Make non-rectangular clip region apply in the correct location.

BUG=9904
R=brettw

Review URL: http://codereview.chromium.org/75020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@13934 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 75 insertions, 16 deletions

diff --git a/skia/ext/bitmap_platform_device_win.cc b/skia/ext/bitmap_platform_device_win.cc
index 5702b55..72eff55 100644
--- a/skia/ext/bitmap_platform_device_win.cc
+++ b/skia/ext/bitmap_platform_device_win.cc
@@ -159,9 +159,6 @@ void BitmapPlatformDeviceWin::BitmapPlatformDeviceWinData::LoadConfig() {
   // Transform.
   SkMatrix t(transform_);
   LoadTransformToDC(hdc_, t);
-  // We don't use transform_ for the clipping region since the translation is
-  // already applied to offset_x_ and offset_y_.
-  t.reset();
   LoadClippingRegionToDC(hdc_, clip_region_, t);
 }
 
diff --git a/skia/ext/platform_canvas_unittest.cc b/skia/ext/platform_canvas_unittest.cc
index c70f238..5e1eadd 100644
--- a/skia/ext/platform_canvas_unittest.cc
+++ b/skia/ext/platform_canvas_unittest.cc
@@ -56,6 +56,37 @@ bool VerifyRect(const PlatformCanvas& canvas,
   return true;
 }
 
+bool IsOfColor(const SkBitmap& bitmap, int x, int y, uint32_t color) {
+  // For masking out the alpha values.
+  static uint32_t alpha_mask = 0xFF << SK_A32_SHIFT;
+  return (*bitmap.getAddr32(x, y) | alpha_mask) == (color | alpha_mask);
+}
+
+// Return true if canvas has something that passes for a rounded-corner
+// rectangle. Basically, we're just checking to make sure that the pixels in the
+// middle are of rect_color and pixels in the corners are of canvas_color.
+bool VerifyRoundedRect(const PlatformCanvas& canvas,
+                       uint32_t canvas_color, uint32_t rect_color,
+                       int x, int y, int w, int h) {
+  PlatformDevice& device = canvas.getTopPlatformDevice();
+  const SkBitmap& bitmap = device.accessBitmap(false);
+  SkAutoLockPixels lock(bitmap);
+
+  // Check corner points first. They should be of canvas_color.
+  if (!IsOfColor(bitmap, x, y, canvas_color)) return false;
+  if (!IsOfColor(bitmap, x + w, y, canvas_color)) return false;
+  if (!IsOfColor(bitmap, x, y + h, canvas_color)) return false;
+  if (!IsOfColor(bitmap, x + w, y, canvas_color)) return false;
+
+  // Check middle points. They should be of rect_color.
+  if (!IsOfColor(bitmap, (x + w / 2), y, rect_color)) return false;
+  if (!IsOfColor(bitmap, x, (y + h / 2), rect_color)) return false;
+  if (!IsOfColor(bitmap, x + w, (y + h / 2), rect_color)) return false;
+  if (!IsOfColor(bitmap, (x + w / 2), y + h, rect_color)) return false;
+
+  return true;
+}
+
 // Checks whether there is a white canvas with a black square at the given
 // location in pixels (not in the canvas coordinate system).
 bool VerifyBlackRect(const PlatformCanvas& canvas, int x, int y, int w, int h) {
@@ -152,6 +183,9 @@ const int kInnerY = 5;
 const int kInnerW = 2;
 const int kInnerH = 3;
 
+// Radius used by some tests to draw a rounded-corner rectangle.
+const SkScalar kRadius = 2.0;
+
 }
 
 // This just checks that our checking code is working properly, it just uses
@@ -313,17 +347,44 @@ TEST(PlatformCanvas, TranslateLayer) {
   canvas.translate(1, 1);
   {
     LayerSaver layer(canvas, kLayerX, kLayerY, kLayerW, kLayerH);
+    canvas.drawColor(SK_ColorWHITE);
     canvas.translate(1, 1);
-    AddClip(canvas, kInnerX, kInnerY, kInnerW, kInnerH);
+    AddClip(canvas, kInnerX + 1, kInnerY + 1, kInnerW - 1, kInnerH - 1);
     DrawNativeRect(canvas, 0, 0, 100, 100);
 #if defined(OS_WIN)
-    canvas.getTopPlatformDevice().makeOpaque(kInnerX, kInnerY,
-                                             kInnerW, kInnerH);
+    canvas.getTopPlatformDevice().makeOpaque(kLayerX, kLayerY,
+                                             kLayerW, kLayerH);
 #endif
   }
   canvas.restore();
-  EXPECT_TRUE(VerifyBlackRect(canvas, kInnerX + 2, kInnerY + 2,
-                              kInnerW, kInnerH));
+  EXPECT_TRUE(VerifyBlackRect(canvas, kInnerX + 3, kInnerY + 3,
+                              kInnerW - 1, kInnerH - 1));
+
+  // Translate both before and after, and have a path clip.
+  canvas.drawColor(SK_ColorWHITE);
+  canvas.save();
+  canvas.translate(1, 1);
+  {
+    LayerSaver layer(canvas, kLayerX, kLayerY, kLayerW, kLayerH);
+    canvas.drawColor(SK_ColorWHITE);
+    canvas.translate(1, 1);
+
+    SkPath path;
+    SkRect rect;
+    rect.iset(kInnerX - 1, kInnerY - 1,
+              kInnerX + kInnerW, kInnerY + kInnerH);
+    path.addRoundRect(rect, kRadius, kRadius);
+    canvas.clipPath(path);
+
+    DrawNativeRect(canvas, 0, 0, 100, 100);
+#if defined(OS_WIN)
+    canvas.getTopPlatformDevice().makeOpaque(kLayerX, kLayerY,
+                                             kLayerW, kLayerH);
+#endif
+  }
+  canvas.restore();
+  EXPECT_TRUE(VerifyRoundedRect(canvas, SK_ColorWHITE, SK_ColorBLACK,
+                                kInnerX + 1, kInnerY + 1, kInnerW, kInnerH));
 }
 
 }  // namespace skia
diff --git a/skia/ext/platform_device_win.cc b/skia/ext/platform_device_win.cc
index 8af393d..34f9c3d 100644
--- a/skia/ext/platform_device_win.cc
+++ b/skia/ext/platform_device_win.cc
@@ -200,20 +200,21 @@ void PlatformDeviceWin::LoadClippingRegionToDC(HDC context,
     // region can be empty, in which case everything will be clipped.
     hrgn = CreateRectRgn(0, 0, 0, 0);
   } else if (region.isRect()) {
-    // Do the transformation.
-    SkRect rect;
-    rect.set(region.getBounds());
-    transformation.mapRect(&rect);
-    SkIRect irect;
-    rect.round(&irect);
-    hrgn = CreateRectRgnIndirect(&SkIRectToRECT(irect));
+    // We don't apply transformation, because the translation is already applied
+    // to the region.
+    hrgn = CreateRectRgnIndirect(&SkIRectToRECT(region.getBounds()));
   } else {
     // It is complex.
     SkPath path;
     region.getBoundaryPath(&path);
     // Clip. Note that windows clipping regions are not affected by the
     // transform so apply it manually.
-    path.transform(transformation);
+    // Since the transform is given as the original translation of canvas, we
+    // should apply it in reverse.
+    SkMatrix t(transformation);
+    t.setTranslateX(-t.getTranslateX());
+    t.setTranslateY(-t.getTranslateY());
+    path.transform(t);
     LoadPathToDC(context, path);
     hrgn = PathToRegion(context);
   }