Revert of Splitting of layers for correct intersections

cc/trees/layer_sorter_unittest.cc

+// Copyright 2011 The Chromium 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 "cc/trees/layer_sorter.h"
+
+#include "cc/base/math_util.h"
+#include "cc/layers/layer_impl.h"
+#include "cc/test/fake_impl_proxy.h"
+#include "cc/test/fake_layer_tree_host_impl.h"
+#include "cc/test/test_shared_bitmap_manager.h"
+#include "cc/trees/single_thread_proxy.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/transform.h"
+
+namespace cc {
+namespace {
+
+// Note: In the following overlap tests, the "camera" is looking down the
+// negative Z axis, meaning that layers with smaller z values (more negative)
+// are further from the camera and therefore must be drawn before layers with
+// higher z values.
+
+TEST(LayerSorterTest, BasicOverlap) {
+  LayerSorter::ABCompareResult overlap_result;
+  const float z_threshold = 0.1f;
+  float weight = 0.f;
+
+  // Trivial test, with one layer directly obscuring the other.
+  gfx::Transform neg4_translate;
+  neg4_translate.Translate3d(0.0, 0.0, -4.0);
+  LayerShape front(2.f, 2.f, neg4_translate);
+
+  gfx::Transform neg5_translate;
+  neg5_translate.Translate3d(0.0, 0.0, -5.0);
+  LayerShape back(2.f, 2.f, neg5_translate);
+
+  overlap_result =
+      LayerSorter::CheckOverlap(&front, &back, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::B_BEFORE_A, overlap_result);
+  EXPECT_EQ(1.f, weight);
+
+  overlap_result =
+      LayerSorter::CheckOverlap(&back, &front, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::A_BEFORE_B, overlap_result);
+  EXPECT_EQ(1.f, weight);
+
+  // One layer translated off to the right. No overlap should be detected.
+  gfx::Transform right_translate;
+  right_translate.Translate3d(10.0, 0.0, -5.0);
+  LayerShape back_right(2.f, 2.f, right_translate);
+  overlap_result =
+      LayerSorter::CheckOverlap(&front, &back_right, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::NONE, overlap_result);
+
+  // When comparing a layer with itself, z difference is always 0.
+  overlap_result =
+      LayerSorter::CheckOverlap(&front, &front, z_threshold, &weight);
+  EXPECT_EQ(0.f, weight);
+}
+
+TEST(LayerSorterTest, RightAngleOverlap) {
+  LayerSorter::ABCompareResult overlap_result;
+  const float z_threshold = 0.1f;
+  float weight = 0.f;
+
+  gfx::Transform perspective_matrix;
+  perspective_matrix.ApplyPerspectiveDepth(1000.0);
+
+  // Two layers forming a right angle with a perspective viewing transform.
+  gfx::Transform left_face_matrix;
+  left_face_matrix.Translate3d(-1.0, 0.0, -5.0);
+  left_face_matrix.RotateAboutYAxis(-90.0);
+  left_face_matrix.Translate(-1.0, -1.0);
+  LayerShape left_face(2.f, 2.f, perspective_matrix * left_face_matrix);
+  gfx::Transform front_face_matrix;
+  front_face_matrix.Translate3d(0.0, 0.0, -4.0);
+  front_face_matrix.Translate(-1.0, -1.0);
+  LayerShape front_face(2.f, 2.f, perspective_matrix * front_face_matrix);
+
+  overlap_result =
+      LayerSorter::CheckOverlap(&front_face, &left_face, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::B_BEFORE_A, overlap_result);
+}
+
+TEST(LayerSorterTest, IntersectingLayerOverlap) {
+  LayerSorter::ABCompareResult overlap_result;
+  const float z_threshold = 0.1f;
+  float weight = 0.f;
+
+  gfx::Transform perspective_matrix;
+  perspective_matrix.ApplyPerspectiveDepth(1000.0);
+
+  // Intersecting layers. An explicit order will be returned based on relative z
+  // values at the overlapping features but the weight returned should be zero.
+  gfx::Transform front_face_matrix;
+  front_face_matrix.Translate3d(0.0, 0.0, -4.0);
+  front_face_matrix.Translate(-1.0, -1.0);
+  LayerShape front_face(2.f, 2.f, perspective_matrix * front_face_matrix);
+
+  gfx::Transform through_matrix;
+  through_matrix.Translate3d(0.0, 0.0, -4.0);
+  through_matrix.RotateAboutYAxis(45.0);
+  through_matrix.Translate(-1.0, -1.0);
+  LayerShape rotated_face(2.f, 2.f, perspective_matrix * through_matrix);
+  overlap_result = LayerSorter::CheckOverlap(&front_face,
+                                             &rotated_face,
+                                             z_threshold,
+                                             &weight);
+  EXPECT_NE(LayerSorter::NONE, overlap_result);
+  EXPECT_EQ(0.f, weight);
+}
+
+TEST(LayerSorterTest, LayersAtAngleOverlap) {
+  LayerSorter::ABCompareResult overlap_result;
+  const float z_threshold = 0.1f;
+  float weight = 0.f;
+
+  // Trickier test with layers at an angle.
+  //
+  //   -x . . . . 0 . . . . +x
+  // -z             /
+  //  :            /----B----
+  //  0           C
+  //  : ----A----/
+  // +z         /
+  //
+  // C is in front of A and behind B (not what you'd expect by comparing
+  // centers). A and B don't overlap, so they're incomparable.
+
+  gfx::Transform transform_a;
+  transform_a.Translate3d(-6.0, 0.0, 1.0);
+  transform_a.Translate(-4.0, -10.0);
+  LayerShape layer_a(8.f, 20.f, transform_a);
+
+  gfx::Transform transform_b;
+  transform_b.Translate3d(6.0, 0.0, -1.0);
+  transform_b.Translate(-4.0, -10.0);
+  LayerShape layer_b(8.f, 20.f, transform_b);
+
+  gfx::Transform transform_c;
+  transform_c.RotateAboutYAxis(40.0);
+  transform_c.Translate(-4.0, -10.0);
+  LayerShape layer_c(8.f, 20.f, transform_c);
+
+  overlap_result =
+      LayerSorter::CheckOverlap(&layer_a, &layer_c, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::A_BEFORE_B, overlap_result);
+  overlap_result =
+      LayerSorter::CheckOverlap(&layer_c, &layer_b, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::A_BEFORE_B, overlap_result);
+  overlap_result =
+      LayerSorter::CheckOverlap(&layer_a, &layer_b, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::NONE, overlap_result);
+}
+
+TEST(LayerSorterTest, LayersUnderPathologicalPerspectiveTransform) {
+  LayerSorter::ABCompareResult overlap_result;
+  const float z_threshold = 0.1f;
+  float weight = 0.f;
+
+  // On perspective projection, if w becomes negative, the re-projected point
+  // will be invalid and un-usable. Correct code needs to clip away portions of
+  // the geometry where w < 0. If the code uses the invalid value, it will think
+  // that a layer has different bounds than it really does, which can cause
+  // things to sort incorrectly.
+
+  gfx::Transform perspective_matrix;
+  perspective_matrix.ApplyPerspectiveDepth(1);
+
+  gfx::Transform transform_a;
+  transform_a.Translate3d(-15.0, 0.0, -2.0);
+  transform_a.Translate(-5.0, -5.0);
+  LayerShape layer_a(10.f, 10.f, perspective_matrix * transform_a);
+
+  // With this sequence of transforms, when layer B is correctly clipped, it
+  // will be visible on the left half of the projection plane, in front of
+  // layer_a. When it is not clipped, its bounds will actually incorrectly
+  // appear much smaller and the correct sorting dependency will not be found.
+  gfx::Transform transform_b;
+  transform_b.Translate3d(0.f, 0.f, 0.7f);
+  transform_b.RotateAboutYAxis(45.0);
+  transform_b.Translate(-5.0, -5.0);
+  LayerShape layer_b(10.f, 10.f, perspective_matrix * transform_b);
+
+  // Sanity check that the test case actually covers the intended scenario,
+  // where part of layer B go behind the w = 0 plane.
+  gfx::QuadF test_quad = gfx::QuadF(gfx::RectF(-0.5f, -0.5f, 1.f, 1.f));
+  bool clipped = false;
+  MathUtil::MapQuad(perspective_matrix * transform_b, test_quad, &clipped);
+  ASSERT_TRUE(clipped);
+
+  overlap_result =
+      LayerSorter::CheckOverlap(&layer_a, &layer_b, z_threshold, &weight);
+  EXPECT_EQ(LayerSorter::A_BEFORE_B, overlap_result);
+}
+
+TEST(LayerSorterTest, VerifyExistingOrderingPreservedWhenNoZDiff) {
+  // If there is no reason to re-sort the layers (i.e. no 3d z difference), then
+  // the existing ordering provided on input should be retained. This test
+  // covers the fix in https://bugs.webkit.org/show_bug.cgi?id=75046. Before
+  // this fix, ordering was accidentally reversed, causing bugs in z-index
+  // ordering on websites when preserves3D triggered the LayerSorter.
+
+  // Input list of layers: [1, 2, 3, 4, 5].
+  // Expected output: [3, 4, 1, 2, 5].
+  //    - 1, 2, and 5 do not have a 3d z difference, and therefore their
+  //      relative ordering should be retained.
+  //    - 3 and 4 do not have a 3d z difference, and therefore their relative
+  //      ordering should be retained.
+  //    - 3 and 4 should be re-sorted so they are in front of 1, 2, and 5.
+
+  FakeImplProxy proxy;
+  TestSharedBitmapManager shared_bitmap_manager;
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+
+  scoped_ptr<LayerImpl> layer1 = LayerImpl::Create(host_impl.active_tree(), 1);
+  scoped_ptr<LayerImpl> layer2 = LayerImpl::Create(host_impl.active_tree(), 2);
+  scoped_ptr<LayerImpl> layer3 = LayerImpl::Create(host_impl.active_tree(), 3);
+  scoped_ptr<LayerImpl> layer4 = LayerImpl::Create(host_impl.active_tree(), 4);
+  scoped_ptr<LayerImpl> layer5 = LayerImpl::Create(host_impl.active_tree(), 5);
+
+  gfx::Transform BehindMatrix;
+  BehindMatrix.Translate3d(0.0, 0.0, 2.0);
+  gfx::Transform FrontMatrix;
+  FrontMatrix.Translate3d(0.0, 0.0, 1.0);
+
+  layer1->SetBounds(gfx::Size(10, 10));
+  layer1->SetContentBounds(gfx::Size(10, 10));
+  layer1->draw_properties().target_space_transform = BehindMatrix;
+  layer1->SetDrawsContent(true);
+
+  layer2->SetBounds(gfx::Size(20, 20));
+  layer2->SetContentBounds(gfx::Size(20, 20));
+  layer2->draw_properties().target_space_transform = BehindMatrix;
+  layer2->SetDrawsContent(true);
+
+  layer3->SetBounds(gfx::Size(30, 30));
+  layer3->SetContentBounds(gfx::Size(30, 30));
+  layer3->draw_properties().target_space_transform = FrontMatrix;
+  layer3->SetDrawsContent(true);
+
+  layer4->SetBounds(gfx::Size(40, 40));
+  layer4->SetContentBounds(gfx::Size(40, 40));
+  layer4->draw_properties().target_space_transform = FrontMatrix;
+  layer4->SetDrawsContent(true);
+
+  layer5->SetBounds(gfx::Size(50, 50));
+  layer5->SetContentBounds(gfx::Size(50, 50));
+  layer5->draw_properties().target_space_transform = BehindMatrix;
+  layer5->SetDrawsContent(true);
+
+  LayerImplList layer_list;
+  layer_list.push_back(layer1.get());
+  layer_list.push_back(layer2.get());
+  layer_list.push_back(layer3.get());
+  layer_list.push_back(layer4.get());
+  layer_list.push_back(layer5.get());
+
+  ASSERT_EQ(5u, layer_list.size());
+  EXPECT_EQ(1, layer_list[0]->id());
+  EXPECT_EQ(2, layer_list[1]->id());
+  EXPECT_EQ(3, layer_list[2]->id());
+  EXPECT_EQ(4, layer_list[3]->id());
+  EXPECT_EQ(5, layer_list[4]->id());
+
+  LayerSorter layer_sorter;
+  layer_sorter.Sort(layer_list.begin(), layer_list.end());
+
+  ASSERT_EQ(5u, layer_list.size());
+  EXPECT_EQ(3, layer_list[0]->id());
+  EXPECT_EQ(4, layer_list[1]->id());
+  EXPECT_EQ(1, layer_list[2]->id());
+  EXPECT_EQ(2, layer_list[3]->id());
+  EXPECT_EQ(5, layer_list[4]->id());
+}
+
+TEST(LayerSorterTest, VerifyConcidentLayerPrecisionLossResultsInDocumentOrder) {
+  FakeImplProxy proxy;
+  TestSharedBitmapManager shared_bitmap_manager;
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+
+  scoped_ptr<LayerImpl> layer1 = LayerImpl::Create(host_impl.active_tree(), 1);
+  scoped_ptr<LayerImpl> layer2 = LayerImpl::Create(host_impl.active_tree(), 2);
+
+  // Layer 1 should occur before layer 2 in paint.  However, due to numeric
+  // issues in the sorter, it will put the layers in the wrong order
+  // in some situations.  Here we test a patch that results in  document
+  // order rather than calculated order when numeric percision is suspect
+  // in calculated order.
+
+  gfx::Transform BehindMatrix;
+  BehindMatrix.Translate3d(0.f, 0.f, 0.999999f);
+  BehindMatrix.RotateAboutXAxis(38.5);
+  BehindMatrix.RotateAboutYAxis(77.0);
+  gfx::Transform FrontMatrix;
+  FrontMatrix.Translate3d(0, 0, 1.0);
+  FrontMatrix.RotateAboutXAxis(38.5);
+  FrontMatrix.RotateAboutYAxis(77.0);
+
+  layer1->SetBounds(gfx::Size(10, 10));
+  layer1->SetContentBounds(gfx::Size(10, 10));
+  layer1->draw_properties().target_space_transform = BehindMatrix;
+  layer1->SetDrawsContent(true);
+
+  layer2->SetBounds(gfx::Size(10, 10));
+  layer2->SetContentBounds(gfx::Size(10, 10));
+  layer2->draw_properties().target_space_transform = FrontMatrix;
+  layer2->SetDrawsContent(true);
+
+  LayerImplList layer_list;
+  layer_list.push_back(layer1.get());
+  layer_list.push_back(layer2.get());
+
+  ASSERT_EQ(2u, layer_list.size());
+  EXPECT_EQ(1, layer_list[0]->id());
+  EXPECT_EQ(2, layer_list[1]->id());
+
+  LayerSorter layer_sorter;
+  layer_sorter.Sort(layer_list.begin(), layer_list.end());
+
+  ASSERT_EQ(2u, layer_list.size());
+  EXPECT_EQ(1, layer_list[0]->id());
+  EXPECT_EQ(2, layer_list[1]->id());
+}
+
+}  // namespace
+}  // namespace cc
+