Test script for the SGI imgfile module.

Lib/test/test_imgfile.py

+from test_support import verbose
+
+import imgfile
+
+     
+def main():       
+
+    getimage('test.rgb')
+    getimage('greytest.rgb')
+
+
+def getimage(name):
+    """return a tuple consisting of
+       image (in 'imgfile' format) width, height, size
+    """
+
+    import sys
+    import os
+    import string
+
+    outputfile = '/tmp/deleteme'
+
+    # try opening the name directly
+    try:
+	# This function returns a tuple (x, y, z) where x and y are the size of
+	# the image in pixels and z is the number of bytes per pixel. Only
+	# 3 byte RGB pixels and 1 byte greyscale pixels are supported.
+	sizes = imgfile.getsizes(name)
+    except imgfile.error:
+	# get a more qualified path component of the script...
+	if __name__ == '__main__':
+	    ourname = sys.argv[0]
+	else: # ...or the full path of the module
+	    ourname = sys.modules[__name__].__file__
+
+	parts = string.splitfields(ourname, os.sep)
+	parts[-1] = name
+	name = string.joinfields(parts, os.sep)
+	sizes = imgfile.getsizes(name)
+    if verbose:
+	print 'Opening test image: %s, sizes: %s' % (name, str(sizes))
+    # This function reads and decodes the image on the specified file,
+    # and returns it as a python string. The string has either 1 byte
+    # greyscale pixels or 4 byte RGBA pixels. The bottom left pixel
+    # is the first in the string. This format is suitable to pass
+    # to gl.lrectwrite, for instance. 
+    image = imgfile.read(name)
+    
+    # This function writes the RGB or greyscale data in data to
+    # image file file. x and y give the size of the image, z is
+    # 1 for 1 byte greyscale images or 3 for RGB images (which
+    # are stored as 4 byte values of which only the lower three
+    # bytes are used). These are the formats returned by gl.lrectread. 
+    if verbose:
+	print 'Writing output file'
+    imgfile.write (outputfile, image, sizes[0], sizes[1], sizes[2]) 
+   
+
+    if verbose:
+	print 'Opening scaled test image: %s, sizes: %s' % (name, str(sizes))
+    # This function is identical to read but it returns an image that
+    # is scaled to the given x and y sizes. If the filter and blur
+    # parameters are omitted scaling is done by simply dropping
+    # or duplicating pixels, so the result will be less than perfect,
+    # especially for computer-generated images.  Alternatively,
+    # you can specify a filter to use to smoothen the image after
+    # scaling. The filter forms supported are 'impulse', 'box',
+    # 'triangle', 'quadratic' and 'gaussian'. If a filter is
+    # specified blur is an optional parameter specifying the
+    # blurriness of the filter. It defaults to 1.0.  readscaled
+    # makes no attempt to keep the aspect ratio correct, so that
+    # is the users' responsibility.
+    if verbose:
+	print 'Filtering with "impulse"'
+    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'impulse', 2.0)
+
+    # This function sets a global flag which defines whether the
+    # scan lines of the image are read or written from bottom to
+    # top (flag is zero, compatible with SGI GL) or from top to
+    # bottom(flag is one, compatible with X). The default is zero. 
+    if verbose:
+	print 'Switching to X compatibility'
+    imgfile.ttob (1) 
+
+    if verbose:
+	print 'Filtering with "triangle"'
+    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'triangle', 3.0)
+    if verbose:
+	print 'Switching back to SGI compatibility'
+    imgfile.ttob (0) 
+    
+    if verbose: print 'Filtering with "quadratic"'
+    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'quadratic')
+    if verbose: print 'Filtering with "gaussian"'
+    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'gaussian', 1.0)
+
+    if verbose:
+	print 'Writing output file'
+    imgfile.write (outputfile, simage, sizes[0]/2, sizes[1]/2, sizes[2]) 
+
+    os.unlink(outputfile)
+
+main()

Lib/test/testall.py

@@ -31,6 +31,7 @@ tests = ['test_grammar',
 	 'test_grp',
 	 'test_operator',
 	 'test_imageop',
+	 'test_imgfile',
 	 ]
 
 if __name__ == '__main__':