Test image transforms

Tests/test_image_transform.py

@@ -2,4 +2,81 @@
 
 from PIL import Image
 
-success()
+def test_extent():
+    im = lena('RGB')
+    (w,h) = im.size
+    transformed = im.transform(im.size, Image.EXTENT,
+                               (0,0,
+                                w//2,h//2), # ul -> lr
+                               Image.BILINEAR)
+
+
+    scaled = im.resize((w*2, h*2), Image.BILINEAR).crop((0,0,w,h))
+
+    assert_image_similar(transformed, scaled, 10) # undone -- precision?
+
+def test_quad():
+    # one simple quad transform, equivalent to scale & crop upper left quad
+    im = lena('RGB')
+    (w,h) = im.size
+    transformed = im.transform(im.size, Image.QUAD,
+                               (0,0,0,h//2,
+                                w//2,h//2,w//2,0), # ul -> ccw around quad
+                               Image.BILINEAR)
+
+    scaled = im.resize((w*2, h*2), Image.BILINEAR).crop((0,0,w,h))
+
+    assert_image_equal(transformed, scaled)
+
+def test_mesh():
+    # this should be a checkerboard of halfsized lenas in ul, lr
+    im = lena('RGBA')
+    (w,h) = im.size
+    transformed = im.transform(im.size, Image.MESH,
+                               [((0,0,w//2,h//2), # box
+                                (0,0,0,h,
+                                 w,h,w,0)), # ul -> ccw around quad
+                                ((w//2,h//2,w,h), # box
+                                (0,0,0,h,
+                                 w,h,w,0))], # ul -> ccw around quad
+                               Image.BILINEAR)
+
+    #transformed.save('transformed.png')
+
+    scaled = im.resize((w//2, h//2), Image.BILINEAR)
+
+    checker = Image.new('RGBA', im.size)
+    checker.paste(scaled, (0,0))
+    checker.paste(scaled, (w//2,h//2))
+
+    assert_image_equal(transformed, checker) 
+
+    # now, check to see that the extra area is (0,0,0,0)
+    blank = Image.new('RGBA', (w//2,h//2), (0,0,0,0))
+
+    assert_image_equal(blank, transformed.crop((w//2,0,w,h//2)))
+    assert_image_equal(blank, transformed.crop((0,h//2,w//2,h)))
+
+
+def test_blank_fill():
+    # attempting to hit
+    # https://github.com/python-imaging/Pillow/issues/254 reported
+    #
+    # issue is that transforms with transparent overflow area
+    # contained junk from previous images, especially on systems with
+    # constrained memory. So, attempt to fill up memory with a
+    # pattern, free it, and then run the mesh test again. Using a 1Mp
+    # image with 4 bands, for 4 megs of data allocated, x 64. OMM (64
+    # bit 12.04 VM with 512 megs available, this fails with Pillow <
+    # a0eaf06cc5f62a6fb6de556989ac1014ff3348ea
+    #
+    # Running by default, but I'd totally understand not doing it in
+    # the future
+
+    foo = [Image.new('RGBA',(1024,1024), (a,a,a,a))
+             for a in range(1,65)]   
+
+    # Yeah. Watch some JIT optimize this out. 
+    foo = None
+
+    test_mesh()