import wx # use the numpy code instead of the raw access code for comparison USE_NUMPY = False # time the execution of making a bitmap? TIMEIT = False # how big to make the bitmaps DIM = 100 #---------------------------------------------------------------------- # attempt to import a numeric module if requested to if USE_NUMPY: try: import numpy def makeByteArray(shape): return numpy.empty(shape, numpy.uint8) numtype = 'numpy' except ImportError: try: import numarray def makeByteArray(shape): arr = numarray.array(shape=shape, typecode='u1') arr[:] = 0 return arr numtype = 'numarray' except ImportError: USE_NUMPY = False #---------------------------------------------------------------------- class TestPanel(wx.Panel): def __init__(self, parent, log): self.log = log wx.Panel.__init__(self, parent, -1) self.Bind(wx.EVT_PAINT, self.OnPaint) if TIMEIT: import timeit timeit.s = self # Put self in timeit's global namespace as # 's' so it can be found in the code # snippets being tested. if not USE_NUMPY: t = timeit.Timer("bmp = s.MakeBitmap(10, 20, 30)") else: t = timeit.Timer("bmp = s.MakeBitmap2(10, 20, 30)") log.write("Timing...\n") num = 100 tm = t.timeit(num) log.write("%d passes in %f seconds == %f seconds per pass " % (num, tm, tm/num)) if not USE_NUMPY: log.write("using raw access\n") self.redBmp = self.MakeBitmap(178, 34, 34) self.greenBmp = self.MakeBitmap( 35, 142, 35) self.blueBmp = self.MakeBitmap( 0, 0, 139) else: log.write("using %s\n" % numtype) self.redBmp = self.MakeBitmap2(178, 34, 34) self.greenBmp = self.MakeBitmap2( 35, 142, 35) self.blueBmp = self.MakeBitmap2( 0, 0, 139) def OnPaint(self, evt): dc = wx.PaintDC(self) dc.DrawBitmap(self.redBmp, 50, 50, True) dc.DrawBitmap(self.greenBmp, 110, 110, True) dc.DrawBitmap(self.blueBmp, 170, 50, True) def MakeBitmap(self, red, green, blue, alpha=128): # Create the bitmap that we will stuff pixel values into using # the raw bitmap access classes. bmp = wx.EmptyBitmap(DIM, DIM, 32) # Create an object that facilitates access to the bitmap's # pixel buffer pixelData = wx.AlphaPixelData(bmp) if not pixelData: raise RuntimeError("Failed to gain raw access to bitmap data.") # We have two ways to access each pixel, first we'll use an # iterator to set every pixel to the colour and alpha values # passed in. for pixel in pixelData: pixel.Set(red, green, blue, alpha) # This block of code is another way to do the same as above, # but with the accessor interface instead of the Python # iterator. It is a bit faster than the above because it # avoids the iterator/generator magic, but it is not nearly as # 'clean' looking ;-) #pixels = pixelData.GetPixels() #for y in xrange(DIM): # for x in xrange(DIM): # pixels.Set(red, green, blue, alpha) # pixels.nextPixel() # pixels.MoveTo(pixelData, 0, y) # Next we'll use the pixel accessor to set the border pixels # to be fully opaque pixels = pixelData.GetPixels() for x in xrange(DIM): pixels.MoveTo(pixelData, x, 0) pixels.Set(red, green, blue, wx.ALPHA_OPAQUE) pixels.MoveTo(pixelData, x, DIM-1) pixels.Set(red, green, blue, wx.ALPHA_OPAQUE) for y in xrange(DIM): pixels.MoveTo(pixelData, 0, y) pixels.Set(red, green, blue, wx.ALPHA_OPAQUE) pixels.MoveTo(pixelData, DIM-1, y) pixels.Set(red, green, blue, wx.ALPHA_OPAQUE) return bmp def MakeBitmap2(self, red, green, blue, alpha=128): # Make an array of bytes that is DIM*DIM in size, with enough # slots for each pixel to have a RGB and A value arr = makeByteArray( (DIM,DIM, 4) ) # just some indexes to keep track of which byte is which R, G, B, A = range(4) # initialize all pixel values to the values passed in arr[:,:,R] = red arr[:,:,G] = green arr[:,:,B] = blue arr[:,:,A] = alpha # Set the alpha for the border pixels to be fully opaque arr[0, 0:DIM, A] = wx.ALPHA_OPAQUE # first row arr[DIM-1, 0:DIM, A] = wx.ALPHA_OPAQUE # last row arr[0:DIM, 0, A] = wx.ALPHA_OPAQUE # first col arr[0:DIM, DIM-1, A] = wx.ALPHA_OPAQUE # last col # finally, use the array to create a bitmap bmp = wx.BitmapFromBufferRGBA(DIM, DIM, arr) return bmp #---------------------------------------------------------------------- def runTest(frame, nb, log): win = TestPanel(nb, log) return win #---------------------------------------------------------------------- overview = """

Raw Bitmap Access

wx.NativePixelData and wx.AlphaPixelData provide a cross-platform way to access the platform-specific pixel buffer within a wx.Bitmap. They provide both a random access method, and an iterator interface.

Unfortunately, although these classes are convienient ways to access and update the contents of a wx.Bitmap, we lose most of the efficiency of the C++ classes by requiring one or more Python-to-C++ transitions for each pixel. In fact it can be much slower than the other ways of creating a bitmap from scratch, especially now that wx.BitmapFromBuffer exists and can save the time needed to copy from a wx.Image.

To see this difference for yourself this module has been instrumented to allow you to experiment with using either the raw access or numpy/numarray, and also to time how long it takes to create 100 bitmaps like you see on the screen. Simply edit this module in the \"Demo Code\" tab and set TIMEIT to True and then watch the log window when the sample is reloaded. To try numpy or numarray (if you have them installed) then set USE_NUMPY to True as well, and watch the log window again. On my machines there is about an order of magnitude difference between the raw access functions and using a numarray.array with wx.BitmapFromBufferRGBA! Almost another order of magnitude improvement can be gained with using the new numpy module! """ if __name__ == '__main__': import sys,os import run run.main(['', os.path.basename(sys.argv[0])] + sys.argv[1:])