Add tests

Author: knopp

ci/licenses_golden/licenses_flutter

@@ -102,6 +102,7 @@ FILE: ../../../flutter/flow/compositor_context.cc
 FILE: ../../../flutter/flow/compositor_context.h
 FILE: ../../../flutter/flow/diff_context.cc
 FILE: ../../../flutter/flow/diff_context.h
+FILE: ../../../flutter/flow/diff_context_unittests.cc
 FILE: ../../../flutter/flow/embedded_view_params_unittests.cc
 FILE: ../../../flutter/flow/embedded_views.cc
 FILE: ../../../flutter/flow/embedded_views.h

flow/BUILD.gn

@@ -128,6 +128,7 @@ if (enable_unittests) {
     testonly = true
 
     sources = [
+      "diff_context_unittests.cc",
       "embedded_view_params_unittests.cc",
       "flow_run_all_unittests.cc",
       "flow_test_utils.cc",

flow/diff_context.cc

@@ -83,8 +83,8 @@ void DiffContext::AlignRect(SkIRect& rect,
   if (right % horizontal_alignment != 0) {
     right += horizontal_alignment - right % horizontal_alignment;
   }
-  if (bottom % horizontal_alignment != 0) {
-    bottom += horizontal_alignment - bottom % horizontal_alignment;
+  if (bottom % vertical_alignment != 0) {
+    bottom += vertical_alignment - bottom % vertical_alignment;
   }
   right = std::min(right, frame_size_.width());
   bottom = std::min(bottom, frame_size_.height());

flow/diff_context.h

@@ -137,8 +137,8 @@ class DiffContext {
   // clip_alignment controls the alignment of resulting frame and surface
   // damage.
   Damage ComputeDamage(const SkIRect& additional_damage,
-                       int horizontal_clip_alignment = 1,
-                       int vertical_clip_alignment = 1) const;
+                       int horizontal_clip_alignment = 0,
+                       int vertical_clip_alignment = 0) const;
 
   double frame_device_pixel_ratio() const { return frame_device_pixel_ratio_; };
 

flow/diff_context_unittests.cc

@@ -0,0 +1,36 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/flow/testing/diff_context_test.h"
+
+namespace flutter {
+namespace testing {
+
+TEST_F(DiffContextTest, ClipAlignment) {
+  MockLayerTree t1;
+  t1.root()->Add(
+      CreatePictureLayer(CreatePicture(SkRect::MakeLTRB(30, 30, 50, 50), 1)));
+  auto damage = DiffLayerTree(t1, MockLayerTree(), SkIRect::MakeEmpty(), 0, 0);
+  EXPECT_EQ(damage.frame_damage, SkIRect::MakeLTRB(30, 30, 50, 50));
+  EXPECT_EQ(damage.buffer_damage, SkIRect::MakeLTRB(30, 30, 50, 50));
+
+  damage = DiffLayerTree(t1, MockLayerTree(), SkIRect::MakeEmpty(), 1, 1);
+  EXPECT_EQ(damage.frame_damage, SkIRect::MakeLTRB(30, 30, 50, 50));
+  EXPECT_EQ(damage.buffer_damage, SkIRect::MakeLTRB(30, 30, 50, 50));
+
+  damage = DiffLayerTree(t1, MockLayerTree(), SkIRect::MakeEmpty(), 8, 1);
+  EXPECT_EQ(damage.frame_damage, SkIRect::MakeLTRB(24, 30, 56, 50));
+  EXPECT_EQ(damage.buffer_damage, SkIRect::MakeLTRB(24, 30, 56, 50));
+
+  damage = DiffLayerTree(t1, MockLayerTree(), SkIRect::MakeEmpty(), 1, 8);
+  EXPECT_EQ(damage.frame_damage, SkIRect::MakeLTRB(30, 24, 50, 56));
+  EXPECT_EQ(damage.buffer_damage, SkIRect::MakeLTRB(30, 24, 50, 56));
+
+  damage = DiffLayerTree(t1, MockLayerTree(), SkIRect::MakeEmpty(), 16, 16);
+  EXPECT_EQ(damage.frame_damage, SkIRect::MakeLTRB(16, 16, 64, 64));
+  EXPECT_EQ(damage.buffer_damage, SkIRect::MakeLTRB(16, 16, 64, 64));
+}
+
+}  // namespace testing
+}  // namespace flutter

flow/testing/diff_context_test.cc

@@ -15,15 +15,18 @@ DiffContextTest::DiffContextTest()
 
 Damage DiffContextTest::DiffLayerTree(MockLayerTree& layer_tree,
                                       const MockLayerTree& old_layer_tree,
-                                      const SkIRect& additional_damage) {
+                                      const SkIRect& additional_damage,
+                                      int horizontal_clip_alignment,
+                                      int vertical_clip_alignment) {
   FML_CHECK(layer_tree.size() == old_layer_tree.size());
 
   DiffContext dc(layer_tree.size(), 1, layer_tree.paint_region_map(),
                  old_layer_tree.paint_region_map());
   dc.PushCullRect(
       SkRect::MakeIWH(layer_tree.size().width(), layer_tree.size().height()));
   layer_tree.root()->Diff(&dc, old_layer_tree.root());
-  return dc.ComputeDamage(additional_damage);
+  return dc.ComputeDamage(additional_damage, horizontal_clip_alignment,
+                          vertical_clip_alignment);
 }
 
 sk_sp<SkPicture> DiffContextTest::CreatePicture(const SkRect& bounds,

flow/testing/diff_context_test.h

@@ -38,7 +38,9 @@ class DiffContextTest : public ThreadTest {
 
   Damage DiffLayerTree(MockLayerTree& layer_tree,
                        const MockLayerTree& old_layer_tree,
-                       const SkIRect& additional_damage = SkIRect::MakeEmpty());
+                       const SkIRect& additional_damage = SkIRect::MakeEmpty(),
+                       int horizontal_clip_alignment = 0,
+                       int vertical_alignment = 0);
 
   // Create picture consisting of filled rect with given color; Being able
   // to specify different color is useful to test deep comparison of pictures