--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/printrun-src/printrun/gui/bufferedcanvas.py	Fri Jun 03 09:16:07 2016 +0200
@@ -0,0 +1,111 @@
+"""
+BufferedCanvas -- flicker-free canvas widget
+Copyright (C) 2005, 2006 Daniel Keep, 2011 Duane Johnson
+
+To use this widget, just override or replace the draw method.
+This will be called whenever the widget size changes, or when
+the update method is explicitly called.
+
+Please submit any improvements/bugfixes/ideas to the following
+url:
+
+  http://wiki.wxpython.org/index.cgi/BufferedCanvas
+
+2006-04-29: Added bugfix for a crash on Mac provided by Marc Jans.
+"""
+
+# Hint: try removing '.sp4msux0rz'
+__author__ = 'Daniel Keep <daniel.keep.sp4msux0rz@gmail.com>'
+
+__license__ = """
+This file is part of the Printrun suite.
+
+Printrun 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 3 of the License, or
+(at your option) any later version.
+
+Printrun 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 Printrun.  If not, see <http://www.gnu.org/licenses/>.
+"""
+
+__all__ = ['BufferedCanvas']
+
+import wx
+
+class BufferedCanvas(wx.Panel):
+    """
+    Implements a flicker-free canvas widget.
+
+    Standard usage is to subclass this class, and override the
+    draw method.  The draw method is passed a device context, which
+    should be used to do your drawing.
+
+    If you want to force a redraw (for whatever reason), you should
+    call the update method.  This is because the draw method is never
+    called as a result of an EVT_PAINT event.
+    """
+
+    # These are our two buffers.  Just be aware that when the buffers
+    # are flipped, the REFERENCES are swapped.  So I wouldn't want to
+    # try holding onto explicit references to one or the other ;)
+    buffer = None
+    backbuffer = None
+
+    def __init__(self,
+                 parent,
+                 ID=-1,
+                 pos = wx.DefaultPosition,
+                 size = wx.DefaultSize,
+                 style = wx.NO_FULL_REPAINT_ON_RESIZE | wx.WANTS_CHARS):
+        wx.Panel.__init__(self, parent, ID, pos, size, style)
+
+        # Bind events
+        self.Bind(wx.EVT_PAINT, self.onPaint)
+
+        # Disable background erasing (flicker-licious)
+        def disable_event(*pargs, **kwargs):
+            pass  # the sauce, please
+        self.Bind(wx.EVT_ERASE_BACKGROUND, disable_event)
+
+    #
+    # General methods
+    #
+
+    def draw(self, dc, w, h):
+        """
+        Stub: called when the canvas needs to be re-drawn.
+        """
+        pass
+
+    def update(self):
+        """
+        Causes the canvas to be updated.
+        """
+        self.Refresh()
+
+    def getWidthHeight(self):
+        width, height = self.GetClientSizeTuple()
+        if width == 0:
+            width = 1
+        if height == 0:
+            height = 1
+        return (width, height)
+
+    #
+    # Event handlers
+    #
+
+    def onPaint(self, event):
+        # Blit the front buffer to the screen
+        w, h = self.GetClientSizeTuple()
+        if not w or not h:
+            return
+        else:
+            dc = wx.BufferedPaintDC(self)
+            self.draw(dc, w, h)