Pinch/Zoom Infrastructure & Plumbing CL

cc/trees/layer_tree_host_impl.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_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 375 matching lines @@
                                 &memory_used_bytes);
   SendManagedMemoryStats(memory_required_bytes,
                          memory_nice_to_have_bytes,
                          memory_used_bytes);
 }
 
 void LayerTreeHostImpl::StartPageScaleAnimation(gfx::Vector2d target_offset,
                                                 bool anchor_point,
                                                 float page_scale,
                                                 base::TimeDelta duration) {
-  if (!RootScrollLayer())
+  if (!InnerViewportScrollLayer())
     return;
 
+  // Should we attempt to set to OuterViewportScrollingLayer if it's available?
+  active_tree_->SetCurrentlyScrollingLayer(InnerViewportScrollLayer());

[enne (OOO), 2013/11/14 22:59:01]

Why do you need to set the currently scrolling layer?

[wjmaclean, 2013/12/24 21:03:49]

It might not be needed ... I'll try to verify this.

+
   gfx::Vector2dF scroll_total =
-      RootScrollLayer()->scroll_offset() + RootScrollLayer()->ScrollDelta();
+      active_tree_->TotalScrollOffset() + active_tree_->TotalScrollDelta();
   gfx::SizeF scaled_scrollable_size = active_tree_->ScrollableSize();
   gfx::SizeF viewport_size = UnscaledScrollableViewportSize();
 
   // Easing constants experimentally determined.
   scoped_ptr<TimingFunction> timing_function =
       CubicBezierTimingFunction::Create(.8, 0, .3, .9).PassAs<TimingFunction>();
 
   page_scale_animation_ =
       PageScaleAnimation::Create(scroll_total,
                                  active_tree_->total_page_scale_factor(),
@@ skipping 837 matching lines @@
   metadata.max_page_scale_factor = active_tree_->max_page_scale_factor();
   metadata.latency_info = active_tree_->GetLatencyInfo();
   if (top_controls_manager_) {
     metadata.location_bar_offset =
         gfx::Vector2dF(0.f, top_controls_manager_->controls_top_offset());
     metadata.location_bar_content_translation =
         gfx::Vector2dF(0.f, top_controls_manager_->content_top_offset());
     metadata.overdraw_bottom_height = overdraw_bottom_height_;
   }
 
-  if (!RootScrollLayer())
+  if (!InnerViewportScrollLayer())
     return metadata;
 
-  metadata.root_scroll_offset = RootScrollLayer()->TotalScrollOffset();
+  metadata.root_scroll_offset = active_tree_->TotalScrollOffset();
 
   return metadata;
 }
 
 static void LayerTreeHostImplDidBeginTracingCallback(LayerImpl* layer) {
   layer->DidBeginTracing();
 }
 
 void LayerTreeHostImpl::DrawLayers(FrameData* frame,
                                    base::TimeTicks frame_begin_time) {
@@ skipping 167 matching lines @@
     client_->DidLoseOutputSurfaceOnImplThread();
 }
 
 void LayerTreeHostImpl::Readback(void* pixels,
                                  gfx::Rect rect_in_device_viewport) {
   DCHECK(renderer_);
   renderer_->GetFramebufferPixels(pixels, rect_in_device_viewport);
 }
 
 bool LayerTreeHostImpl::HaveRootScrollLayer() const {
-  return !!RootScrollLayer();
+  return !!InnerViewportScrollLayer();
 }
 
 LayerImpl* LayerTreeHostImpl::RootLayer() const {
   return active_tree_->root_layer();
 }
 
-LayerImpl* LayerTreeHostImpl::RootScrollLayer() const {
-  return active_tree_->RootScrollLayer();
+LayerImpl* LayerTreeHostImpl::InnerViewportScrollLayer() const {
+  return active_tree_->InnerViewportScrollLayer();
+}
+
+LayerImpl* LayerTreeHostImpl::OuterViewportScrollLayer() const {
+  return active_tree_->OuterViewportScrollLayer();
 }
 
 LayerImpl* LayerTreeHostImpl::CurrentlyScrollingLayer() const {
   return active_tree_->CurrentlyScrollingLayer();
 }
 
 bool LayerTreeHostImpl::IsCurrentlyScrolling() const {
   return CurrentlyScrollingLayer() ||
-         (RootScrollLayer() && RootScrollLayer()->IsExternalFlingActive());
+         (InnerViewportScrollLayer() &&
+          InnerViewportScrollLayer()->IsExternalFlingActive()) ||
+         (OuterViewportScrollLayer() &&
+          OuterViewportScrollLayer()->IsExternalFlingActive());
 }
 
 // Content layers can be either directly scrollable or contained in an outer
 // scrolling layer which applies the scroll transform. Given a content layer,
 // this function returns the associated scroll layer if any.
 static LayerImpl* FindScrollLayerForContentLayer(LayerImpl* layer_impl) {
   if (!layer_impl)
     return NULL;
 
   if (layer_impl->scrollable())
@@ skipping 346 matching lines @@
 
 void LayerTreeHostImpl::SetViewportSize(gfx::Size device_viewport_size) {
   if (device_viewport_size == device_viewport_size_)
     return;
 
   if (pending_tree_)
     active_tree_->SetViewportSizeInvalid();
 
   device_viewport_size_ = device_viewport_size;
 
-  UpdateMaxScrollOffset();
-
   if (renderer_)
     renderer_->ViewportChanged();
 
   client_->OnCanDrawStateChanged(CanDraw());
   SetFullRootLayerDamage();
 }
 
 void LayerTreeHostImpl::SetOverdrawBottomHeight(float overdraw_bottom_height) {
   if (overdraw_bottom_height == overdraw_bottom_height_)
     return;
   overdraw_bottom_height_ = overdraw_bottom_height;
 
-  UpdateMaxScrollOffset();
   SetFullRootLayerDamage();
 }
 
 void LayerTreeHostImpl::SetOverhangUIResource(
     UIResourceId overhang_ui_resource_id,
     gfx::Size overhang_ui_resource_size) {
   overhang_ui_resource_id_ = overhang_ui_resource_id;
   overhang_ui_resource_size_ = overhang_ui_resource_size;
 }
 
 void LayerTreeHostImpl::SetDeviceScaleFactor(float device_scale_factor) {
   if (device_scale_factor == device_scale_factor_)
     return;
   device_scale_factor_ = device_scale_factor;
 
   if (renderer_)
     renderer_->ViewportChanged();
 
-  UpdateMaxScrollOffset();
   SetFullRootLayerDamage();
 }
 
 gfx::Size LayerTreeHostImpl::DrawViewportSize() const {
   return DeviceViewport().size();
 }
 
 gfx::Rect LayerTreeHostImpl::DeviceViewport() const {
   if (external_viewport_.IsEmpty())
     return gfx::Rect(device_viewport_size_);
 
   return external_viewport_;
 }
 
 gfx::Rect LayerTreeHostImpl::DeviceClip() const {
   if (external_clip_.IsEmpty())
     return DeviceViewport();
 
   return external_clip_;
 }
 
 const gfx::Transform& LayerTreeHostImpl::DrawTransform() const {
   return external_transform_;
 }
 
-void LayerTreeHostImpl::UpdateMaxScrollOffset() {
-  active_tree_->UpdateMaxScrollOffset();
-}
-
 void LayerTreeHostImpl::DidChangeTopControlsPosition() {
   client_->SetNeedsRedrawOnImplThread();
   active_tree_->set_needs_update_draw_properties();
   SetFullRootLayerDamage();
 }
 
 bool LayerTreeHostImpl::EnsureRenderSurfaceLayerList() {
   active_tree_->UpdateDrawProperties();
   return !active_tree_->RenderSurfaceLayerList().empty();
 }
@@ skipping 39 matching lines @@
     if (status == ScrollStarted && !potentially_scrolling_layer_impl)
       potentially_scrolling_layer_impl = scroll_layer_impl;
   }
 
   // When hiding top controls is enabled and the controls are hidden or
   // overlaying the content, force scrolls to be enabled on the root layer to
   // allow bringing the top controls back into view.
   if (!potentially_scrolling_layer_impl && top_controls_manager_ &&
       top_controls_manager_->content_top_offset() !=
       settings_.top_controls_height) {
-    potentially_scrolling_layer_impl = RootScrollLayer();
+    potentially_scrolling_layer_impl =
+        OuterViewportScrollLayer() ? OuterViewportScrollLayer()
+                                   : InnerViewportScrollLayer();
   }
 
   return potentially_scrolling_layer_impl;
 }
 
 InputHandler::ScrollStatus LayerTreeHostImpl::ScrollBegin(
     gfx::Point viewport_point, InputHandler::ScrollInputType type) {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::ScrollBegin");
 
   if (top_controls_manager_)
@@ skipping 15 matching lines @@
       FindScrollLayerForDeviceViewportPoint(device_viewport_point, type,
           layer_impl, &scroll_on_main_thread);
 
   if (scroll_on_main_thread) {
     UMA_HISTOGRAM_BOOLEAN("TryScroll.SlowScroll", true);
     return ScrollOnMainThread;
   }
 
   // If we want to send a DidOverscroll for this scroll it can't be ignored.
   if (!potentially_scrolling_layer_impl && settings_.always_overscroll)
-    potentially_scrolling_layer_impl = RootScrollLayer();
+    potentially_scrolling_layer_impl =
+        OuterViewportScrollLayer() ? OuterViewportScrollLayer()
+                                   : InnerViewportScrollLayer();
 
   if (potentially_scrolling_layer_impl) {
     active_tree_->SetCurrentlyScrollingLayer(
         potentially_scrolling_layer_impl);
     should_bubble_scrolls_ = (type != NonBubblingGesture);
     last_scroll_did_bubble_ = false;
     wheel_scrolling_ = (type == Wheel);
     client_->RenewTreePriority();
     UMA_HISTOGRAM_BOOLEAN("TryScroll.SlowScroll", false);
     return ScrollStarted;
@@ skipping 87 matching lines @@
 bool LayerTreeHostImpl::ScrollBy(gfx::Point viewport_point,
                                  gfx::Vector2dF scroll_delta) {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::ScrollBy");
   if (!CurrentlyScrollingLayer())
     return false;
 
   gfx::Vector2dF pending_delta = scroll_delta;
   gfx::Vector2dF unused_root_delta;
   bool did_scroll_x = false;
   bool did_scroll_y = false;
-  bool consume_by_top_controls = top_controls_manager_ &&
-      (CurrentlyScrollingLayer() == RootScrollLayer() || scroll_delta.y() < 0);
+  bool consume_by_top_controls =
+      top_controls_manager_ &&
+      (CurrentlyScrollingLayer() == InnerViewportScrollLayer() ||
+       scroll_delta.y() < 0);
   last_scroll_did_bubble_ = false;
 
   for (LayerImpl* layer_impl = CurrentlyScrollingLayer();
        layer_impl;
        layer_impl = layer_impl->parent()) {
     if (!layer_impl->scrollable())
       continue;
 
-    if (layer_impl == RootScrollLayer()) {
+    if (layer_impl == InnerViewportScrollLayer()) {
       // Only allow bubble scrolling when the scroll is in the direction to make
       // the top controls visible.
-      if (consume_by_top_controls && layer_impl == RootScrollLayer()) {
+      if (consume_by_top_controls && layer_impl == InnerViewportScrollLayer())
         pending_delta = top_controls_manager_->ScrollBy(pending_delta);
-        UpdateMaxScrollOffset();
-      }
       // Track root layer deltas for reporting overscroll.
       unused_root_delta = pending_delta;
     }
 
     gfx::Vector2dF applied_delta;
     // Gesture events need to be transformed from viewport coordinates to local
     // layer coordinates so that the scrolling contents exactly follow the
     // user's finger. In contrast, wheel events represent a fixed amount of
     // scrolling so we can just apply them directly.
     if (!wheel_scrolling_) {
@@ skipping 17 matching lines @@
         continue;
 
       if (should_bubble_scrolls_) {
         last_scroll_did_bubble_ = true;
         continue;
       }
 
       break;
     }
 
-    if (layer_impl == RootScrollLayer())
+    if (layer_impl == InnerViewportScrollLayer() ||
+        layer_impl == OuterViewportScrollLayer())
       unused_root_delta.Subtract(applied_delta);
 
     did_lock_scrolling_layer_ = true;
     if (!should_bubble_scrolls_) {
       active_tree_->SetCurrentlyScrollingLayer(layer_impl);
       break;
     }
 
     // If the applied delta is within 45 degrees of the input delta, bail out to
     // make it easier to scroll just one layer in one direction without
@@ skipping 46 matching lines @@
 bool LayerTreeHostImpl::ScrollVerticallyByPage(gfx::Point viewport_point,
                                                ScrollDirection direction) {
   DCHECK(wheel_scrolling_);
 
   for (LayerImpl* layer_impl = CurrentlyScrollingLayer();
        layer_impl;
        layer_impl = layer_impl->parent()) {
     if (!layer_impl->scrollable())
       continue;
 
-    if (!layer_impl->vertical_scrollbar_layer())
+    if (!layer_impl->HasScrollbar(VERTICAL))
       continue;
 
-    float height = layer_impl->vertical_scrollbar_layer()->bounds().height();
+    float height = layer_impl->clip_height();
 
     // These magical values match WebKit and are designed to scroll nearly the
     // entire visible content height but leave a bit of overlap.
     float page = std::max(height * 0.875f, 1.f);
     if (direction == SCROLL_BACKWARD)
       page = -page;
 
     gfx::Vector2dF delta = gfx::Vector2dF(0.f, page);
 
     gfx::Vector2dF applied_delta = ScrollLayerWithLocalDelta(layer_impl, delta);
@@ skipping 35 matching lines @@
     top_controls_manager_->ScrollEnd();
   ClearCurrentlyScrollingLayer();
   StartScrollbarAnimation();
 }
 
 InputHandler::ScrollStatus LayerTreeHostImpl::FlingScrollBegin() {
   if (!active_tree_->CurrentlyScrollingLayer())
     return ScrollIgnored;
 
   if (settings_.ignore_root_layer_flings &&
-      active_tree_->CurrentlyScrollingLayer() ==
-          active_tree_->RootScrollLayer()) {
+      (active_tree_->CurrentlyScrollingLayer() == InnerViewportScrollLayer() ||
+       active_tree_->CurrentlyScrollingLayer() == OuterViewportScrollLayer())) {
     ClearCurrentlyScrollingLayer();
     return ScrollIgnored;
   }
 
   if (!wheel_scrolling_)
     should_bubble_scrolls_ = last_scroll_did_bubble_;
 
   return ScrollStarted;
 }
 
@@ skipping 50 matching lines @@
       device_viewport_point, InputHandler::Gesture, layer_impl,
       &scroll_on_main_thread);
   if (scroll_on_main_thread || !scroll_layer_impl)
     return;
 
   ScrollbarAnimationController* animation_controller =
       scroll_layer_impl->scrollbar_animation_controller();
   if (!animation_controller)
     return;
 
-  float distance_to_scrollbar = std::min(
-      DeviceSpaceDistanceToLayer(device_viewport_point,
-          scroll_layer_impl->horizontal_scrollbar_layer()),
-      DeviceSpaceDistanceToLayer(device_viewport_point,
-          scroll_layer_impl->vertical_scrollbar_layer()));
+  // TODO(wjmaclean) Is it ok to choose distance from more than two scrollbars?

[enne (OOO), 2013/11/19 19:30:22]

Ask tony@ what's desired here.

[wjmaclean, 2013/12/24 21:03:49]

I have asked Tony, will report back when I hear.

[tony, 2013/12/26 21:06:50]

This is fine for now.  The old code would animate both scrollbars if the mouse
pointer was close enough to either scrollbar.  This maintains that behavior,
which seems fine for now.

+  float distance_to_scrollbar = std::numeric_limits<float>::max();
+  for (LayerImpl::ScrollbarSet::iterator it =
+           scroll_layer_impl->scrollbars()->begin();
+       it != scroll_layer_impl->scrollbars()->end();
+       ++it)
+    distance_to_scrollbar = std::min(distance_to_scrollbar,
+        DeviceSpaceDistanceToLayer(device_viewport_point, *it));
 
   bool should_animate = animation_controller->DidMouseMoveNear(
       CurrentPhysicalTimeTicks(), distance_to_scrollbar / device_scale_factor_);
   if (should_animate)
     StartScrollbarAnimation();
 }
 
 bool LayerTreeHostImpl::HandleMouseOverScrollbar(LayerImpl* layer_impl,
     gfx::PointF device_viewport_point) {
   if (layer_impl && layer_impl->ToScrollbarLayer()) {
@@ skipping 14 matching lines @@
   }
 
   return false;
 }
 
 void LayerTreeHostImpl::PinchGestureBegin() {
   pinch_gesture_active_ = true;
   previous_pinch_anchor_ = gfx::Point();
   client_->RenewTreePriority();
   pinch_gesture_end_should_clear_scrolling_layer_ = !CurrentlyScrollingLayer();
-  active_tree_->SetCurrentlyScrollingLayer(RootScrollLayer());
+  if (active_tree_->OuterViewportScrollLayer()) {
+    active_tree_->SetCurrentlyScrollingLayer(
+        active_tree_->OuterViewportScrollLayer());
+  } else {
+    active_tree_->SetCurrentlyScrollingLayer(
+        active_tree_->InnerViewportScrollLayer());
+  }
   if (top_controls_manager_)
     top_controls_manager_->PinchBegin();
 }
 
 void LayerTreeHostImpl::PinchGestureUpdate(float magnify_delta,
                                            gfx::Point anchor) {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::PinchGestureUpdate");
 
-  if (!RootScrollLayer())
+  LayerImpl* pinch_scroll_layer = CurrentlyScrollingLayer();
+  if (!pinch_scroll_layer)
+    pinch_scroll_layer = InnerViewportScrollLayer();
+
+  if (!pinch_scroll_layer)
     return;
 
   // Keep the center-of-pinch anchor specified by (x, y) in a stable
   // position over the course of the magnify.
   float page_scale_delta = active_tree_->page_scale_delta();
   gfx::PointF previous_scale_anchor =
       gfx::ScalePoint(anchor, 1.f / page_scale_delta);
   active_tree_->SetPageScaleDelta(page_scale_delta * magnify_delta);
   page_scale_delta = active_tree_->page_scale_delta();
   gfx::PointF new_scale_anchor =
       gfx::ScalePoint(anchor, 1.f / page_scale_delta);
   gfx::Vector2dF move = previous_scale_anchor - new_scale_anchor;
 
   previous_pinch_anchor_ = anchor;
 
   move.Scale(1 / active_tree_->page_scale_factor());
+  // When shrinking the page, the current scroll offset of the inner viewport
+  // scroll layer may need to be adjusted so that it doesn't exceed its maximum
+  // at the new page scale factor.
+  if (magnify_delta < 1.f) {
+    // If clamping the inner viewport scroll offset causes a change, it should
+    // be accounted for from the intended move.
+    move -= InnerViewportScrollLayer()->ClampScrollToMaxScrollOffset();
+  }
 
-  RootScrollLayer()->ScrollBy(move);
+  // We manually manage the bubbling behaviour here as it is different to that

[enne (OOO), 2013/11/14 22:59:01]

Huh! I had hoped we wouldn't have to special case thsi, but these are all good
reasons.

[enne (OOO), 2013/11/19 19:30:22]

These changes in LayerTreeHostImpl about handling multiple viewports definitely
need a bunch of unit tests.  Unit tests with and without page scale, testing
bubbling while scrolling, and testing scroll offset changes when pinching, unit
tests with a scroll offset delegate.

[wjmaclean, 2013/12/24 21:03:49]

Since we only have multiple viewports when the flag is on, and since this CL
doesn't turn the flag on, I assume it suffices for this CL to pass with existing
tests, and the new tests can come with the follow on CL to turn on the flag?

[wjmaclean, 2013/12/24 21:03:49]

Agreed!

+  // implemented in LayerTreeHostImpl::ScrollBy(). Specifically:
+  // 1) we want to explicit limit the bubbling to the outer/inner viewports,
+  // 2) we don't want the directional limitations on the unused parts that
+  //    ScrollBy() implements, and
+  // 3) pinching should not engage the top controls manager.
+  gfx::Vector2dF unused = pinch_scroll_layer->ScrollBy(move);
+
+  if (!unused.IsZero() && pinch_scroll_layer == OuterViewportScrollLayer()) {
+    InnerViewportScrollLayer()->ScrollBy(unused);
+    InnerViewportScrollLayer()->ClampScrollToMaxScrollOffset();
+    active_tree_->SetCurrentlyScrollingLayer(
+        active_tree_->InnerViewportScrollLayer());
+  }
 
   client_->SetNeedsCommitOnImplThread();
   client_->SetNeedsRedrawOnImplThread();
   client_->RenewTreePriority();
 }
 
 void LayerTreeHostImpl::PinchGestureEnd() {
   pinch_gesture_active_ = false;
   if (pinch_gesture_end_should_clear_scrolling_layer_) {
     pinch_gesture_end_should_clear_scrolling_layer_ = false;
@@ skipping 31 matching lines @@
   active_tree_->set_sent_page_scale_delta(scroll_info->page_scale_delta);
 
   return scroll_info.Pass();
 }
 
 void LayerTreeHostImpl::SetFullRootLayerDamage() {
   SetViewportDamage(gfx::Rect(DrawViewportSize()));
 }
 
 void LayerTreeHostImpl::AnimatePageScale(base::TimeTicks time) {
-  if (!page_scale_animation_ || !RootScrollLayer())
+  if (!page_scale_animation_)
     return;
 
   double monotonic_time = (time - base::TimeTicks()).InSecondsF();
-  gfx::Vector2dF scroll_total = RootScrollLayer()->scroll_offset() +
-                                RootScrollLayer()->ScrollDelta();
+  gfx::Vector2dF scroll_total = active_tree_->TotalScrollOffset();
 
   if (!page_scale_animation_->IsAnimationStarted())
     page_scale_animation_->StartAnimation(monotonic_time);
 
   active_tree_->SetPageScaleDelta(
       page_scale_animation_->PageScaleFactorAtTime(monotonic_time) /
       active_tree_->page_scale_factor());
   gfx::Vector2dF next_scroll =
       page_scale_animation_->ScrollOffsetAtTime(monotonic_time);
 
-  RootScrollLayer()->ScrollBy(next_scroll - scroll_total);
+  ScrollBy(gfx::Point(), next_scroll - scroll_total);
   client_->SetNeedsRedrawOnImplThread();
 
   if (page_scale_animation_->IsAnimationCompleteAtTime(monotonic_time)) {
     page_scale_animation_.reset();
     client_->SetNeedsCommitOnImplThread();
     client_->RenewTreePriority();
   }
 }
 
 void LayerTreeHostImpl::AnimateTopControls(base::TimeTicks time) {
-  if (!top_controls_manager_ || !RootScrollLayer())
+  if (!top_controls_manager_)
     return;
   gfx::Vector2dF scroll = top_controls_manager_->Animate(time);
-  UpdateMaxScrollOffset();
-  if (RootScrollLayer()->TotalScrollOffset().y() == 0.f)
+  if (active_tree_->TotalScrollOffset().y() == 0.f)
     return;
-  RootScrollLayer()->ScrollBy(gfx::ScaleVector2d(
-      scroll, 1.f / active_tree_->total_page_scale_factor()));
+  ScrollBy(gfx::Point(),
+           gfx::ScaleVector2d(scroll,
+                              1.f / active_tree_->total_page_scale_factor()));
 }
 
 void LayerTreeHostImpl::AnimateLayers(base::TimeTicks monotonic_time,
                                       base::Time wall_clock_time) {
   if (!settings_.accelerated_animation_enabled ||
       animation_registrar_->active_animation_controllers().empty() ||
       !active_tree_->root_layer())
     return;
 
   TRACE_EVENT0("cc", "LayerTreeHostImpl::AnimateLayers");
@@ skipping 321 matching lines @@
   std::set<UIResourceId>::iterator found_in_evicted =
       evicted_ui_resources_.find(uid);
   if (found_in_evicted == evicted_ui_resources_.end())
     return;
   evicted_ui_resources_.erase(found_in_evicted);
   if (evicted_ui_resources_.empty())
     client_->OnCanDrawStateChanged(CanDraw());
 }
 
 }  // namespace cc