWidth * math.cos(radians))
+                       - 4,
+                       y + (labelWidth * math.sin(radians))
+                       + labelHeight / (2.0 / math.cos(radians)))
+            cx.rotate(-radians)
+            cx.show_text(label)
+            cx.rotate(radians)  # this is probably faster than a save/restore
+        else:
+            cx.move_to(x - self.options.axis.tickSize - labelWidth - 4,
+                       y + labelHeight / 2.0)
+            cx.rel_move_to(0.0, -labelHeight / 2.0)
+            cx.show_text(label)
+
+        return label
+
+    def _renderYAxis(self, cx):
+        """Draws the vertical line for the Y axis"""
+
+        centerx = self.layout.chart.x + self.layout.chart.w / 2
+        centery = self.layout.chart.y + self.layout.chart.h / 2
+
+        offset = math.pi / 2
+
+        r1 = self.layout.chart.h / 2
+
+        x1 = centerx - math.cos(offset) * r1
+        y1 = centery - math.sin(offset) * r1
+
+        cx.new_path()
+        cx.move_to(centerx, centery)
+        cx.line_to(x1, y1)
+        cx.close_path()
+        cx.stroke()
+
+    def _renderAxis(self, cx):
+        """Renders axis"""
+        if self.options.axis.x.hide and self.options.axis.y.hide:
+            return
+
+        cx.save()
+        cx.set_source_rgb(*hex2rgb(self.options.axis.lineColor))
+        cx.set_line_width(self.options.axis.lineWidth)
+
+        centerx = self.layout.chart.x + self.layout.chart.w / 2
+        centery = self.layout.chart.y + self.layout.chart.h / 2
+
+        if not self.options.axis.y.hide:
+            if self.yticks:
+
+                count = len(self.yticks)
+
+                for i in range(0, count):
+                    self._renderYTick(cx, i, (centerx, centery))
+
+            if self.options.axis.y.label:
+                self._renderYAxisLabel(cx, self.options.axis.y.label)
+
+            self._renderYAxis(cx)
+
+        if not self.options.axis.x.hide:
+            fontAscent = cx.font_extents()[0]
+            if self.xticks:
+
+                count = len(self.xticks)
+
+                for i in range(0, count):
+                    self._renderXTick(cx, i, fontAscent, (centerx, centery))
+
+            if self.options.axis.x.label:
+                self._renderXAxisLabel(cx, self.options.axis.x.label)
+
+            self._renderXAxis(cx)
+
+        cx.restore()
+
+    def _renderXTick(self, cx, i, fontAscent, center):
+        tick = self.xticks[i]
+        if callable(tick):
+            return
+
+        count = len(self.xticks)
+        cx.select_font_face(self.options.axis.tickFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(self.options.axis.tickFontSize)
+
+        label = safe_unicode(tick[1], self.options.encoding)
+        extents = cx.text_extents(label)
+        labelWidth = extents[2]
+        labelHeight = extents[3]
+
+        x, y = center
+        cx.move_to(x, y)
+
+        if self.options.axis.x.rotate:
+            radians = math.radians(self.options.axis.x.rotate)
+            cx.move_to(x - (labelHeight * math.cos(radians)),
+                       y + self.options.axis.tickSize
+                       + (labelHeight * math.cos(radians))
+                       + 4.0)
+            cx.rotate(radians)
+            cx.show_text(label)
+            cx.rotate(-radians)
+        else:
+            offset1 = i * 2 * math.pi / count
+            offset = math.pi / 2 - offset1
+
+            rad = self.layout.chart.h / 2 + 10
+
+            x = center[0] - math.cos(offset) * rad
+            y = center[1] - math.sin(offset) * rad
+
+            cx.move_to(x, y)
+            cx.rotate(offset - math.pi / 2)
+
+            if math.sin(offset) < 0.0:
+                cx.rotate(math.pi)
+                cx.rel_move_to(0.0, 5.0)
+
+            cx.rel_move_to(-labelWidth / 2.0, 0)
+            cx.show_text(label)
+            if math.sin(offset) < 0.0:
+                cx.rotate(-math.pi)
+
+            cx.rotate(-(offset - math.pi / 2))
+        return label
+
+    def _renderChart(self, cx):
+        """Renders a polygonal chart"""
+        # draw the polygon.
+        def preparePath(storeName):
+            cx.new_path()
+            firstPoint = True
+
+            count = len(self.points) / len(self.datasets)
+            centerx = self.layout.chart.x + self.layout.chart.w / 2
+            centery = self.layout.chart.y + self.layout.chart.h / 2
+
+            firstPointCoord = None
+
+            for index, point in enumerate(self.points):
+                if point.name == storeName:
+                    offset1 = index * 2 * math.pi / count
+                    offset = math.pi / 2 - offset1
+
+                    rad = (self.layout.chart.h / 2) * (1 - point.y)
+
+                    x = centerx - math.cos(offset) * rad
+                    y = centery - math.sin(offset) * rad
+
+                    if firstPointCoord is None:
+                        firstPointCoord = (x, y)
+
+                    if not self.options.shouldFill and firstPoint:
+                        # starts the first point of the line
+                        cx.move_to(x, y)
+                        firstPoint = False
+                        continue
+                    cx.line_to(x, y)
+
+            if not firstPointCoord is None:
+                cx.line_to(firstPointCoord[0], firstPointCoord[1])
+
+            if self.options.shouldFill:
+                # Close the path to the start point
+                y = ((1.0 - self.origin)
+                     * self.layout.chart.h + self.layout.chart.y)
+            else:
+                cx.set_source_rgb(*self.colorScheme[storeName])
+                cx.stroke()
+
+        cx.save()
+        cx.set_line_width(self.options.stroke.width)
+        if self.options.shouldFill:
+
+            def drawLine(storeName):
+                if self.options.stroke.shadow:
+                    # draw shadow
+                    cx.save()
+                    cx.set_source_rgba(0, 0, 0, 0.15)
+                    cx.translate(2, -2)
+                    preparePath(storeName)
+                    cx.fill()
+                    cx.restore()
+
+                # fill the line
+                cx.set_source_rgb(*self.colorScheme[storeName])
+                preparePath(storeName)
+                cx.fill()
+
+                if not self.options.stroke.hide:
+                    # draw stroke
+                    cx.set_source_rgb(*hex2rgb(self.options.stroke.color))
+                    preparePath(storeName)
+                    cx.stroke()
+
+            # draw the lines
+            for key in self._getDatasetsKeys():
+                drawLine(key)
+        else:
+            for key in self._getDatasetsKeys():
+                preparePath(key)
+        cx.restore()
diff --git a/sugarpycha/radial.py b/sugarpycha/radial.py
new file mode 100644
index 0000000..9055e26
--- /dev/null
+++ b/sugarpycha/radial.py
@@ -0,0 +1,346 @@
+# Copyright(c) 2011 by Roberto Garcia Carvajal <roberpot@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+import math
+
+import cairo
+
+from pycha.chart import Chart
+from pycha.line import Point
+from pycha.color import hex2rgb
+from pycha.utils import safe_unicode
+
+
+class RadialChart(Chart):
+
+    def __init__(self, surface=None, options={}):
+        super(RadialChart, self).__init__(surface, options)
+        self.points = []
+
+    def _updateChart(self):
+        """Evaluates measures for radial charts"""
+        self.points = []
+
+        for i, (name, store) in enumerate(self.datasets):
+            for item in store:
+                xval, yval = item
+                x = (xval - self.minxval) * self.xscale
+                y = 1.0 - (yval - self.minyval) * self.yscale
+                point = Point(x, y, xval, yval, name)
+
+                if 0.0 <= point.x <= 1.0 and 0.0 <= point.y <= 1.0:
+                    self.points.append(point)
+
+    def _renderBackground(self, cx):
+        """Renders the background area of the chart"""
+        if self.options.background.hide:
+            return
+
+        cx.save()
+
+        if self.options.background.baseColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.baseColor))
+            cx.paint()
+
+        if self.options.background.chartColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.chartColor))
+            cx.set_line_width(10.0)
+            cx.arc(self.layout.chart.x + self.layout.chart.w / 2,
+                   self.layout.chart.y + self.layout.chart.h / 2,
+                   min(self.layout.chart.w / 2, self.layout.chart.h / 2),
+                   0, 2 * math.pi)
+            cx.fill()
+
+        if self.options.background.lineColor:
+            cx.set_source_rgb(*hex2rgb(self.options.background.lineColor))
+            cx.set_line_width(self.options.axis.lineWidth)
+            self._renderLines(cx)
+
+        cx.restore()
+
+    def _renderLine(self, cx, tick, horiz):
+        """Aux function for _renderLines"""
+
+        rad = (self.layout.chart.h / 2) * (1 - tick[0])
+        cx.arc(self.layout.chart.x + self.layout.chart.w / 2,
+               self.layout.chart.y + self.layout.chart.h / 2,
+               rad, 0, 2 * math.pi)
+        cx.stroke()
+
+    def _renderXAxis(self, cx):
+        """Draws the horizontal line representing the X axis"""
+
+        count = len(self.xticks)
+
+        centerx = self.layout.chart.x + self.layout.chart.w / 2
+        centery = self.layout.chart.y + self.layout.chart.h / 2
+
+        for i in range(0, count):
+            offset1 = i * 2 * math.pi / count
+            offset = math.pi / 2 - offset1
+
+            rad = self.layout.chart.h / 2
+            (r1, r2) = (0, rad + 5)
+
+            x1 = centerx - math.cos(offset) * r1
+            x2 = centerx - math.cos(offset) * r2
+            y1 = centery - math.sin(offset) * r1
+            y2 = centery - math.sin(offset) * r2
+
+            cx.new_path()
+            cx.move_to(x1, y1)
+            cx.line_to(x2, y2)
+            cx.close_path()
+            cx.stroke()
+
+    def _renderYTick(self, cx, tick, center):
+        """Aux method for _renderAxis"""
+
+        i = tick
+        tick = self.yticks[i]
+
+        count = len(self.yticks)
+
+        if callable(tick):
+            return
+
+        x = center[0]
+        y = center[1] - i * (self.layout.chart.h / 2) / count
+
+        cx.new_path()
+        cx.move_to(x, y)
+        cx.line_to(x - self.options.axis.tickSize, y)
+        cx.close_path()
+        cx.stroke()
+
+        cx.select_font_face(self.options.axis.tickFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(self.options.axis.tickFontSize)
+
+        label = safe_unicode(tick[1], self.options.encoding)
+        extents = cx.text_extents(label)
+        labelWidth = extents[2]
+        labelHeight = extents[3]
+
+        if self.options.axis.y.rotate:
+            radians = math.radians(self.options.axis.y.rotate)
+            cx.move_to(x - self.options.axis.tickSize
+                       - (labelWidth * math.cos(radians))
+                       - 4,
+                       y + (labelWidth * math.sin(radians))
+                       + labelHeight / (2.0 / math.cos(radians)))
+            cx.rotate(-radians)
+            cx.show_text(label)
+            cx.rotate(radians)  # this is probably faster than a save/restore
+        else:
+            cx.move_to(x - self.options.axis.tickSize - labelWidth - 4,
+                       y + labelHeight / 2.0)
+            cx.rel_move_to(0.0, -labelHeight / 2.0)
+            cx.show_text(label)
+
+        return label
+
+    def _renderYAxis(self, cx):
+        """Draws the vertical line for the Y axis"""
+
+        centerx = self.layout.chart.x + self.layout.chart.w / 2
+        centery = self.layout.chart.y + self.layout.chart.h / 2
+
+        offset = math.pi / 2
+
+        r1 = self.layout.chart.h / 2
+
+        x1 = centerx - math.cos(offset) * r1
+        y1 = centery - math.sin(offset) * r1
+
+        cx.new_path()
+        cx.move_to(centerx, centery)
+        cx.line_to(x1, y1)
+        cx.close_path()
+        cx.stroke()
+
+    def _renderAxis(self, cx):
+        """Renders axis"""
+        if self.options.axis.x.hide and self.options.axis.y.hide:
+            return
+
+        cx.save()
+        cx.set_source_rgb(*hex2rgb(self.options.axis.lineColor))
+        cx.set_line_width(self.options.axis.lineWidth)
+
+        centerx = self.layout.chart.x + self.layout.chart.w / 2
+        centery = self.layout.chart.y + self.layout.chart.h / 2
+
+        if not self.options.axis.y.hide:
+            if self.yticks:
+
+                count = len(self.yticks)
+
+                for i in range(0, count):
+                    self._renderYTick(cx, i, (centerx, centery))
+
+            if self.options.axis.y.label:
+                self._renderYAxisLabel(cx, self.options.axis.y.label)
+
+            self._renderYAxis(cx)
+
+        if not self.options.axis.x.hide:
+            fontAscent = cx.font_extents()[0]
+            if self.xticks:
+
+                count = len(self.xticks)
+
+                for i in range(0, count):
+                    self._renderXTick(cx, i, fontAscent, (centerx, centery))
+
+            if self.options.axis.x.label:
+                self._renderXAxisLabel(cx, self.options.axis.x.label)
+
+            self._renderXAxis(cx)
+
+        cx.restore()
+
+    def _renderXTick(self, cx, i, fontAscent, center):
+        tick = self.xticks[i]
+        if callable(tick):
+            return
+
+        count = len(self.xticks)
+        cx.select_font_face(self.options.axis.tickFont,
+                            cairo.FONT_SLANT_NORMAL,
+                            cairo.FONT_WEIGHT_NORMAL)
+        cx.set_font_size(self.options.axis.tickFontSize)
+
+        label = safe_unicode(tick[1], self.options.encoding)
+        extents = cx.text_extents(label)
+        labelWidth = extents[2]
+        labelHeight = extents[3]
+
+        x, y = center
+        cx.move_to(x, y)
+
+        if self.options.axis.x.rotate:
+            radians = math.radians(self.options.axis.x.rotate)
+            cx.move_to(x - (labelHeight * math.cos(radians)),
+                       y + self.options.axis.tickSize
+                       + (labelHeight * math.cos(radians))
+                       + 4.0)
+            cx.rotate(radians)
+            cx.show_text(label)
+            cx.rotate(-radians)
+        else:
+            offset1 = i * 2 * math.pi / count
+            offset = math.pi / 2 - offset1
+
+            rad = self.layout.chart.h / 2 + 10
+
+            x = center[0] - math.cos(offset) * rad
+            y = center[1] - math.sin(offset) * rad
+
+            cx.move_to(x, y)
+            cx.rotate(offset - math.pi / 2)
+
+            if math.sin(offset) < 0.0:
+                cx.rotate(math.pi)
+                cx.rel_move_to(0.0, 5.0)
+
+            cx.rel_move_to(-labelWidth / 2.0, 0)
+            cx.show_text(label)
+            if math.sin(offset) < 0.0:
+                cx.rotate(-math.pi)
+
+            cx.rotate(-(offset - math.pi / 2))
+        return label
+
+    def _renderChart(self, cx):
+        """Renders a line chart"""
+
+        # draw the circle
+        def preparePath(storeName):
+            cx.new_path()
+            firstPoint = True
+
+            count = len(self.points) / len(self.datasets)
+            centerx = self.layout.chart.x + self.layout.chart.w / 2
+            centery = self.layout.chart.y + self.layout.chart.h / 2
+
+            firstPointCoord = None
+
+            for index, point in enumerate(self.points):
+                if point.name == storeName:
+                    offset1 = index * 2 * math.pi / count
+                    offset = math.pi / 2 - offset1
+
+                    rad = (self.layout.chart.h / 2) * (1 - point.y)
+
+                    x = centerx - math.cos(offset) * rad
+                    y = centery - math.sin(offset) * rad
+
+                    if firstPointCoord is None:
+                        firstPointCoord = (x, y)
+
+                    if not self.options.shouldFill and firstPoint:
+                        # starts the first point of the line
+                        cx.move_to(x, y)
+                        firstPoint = False
+                        continue
+                    cx.line_to(x, y)
+
+            if not firstPointCoord is None:
+                cx.line_to(firstPointCoord[0], firstPointCoord[1])
+
+            if self.options.shouldFill:
+                # Close the path to the start point
+                y = ((1.0 - self.origin)
+                     * self.layout.chart.h + self.layout.chart.y)
+            else:
+                cx.set_source_rgb(*self.colorScheme[storeName])
+                cx.stroke()
+
+        cx.save()
+        cx.set_line_width(self.options.stroke.width)
+        if self.options.shouldFill:
+
+            def drawLine(storeName):
+                if self.options.stroke.shadow:
+                    # draw shadow
+                    cx.save()
+                    cx.set_source_rgba(0, 0, 0, 0.15)
+                    cx.translate(2, -2)
+                    preparePath(storeName)
+                    cx.fill()
+                    cx.restore()
+
+                # fill the line
+                cx.set_source_rgb(*self.colorScheme[storeName])
+                preparePath(storeName)
+                cx.fill()
+
+                if not self.options.stroke.hide:
+                    # draw stroke
+                    cx.set_source_rgb(*hex2rgb(self.options.stroke.color))
+                    preparePath(storeName)
+                    cx.stroke()
+
+            # draw the lines
+            for key in self._getDatasetsKeys():
+                drawLine(key)
+        else:
+            for key in self._getDatasetsKeys():
+                preparePath(key)
+        cx.restore()
diff --git a/sugarpycha/scatter.py b/sugarpycha/scatter.py
new file mode 100644
index 0000000..27656de
--- /dev/null
+++ b/sugarpycha/scatter.py
@@ -0,0 +1,38 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+import math
+
+from pycha.line import LineChart
+
+
+class ScatterplotChart(LineChart):
+
+    def _renderChart(self, cx):
+        """Renders a scatterplot"""
+
+        def drawSymbol(point, size):
+            ox = point.x * self.layout.chart.w + self.layout.chart.x
+            oy = point.y * self.layout.chart.h + self.layout.chart.y
+            cx.arc(ox, oy, size, 0.0, 2 * math.pi)
+            cx.fill()
+
+        for key in self._getDatasetsKeys():
+            cx.set_source_rgb(*self.colorScheme[key])
+            for point in self.points:
+                if point.name == key:
+                    drawSymbol(point, self.options.stroke.width)
diff --git a/sugarpycha/stackedbar.py b/sugarpycha/stackedbar.py
new file mode 100644
index 0000000..a728e50
--- /dev/null
+++ b/sugarpycha/stackedbar.py
@@ -0,0 +1,121 @@
+# Copyright(c) 2009 by Yaco S.L. <lgs@yaco.es>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+from pycha.bar import BarChart, VerticalBarChart, HorizontalBarChart, Rect
+from pycha.chart import uniqueIndices
+
+
+class StackedBarChart(BarChart):
+
+    def __init__(self, surface=None, options={}, debug=False):
+        super(StackedBarChart, self).__init__(surface, options, debug)
+        self.barWidth = 0.0
+
+    def _updateXY(self):
+        super(StackedBarChart, self)._updateXY()
+        # each dataset is centered around a line segment. that's why we
+        # need n + 1 divisions on the x axis
+        self.xscale = 1 / (self.xrange + 1.0)
+
+        if self.options.axis.y.range is None:
+            # Fix the yscale as we accumulate the y values
+            stores = self._getDatasetsValues()
+            n_stores = len(stores)
+            flat_y = [pair[1] for pair in reduce(lambda a, b: a + b, stores)]
+            store_size = len(flat_y) / n_stores
+            accum = [sum(flat_y[j]for j in xrange(i,
+                                                  i + store_size * n_stores,
+                                                  store_size))
+                     for i in range(len(flat_y) / n_stores)]
+            self.yrange = float(max(accum))
+            if self.yrange == 0:
+                self.yscale = 1.0
+            else:
+                self.yscale = 1.0 / self.yrange
+
+    def _updateChart(self):
+        """Evaluates measures for vertical bars"""
+        stores = self._getDatasetsValues()
+        uniqx = uniqueIndices(stores)
+
+        if len(uniqx) == 1:
+            self.minxdelta = 1.0
+        else:
+            self.minxdelta = min([abs(uniqx[j] - uniqx[j - 1])
+                                  for j in range(1, len(uniqx))])
+
+        k = self.minxdelta * self.xscale
+        self.barWidth = k * self.options.barWidthFillFraction
+        self.barMargin = k * (1.0 - self.options.barWidthFillFraction) / 2
+
+        self.bars = []
+
+
+class StackedVerticalBarChart(StackedBarChart, VerticalBarChart):
+
+    def _updateChart(self):
+        """Evaluates measures for vertical bars"""
+        super(StackedVerticalBarChart, self)._updateChart()
+
+        accumulated_heights = {}
+        for i, (name, store) in enumerate(self.datasets):
+            for item in store:
+                xval, yval = item
+                x = ((xval - self.minxval) * self.xscale) + self.barMargin
+                w = self.barWidth
+                h = abs(yval) * self.yscale
+                if yval > 0:
+                    y = (1.0 - h) - self.origin
+                else:
+                    y = 1 - self.origin
+
+                accumulated_height = accumulated_heights.setdefault(xval, 0)
+                y -= accumulated_height
+                accumulated_heights[xval] += h
+
+                rect = Rect(x, y, w, h, xval, yval, name)
+
+                if (0.0 <= rect.x <= 1.0) and (0.0 <= rect.y <= 1.0):
+                    self.bars.append(rect)
+
+
+class StackedHorizontalBarChart(StackedBarChart, HorizontalBarChart):
+
+    def _updateChart(self):
+        """Evaluates measures for horizontal bars"""
+        super(StackedHorizontalBarChart, self)._updateChart()
+
+        accumulated_widths = {}
+        for i, (name, store) in enumerate(self.datasets):
+            for item in store:
+                xval, yval = item
+                y = ((xval - self.minxval) * self.xscale) + self.barMargin
+                h = self.barWidth
+                w = abs(yval) * self.yscale
+                if yval > 0:
+                    x = self.origin
+                else:
+                    x = self.origin - w
+
+                accumulated_width = accumulated_widths.setdefault(xval, 0)
+                x += accumulated_width
+                accumulated_widths[xval] += w
+
+                rect = Rect(x, y, w, h, xval, yval, name)
+
+                if (0.0 <= rect.x <= 1.0) and (0.0 <= rect.y <= 1.0):
+                    self.bars.append(rect)
diff --git a/sugarpycha/utils.py b/sugarpycha/utils.py
new file mode 100644
index 0000000..9e1b692
--- /dev/null
+++ b/sugarpycha/utils.py
@@ -0,0 +1,40 @@
+# Copyright(c) 2007-2010 by Lorenzo Gil Sanchez <lorenzo.gil.sanchez@gmail.com>
+#              2009-2010 by Yaco S.L. <lgs@yaco.es>
+#
+# This file is part of PyCha.
+#
+# PyCha is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# PyCha is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PyCha.  If not, see <http://www.gnu.org/licenses/>.
+
+
+def clamp(minValue, maxValue, value):
+    """Make sure value is between minValue and maxValue"""
+    if value < minValue:
+        return minValue
+    if value > maxValue:
+        return maxValue
+    return value
+
+
+def safe_unicode(obj, encoding=None):
+    """Return a unicode value from the argument"""
+    if isinstance(obj, unicode):
+        return obj
+    elif isinstance(obj, str):
+        if encoding is None:
+            return unicode(obj)
+        else:
+            return unicode(obj, encoding)
+    else:
+        # it may be an int or a float
+        return unicode(obj)