wxPython/demo/RawBitmapAccess.py

   1 import wx
   2
   3 # use the numpy code instead of the raw access code for comparison
   4 USE_NUMPY = False
   5
   6 # time the execution of making a bitmap?
   7 TIMEIT = False
   8
   9 # how big to make the bitmaps
  10 DIM = 100
  11
  12 #----------------------------------------------------------------------
  13 # attempt to import a numeric module if requested to
  14
  15 if USE_NUMPY:
  16     try:
  17         import numpy
  18         def makeByteArray(shape):
  19             return numpy.empty(shape, numpy.uint8)
  20         numtype = 'numpy'
  21     except ImportError:
  22         try:
  23             import numarray
  24             def makeByteArray(shape):
  25                 arr =  numarray.array(shape=shape, typecode='u1')
  26                 arr[:] = 0
  27                 return arr
  28             numtype = 'numarray'
  29         except ImportError:
  30             USE_NUMPY = False
  31
  32
  33 #----------------------------------------------------------------------
  34
  35 class TestPanel(wx.Panel):
  36     def __init__(self, parent, log):
  37         self.log = log
  38         wx.Panel.__init__(self, parent, -1)
  39         self.Bind(wx.EVT_PAINT, self.OnPaint)
  40
  41         if TIMEIT:
  42             import timeit
  43             timeit.s = self # Put self in timeit's global namespace as
  44                             # 's' so it can be found in the code
  45                             # snippets being tested.
  46             if not USE_NUMPY:
  47                 t = timeit.Timer("bmp = s.MakeBitmap(10, 20, 30)")
  48             else:
  49                 t = timeit.Timer("bmp = s.MakeBitmap2(10, 20, 30)")
  50             log.write("Timing...\n")
  51             num = 100
  52             tm = t.timeit(num)
  53             log.write("%d passes in %f seconds ==  %f seconds per pass " %
  54                   (num, tm, tm/num))
  55
  56         if not USE_NUMPY:
  57             log.write("using raw access\n")
  58             self.redBmp   = self.MakeBitmap(178,  34,  34)
  59             self.greenBmp = self.MakeBitmap( 35, 142,  35)
  60             self.blueBmp  = self.MakeBitmap(  0,   0, 139)
  61         else:
  62             log.write("using %s\n" % numtype)
  63             self.redBmp   = self.MakeBitmap2(178,  34,  34)
  64             self.greenBmp = self.MakeBitmap2( 35, 142,  35)
  65             self.blueBmp  = self.MakeBitmap2(  0,   0, 139)
  66
  67
  68     def OnPaint(self, evt):
  69         dc = wx.PaintDC(self)
  70         dc.DrawBitmap(self.redBmp,    50,  50, True)
  71         dc.DrawBitmap(self.greenBmp, 110, 110, True)
  72         dc.DrawBitmap(self.blueBmp,  170,  50, True)
  73
  74
  75     def MakeBitmap(self, red, green, blue, alpha=128):
  76         # Create the bitmap that we will stuff pixel values into using
  77         # the raw bitmap access classes.
  78         bmp = wx.EmptyBitmap(DIM, DIM, 32)
  79
  80         # Create an object that facilitates access to the bitmap's
  81         # pixel buffer
  82         pixelData = wx.AlphaPixelData(bmp)
  83         if not pixelData:
  84             raise RuntimeError("Failed to gain raw access to bitmap data.")
  85
  86         # We have two ways to access each pixel, first we'll use an
  87         # iterator to set every pixel to the colour and alpha values
  88         # passed in.
  89         for pixel in pixelData:
  90             pixel.Set(red, green, blue, alpha)
  91
  92         # This block of code is another way to do the same as above,
  93         # but with the accessor interface instead of the Python
  94         # iterator.  It is a bit faster than the above because it
  95         # avoids the iterator/generator magic, but it is not nearly as
  96         # 'clean' looking ;-)
  97         #pixels = pixelData.GetPixels()
  98         #for y in xrange(DIM):
  99         #    for x in xrange(DIM):
 100         #        pixels.Set(red, green, blue, alpha)
 101         #        pixels.nextPixel()
 102         #    pixels.MoveTo(pixelData, 0, y)
 103
 104
 105         # Next we'll use the pixel accessor to set the border pixels
 106         # to be fully opaque
 107         pixels = pixelData.GetPixels()
 108         for x in xrange(DIM):
 109             pixels.MoveTo(pixelData, x, 0)
 110             pixels.Set(red, green, blue, wx.ALPHA_OPAQUE)
 111             pixels.MoveTo(pixelData, x, DIM-1)
 112             pixels.Set(red, green, blue, wx.ALPHA_OPAQUE)
 113         for y in xrange(DIM):
 114             pixels.MoveTo(pixelData, 0, y)
 115             pixels.Set(red, green, blue, wx.ALPHA_OPAQUE)
 116             pixels.MoveTo(pixelData, DIM-1, y)
 117             pixels.Set(red, green, blue, wx.ALPHA_OPAQUE)
 118
 119         return bmp
 120
 121
 122     def MakeBitmap2(self, red, green, blue, alpha=128):
 123         # Make an array of bytes that is DIM*DIM in size, with enough
 124         # slots for each pixel to have a RGB and A value
 125         arr = makeByteArray( (DIM,DIM, 4) )
 126
 127         # just some indexes to keep track of which byte is which
 128         R, G, B, A = range(4)
 129
 130         # initialize all pixel values to the values passed in
 131         arr[:,:,R] = red
 132         arr[:,:,G] = green
 133         arr[:,:,B] = blue
 134         arr[:,:,A] = alpha
 135
 136         # Set the alpha for the border pixels to be fully opaque
 137         arr[0,     0:DIM, A] = wx.ALPHA_OPAQUE  # first row
 138         arr[DIM-1, 0:DIM, A] = wx.ALPHA_OPAQUE  # last row
 139         arr[0:DIM, 0,     A] = wx.ALPHA_OPAQUE  # first col
 140         arr[0:DIM, DIM-1, A] = wx.ALPHA_OPAQUE  # last col
 141
 142         # finally, use the array to create a bitmap
 143         bmp = wx.BitmapFromBufferRGBA(DIM, DIM, arr)
 144         return bmp
 145
 146
 147
 148 #----------------------------------------------------------------------
 149
 150 def runTest(frame, nb, log):
 151     win = TestPanel(nb, log)
 152     return win
 153
 154 #----------------------------------------------------------------------
 155
 156
 157
 158 overview = """<html><body>
 159 <h2><center>Raw Bitmap Access</center></h2>
 160
 161 wx.NativePixelData and wx.AlphaPixelData provide a cross-platform way
 162 to access the platform-specific pixel buffer within a wx.Bitmap.  They
 163 provide both a random access method, and an iterator interface.
 164
 165 <p>Unfortunately, although these classes are convienient ways to access
 166 and update the contents of a wx.Bitmap, we lose most of the efficiency
 167 of the C++ classes by requiring one or more Python-to-C++ transitions
 168 for each pixel.  In fact it can be <b>much</b> slower than the other
 169 ways of creating a bitmap from scratch, especially now that
 170 wx.BitmapFromBuffer exists and can save the time needed to copy from a
 171 wx.Image.
 172
 173 <p>To see this difference for yourself this module has been
 174 instrumented to allow you to experiment with using either the raw
 175 access or numpy/numarray, and also to time how long it takes to create
 176 100 bitmaps like you see on the screen.  Simply edit this module in
 177 the \"Demo Code\" tab and set TIMEIT to True and then watch
 178 the log window when the sample is reloaded.  To try numpy or numarray
 179 (if you have them installed) then set USE_NUMPY to True as well, and
 180 watch the log window again. On my machines there is about <b>an
 181 order of magnitude</b> difference between the raw access functions
 182 and using a numarray.array with wx.BitmapFromBufferRGBA!  Almost
 183 another order of magnitude improvement can be gained with using the
 184 new numpy module!
 185
 186 </body></html>
 187 """
 188
 189
 190
 191 if __name__ == '__main__':
 192     import sys,os
 193     import run
 194     run.main(['', os.path.basename(sys.argv[0])] + sys.argv[1:])
 195