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#!/usr/bin/env python
#
# chart_object.py
#
# Copyright 2009 Sven Festersen <sven@sven-festersen.de>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301, USA.
"""
This module contains the ChartObject class.
Author: Sven Festersen (sven@sven-festersen.de)
"""
import cairo
import gobject
class ChartObject(gobject.GObject):
"""
This is the base class for all things that can be drawn on a chart
widget.
It emits the signal 'appearance-changed' when it needs to be
redrawn.
Properties
==========
ChartObject inherits properties from gobject.GObject.
Additional properties:
- visible (sets whether the object should be visible,
type: boolean)
- antialias (sets whether the object should be antialiased,
type: boolean).
Signals
=======
ChartObject inherits signals from gobject.GObject,
Additional signals:
- appearance-changed (emitted if the object needs to be redrawn).
"""
__gsignals__ = {"appearance-changed": (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE, [])}
__gproperties__ = {"visible": (gobject.TYPE_BOOLEAN,
"visibilty of the object",
"Set whether to draw the object or not.",
True, gobject.PARAM_READWRITE),
"antialias": (gobject.TYPE_BOOLEAN,
"use antialiasing",
"Set whether to use antialiasing when drawing the object.",
True, gobject.PARAM_READWRITE)}
def __init__(self):
gobject.GObject.__init__(self)
self._show = True
self._antialias = True
def do_get_property(self, property):
if property.name == "visible":
return self._show
elif property.name == "antialias":
return self._antialias
else:
raise AttributeError, "Property %s does not exist." % property.name
def do_set_property(self, property, value):
if property.name == "visible":
self._show = value
elif property.name == "antialias":
self._antialias = value
else:
raise AttributeError, "Property %s does not exist." % property.name
def _do_draw(self, context, rect):
"""
A derived class should override this method. The drawing stuff
should happen here.
@type context: cairo.Context
@param context: The context to draw on.
@type rect: gtk.gdk.Rectangle
@param rect: A rectangle representing the charts area.
"""
pass
def draw(self, context, rect, *args):
"""
This method is called by the parent Chart instance. It
calls _do_draw.
@type context: cairo.Context
@param context: The context to draw on.
@type rect: gtk.gdk.Rectangle
@param rect: A rectangle representing the charts area.
"""
res = None
if self._show:
if not self._antialias:
context.set_antialias(cairo.ANTIALIAS_NONE)
res = self._do_draw(context, rect, *args)
context.set_antialias(cairo.ANTIALIAS_DEFAULT)
return res
def set_antialias(self, antialias):
"""
This method sets the antialiasing mode of the ChartObject. Antialiasing
is enabled by default.
@type antialias: boolean
@param antialias: If False, antialiasing is disabled for this
ChartObject.
"""
self.set_property("antialias", antialias)
self.emit("appearance_changed")
def get_antialias(self):
"""
Returns True if antialiasing is enabled for the object.
@return: boolean.
"""
return self.get_property("antialias")
def set_visible(self, visible):
"""
Use this method to set whether the ChartObject should be visible or
not.
@type visible: boolean
@param visible: If False, the PlotObject won't be drawn.
"""
self.set_property("visible", visible)
self.emit("appearance_changed")
def get_visible(self):
"""
Returns True if the object is visble.
@return: boolean.
"""
return self.get_property("visible")
gobject.type_register(ChartObject)
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