ppapi/tests/test_graphics2d: Implement TestScroll.

ppapi/tests/test_graphics_2d.cc

Index: ppapi/tests/test_graphics_2d.cc
===================================================================
--- ppapi/tests/test_graphics_2d.cc	(revision 109319)
+++ ppapi/tests/test_graphics_2d.cc	(working copy)
@@ -48,7 +48,7 @@
   RUN_TEST(InitToZero);
   RUN_TEST(Describe);
   RUN_TEST_FORCEASYNC_AND_NOT(Paint);
-  // RUN_TEST_FORCEASYNC_AND_NOT(Scroll);  // TODO(brettw) implement.
+  RUN_TEST_FORCEASYNC_AND_NOT(Scroll);
   RUN_TEST_FORCEASYNC_AND_NOT(Replace);
   RUN_TEST_FORCEASYNC_AND_NOT(Flush);
 }
@@ -390,60 +390,135 @@
   pp::Graphics2D dc(instance_, pp::Size(w, h), false);
   if (dc.is_null())
     return "Failure creating a boring device.";
+  if (!instance_->BindGraphics(dc))
+    return "Failure to bind the boring device.";
 
   // Make sure the device background is 0.
   if (!IsDCUniformColor(dc, 0))
     return "Bad initial color.";
 
-  const int image_w = 15, image_h = 23;
+  const int image_width = 15, image_height = 23;
   pp::ImageData test_image(instance_, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
-                           pp::Size(image_w, image_h), false);
+                           pp::Size(image_width, image_height), false);
   FillImageWithGradient(&test_image);
+  pp::ImageData no_image(instance_, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
+                         pp::Size(image_width, image_height), false);
+  FillRectInImage(&no_image, pp::Rect(0, 0, image_width, image_height), 0);
+  pp::ImageData readback_image(instance_, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
+                               pp::Size(image_width, image_height), false);
+  pp::ImageData readback_scroll(instance_, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
+                                pp::Size(image_width, image_height), false);
 
+  if (test_image.size() != pp::Size(image_width, image_height))
+    return "Wrong test image size\n";
+
   int image_x = 51, image_y = 72;
   dc.PaintImageData(test_image, pp::Point(image_x, image_y));
   if (!FlushAndWaitForDone(&dc))
     return "Couldn't flush to fill backing store.";
 
-  // TC1, Scroll image to a free space.
+  // Test Case 1. Incorrect usage when scrolling image to a free space.
+  // The clip area is *not* the area to shift around within the graphics device
+  // by specified amount. It's the area to which the scroll is limited. So if
+  // the clip area is the size of the image and the amount points to free space,
+  // the scroll won't result in additional images.
   int dx = -40, dy = -48;
-  pp::Rect clip = pp::Rect(image_x, image_y, test_image.size().width(),
-                           test_image.size().height());
+  int scroll_x = image_x + dx, scroll_y = image_y + dy;
+  pp::Rect clip(image_x, image_y, image_width, image_height);
   dc.Scroll(clip, pp::Point(dx, dy));
-
   if (!FlushAndWaitForDone(&dc))
     return "TC1, Couldn't flush to scroll.";
+  if (!ReadImageData(dc, &readback_scroll, pp::Point(scroll_x, scroll_y)))
+    return "TC1, Couldn't read back scrolled image data.";
+  if (!CompareImages(no_image, readback_scroll))
+    return "TC1, Read back scrolled image is not the same as no image.";
 
-  image_x += dx;
-  image_y += dy;
+  // Test Case 2.
+  // The amount is intended to place the image in the free space outside
+  // of the original, but the clip area extends beyond the graphics device area.
+  // This scroll is invalid and will be a noop.
+  scroll_x = 11, scroll_y = 24;
+  clip = pp::Rect(0, 0, w, h + 1);
+  dc.Scroll(clip, pp::Point(scroll_x - image_x, scroll_y - image_y));
+  if (!FlushAndWaitForDone(&dc))
+    return "TC2, Couldn't flush to scroll.";
+  if (!ReadImageData(dc, &readback_scroll, pp::Point(scroll_x, scroll_y)))
+    return "TC2, Couldn't read back scrolled image data.";
+  if (!CompareImages(no_image, readback_scroll))
+    return "TC2, Read back scrolled image is not the same as no image.";
 
-  pp::ImageData readback(instance_, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
-                         pp::Size(image_w, image_h), false);
-  if (!ReadImageData(dc, &readback, pp::Point(image_x, image_y)))
-    return "TC1, Couldn't read back image data.";
+  // Test Case 3.
+  // The amount is intended to place the image in the free space outside
+  // of the original, but the clip area does not cover the image,
+  // so there is nothing to scroll.
+  scroll_x = 11, scroll_y = 24;
+  clip = pp::Rect(0, 0, image_x, image_y);
+  dc.Scroll(clip, pp::Point(scroll_x - image_x, scroll_y - image_y));
+  if (!FlushAndWaitForDone(&dc))
+    return "TC3, Couldn't flush to scroll.";
+  if (!ReadImageData(dc, &readback_scroll, pp::Point(scroll_x, scroll_y)))
+    return "TC3, Couldn't read back scrolled image data.";
+  if (!CompareImages(no_image, readback_scroll))
+    return "TC3, Read back scrolled image is not the same as no image.";
 
-  if (!CompareImages(test_image, readback))
-    return "TC1, Read back image is not the same as test image.";
+  // Test Case 4.
+  // Same as TC3, but the clip covers part of the image.
+  // This part will be scrolled to the intended origin.
+  int part_w = image_width / 2, part_h = image_height / 2;
+  clip = pp::Rect(0, 0, image_x + part_w, image_y + part_h);
+  dc.Scroll(clip, pp::Point(scroll_x - image_x, scroll_y - image_y));
+  if (!FlushAndWaitForDone(&dc))
+    return "TC4, Couldn't flush to scroll.";
+  if (!ReadImageData(dc, &readback_scroll, pp::Point(scroll_x, scroll_y)))
+    return "TC4, Couldn't read back scrolled image data.";
+  if (CompareImages(test_image, readback_scroll))
+    return "TC4, Read back scrolled image is the same as test image.";
+  pp::Rect part_rect(part_w, part_h);
+  if (!CompareImageRect(test_image, part_rect, readback_scroll, part_rect))
+    return "TC4, Read back scrolled image is not the same as part test image.";
 
-  // TC2, Scroll image to an overlapping space.
+  // Test Case 5
+  // Same as TC3, but the clip area covers the entire image.
+  // It will be scrolled to the intended origin.
+  clip = pp::Rect(0, 0, image_x + image_width, image_y + image_height);
+  dc.Scroll(clip, pp::Point(scroll_x - image_x, scroll_y - image_y));
+  if (!FlushAndWaitForDone(&dc))
+    return "TC5, Couldn't flush to scroll.";
+  if (!ReadImageData(dc, &readback_scroll, pp::Point(scroll_x, scroll_y)))
+    return "TC5, Couldn't read back scrolled image data.";
+  if (!CompareImages(test_image, readback_scroll))
+    return "TC5, Read back scrolled image is not the same as test image.";
+
+  // Note that the undefined area left by the scroll does not actually get
+  // cleared, so the original image is still there. This is not guaranteed and
+  // is not something for users to rely on, but we can test for this here, so
+  // we know when the underlying behavior changes.
+  if (!ReadImageData(dc, &readback_image, pp::Point(image_x, image_y)))
+    return "Couldn't read back original image data.";
+  if (!CompareImages(test_image, readback_image))
+    return "Read back original image is not the same as test image.";
+
+  // Test Case 6.
+  // Scroll image to an overlapping space. The clip area is limited
+  // to the image, so this will just modify its area.
   dx = 6;
   dy = 9;
-  clip = pp::Rect(image_x, image_y, test_image.size().width(),
-                  test_image.size().height());
+  scroll_x = image_x + dx;
+  scroll_y = image_y + dy;
+  clip = pp::Rect(image_x, image_y, image_width, image_height);
   dc.Scroll(clip, pp::Point(dx, dy));
-
   if (!FlushAndWaitForDone(&dc))
-    return "TC2, Couldn't flush to scroll.";
+    return "TC6, Couldn't flush to scroll.";
+  if (!ReadImageData(dc, &readback_image, pp::Point(image_x, image_y)))
+    return "TC6, Couldn't read back image data.";
+  if (CompareImages(test_image, readback_image))
+    return "TC6, Read back image is still the same as test image.";
+  pp::Rect scroll_rect(image_width - dx, image_height - dy);
+  if (!ReadImageData(dc, &readback_scroll, pp::Point(scroll_x, scroll_y)))
+    return "TC6, Couldn't read back scrolled image data.";
+  if (!CompareImageRect(test_image, scroll_rect, readback_scroll, scroll_rect))
+    return "TC6, Read back scrolled image is not the same as part test image.";
 
-  image_x += dx;
-  image_y += dy;
-
-  if (!ReadImageData(dc, &readback, pp::Point(image_x, image_y)))
-    return "TC2, Couldn't read back image data.";
-
-  if (!CompareImages(test_image, readback))
-    return "TC2, Read back image is not the same as test image.";
-
   PASS();
 }