cc: Do not allow gesture-scrolling 'overflow[-{x|y}]:hidden' layers.

BUG=175502
R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/30793002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230032 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 68 insertions, 1 deletions

diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 15de223..80fad6a 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -41,6 +41,8 @@ Layer::Layer()
       scrollable_(false),
       should_scroll_on_main_thread_(false),
       have_wheel_event_handlers_(false),
+      user_scrollable_horizontal_(true),
+      user_scrollable_vertical_(true),
       anchor_point_(0.5f, 0.5f),
       background_color_(0),
       compositing_reasons_(kCompositingReasonUnknown),
@@ -646,6 +648,16 @@ void Layer::SetScrollable(bool scrollable) {
   SetNeedsCommit();
 }
 
+void Layer::SetUserScrollable(bool horizontal, bool vertical) {
+  DCHECK(IsPropertyChangeAllowed());
+  if (user_scrollable_horizontal_ == horizontal &&
+      user_scrollable_vertical_ == vertical)
+    return;
+  user_scrollable_horizontal_ = horizontal;
+  user_scrollable_vertical_ = vertical;
+  SetNeedsCommit();
+}
+
 void Layer::SetShouldScrollOnMainThread(bool should_scroll_on_main_thread) {
   DCHECK(IsPropertyChangeAllowed());
   if (should_scroll_on_main_thread_ == should_scroll_on_main_thread)
@@ -833,6 +845,8 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   DCHECK(!(TransformIsAnimating() && layer->TransformIsAnimatingOnImplOnly()));
 
   layer->SetScrollable(scrollable_);
+  layer->set_user_scrollable_horizontal(user_scrollable_horizontal_);
+  layer->set_user_scrollable_vertical(user_scrollable_vertical_);
   layer->SetMaxScrollOffset(max_scroll_offset_);
 
   LayerImpl* scroll_parent = NULL;
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index e1bed9b..1328b07 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -251,6 +251,12 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   void SetScrollable(bool scrollable);
   bool scrollable() const { return scrollable_; }
 
+  void SetUserScrollable(bool horizontal, bool vertical);
+  bool user_scrollable_horizontal() const {
+    return user_scrollable_horizontal_;
+  }
+  bool user_scrollable_vertical() const { return user_scrollable_vertical_; }
+
   void SetShouldScrollOnMainThread(bool should_scroll_on_main_thread);
   bool should_scroll_on_main_thread() const {
     return should_scroll_on_main_thread_;
@@ -539,6 +545,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   bool scrollable_;
   bool should_scroll_on_main_thread_;
   bool have_wheel_event_handlers_;
+  bool user_scrollable_horizontal_;
+  bool user_scrollable_vertical_;
   Region non_fast_scrollable_region_;
   Region touch_event_handler_region_;
   gfx::PointF position_;
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index d42ec31..14f3e2a 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -42,6 +42,8 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       scrollable_(false),
       should_scroll_on_main_thread_(false),
       have_wheel_event_handlers_(false),
+      user_scrollable_horizontal_(true),
+      user_scrollable_vertical_(true),
       background_color_(0),
       stacking_order_changed_(false),
       double_sided_(true),
@@ -341,6 +343,15 @@ void LayerImpl::SetSentScrollDelta(gfx::Vector2d sent_scroll_delta) {
 
 gfx::Vector2dF LayerImpl::ScrollBy(gfx::Vector2dF scroll) {
   DCHECK(scrollable());
+  gfx::Vector2dF scroll_hidden;
+  if (!user_scrollable_horizontal_) {
+    scroll_hidden.set_x(scroll.x());
+    scroll.set_x(0.f);
+  }
+  if (!user_scrollable_vertical_) {
+    scroll_hidden.set_y(scroll.y());
+    scroll.set_y(0.f);
+  }
 
   gfx::Vector2dF min_delta = -scroll_offset_;
   gfx::Vector2dF max_delta = max_scroll_offset_ - scroll_offset_;
@@ -348,7 +359,8 @@ gfx::Vector2dF LayerImpl::ScrollBy(gfx::Vector2dF scroll) {
   gfx::Vector2dF new_delta = (ScrollDelta() + scroll);
   new_delta.SetToMax(min_delta);
   new_delta.SetToMin(max_delta);
-  gfx::Vector2dF unscrolled = ScrollDelta() + scroll - new_delta;
+  gfx::Vector2dF unscrolled =
+      ScrollDelta() + scroll + scroll_hidden - new_delta;
   SetScrollDelta(new_delta);
   return unscrolled;
 }
@@ -449,6 +461,13 @@ InputHandler::ScrollStatus LayerImpl::TryScroll(
     return InputHandler::ScrollIgnored;
   }
 
+  if (!user_scrollable_horizontal_ && !user_scrollable_vertical_) {
+    TRACE_EVENT0("cc",
+                 "LayerImpl::TryScroll: Ignored. User gesture is not allowed"
+                 " to scroll this layer.");
+    return InputHandler::ScrollIgnored;
+  }
+
   return InputHandler::ScrollStarted;
 }
 
@@ -514,6 +533,8 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->SetTransform(transform_);
 
   layer->SetScrollable(scrollable_);
+  layer->set_user_scrollable_horizontal(user_scrollable_horizontal_);
+  layer->set_user_scrollable_vertical(user_scrollable_vertical_);
   layer->SetScrollOffsetAndDelta(
       scroll_offset_, layer->ScrollDelta() - layer->sent_scroll_delta());
   layer->SetSentScrollDelta(gfx::Vector2d());
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index 2048840..4bd91da 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -374,6 +374,13 @@ class CC_EXPORT LayerImpl : LayerAnimationValueObserver {
   void SetScrollable(bool scrollable) { scrollable_ = scrollable; }
   bool scrollable() const { return scrollable_; }
 
+  void set_user_scrollable_horizontal(bool scrollable) {
+    user_scrollable_horizontal_ = scrollable;
+  }
+  void set_user_scrollable_vertical(bool scrollable) {
+    user_scrollable_vertical_ = scrollable;
+  }
+
   void ApplySentScrollDeltasFromAbortedCommit();
   void ApplyScrollDeltasSinceBeginFrame();
 
@@ -544,6 +551,8 @@ class CC_EXPORT LayerImpl : LayerAnimationValueObserver {
   bool scrollable_;
   bool should_scroll_on_main_thread_;
   bool have_wheel_event_handlers_;
+  bool user_scrollable_horizontal_;
+  bool user_scrollable_vertical_;
   Region non_fast_scrollable_region_;
   Region touch_event_handler_region_;
   SkColor background_color_;
diff --git a/cc/layers/layer_impl_unittest.cc b/cc/layers/layer_impl_unittest.cc
index 83cd346..2d3305c 100644
--- a/cc/layers/layer_impl_unittest.cc
+++ b/cc/layers/layer_impl_unittest.cc
@@ -547,5 +547,19 @@ TEST_F(LayerImplScrollTest, ApplySentScrollsWithAcceptingDelegate) {
   EXPECT_VECTOR_EQ(gfx::Vector2d(), layer()->sent_scroll_delta());
 }
 
+TEST_F(LayerImplScrollTest, ScrollUserUnscrollableLayer) {
+  gfx::Vector2d max_scroll_offset(50, 80);
+  gfx::Vector2d scroll_offset(10, 5);
+  gfx::Vector2dF scroll_delta(20.5f, 8.5f);
+
+  layer()->set_user_scrollable_vertical(false);
+  layer()->SetMaxScrollOffset(max_scroll_offset);
+  layer()->SetScrollOffset(scroll_offset);
+  gfx::Vector2dF unscrolled = layer()->ScrollBy(scroll_delta);
+
+  EXPECT_VECTOR_EQ(gfx::Vector2dF(0, 8.5f), unscrolled);
+  EXPECT_VECTOR_EQ(gfx::Vector2dF(30.5f, 5), layer()->TotalScrollOffset());
+}
+
 }  // namespace
 }  // namespace cc
diff --git a/cc/layers/layer_unittest.cc b/cc/layers/layer_unittest.cc
index 3bbff6b..3a7a1c1 100644
--- a/cc/layers/layer_unittest.cc
+++ b/cc/layers/layer_unittest.cc
@@ -550,6 +550,7 @@ TEST_F(LayerTest, CheckPropertyChangeCausesCorrectBehavior) {
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetSublayerTransform(
       gfx::Transform(0.0, 0.0, 0.0, 0.0, 0.0, 0.0)));
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetScrollable(true));
+  EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetUserScrollable(true, false));
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetScrollOffset(
       gfx::Vector2d(10, 10)));
   EXPECT_SET_NEEDS_COMMIT(1, test_layer->SetShouldScrollOnMainThread(true));