Fix high DPI with Surfaces by treating Surface size as content bounds of layer

The size of the surface can be different from the bounds of the layer, so set the contents scale to convert between the two.

Review URL: https://codereview.chromium.org/708693002

Cr-Commit-Position: refs/heads/master@{#303157}

3 files changed, 52 insertions, 5 deletions

diff --git a/cc/layers/surface_layer.cc b/cc/layers/surface_layer.cc
index f1909b4..ee376aa 100644
--- a/cc/layers/surface_layer.cc
+++ b/cc/layers/surface_layer.cc
@@ -53,9 +53,10 @@ SurfaceLayer::~SurfaceLayer() {
   DCHECK(destroy_sequence_.is_null());
 }
 
-void SurfaceLayer::SetSurfaceId(SurfaceId surface_id) {
+void SurfaceLayer::SetSurfaceId(SurfaceId surface_id, const gfx::Size& size) {
   SatisfyDestroySequence();
   surface_id_ = surface_id;
+  surface_size_ = size;
   CreateNewDestroySequence();
 
   UpdateDrawsContent(HasDrawableContent());
@@ -88,6 +89,19 @@ void SurfaceLayer::PushPropertiesTo(LayerImpl* layer) {
   layer_impl->SetSurfaceId(surface_id_);
 }
 
+void SurfaceLayer::CalculateContentsScale(float ideal_contents_scale,
+                                          float* contents_scale_x,
+                                          float* contents_scale_y,
+                                          gfx::Size* content_bounds) {
+  *content_bounds = surface_size_;
+  *contents_scale_x =
+      bounds().IsEmpty() ? 1.f : static_cast<float>(content_bounds->width()) /
+                                     bounds().width();
+  *contents_scale_y =
+      bounds().IsEmpty() ? 1.f : static_cast<float>(content_bounds->height()) /
+                                     bounds().height();
+}
+
 void SurfaceLayer::CreateNewDestroySequence() {
   DCHECK(destroy_sequence_.is_null());
   if (layer_tree_host()) {
diff --git a/cc/layers/surface_layer.h b/cc/layers/surface_layer.h
index 4292549..29d821f 100644
--- a/cc/layers/surface_layer.h
+++ b/cc/layers/surface_layer.h
@@ -9,6 +9,7 @@
 #include "cc/layers/layer.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surface_sequence.h"
+#include "ui/gfx/size.h"
 
 namespace cc {
 
@@ -29,12 +30,16 @@ class CC_EXPORT SurfaceLayer : public Layer {
       const SatisfyCallback& satisfy_callback,
       const RequireCallback& require_callback);
 
-  void SetSurfaceId(SurfaceId surface_id);
+  void SetSurfaceId(SurfaceId surface_id, const gfx::Size& size);
 
   // Layer overrides.
   scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
   void SetLayerTreeHost(LayerTreeHost* host) override;
   void PushPropertiesTo(LayerImpl* layer) override;
+  void CalculateContentsScale(float ideal_contents_scale,
+                              float* contents_scale_x,
+                              float* contents_scale_y,
+                              gfx::Size* content_bounds) override;
 
  protected:
   SurfaceLayer(const SatisfyCallback& satisfy_callback,
@@ -47,6 +52,7 @@ class CC_EXPORT SurfaceLayer : public Layer {
   void SatisfyDestroySequence();
 
   SurfaceId surface_id_;
+  gfx::Size surface_size_;
   SurfaceSequence destroy_sequence_;
   SatisfyCallback satisfy_callback_;
   RequireCallback require_callback_;
diff --git a/cc/layers/surface_layer_unittest.cc b/cc/layers/surface_layer_unittest.cc
index 99d0e17..7323bf4 100644
--- a/cc/layers/surface_layer_unittest.cc
+++ b/cc/layers/surface_layer_unittest.cc
@@ -65,7 +65,7 @@ TEST_F(SurfaceLayerTest, MultipleFramesOneSurface) {
   scoped_refptr<SurfaceLayer> layer(SurfaceLayer::Create(
       base::Bind(&SatisfyCallback, &blank_change),
       base::Bind(&RequireCallback, &required_id, &required_seq)));
-  layer->SetSurfaceId(SurfaceId(1));
+  layer->SetSurfaceId(SurfaceId(1), gfx::Size(1, 1));
   layer_tree_host_->set_surface_id_namespace(1);
   layer_tree_host_->SetRootLayer(layer);
 
@@ -74,7 +74,7 @@ TEST_F(SurfaceLayerTest, MultipleFramesOneSurface) {
   scoped_refptr<SurfaceLayer> layer2(SurfaceLayer::Create(
       base::Bind(&SatisfyCallback, &blank_change),
       base::Bind(&RequireCallback, &required_id, &required_seq)));
-  layer2->SetSurfaceId(SurfaceId(1));
+  layer2->SetSurfaceId(SurfaceId(1), gfx::Size(1, 1));
   layer_tree_host2->set_surface_id_namespace(2);
   layer_tree_host2->SetRootLayer(layer2);
 
@@ -110,6 +110,33 @@ TEST_F(SurfaceLayerTest, MultipleFramesOneSurface) {
   EXPECT_EQ(2u, required_seq.size());
 }
 
+// Check that setting content scale on the surface works.
+TEST_F(SurfaceLayerTest, ScaleSurface) {
+  SurfaceSequence blank_change;
+  SurfaceId required_id;
+  std::set<SurfaceSequence> required_seq;
+  scoped_refptr<SurfaceLayer> layer(SurfaceLayer::Create(
+      base::Bind(&SatisfyCallback, &blank_change),
+      base::Bind(&RequireCallback, &required_id, &required_seq)));
+  gfx::Size surface_size(10, 15);
+  layer->SetSurfaceId(SurfaceId(1), surface_size);
+  layer->SetBounds(gfx::Size(25, 45));
+
+  float scale_x;
+  float scale_y;
+  gfx::Size bounds;
+  layer->CalculateContentsScale(2.f, &scale_x, &scale_y, &bounds);
+  EXPECT_EQ(10.f / 25.f, scale_x);
+  EXPECT_EQ(15.f / 45.f, scale_y);
+  EXPECT_EQ(surface_size.ToString(), bounds.ToString());
+
+  layer->SetBounds(gfx::Size(0, 0));
+  layer->CalculateContentsScale(2.f, &scale_x, &scale_y, &bounds);
+  EXPECT_EQ(1.f, scale_x);
+  EXPECT_EQ(1.f, scale_y);
+  EXPECT_EQ(surface_size.ToString(), bounds.ToString());
+}
+
 // Check that SurfaceSequence is sent through swap promise.
 class SurfaceLayerSwapPromise : public LayerTreeTest {
  public:
@@ -121,7 +148,7 @@ class SurfaceLayerSwapPromise : public LayerTreeTest {
     layer_ = SurfaceLayer::Create(
         base::Bind(&SatisfyCallback, &satisfied_sequence_),
         base::Bind(&RequireCallback, &required_id_, &required_set_));
-    layer_->SetSurfaceId(SurfaceId(1));
+    layer_->SetSurfaceId(SurfaceId(1), gfx::Size(1, 1));
 
     // Layer hasn't been added to tree so no SurfaceSequence generated yet.
     EXPECT_EQ(0u, required_set_.size());