Implement cc::FilterOperations::MapRect.

cc/output/filter_operations_unittest.cc

Index: cc/output/filter_operations_unittest.cc
diff --git a/cc/output/filter_operations_unittest.cc b/cc/output/filter_operations_unittest.cc
index 05c0289ea9f3b7af83a016efb97b93d841c45531..59a07bbd2e8a230305aedd6a2d3336f868f8679f 100644
--- a/cc/output/filter_operations_unittest.cc
+++ b/cc/output/filter_operations_unittest.cc
@@ -10,6 +10,7 @@
 #include "third_party/skia/include/effects/SkBlurImageFilter.h"
 #include "third_party/skia/include/effects/SkDropShadowImageFilter.h"
 #include "ui/gfx/geometry/point.h"
+#include "ui/gfx/geometry/rect.h"
 
 namespace cc {
 namespace {
@@ -26,6 +27,13 @@ TEST(FilterOperationsTest, GetOutsetsBlur) {
   EXPECT_EQ(57, left);
 }
 
+TEST(FilterOperationsTest, MapRectBlur) {
+  FilterOperations ops;
+  ops.Append(FilterOperation::CreateBlurFilter(20));
+  EXPECT_EQ(gfx::Rect(-57, -57, 124, 124),
+            ops.MapRect(gfx::Rect(0, 0, 10, 10)));
+}
+
 TEST(FilterOperationsTest, GetOutsetsDropShadowReferenceFilter) {
   // TODO(hendrikw): We need to make outsets for reference filters be in line
   // with non-reference filters. See crbug.com/523534
@@ -46,6 +54,19 @@ TEST(FilterOperationsTest, GetOutsetsDropShadowReferenceFilter) {
   EXPECT_EQ(15, left);
 }
 
+TEST(FilterOperationsTest, MapRectDropShadowReferenceFilter) {
+  // TODO(hendrikw): We need to make outsets for reference filters be in line

[Stephen White, 2016/04/11 18:05:00]

Is this comment still valid? If not, remove it.

[jbroman, 2016/04/11 20:21:52]

I'm not entirely clear on what it means, so I figured I'd better not let it get
removed.

[Stephen White, 2016/04/11 20:56:04]

The referenced bug is basically what you're doing here: use real rect mapping,
not outsets (see my comment#2 on that bug). So I think you can remove it from
this flavour of the test.

[jbroman, 2016/04/12 19:32:36]

Done.

+  // with non-reference filters. See crbug.com/523534
+  skia::RefPtr<SkImageFilter> filter =
+      skia::AdoptRef(SkDropShadowImageFilter::Create(
+          SkIntToScalar(3), SkIntToScalar(8), SkIntToScalar(4),
+          SkIntToScalar(9), SK_ColorBLACK,
+          SkDropShadowImageFilter::kDrawShadowAndForeground_ShadowMode));
+  FilterOperations ops;
+  ops.Append(FilterOperation::CreateReferenceFilter(filter));
+  EXPECT_EQ(gfx::Rect(-15, -35, 34, 64), ops.MapRect(gfx::Rect(0, 0, 10, 10)));

[Stephen White, 2016/04/11 18:05:00]

This does look like a reverse mapping. Maybe the code was wrong?

[jbroman, 2016/04/11 20:21:52]

These expectations were taken from GetOutsets (with conversion to a rectangle).
See previous comment.

[Stephen White, 2016/04/11 20:56:04]

Yeah, I think there is/was a bug in GetOutsets().

[jbroman, 2016/04/12 19:32:37]

Acknowledged.

+}
+
 TEST(FilterOperationsTest, GetOutsetsNullReferenceFilter) {
   FilterOperations ops;
   ops.Append(FilterOperation::CreateReferenceFilter(nullptr));
@@ -59,6 +80,12 @@ TEST(FilterOperationsTest, GetOutsetsNullReferenceFilter) {
   EXPECT_EQ(0, left);
 }
 
+TEST(FilterOperationsTest, MapRectNullReferenceFilter) {
+  FilterOperations ops;
+  ops.Append(FilterOperation::CreateReferenceFilter(nullptr));
+  EXPECT_EQ(gfx::Rect(0, 0, 10, 10), ops.MapRect(gfx::Rect(0, 0, 10, 10)));

[Stephen White, 2016/04/11 18:05:00]

Could you add a test for a non-null Reference filter, e.g., an
SkOffsetImageFilter?

[jbroman, 2016/04/11 20:21:52]

Is the drop shadow reference filter (above) insufficient? I've mirrored the
existing tests. I'm happy to add one for SkOffsetImageFilter if you think that's
additionally useful.

[Stephen White, 2016/04/11 20:56:04]

The advantage of SkOffsetImageFilter is that it doesn't union with the original
primitive, so it tends to show bugs which don't show up in drop shadow (which
does).

[jbroman, 2016/04/12 19:32:36]

Done.

+}
+
 TEST(FilterOperationsTest, GetOutsetsDropShadow) {
   FilterOperations ops;
   ops.Append(FilterOperation::CreateDropShadowFilter(gfx::Point(3, 8), 20, 0));
@@ -71,6 +98,13 @@ TEST(FilterOperationsTest, GetOutsetsDropShadow) {
   EXPECT_EQ(54, left);
 }
 
+TEST(FilterOperationsTest, MapRectDropShadow) {
+  FilterOperations ops;
+  ops.Append(FilterOperation::CreateDropShadowFilter(gfx::Point(3, 8), 20, 0));
+  EXPECT_EQ(gfx::Rect(-54, -49, 124, 124),
+            ops.MapRect(gfx::Rect(0, 0, 10, 10)));
+}
+
 #define SAVE_RESTORE_AMOUNT(filter_name, filter_type, a)                  \
   {                                                                       \
     FilterOperation op = FilterOperation::Create##filter_name##Filter(a); \