[Pythoncard-users] bitmapcanvas batch refresh

[Neil H. <ne...@sc...>]

   I have been playing around with the turtle sample and the bitmap canvas
to allow a reasonable compromise between performance and watching the
demonstrations as they are drawing. The idea is to avoid doing a full blit
of the backing surface to the display after every drawing operation but
rather after every n drawing operations and also when drawing is completed.
The code added to bitmapcanvas.py looks like this (along with initialisation
of _autoCounter):

    def FlushRefresh(self):
        if self.autoRefresh and (self._autoCounter > 0):
            dc = wx.wxClientDC(self)
            dc.Blit(0, 0, self._size[0],self._size[1], self._bufImage, 0, 0)
            self._autoCounter = 0

    def AutomaticRefresh(self):
        if self.autoRefresh:
            self._autoCounter += 1
            if self._autoCounter > 50:
                self.FlushRefresh()

   Then all the individual drawing methods call self.AutomaticRefresh()
rather than having their own blit code. In turtle.py, the current calls to
refresh are dropped but an idle event is added:

    def on_idle(self, event):
        self.components.bufOff.FlushRefresh()

   Setting the number of drawing operations between flushes to 50 results in
ChaosScript2and3.txt taking 6.3 seconds rather than 5.3 seconds without
auto-refresh on my machine. Continuous auto-refresh takes 120 seconds.

   I can commit this to CVS if it looks OK.

   Neil