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#------------------------------------------------------------------------------
# Copyright (c) 2007, Riverbank Computing Limited
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license.
#
# Author: Riverbank Computing Limited
# Description: <Enthought kiva PyQt backend>
#
# In an e-mail to enthought-dev on 2008.09.12 at 2:49 AM CDT, Phil Thompson said:
# The advantage is that all of the PyQt code in ETS can now be re-licensed to
# use the BSD - and I hereby give my permission for that to be done. It's
# been on my list of things to do.
#------------------------------------------------------------------------------
""" This is the Qt backend for kiva. """
# These are the symbols that a backend has to define.
__all__ = ["GraphicsContext", "Canvas", "CompiledPath",
"font_metrics_provider"]
# Major package imports.
from PyQt4 import QtCore, QtGui
# Local imports.
from backend_image import GraphicsContextSystem as GraphicsContext
from agg import CompiledPath
from fonttools import Font
class Canvas(QtGui.QWidget):
def __init__(self, *args):
QtGui.QWidget.__init__(self, *args)
self.setAttribute(QtCore.Qt.WA_OpaquePaintEvent)
self.clear_color = (1,1,1)
self.gc = None
self.new_gc(size=None)
def do_draw(self, gc):
""" Method to be implemented by subclasses to actually perform various
GC drawing commands before the GC is blitted into the screen.
"""
pass
def paintEvent(self, event):
# Clear the gc.
self.gc.clear(self.clear_color)
# Draw on the GC.
self.do_draw(self.gc)
# Render the pixel data from the graphics context.
s = self.gc.pixel_map.convert_to_argb32string()
img = QtGui.QImage(s, self.gc.width(), self.gc.height(),
QtGui.QImage.Format_ARGB32)
p = QtGui.QPainter(self)
p.drawPixmap(0, 0, QtGui.QPixmap.fromImage(img))
def resizeEvent(self, event):
width = self.width()
height = self.height()
if width != self.gc.width() or height != self.gc.height():
self.new_gc((width, height))
def new_gc(self, size):
""" Creates a new GC of the requested size (or of the widget's current
size if size is None) and stores it in self.gc.
"""
if size is None:
width = self.width()
height = self.height()
else:
width, height = size
if self.gc is not None:
del self.gc
self.gc = None
self.gc = GraphicsContext((width, height), bottom_up=0)
def font_metrics_provider():
""" Creates an object to be used for querying font metrics. Typically
this can just be an empty/dummy graphics context
"""
gc = GraphicsContext((1,1))
gc.set_font(Font())
return gc
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