--- test_libartdevice.orig.py	2006-04-10 16:27:24.000000000 +0300
+++ test_libartdevice.py	2006-04-10 16:26:52.000000000 +0300
@@ -30,7 +30,7 @@
 import support
 support.add_sketch_dir_to_path()
 
-from Sketch import Identity, Trafo, Rect
+from Sketch import Identity, Trafo, Translation, Scale, Rotation, Rect
 from Sketch.Graphics import Document, Rectangle, SolidPattern, StandardColors
 from Sketch.UI.libartdevice import LibartDevice
 
@@ -158,5 +158,83 @@
         self.check_images()
 
 
+class TestTrafoStack(LibartDeviceTest):
+
+    """Test LibartDevice with PushTrafo/PopTrafo"""
+
+    width = 100
+    height = 100
+
+    def setUp(self):
+        self.obj = Rectangle(Trafo(30, 0, 0, 30, 10, 10))
+        pattern = SolidPattern(StandardColors.red)
+        self.obj.Properties().SetProperty(fill_pattern = pattern)
+        LibartDeviceTest.setUp(self)
+
+    def tearDown(self):
+        self.obj = None
+        LibartDeviceTest.tearDown(self)
+
+    def check_renderings(self, trafo):
+        """Compare two renderings of self.obj with trafo.
+
+        The first image is created by rendering self.obj and a transformed
+        duplicate of self.obj.  The second renders self.obj, adds the trafo to
+        the trafo_stack of the device and renders again self.obj.  The
+        resulting images should be identical.
+        """
+        rect = Rect(0, 0, self.width, self.height)
+        overlaps = rect.overlaps
+
+        # Draw and export the first image.
+        # First transform with trafo a duplicate of self.obj
+        obj2 = self.obj.Duplicate()
+        obj2.Transform(trafo)
+        # Draw the two objects and save the image
+        self.dev.BeginDraw(None)
+        self.dev.DrawObjects([self.obj, obj2], rect, overlaps)
+        self.dev.EndDraw(None)
+        im1_name = self.make_image_filename(suffix = "-with-duplicate")
+        self.dev.export_image(im1_name)
+
+        # Draw and export the second image.
+        # Start by drawing self.obj
+        self.dev.BeginDraw(None)
+        self.dev.DrawObjects([self.obj], rect, overlaps)
+        # Push trafo onto the stack, draw self.obj again and save the image.
+        self.dev.PushTrafo()
+        self.dev.Concat(trafo)
+        self.dev.DrawObjects([self.obj], rect, overlaps)
+        self.dev.PopTrafo()
+        self.dev.EndDraw(None)
+        im2_name = self.make_image_filename(suffix = "-with-stack")
+        self.dev.export_image(im2_name)
+
+        # Compare the images
+        im1 = PIL.Image.open(im1_name)
+        im2 = PIL.Image.open(im2_name)
+        difference = PIL.ImageChops.difference(im1, im2)
+        difference.save(self.make_image_filename("-difference"))
+
+        self.failUnless(max(map(max, difference.getextrema())) <= 1)
+        hist = difference.histogram()
+        num_pixels = difference.size[0] * difference.size[1]
+        max_ratio = 0.015
+        self.failUnless(float(hist[1]) / num_pixels < max_ratio)
+        self.failUnless(float(hist[256 + 1]) / num_pixels < max_ratio)
+        self.failUnless(float(hist[2 * 256 + 1]) / num_pixels < max_ratio)
+
+    def test_scale(self):
+        trafo = Scale(1.2)
+        self.check_renderings(trafo)
+
+    def test_translation(self):
+        trafo = Translation(50, 50)
+        self.check_renderings(trafo)
+
+    def test_rotation(self):
+        trafo = Rotation(0.2618, self.obj.coord_rect.center())
+        self.check_renderings(trafo)
+
 if __name__ == "__main__":
     unittest.main()