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# 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
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