/Lib/test/test_imgfile.py

  1#! /usr/bin/env python
  2
  3"""Simple test script for imgfile.c
  4   Roger E. Masse
  5"""
  6
  7from test.test_support import verbose, unlink, findfile, import_module
  8
  9imgfile = import_module('imgfile', deprecated=True)
 10import uu
 11
 12
 13def testimage(name):
 14    """Run through the imgfile's battery of possible methods
 15       on the image passed in name.
 16    """
 17
 18    import sys
 19    import os
 20
 21    outputfile = '/tmp/deleteme'
 22
 23    # try opening the name directly
 24    try:
 25        # This function returns a tuple (x, y, z) where x and y are the size
 26        # of the image in pixels and z is the number of bytes per pixel. Only
 27        # 3 byte RGB pixels and 1 byte greyscale pixels are supported.
 28        sizes = imgfile.getsizes(name)
 29    except imgfile.error:
 30        # get a more qualified path component of the script...
 31        if __name__ == '__main__':
 32            ourname = sys.argv[0]
 33        else: # ...or the full path of the module
 34            ourname = sys.modules[__name__].__file__
 35
 36        parts = ourname.split(os.sep)
 37        parts[-1] = name
 38        name = os.sep.join(parts)
 39        sizes = imgfile.getsizes(name)
 40    if verbose:
 41        print 'Opening test image: %s, sizes: %s' % (name, str(sizes))
 42    # This function reads and decodes the image on the specified file,
 43    # and returns it as a python string. The string has either 1 byte
 44    # greyscale pixels or 4 byte RGBA pixels. The bottom left pixel
 45    # is the first in the string. This format is suitable to pass
 46    # to gl.lrectwrite, for instance.
 47    image = imgfile.read(name)
 48
 49    # This function writes the RGB or greyscale data in data to
 50    # image file file. x and y give the size of the image, z is
 51    # 1 for 1 byte greyscale images or 3 for RGB images (which
 52    # are stored as 4 byte values of which only the lower three
 53    # bytes are used). These are the formats returned by gl.lrectread.
 54    if verbose:
 55        print 'Writing output file'
 56    imgfile.write (outputfile, image, sizes[0], sizes[1], sizes[2])
 57
 58
 59    if verbose:
 60        print 'Opening scaled test image: %s, sizes: %s' % (name, str(sizes))
 61    # This function is identical to read but it returns an image that
 62    # is scaled to the given x and y sizes. If the filter and blur
 63    # parameters are omitted scaling is done by simply dropping
 64    # or duplicating pixels, so the result will be less than perfect,
 65    # especially for computer-generated images.  Alternatively,
 66    # you can specify a filter to use to smoothen the image after
 67    # scaling. The filter forms supported are 'impulse', 'box',
 68    # 'triangle', 'quadratic' and 'gaussian'. If a filter is
 69    # specified blur is an optional parameter specifying the
 70    # blurriness of the filter. It defaults to 1.0.  readscaled
 71    # makes no attempt to keep the aspect ratio correct, so that
 72    # is the users' responsibility.
 73    if verbose:
 74        print 'Filtering with "impulse"'
 75    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'impulse', 2.0)
 76
 77    # This function sets a global flag which defines whether the
 78    # scan lines of the image are read or written from bottom to
 79    # top (flag is zero, compatible with SGI GL) or from top to
 80    # bottom(flag is one, compatible with X). The default is zero.
 81    if verbose:
 82        print 'Switching to X compatibility'
 83    imgfile.ttob (1)
 84
 85    if verbose:
 86        print 'Filtering with "triangle"'
 87    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'triangle', 3.0)
 88    if verbose:
 89        print 'Switching back to SGI compatibility'
 90    imgfile.ttob (0)
 91
 92    if verbose: print 'Filtering with "quadratic"'
 93    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'quadratic')
 94    if verbose: print 'Filtering with "gaussian"'
 95    simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'gaussian', 1.0)
 96
 97    if verbose:
 98        print 'Writing output file'
 99    imgfile.write (outputfile, simage, sizes[0]/2, sizes[1]/2, sizes[2])
100
101    os.unlink(outputfile)
102
103
104def test_main():
105
106    uu.decode(findfile('testrgb.uue'), 'test.rgb')
107    uu.decode(findfile('greyrgb.uue'), 'greytest.rgb')
108
109    # Test a 3 byte color image
110    testimage('test.rgb')
111
112    # Test a 1 byte greyscale image
113    testimage('greytest.rgb')
114
115    unlink('test.rgb')
116    unlink('greytest.rgb')
117
118if __name__ == '__main__':
119    test_main()