cc/trees/layer_tree_impl.cc

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/trees/layer_tree_impl.h"
   6
   7 #include <limits>
   8 #include <set>
   9
  10 #include "base/debug/trace_event.h"
  11 #include "base/debug/trace_event_argument.h"
  12 #include "cc/animation/keyframed_animation_curve.h"
  13 #include "cc/animation/scrollbar_animation_controller.h"
  14 #include "cc/animation/scrollbar_animation_controller_linear_fade.h"
  15 #include "cc/animation/scrollbar_animation_controller_thinning.h"
  16 #include "cc/base/math_util.h"
  17 #include "cc/base/util.h"
  18 #include "cc/debug/devtools_instrumentation.h"
  19 #include "cc/debug/traced_value.h"
  20 #include "cc/layers/heads_up_display_layer_impl.h"
  21 #include "cc/layers/layer.h"
  22 #include "cc/layers/layer_iterator.h"
  23 #include "cc/layers/render_surface_impl.h"
  24 #include "cc/layers/scrollbar_layer_impl_base.h"
  25 #include "cc/resources/ui_resource_request.h"
  26 #include "cc/trees/layer_tree_host_common.h"
  27 #include "cc/trees/layer_tree_host_impl.h"
  28 #include "cc/trees/occlusion_tracker.h"
  29 #include "ui/gfx/point_conversions.h"
  30 #include "ui/gfx/size_conversions.h"
  31 #include "ui/gfx/vector2d_conversions.h"
  32
  33 namespace cc {
  34
  35 // This class exists to split the LayerScrollOffsetDelegate between the
  36 // InnerViewportScrollLayer and the OuterViewportScrollLayer in a manner
  37 // that never requires the embedder or LayerImpl to know about.
  38 class LayerScrollOffsetDelegateProxy : public LayerImpl::ScrollOffsetDelegate {
  39  public:
  40   LayerScrollOffsetDelegateProxy(LayerImpl* layer,
  41                                  LayerScrollOffsetDelegate* delegate,
  42                                  LayerTreeImpl* layer_tree)
  43       : layer_(layer), delegate_(delegate), layer_tree_impl_(layer_tree) {}
  44   virtual ~LayerScrollOffsetDelegateProxy() {}
  45
  46   gfx::Vector2dF last_set_scroll_offset() const {
  47     return last_set_scroll_offset_;
  48   }
  49
  50   // LayerScrollOffsetDelegate implementation.
  51   virtual void SetTotalScrollOffset(const gfx::Vector2dF& new_offset) OVERRIDE {
  52     last_set_scroll_offset_ = new_offset;
  53     layer_tree_impl_->UpdateScrollOffsetDelegate();
  54   }
  55
  56   virtual gfx::Vector2dF GetTotalScrollOffset() OVERRIDE {
  57     return layer_tree_impl_->GetDelegatedScrollOffset(layer_);
  58   }
  59
  60   virtual bool IsExternalFlingActive() const OVERRIDE {
  61     return delegate_->IsExternalFlingActive();
  62   }
  63
  64  private:
  65   LayerImpl* layer_;
  66   LayerScrollOffsetDelegate* delegate_;
  67   LayerTreeImpl* layer_tree_impl_;
  68   gfx::Vector2dF last_set_scroll_offset_;
  69 };
  70
  71 LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
  72     : layer_tree_host_impl_(layer_tree_host_impl),
  73       source_frame_number_(-1),
  74       hud_layer_(0),
  75       currently_scrolling_layer_(NULL),
  76       root_layer_scroll_offset_delegate_(NULL),
  77       background_color_(0),
  78       has_transparent_background_(false),
  79       page_scale_layer_(NULL),
  80       inner_viewport_scroll_layer_(NULL),
  81       outer_viewport_scroll_layer_(NULL),
  82       page_scale_factor_(1),
  83       page_scale_delta_(1),
  84       sent_page_scale_delta_(1),
  85       min_page_scale_factor_(0),
  86       max_page_scale_factor_(0),
  87       scrolling_layer_id_from_previous_tree_(0),
  88       contents_textures_purged_(false),
  89       requires_high_res_to_draw_(false),
  90       viewport_size_invalid_(false),
  91       needs_update_draw_properties_(true),
  92       needs_full_tree_sync_(true),
  93       next_activation_forces_redraw_(false),
  94       has_ever_been_drawn_(false),
  95       render_surface_layer_list_id_(0) {
  96 }
  97
  98 LayerTreeImpl::~LayerTreeImpl() {
  99   BreakSwapPromises(SwapPromise::SWAP_FAILS);
 100
 101   // Need to explicitly clear the tree prior to destroying this so that
 102   // the LayerTreeImpl pointer is still valid in the LayerImpl dtor.
 103   DCHECK(!root_layer_);
 104   DCHECK(layers_with_copy_output_request_.empty());
 105 }
 106
 107 void LayerTreeImpl::Shutdown() { root_layer_.reset(); }
 108
 109 void LayerTreeImpl::ReleaseResources() {
 110   if (root_layer_)
 111     ReleaseResourcesRecursive(root_layer_.get());
 112 }
 113
 114 void LayerTreeImpl::SetRootLayer(scoped_ptr<LayerImpl> layer) {
 115   if (inner_viewport_scroll_layer_)
 116     inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 117   if (outer_viewport_scroll_layer_)
 118     outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 119   inner_viewport_scroll_delegate_proxy_.reset();
 120   outer_viewport_scroll_delegate_proxy_.reset();
 121
 122   root_layer_ = layer.Pass();
 123   currently_scrolling_layer_ = NULL;
 124   inner_viewport_scroll_layer_ = NULL;
 125   outer_viewport_scroll_layer_ = NULL;
 126   page_scale_layer_ = NULL;
 127
 128   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 129 }
 130
 131 LayerImpl* LayerTreeImpl::InnerViewportScrollLayer() const {
 132   return inner_viewport_scroll_layer_;
 133 }
 134
 135 LayerImpl* LayerTreeImpl::OuterViewportScrollLayer() const {
 136   return outer_viewport_scroll_layer_;
 137 }
 138
 139 gfx::Vector2dF LayerTreeImpl::TotalScrollOffset() const {
 140   gfx::Vector2dF offset;
 141
 142   if (inner_viewport_scroll_layer_)
 143     offset += inner_viewport_scroll_layer_->TotalScrollOffset();
 144
 145   if (outer_viewport_scroll_layer_)
 146     offset += outer_viewport_scroll_layer_->TotalScrollOffset();
 147
 148   return offset;
 149 }
 150
 151 gfx::Vector2dF LayerTreeImpl::TotalMaxScrollOffset() const {
 152   gfx::Vector2dF offset;
 153
 154   if (inner_viewport_scroll_layer_)
 155     offset += inner_viewport_scroll_layer_->MaxScrollOffset();
 156
 157   if (outer_viewport_scroll_layer_)
 158     offset += outer_viewport_scroll_layer_->MaxScrollOffset();
 159
 160   return offset;
 161 }
 162 gfx::Vector2dF LayerTreeImpl::TotalScrollDelta() const {
 163   DCHECK(inner_viewport_scroll_layer_);
 164   gfx::Vector2dF delta = inner_viewport_scroll_layer_->ScrollDelta();
 165
 166   if (outer_viewport_scroll_layer_)
 167     delta += outer_viewport_scroll_layer_->ScrollDelta();
 168
 169   return delta;
 170 }
 171
 172 scoped_ptr<LayerImpl> LayerTreeImpl::DetachLayerTree() {
 173   // Clear all data structures that have direct references to the layer tree.
 174   scrolling_layer_id_from_previous_tree_ =
 175     currently_scrolling_layer_ ? currently_scrolling_layer_->id() : 0;
 176   if (inner_viewport_scroll_layer_)
 177     inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 178   if (outer_viewport_scroll_layer_)
 179     outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 180   inner_viewport_scroll_delegate_proxy_.reset();
 181   outer_viewport_scroll_delegate_proxy_.reset();
 182   inner_viewport_scroll_layer_ = NULL;
 183   outer_viewport_scroll_layer_ = NULL;
 184   page_scale_layer_ = NULL;
 185   currently_scrolling_layer_ = NULL;
 186
 187   render_surface_layer_list_.clear();
 188   set_needs_update_draw_properties();
 189   return root_layer_.Pass();
 190 }
 191
 192 void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
 193   // The request queue should have been processed and does not require a push.
 194   DCHECK_EQ(ui_resource_request_queue_.size(), 0u);
 195
 196   if (next_activation_forces_redraw_) {
 197     target_tree->ForceRedrawNextActivation();
 198     next_activation_forces_redraw_ = false;
 199   }
 200
 201   target_tree->PassSwapPromises(&swap_promise_list_);
 202
 203   target_tree->SetPageScaleValues(
 204       page_scale_factor(), min_page_scale_factor(), max_page_scale_factor(),
 205       target_tree->page_scale_delta() / target_tree->sent_page_scale_delta());
 206   target_tree->set_sent_page_scale_delta(1);
 207
 208   if (page_scale_layer_ && inner_viewport_scroll_layer_) {
 209     target_tree->SetViewportLayersFromIds(
 210         page_scale_layer_->id(),
 211         inner_viewport_scroll_layer_->id(),
 212         outer_viewport_scroll_layer_ ? outer_viewport_scroll_layer_->id()
 213                                      : Layer::INVALID_ID);
 214   } else {
 215     target_tree->ClearViewportLayers();
 216   }
 217
 218   target_tree->RegisterSelection(selection_start_, selection_end_);
 219
 220   // This should match the property synchronization in
 221   // LayerTreeHost::finishCommitOnImplThread().
 222   target_tree->set_source_frame_number(source_frame_number());
 223   target_tree->set_background_color(background_color());
 224   target_tree->set_has_transparent_background(has_transparent_background());
 225
 226   if (ContentsTexturesPurged())
 227     target_tree->SetContentsTexturesPurged();
 228   else
 229     target_tree->ResetContentsTexturesPurged();
 230
 231   if (ViewportSizeInvalid())
 232     target_tree->SetViewportSizeInvalid();
 233   else
 234     target_tree->ResetViewportSizeInvalid();
 235
 236   if (hud_layer())
 237     target_tree->set_hud_layer(static_cast<HeadsUpDisplayLayerImpl*>(
 238         LayerTreeHostCommon::FindLayerInSubtree(
 239             target_tree->root_layer(), hud_layer()->id())));
 240   else
 241     target_tree->set_hud_layer(NULL);
 242
 243   target_tree->has_ever_been_drawn_ = false;
 244 }
 245
 246 LayerImpl* LayerTreeImpl::InnerViewportContainerLayer() const {
 247   return inner_viewport_scroll_layer_
 248              ? inner_viewport_scroll_layer_->scroll_clip_layer()
 249              : NULL;
 250 }
 251
 252 LayerImpl* LayerTreeImpl::CurrentlyScrollingLayer() const {
 253   DCHECK(IsActiveTree());
 254   return currently_scrolling_layer_;
 255 }
 256
 257 void LayerTreeImpl::SetCurrentlyScrollingLayer(LayerImpl* layer) {
 258   if (currently_scrolling_layer_ == layer)
 259     return;
 260
 261   if (currently_scrolling_layer_ &&
 262       currently_scrolling_layer_->scrollbar_animation_controller())
 263     currently_scrolling_layer_->scrollbar_animation_controller()
 264         ->DidScrollEnd();
 265   currently_scrolling_layer_ = layer;
 266   if (layer && layer->scrollbar_animation_controller())
 267     layer->scrollbar_animation_controller()->DidScrollBegin();
 268 }
 269
 270 void LayerTreeImpl::ClearCurrentlyScrollingLayer() {
 271   SetCurrentlyScrollingLayer(NULL);
 272   scrolling_layer_id_from_previous_tree_ = 0;
 273 }
 274
 275 namespace {
 276
 277 void ForceScrollbarParameterUpdateAfterScaleChange(LayerImpl* current_layer) {
 278   if (!current_layer)
 279     return;
 280
 281   while (current_layer) {
 282     current_layer->ScrollbarParametersDidChange();
 283     current_layer = current_layer->parent();
 284   }
 285 }
 286
 287 }  // namespace
 288
 289 void LayerTreeImpl::SetPageScaleFactorAndLimits(float page_scale_factor,
 290     float min_page_scale_factor, float max_page_scale_factor) {
 291   SetPageScaleValues(page_scale_factor, min_page_scale_factor,
 292       max_page_scale_factor, page_scale_delta_);
 293 }
 294
 295 void LayerTreeImpl::SetPageScaleDelta(float delta) {
 296   SetPageScaleValues(page_scale_factor_, min_page_scale_factor_,
 297       max_page_scale_factor_, delta);
 298 }
 299
 300 void LayerTreeImpl::SetPageScaleValues(float page_scale_factor,
 301       float min_page_scale_factor, float max_page_scale_factor,
 302       float page_scale_delta) {
 303   bool page_scale_changed =
 304       min_page_scale_factor != min_page_scale_factor_ ||
 305       max_page_scale_factor != max_page_scale_factor_ ||
 306       page_scale_factor != page_scale_factor_;
 307
 308   min_page_scale_factor_ = min_page_scale_factor;
 309   max_page_scale_factor_ = max_page_scale_factor;
 310   page_scale_factor_ = page_scale_factor;
 311
 312   float total = page_scale_factor_ * page_scale_delta;
 313   if (min_page_scale_factor_ && total < min_page_scale_factor_)
 314     page_scale_delta = min_page_scale_factor_ / page_scale_factor_;
 315   else if (max_page_scale_factor_ && total > max_page_scale_factor_)
 316     page_scale_delta = max_page_scale_factor_ / page_scale_factor_;
 317
 318   if (page_scale_delta_ == page_scale_delta && !page_scale_changed)
 319     return;
 320
 321   if (page_scale_delta_ != page_scale_delta) {
 322     page_scale_delta_ = page_scale_delta;
 323
 324     if (IsActiveTree()) {
 325       LayerTreeImpl* pending_tree = layer_tree_host_impl_->pending_tree();
 326       if (pending_tree) {
 327         DCHECK_EQ(1, pending_tree->sent_page_scale_delta());
 328         pending_tree->SetPageScaleDelta(
 329             page_scale_delta_ / sent_page_scale_delta_);
 330       }
 331     }
 332
 333     set_needs_update_draw_properties();
 334   }
 335
 336   if (root_layer_scroll_offset_delegate_) {
 337     root_layer_scroll_offset_delegate_->UpdateRootLayerState(
 338         TotalScrollOffset(),
 339         TotalMaxScrollOffset(),
 340         ScrollableSize(),
 341         total_page_scale_factor(),
 342         min_page_scale_factor_,
 343         max_page_scale_factor_);
 344   }
 345
 346   ForceScrollbarParameterUpdateAfterScaleChange(page_scale_layer());
 347 }
 348
 349 gfx::SizeF LayerTreeImpl::ScrollableViewportSize() const {
 350   if (!InnerViewportContainerLayer())
 351     return gfx::SizeF();
 352
 353   return gfx::ScaleSize(InnerViewportContainerLayer()->bounds(),
 354                         1.0f / total_page_scale_factor());
 355 }
 356
 357 gfx::Rect LayerTreeImpl::RootScrollLayerDeviceViewportBounds() const {
 358   LayerImpl* root_scroll_layer = OuterViewportScrollLayer()
 359                                      ? OuterViewportScrollLayer()
 360                                      : InnerViewportScrollLayer();
 361   if (!root_scroll_layer || root_scroll_layer->children().empty())
 362     return gfx::Rect();
 363   LayerImpl* layer = root_scroll_layer->children()[0];
 364   return MathUtil::MapEnclosingClippedRect(layer->screen_space_transform(),
 365                                            gfx::Rect(layer->content_bounds()));
 366 }
 367
 368 static void ApplySentScrollDeltasFromAbortedCommitTo(LayerImpl* layer) {
 369   layer->ApplySentScrollDeltasFromAbortedCommit();
 370 }
 371
 372 void LayerTreeImpl::ApplySentScrollAndScaleDeltasFromAbortedCommit() {
 373   DCHECK(IsActiveTree());
 374
 375   page_scale_factor_ *= sent_page_scale_delta_;
 376   page_scale_delta_ /= sent_page_scale_delta_;
 377   sent_page_scale_delta_ = 1.f;
 378
 379   if (!root_layer())
 380     return;
 381
 382   LayerTreeHostCommon::CallFunctionForSubtree(
 383       root_layer(), base::Bind(&ApplySentScrollDeltasFromAbortedCommitTo));
 384 }
 385
 386 static void ApplyScrollDeltasSinceBeginMainFrameTo(LayerImpl* layer) {
 387   layer->ApplyScrollDeltasSinceBeginMainFrame();
 388 }
 389
 390 void LayerTreeImpl::ApplyScrollDeltasSinceBeginMainFrame() {
 391   DCHECK(IsPendingTree());
 392   if (!root_layer())
 393     return;
 394
 395   LayerTreeHostCommon::CallFunctionForSubtree(
 396       root_layer(), base::Bind(&ApplyScrollDeltasSinceBeginMainFrameTo));
 397 }
 398
 399 void LayerTreeImpl::SetViewportLayersFromIds(
 400     int page_scale_layer_id,
 401     int inner_viewport_scroll_layer_id,
 402     int outer_viewport_scroll_layer_id) {
 403   page_scale_layer_ = LayerById(page_scale_layer_id);
 404   DCHECK(page_scale_layer_);
 405
 406   inner_viewport_scroll_layer_ =
 407       LayerById(inner_viewport_scroll_layer_id);
 408   DCHECK(inner_viewport_scroll_layer_);
 409
 410   outer_viewport_scroll_layer_ =
 411       LayerById(outer_viewport_scroll_layer_id);
 412   DCHECK(outer_viewport_scroll_layer_ ||
 413          outer_viewport_scroll_layer_id == Layer::INVALID_ID);
 414
 415   if (!root_layer_scroll_offset_delegate_)
 416     return;
 417
 418   inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 419       new LayerScrollOffsetDelegateProxy(inner_viewport_scroll_layer_,
 420                                          root_layer_scroll_offset_delegate_,
 421                                          this));
 422
 423   if (outer_viewport_scroll_layer_)
 424     outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 425         new LayerScrollOffsetDelegateProxy(outer_viewport_scroll_layer_,
 426                                            root_layer_scroll_offset_delegate_,
 427                                            this));
 428 }
 429
 430 void LayerTreeImpl::ClearViewportLayers() {
 431   page_scale_layer_ = NULL;
 432   inner_viewport_scroll_layer_ = NULL;
 433   outer_viewport_scroll_layer_ = NULL;
 434 }
 435
 436 bool LayerTreeImpl::UpdateDrawProperties() {
 437   if (!needs_update_draw_properties_)
 438     return true;
 439
 440   // For max_texture_size.
 441   if (!layer_tree_host_impl_->renderer())
 442     return false;
 443
 444   if (!root_layer())
 445     return false;
 446
 447   needs_update_draw_properties_ = false;
 448   render_surface_layer_list_.clear();
 449
 450   {
 451     TRACE_EVENT2("cc",
 452                  "LayerTreeImpl::UpdateDrawProperties",
 453                  "IsActive",
 454                  IsActiveTree(),
 455                  "SourceFrameNumber",
 456                  source_frame_number_);
 457     LayerImpl* page_scale_layer =
 458         page_scale_layer_ ? page_scale_layer_ : InnerViewportContainerLayer();
 459     bool can_render_to_separate_surface =
 460         (layer_tree_host_impl_->GetDrawMode() !=
 461          DRAW_MODE_RESOURCELESS_SOFTWARE);
 462
 463     ++render_surface_layer_list_id_;
 464     LayerTreeHostCommon::CalcDrawPropsImplInputs inputs(
 465         root_layer(),
 466         DrawViewportSize(),
 467         layer_tree_host_impl_->DrawTransform(),
 468         device_scale_factor(),
 469         total_page_scale_factor(),
 470         page_scale_layer,
 471         resource_provider()->max_texture_size(),
 472         settings().can_use_lcd_text,
 473         can_render_to_separate_surface,
 474         settings().layer_transforms_should_scale_layer_contents,
 475         &render_surface_layer_list_,
 476         render_surface_layer_list_id_);
 477     LayerTreeHostCommon::CalculateDrawProperties(&inputs);
 478   }
 479
 480   {
 481     TRACE_EVENT2("cc",
 482                  "LayerTreeImpl::UpdateTilePriorities",
 483                  "IsActive",
 484                  IsActiveTree(),
 485                  "SourceFrameNumber",
 486                  source_frame_number_);
 487     scoped_ptr<OcclusionTracker<LayerImpl> > occlusion_tracker;
 488     if (settings().use_occlusion_for_tile_prioritization) {
 489       occlusion_tracker.reset(new OcclusionTracker<LayerImpl>(
 490           root_layer()->render_surface()->content_rect()));
 491       occlusion_tracker->set_minimum_tracking_size(
 492           settings().minimum_occlusion_tracking_size);
 493     }
 494
 495     // LayerIterator is used here instead of CallFunctionForSubtree to only
 496     // UpdateTilePriorities on layers that will be visible (and thus have valid
 497     // draw properties) and not because any ordering is required.
 498     typedef LayerIterator<LayerImpl> LayerIteratorType;
 499     LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
 500     for (LayerIteratorType it =
 501              LayerIteratorType::Begin(&render_surface_layer_list_);
 502          it != end;
 503          ++it) {
 504       if (occlusion_tracker)
 505         occlusion_tracker->EnterLayer(it);
 506
 507       LayerImpl* layer = *it;
 508       if (it.represents_itself())
 509         layer->UpdateTiles(occlusion_tracker.get());
 510
 511       if (!it.represents_contributing_render_surface()) {
 512         if (occlusion_tracker)
 513           occlusion_tracker->LeaveLayer(it);
 514         continue;
 515       }
 516
 517       if (layer->mask_layer())
 518         layer->mask_layer()->UpdateTiles(occlusion_tracker.get());
 519       if (layer->replica_layer() && layer->replica_layer()->mask_layer())
 520         layer->replica_layer()->mask_layer()->UpdateTiles(
 521             occlusion_tracker.get());
 522
 523       if (occlusion_tracker)
 524         occlusion_tracker->LeaveLayer(it);
 525     }
 526   }
 527
 528   DCHECK(!needs_update_draw_properties_) <<
 529       "CalcDrawProperties should not set_needs_update_draw_properties()";
 530   return true;
 531 }
 532
 533 const LayerImplList& LayerTreeImpl::RenderSurfaceLayerList() const {
 534   // If this assert triggers, then the list is dirty.
 535   DCHECK(!needs_update_draw_properties_);
 536   return render_surface_layer_list_;
 537 }
 538
 539 gfx::Size LayerTreeImpl::ScrollableSize() const {
 540   LayerImpl* root_scroll_layer = OuterViewportScrollLayer()
 541                                      ? OuterViewportScrollLayer()
 542                                      : InnerViewportScrollLayer();
 543   if (!root_scroll_layer || root_scroll_layer->children().empty())
 544     return gfx::Size();
 545   return root_scroll_layer->children()[0]->bounds();
 546 }
 547
 548 LayerImpl* LayerTreeImpl::LayerById(int id) {
 549   LayerIdMap::iterator iter = layer_id_map_.find(id);
 550   return iter != layer_id_map_.end() ? iter->second : NULL;
 551 }
 552
 553 void LayerTreeImpl::RegisterLayer(LayerImpl* layer) {
 554   DCHECK(!LayerById(layer->id()));
 555   layer_id_map_[layer->id()] = layer;
 556 }
 557
 558 void LayerTreeImpl::UnregisterLayer(LayerImpl* layer) {
 559   DCHECK(LayerById(layer->id()));
 560   layer_id_map_.erase(layer->id());
 561 }
 562
 563 size_t LayerTreeImpl::NumLayers() {
 564   return layer_id_map_.size();
 565 }
 566
 567 void LayerTreeImpl::PushPersistedState(LayerTreeImpl* pending_tree) {
 568   pending_tree->SetCurrentlyScrollingLayer(
 569       LayerTreeHostCommon::FindLayerInSubtree(pending_tree->root_layer(),
 570           currently_scrolling_layer_ ? currently_scrolling_layer_->id() : 0));
 571 }
 572
 573 static void DidBecomeActiveRecursive(LayerImpl* layer) {
 574   layer->DidBecomeActive();
 575   if (layer->mask_layer())
 576     layer->mask_layer()->DidBecomeActive();
 577   if (layer->replica_layer() && layer->replica_layer()->mask_layer())
 578     layer->replica_layer()->mask_layer()->DidBecomeActive();
 579
 580   for (size_t i = 0; i < layer->children().size(); ++i)
 581     DidBecomeActiveRecursive(layer->children()[i]);
 582 }
 583
 584 void LayerTreeImpl::DidBecomeActive() {
 585   if (next_activation_forces_redraw_) {
 586     layer_tree_host_impl_->SetFullRootLayerDamage();
 587     next_activation_forces_redraw_ = false;
 588   }
 589
 590   if (scrolling_layer_id_from_previous_tree_) {
 591     currently_scrolling_layer_ = LayerTreeHostCommon::FindLayerInSubtree(
 592         root_layer(), scrolling_layer_id_from_previous_tree_);
 593   }
 594
 595   // Always reset this flag on activation, as we would only have activated
 596   // if we were in a good state.
 597   ResetRequiresHighResToDraw();
 598
 599   if (root_layer())
 600     DidBecomeActiveRecursive(root_layer());
 601
 602   devtools_instrumentation::DidActivateLayerTree(layer_tree_host_impl_->id(),
 603                                                  source_frame_number_);
 604 }
 605
 606 bool LayerTreeImpl::ContentsTexturesPurged() const {
 607   return contents_textures_purged_;
 608 }
 609
 610 void LayerTreeImpl::SetContentsTexturesPurged() {
 611   if (contents_textures_purged_)
 612     return;
 613   contents_textures_purged_ = true;
 614   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 615 }
 616
 617 void LayerTreeImpl::ResetContentsTexturesPurged() {
 618   if (!contents_textures_purged_)
 619     return;
 620   contents_textures_purged_ = false;
 621   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 622 }
 623
 624 void LayerTreeImpl::SetRequiresHighResToDraw() {
 625   requires_high_res_to_draw_ = true;
 626 }
 627
 628 void LayerTreeImpl::ResetRequiresHighResToDraw() {
 629   requires_high_res_to_draw_ = false;
 630 }
 631
 632 bool LayerTreeImpl::RequiresHighResToDraw() const {
 633   return requires_high_res_to_draw_;
 634 }
 635
 636 bool LayerTreeImpl::ViewportSizeInvalid() const {
 637   return viewport_size_invalid_;
 638 }
 639
 640 void LayerTreeImpl::SetViewportSizeInvalid() {
 641   viewport_size_invalid_ = true;
 642   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 643 }
 644
 645 void LayerTreeImpl::ResetViewportSizeInvalid() {
 646   viewport_size_invalid_ = false;
 647   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 648 }
 649
 650 Proxy* LayerTreeImpl::proxy() const {
 651   return layer_tree_host_impl_->proxy();
 652 }
 653
 654 const LayerTreeSettings& LayerTreeImpl::settings() const {
 655   return layer_tree_host_impl_->settings();
 656 }
 657
 658 const RendererCapabilitiesImpl& LayerTreeImpl::GetRendererCapabilities() const {
 659   return layer_tree_host_impl_->GetRendererCapabilities();
 660 }
 661
 662 ContextProvider* LayerTreeImpl::context_provider() const {
 663   return output_surface()->context_provider();
 664 }
 665
 666 OutputSurface* LayerTreeImpl::output_surface() const {
 667   return layer_tree_host_impl_->output_surface();
 668 }
 669
 670 ResourceProvider* LayerTreeImpl::resource_provider() const {
 671   return layer_tree_host_impl_->resource_provider();
 672 }
 673
 674 TileManager* LayerTreeImpl::tile_manager() const {
 675   return layer_tree_host_impl_->tile_manager();
 676 }
 677
 678 FrameRateCounter* LayerTreeImpl::frame_rate_counter() const {
 679   return layer_tree_host_impl_->fps_counter();
 680 }
 681
 682 PaintTimeCounter* LayerTreeImpl::paint_time_counter() const {
 683   return layer_tree_host_impl_->paint_time_counter();
 684 }
 685
 686 MemoryHistory* LayerTreeImpl::memory_history() const {
 687   return layer_tree_host_impl_->memory_history();
 688 }
 689
 690 gfx::Size LayerTreeImpl::device_viewport_size() const {
 691   return layer_tree_host_impl_->device_viewport_size();
 692 }
 693
 694 bool LayerTreeImpl::IsActiveTree() const {
 695   return layer_tree_host_impl_->active_tree() == this;
 696 }
 697
 698 bool LayerTreeImpl::IsPendingTree() const {
 699   return layer_tree_host_impl_->pending_tree() == this;
 700 }
 701
 702 bool LayerTreeImpl::IsRecycleTree() const {
 703   return layer_tree_host_impl_->recycle_tree() == this;
 704 }
 705
 706 LayerImpl* LayerTreeImpl::FindActiveTreeLayerById(int id) {
 707   LayerTreeImpl* tree = layer_tree_host_impl_->active_tree();
 708   if (!tree)
 709     return NULL;
 710   return tree->LayerById(id);
 711 }
 712
 713 LayerImpl* LayerTreeImpl::FindPendingTreeLayerById(int id) {
 714   LayerTreeImpl* tree = layer_tree_host_impl_->pending_tree();
 715   if (!tree)
 716     return NULL;
 717   return tree->LayerById(id);
 718 }
 719
 720 LayerImpl* LayerTreeImpl::FindRecycleTreeLayerById(int id) {
 721   LayerTreeImpl* tree = layer_tree_host_impl_->recycle_tree();
 722   if (!tree)
 723     return NULL;
 724   return tree->LayerById(id);
 725 }
 726
 727 bool LayerTreeImpl::PinchGestureActive() const {
 728   return layer_tree_host_impl_->pinch_gesture_active();
 729 }
 730
 731 BeginFrameArgs LayerTreeImpl::CurrentBeginFrameArgs() const {
 732   return layer_tree_host_impl_->CurrentBeginFrameArgs();
 733 }
 734
 735 base::TimeDelta LayerTreeImpl::begin_impl_frame_interval() const {
 736   return layer_tree_host_impl_->begin_impl_frame_interval();
 737 }
 738
 739 void LayerTreeImpl::SetNeedsCommit() {
 740   layer_tree_host_impl_->SetNeedsCommit();
 741 }
 742
 743 gfx::Rect LayerTreeImpl::DeviceViewport() const {
 744   return layer_tree_host_impl_->DeviceViewport();
 745 }
 746
 747 gfx::Size LayerTreeImpl::DrawViewportSize() const {
 748   return layer_tree_host_impl_->DrawViewportSize();
 749 }
 750
 751 const gfx::Rect LayerTreeImpl::ViewportRectForTilePriority() const {
 752   return layer_tree_host_impl_->ViewportRectForTilePriority();
 753 }
 754
 755 scoped_ptr<ScrollbarAnimationController>
 756 LayerTreeImpl::CreateScrollbarAnimationController(LayerImpl* scrolling_layer) {
 757   DCHECK(settings().scrollbar_fade_delay_ms);
 758   DCHECK(settings().scrollbar_fade_duration_ms);
 759   base::TimeDelta delay =
 760       base::TimeDelta::FromMilliseconds(settings().scrollbar_fade_delay_ms);
 761   base::TimeDelta duration =
 762       base::TimeDelta::FromMilliseconds(settings().scrollbar_fade_duration_ms);
 763   switch (settings().scrollbar_animator) {
 764     case LayerTreeSettings::LinearFade: {
 765       return ScrollbarAnimationControllerLinearFade::Create(
 766                  scrolling_layer, layer_tree_host_impl_, delay, duration)
 767           .PassAs<ScrollbarAnimationController>();
 768     }
 769     case LayerTreeSettings::Thinning: {
 770       return ScrollbarAnimationControllerThinning::Create(
 771                  scrolling_layer, layer_tree_host_impl_, delay, duration)
 772           .PassAs<ScrollbarAnimationController>();
 773     }
 774     case LayerTreeSettings::NoAnimator:
 775       NOTREACHED();
 776       break;
 777   }
 778   return scoped_ptr<ScrollbarAnimationController>();
 779 }
 780
 781 void LayerTreeImpl::DidAnimateScrollOffset() {
 782   layer_tree_host_impl_->DidAnimateScrollOffset();
 783 }
 784
 785 bool LayerTreeImpl::use_gpu_rasterization() const {
 786   return layer_tree_host_impl_->use_gpu_rasterization();
 787 }
 788
 789 bool LayerTreeImpl::create_low_res_tiling() const {
 790   return layer_tree_host_impl_->create_low_res_tiling();
 791 }
 792
 793 void LayerTreeImpl::SetNeedsRedraw() {
 794   layer_tree_host_impl_->SetNeedsRedraw();
 795 }
 796
 797 const LayerTreeDebugState& LayerTreeImpl::debug_state() const {
 798   return layer_tree_host_impl_->debug_state();
 799 }
 800
 801 float LayerTreeImpl::device_scale_factor() const {
 802   return layer_tree_host_impl_->device_scale_factor();
 803 }
 804
 805 DebugRectHistory* LayerTreeImpl::debug_rect_history() const {
 806   return layer_tree_host_impl_->debug_rect_history();
 807 }
 808
 809 AnimationRegistrar* LayerTreeImpl::animationRegistrar() const {
 810   return layer_tree_host_impl_->animation_registrar();
 811 }
 812
 813 void LayerTreeImpl::GetAllTilesForTracing(std::set<const Tile*>* tiles) const {
 814   typedef LayerIterator<LayerImpl> LayerIteratorType;
 815   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
 816   for (LayerIteratorType it =
 817            LayerIteratorType::Begin(&render_surface_layer_list_);
 818        it != end;
 819        ++it) {
 820     if (!it.represents_itself())
 821       continue;
 822     LayerImpl* layer_impl = *it;
 823     layer_impl->GetAllTilesForTracing(tiles);
 824   }
 825 }
 826
 827 void LayerTreeImpl::AsValueInto(base::debug::TracedValue* state) const {
 828   TracedValue::MakeDictIntoImplicitSnapshot(state, "cc::LayerTreeImpl", this);
 829   state->SetInteger("source_frame_number", source_frame_number_);
 830
 831   state->BeginDictionary("root_layer");
 832   root_layer_->AsValueInto(state);
 833   state->EndDictionary();
 834
 835   state->BeginArray("render_surface_layer_list");
 836   typedef LayerIterator<LayerImpl> LayerIteratorType;
 837   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
 838   for (LayerIteratorType it = LayerIteratorType::Begin(
 839            &render_surface_layer_list_); it != end; ++it) {
 840     if (!it.represents_itself())
 841       continue;
 842     TracedValue::AppendIDRef(*it, state);
 843   }
 844   state->EndArray();
 845 }
 846
 847 void LayerTreeImpl::SetRootLayerScrollOffsetDelegate(
 848     LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) {
 849   if (root_layer_scroll_offset_delegate_ == root_layer_scroll_offset_delegate)
 850     return;
 851
 852   if (!root_layer_scroll_offset_delegate) {
 853     // Make sure we remove the proxies from their layers before
 854     // releasing them.
 855     if (InnerViewportScrollLayer())
 856       InnerViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
 857     if (OuterViewportScrollLayer())
 858       OuterViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
 859     inner_viewport_scroll_delegate_proxy_.reset();
 860     outer_viewport_scroll_delegate_proxy_.reset();
 861   }
 862
 863   root_layer_scroll_offset_delegate_ = root_layer_scroll_offset_delegate;
 864
 865   if (root_layer_scroll_offset_delegate_) {
 866     root_layer_scroll_offset_delegate_->UpdateRootLayerState(
 867         TotalScrollOffset(),
 868         TotalMaxScrollOffset(),
 869         ScrollableSize(),
 870         total_page_scale_factor(),
 871         min_page_scale_factor(),
 872         max_page_scale_factor());
 873
 874     if (inner_viewport_scroll_layer_) {
 875       inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 876           new LayerScrollOffsetDelegateProxy(InnerViewportScrollLayer(),
 877                                              root_layer_scroll_offset_delegate_,
 878                                              this));
 879       inner_viewport_scroll_layer_->SetScrollOffsetDelegate(
 880           inner_viewport_scroll_delegate_proxy_.get());
 881     }
 882
 883     if (outer_viewport_scroll_layer_) {
 884       outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 885           new LayerScrollOffsetDelegateProxy(OuterViewportScrollLayer(),
 886                                              root_layer_scroll_offset_delegate_,
 887                                              this));
 888       outer_viewport_scroll_layer_->SetScrollOffsetDelegate(
 889           outer_viewport_scroll_delegate_proxy_.get());
 890     }
 891   }
 892 }
 893
 894 void LayerTreeImpl::UpdateScrollOffsetDelegate() {
 895   DCHECK(InnerViewportScrollLayer());
 896   DCHECK(root_layer_scroll_offset_delegate_);
 897
 898   gfx::Vector2dF offset =
 899       inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 900
 901   if (OuterViewportScrollLayer())
 902     offset += outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 903
 904   root_layer_scroll_offset_delegate_->UpdateRootLayerState(
 905       offset,
 906       TotalMaxScrollOffset(),
 907       ScrollableSize(),
 908       total_page_scale_factor(),
 909       min_page_scale_factor(),
 910       max_page_scale_factor());
 911 }
 912
 913 gfx::Vector2dF LayerTreeImpl::GetDelegatedScrollOffset(LayerImpl* layer) {
 914   DCHECK(root_layer_scroll_offset_delegate_);
 915   DCHECK(InnerViewportScrollLayer());
 916   if (layer == InnerViewportScrollLayer() && !OuterViewportScrollLayer())
 917     return root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
 918
 919   // If we get here, we have both inner/outer viewports, and need to distribute
 920   // the scroll offset between them.
 921   DCHECK(inner_viewport_scroll_delegate_proxy_);
 922   DCHECK(outer_viewport_scroll_delegate_proxy_);
 923   gfx::Vector2dF inner_viewport_offset =
 924       inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 925   gfx::Vector2dF outer_viewport_offset =
 926       outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 927
 928   // It may be nothing has changed.
 929   gfx::Vector2dF delegate_offset =
 930       root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
 931   if (inner_viewport_offset + outer_viewport_offset == delegate_offset) {
 932     if (layer == InnerViewportScrollLayer())
 933       return inner_viewport_offset;
 934     else
 935       return outer_viewport_offset;
 936   }
 937
 938   gfx::Vector2d max_outer_viewport_scroll_offset =
 939       OuterViewportScrollLayer()->MaxScrollOffset();
 940
 941   outer_viewport_offset = delegate_offset - inner_viewport_offset;
 942   outer_viewport_offset.SetToMin(max_outer_viewport_scroll_offset);
 943   outer_viewport_offset.SetToMax(gfx::Vector2d());
 944
 945   if (layer == OuterViewportScrollLayer())
 946     return outer_viewport_offset;
 947
 948   inner_viewport_offset = delegate_offset - outer_viewport_offset;
 949
 950   return inner_viewport_offset;
 951 }
 952
 953 void LayerTreeImpl::QueueSwapPromise(scoped_ptr<SwapPromise> swap_promise) {
 954   DCHECK(swap_promise);
 955   swap_promise_list_.push_back(swap_promise.Pass());
 956 }
 957
 958 void LayerTreeImpl::PassSwapPromises(
 959     ScopedPtrVector<SwapPromise>* new_swap_promise) {
 960   swap_promise_list_.insert_and_take(swap_promise_list_.end(),
 961                                      new_swap_promise);
 962   new_swap_promise->clear();
 963 }
 964
 965 void LayerTreeImpl::FinishSwapPromises(CompositorFrameMetadata* metadata) {
 966   for (size_t i = 0; i < swap_promise_list_.size(); i++)
 967     swap_promise_list_[i]->DidSwap(metadata);
 968   swap_promise_list_.clear();
 969 }
 970
 971 void LayerTreeImpl::BreakSwapPromises(SwapPromise::DidNotSwapReason reason) {
 972   for (size_t i = 0; i < swap_promise_list_.size(); i++)
 973     swap_promise_list_[i]->DidNotSwap(reason);
 974   swap_promise_list_.clear();
 975 }
 976
 977 void LayerTreeImpl::DidModifyTilePriorities() {
 978   layer_tree_host_impl_->DidModifyTilePriorities();
 979 }
 980
 981 void LayerTreeImpl::set_ui_resource_request_queue(
 982     const UIResourceRequestQueue& queue) {
 983   ui_resource_request_queue_ = queue;
 984 }
 985
 986 ResourceProvider::ResourceId LayerTreeImpl::ResourceIdForUIResource(
 987     UIResourceId uid) const {
 988   return layer_tree_host_impl_->ResourceIdForUIResource(uid);
 989 }
 990
 991 bool LayerTreeImpl::IsUIResourceOpaque(UIResourceId uid) const {
 992   return layer_tree_host_impl_->IsUIResourceOpaque(uid);
 993 }
 994
 995 void LayerTreeImpl::ProcessUIResourceRequestQueue() {
 996   while (ui_resource_request_queue_.size() > 0) {
 997     UIResourceRequest req = ui_resource_request_queue_.front();
 998     ui_resource_request_queue_.pop_front();
 999
1000     switch (req.GetType()) {
1001       case UIResourceRequest::UIResourceCreate:
1002         layer_tree_host_impl_->CreateUIResource(req.GetId(), req.GetBitmap());
1003         break;
1004       case UIResourceRequest::UIResourceDelete:
1005         layer_tree_host_impl_->DeleteUIResource(req.GetId());
1006         break;
1007       case UIResourceRequest::UIResourceInvalidRequest:
1008         NOTREACHED();
1009         break;
1010     }
1011   }
1012
1013   // If all UI resource evictions were not recreated by processing this queue,
1014   // then another commit is required.
1015   if (layer_tree_host_impl_->EvictedUIResourcesExist())
1016     layer_tree_host_impl_->SetNeedsCommit();
1017 }
1018
1019 void LayerTreeImpl::AddLayerWithCopyOutputRequest(LayerImpl* layer) {
1020   // Only the active tree needs to know about layers with copy requests, as
1021   // they are aborted if not serviced during draw.
1022   DCHECK(IsActiveTree());
1023
1024   // DCHECK(std::find(layers_with_copy_output_request_.begin(),
1025   //                 layers_with_copy_output_request_.end(),
1026   //                 layer) == layers_with_copy_output_request_.end());
1027   // TODO(danakj): Remove this once crash is found crbug.com/309777
1028   for (size_t i = 0; i < layers_with_copy_output_request_.size(); ++i) {
1029     CHECK(layers_with_copy_output_request_[i] != layer)
1030         << i << " of " << layers_with_copy_output_request_.size();
1031   }
1032   layers_with_copy_output_request_.push_back(layer);
1033 }
1034
1035 void LayerTreeImpl::RemoveLayerWithCopyOutputRequest(LayerImpl* layer) {
1036   // Only the active tree needs to know about layers with copy requests, as
1037   // they are aborted if not serviced during draw.
1038   DCHECK(IsActiveTree());
1039
1040   std::vector<LayerImpl*>::iterator it = std::find(
1041       layers_with_copy_output_request_.begin(),
1042       layers_with_copy_output_request_.end(),
1043       layer);
1044   DCHECK(it != layers_with_copy_output_request_.end());
1045   layers_with_copy_output_request_.erase(it);
1046
1047   // TODO(danakj): Remove this once crash is found crbug.com/309777
1048   for (size_t i = 0; i < layers_with_copy_output_request_.size(); ++i) {
1049     CHECK(layers_with_copy_output_request_[i] != layer)
1050         << i << " of " << layers_with_copy_output_request_.size();
1051   }
1052 }
1053
1054 const std::vector<LayerImpl*>& LayerTreeImpl::LayersWithCopyOutputRequest()
1055     const {
1056   // Only the active tree needs to know about layers with copy requests, as
1057   // they are aborted if not serviced during draw.
1058   DCHECK(IsActiveTree());
1059
1060   return layers_with_copy_output_request_;
1061 }
1062
1063 void LayerTreeImpl::ReleaseResourcesRecursive(LayerImpl* current) {
1064   DCHECK(current);
1065   current->ReleaseResources();
1066   if (current->mask_layer())
1067     ReleaseResourcesRecursive(current->mask_layer());
1068   if (current->replica_layer())
1069     ReleaseResourcesRecursive(current->replica_layer());
1070   for (size_t i = 0; i < current->children().size(); ++i)
1071     ReleaseResourcesRecursive(current->children()[i]);
1072 }
1073
1074 template <typename LayerType>
1075 static inline bool LayerClipsSubtree(LayerType* layer) {
1076   return layer->masks_to_bounds() || layer->mask_layer();
1077 }
1078
1079 static bool PointHitsRect(
1080     const gfx::PointF& screen_space_point,
1081     const gfx::Transform& local_space_to_screen_space_transform,
1082     const gfx::RectF& local_space_rect,
1083     float* distance_to_camera) {
1084   // If the transform is not invertible, then assume that this point doesn't hit
1085   // this rect.
1086   gfx::Transform inverse_local_space_to_screen_space(
1087       gfx::Transform::kSkipInitialization);
1088   if (!local_space_to_screen_space_transform.GetInverse(
1089           &inverse_local_space_to_screen_space))
1090     return false;
1091
1092   // Transform the hit test point from screen space to the local space of the
1093   // given rect.
1094   bool clipped = false;
1095   gfx::Point3F planar_point = MathUtil::ProjectPoint3D(
1096       inverse_local_space_to_screen_space, screen_space_point, &clipped);
1097   gfx::PointF hit_test_point_in_local_space =
1098       gfx::PointF(planar_point.x(), planar_point.y());
1099
1100   // If ProjectPoint could not project to a valid value, then we assume that
1101   // this point doesn't hit this rect.
1102   if (clipped)
1103     return false;
1104
1105   if (!local_space_rect.Contains(hit_test_point_in_local_space))
1106     return false;
1107
1108   if (distance_to_camera) {
1109     // To compute the distance to the camera, we have to take the planar point
1110     // and pull it back to world space and compute the displacement along the
1111     // z-axis.
1112     gfx::Point3F planar_point_in_screen_space(planar_point);
1113     local_space_to_screen_space_transform.TransformPoint(
1114         &planar_point_in_screen_space);
1115     *distance_to_camera = planar_point_in_screen_space.z();
1116   }
1117
1118   return true;
1119 }
1120
1121 static bool PointHitsRegion(const gfx::PointF& screen_space_point,
1122                             const gfx::Transform& screen_space_transform,
1123                             const Region& layer_space_region,
1124                             float layer_content_scale_x,
1125                             float layer_content_scale_y) {
1126   // If the transform is not invertible, then assume that this point doesn't hit
1127   // this region.
1128   gfx::Transform inverse_screen_space_transform(
1129       gfx::Transform::kSkipInitialization);
1130   if (!screen_space_transform.GetInverse(&inverse_screen_space_transform))
1131     return false;
1132
1133   // Transform the hit test point from screen space to the local space of the
1134   // given region.
1135   bool clipped = false;
1136   gfx::PointF hit_test_point_in_content_space = MathUtil::ProjectPoint(
1137       inverse_screen_space_transform, screen_space_point, &clipped);
1138   gfx::PointF hit_test_point_in_layer_space =
1139       gfx::ScalePoint(hit_test_point_in_content_space,
1140                       1.f / layer_content_scale_x,
1141                       1.f / layer_content_scale_y);
1142
1143   // If ProjectPoint could not project to a valid value, then we assume that
1144   // this point doesn't hit this region.
1145   if (clipped)
1146     return false;
1147
1148   return layer_space_region.Contains(
1149       gfx::ToRoundedPoint(hit_test_point_in_layer_space));
1150 }
1151
1152 static const LayerImpl* GetNextClippingLayer(const LayerImpl* layer) {
1153   if (layer->scroll_parent())
1154     return layer->scroll_parent();
1155   if (layer->clip_parent())
1156     return layer->clip_parent();
1157   return layer->parent();
1158 }
1159
1160 static bool PointIsClippedBySurfaceOrClipRect(
1161     const gfx::PointF& screen_space_point,
1162     const LayerImpl* layer) {
1163   // Walk up the layer tree and hit-test any render_surfaces and any layer
1164   // clip rects that are active.
1165   for (; layer; layer = GetNextClippingLayer(layer)) {
1166     if (layer->render_surface() &&
1167         !PointHitsRect(screen_space_point,
1168                        layer->render_surface()->screen_space_transform(),
1169                        layer->render_surface()->content_rect(),
1170                        NULL))
1171       return true;
1172
1173     if (LayerClipsSubtree(layer) &&
1174         !PointHitsRect(screen_space_point,
1175                        layer->screen_space_transform(),
1176                        gfx::Rect(layer->content_bounds()),
1177                        NULL))
1178       return true;
1179   }
1180
1181   // If we have finished walking all ancestors without having already exited,
1182   // then the point is not clipped by any ancestors.
1183   return false;
1184 }
1185
1186 static bool PointHitsLayer(const LayerImpl* layer,
1187                            const gfx::PointF& screen_space_point,
1188                            float* distance_to_intersection) {
1189   gfx::RectF content_rect(layer->content_bounds());
1190   if (!PointHitsRect(screen_space_point,
1191                      layer->screen_space_transform(),
1192                      content_rect,
1193                      distance_to_intersection))
1194     return false;
1195
1196   // At this point, we think the point does hit the layer, but we need to walk
1197   // up the parents to ensure that the layer was not clipped in such a way
1198   // that the hit point actually should not hit the layer.
1199   if (PointIsClippedBySurfaceOrClipRect(screen_space_point, layer))
1200     return false;
1201
1202   // Skip the HUD layer.
1203   if (layer == layer->layer_tree_impl()->hud_layer())
1204     return false;
1205
1206   return true;
1207 }
1208
1209 struct FindClosestMatchingLayerDataForRecursion {
1210   FindClosestMatchingLayerDataForRecursion()
1211       : closest_match(NULL),
1212         closest_distance(-std::numeric_limits<float>::infinity()) {}
1213   LayerImpl* closest_match;
1214   // Note that the positive z-axis points towards the camera, so bigger means
1215   // closer in this case, counterintuitively.
1216   float closest_distance;
1217 };
1218
1219 template <typename Functor>
1220 static void FindClosestMatchingLayer(
1221     const gfx::PointF& screen_space_point,
1222     LayerImpl* layer,
1223     const Functor& func,
1224     FindClosestMatchingLayerDataForRecursion* data_for_recursion) {
1225   for (int i = layer->children().size() - 1; i >= 0; --i) {
1226     FindClosestMatchingLayer(
1227         screen_space_point, layer->children()[i], func, data_for_recursion);
1228   }
1229
1230   float distance_to_intersection = 0.f;
1231   if (func(layer) &&
1232       PointHitsLayer(layer, screen_space_point, &distance_to_intersection) &&
1233       ((!data_for_recursion->closest_match ||
1234         distance_to_intersection > data_for_recursion->closest_distance))) {
1235     data_for_recursion->closest_distance = distance_to_intersection;
1236     data_for_recursion->closest_match = layer;
1237   }
1238 }
1239
1240 static bool ScrollsAnyDrawnRenderSurfaceLayerListMember(LayerImpl* layer) {
1241   if (!layer->scrollable())
1242     return false;
1243   if (layer->IsDrawnRenderSurfaceLayerListMember())
1244     return true;
1245   if (!layer->scroll_children())
1246     return false;
1247   for (std::set<LayerImpl*>::const_iterator it =
1248            layer->scroll_children()->begin();
1249        it != layer->scroll_children()->end();
1250        ++it) {
1251     if ((*it)->IsDrawnRenderSurfaceLayerListMember())
1252       return true;
1253   }
1254   return false;
1255 }
1256
1257 struct FindScrollingLayerFunctor {
1258   bool operator()(LayerImpl* layer) const {
1259     return ScrollsAnyDrawnRenderSurfaceLayerListMember(layer);
1260   }
1261 };
1262
1263 LayerImpl* LayerTreeImpl::FindFirstScrollingLayerThatIsHitByPoint(
1264     const gfx::PointF& screen_space_point) {
1265   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1266   FindClosestMatchingLayer(screen_space_point,
1267                            root_layer(),
1268                            FindScrollingLayerFunctor(),
1269                            &data_for_recursion);
1270   return data_for_recursion.closest_match;
1271 }
1272
1273 struct HitTestVisibleScrollableOrTouchableFunctor {
1274   bool operator()(LayerImpl* layer) const {
1275     return layer->IsDrawnRenderSurfaceLayerListMember() ||
1276            ScrollsAnyDrawnRenderSurfaceLayerListMember(layer) ||
1277            !layer->touch_event_handler_region().IsEmpty() ||
1278            layer->have_wheel_event_handlers();
1279   }
1280 };
1281
1282 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPoint(
1283     const gfx::PointF& screen_space_point) {
1284   if (!root_layer())
1285     return NULL;
1286   if (!UpdateDrawProperties())
1287     return NULL;
1288   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1289   FindClosestMatchingLayer(screen_space_point,
1290                            root_layer(),
1291                            HitTestVisibleScrollableOrTouchableFunctor(),
1292                            &data_for_recursion);
1293   return data_for_recursion.closest_match;
1294 }
1295
1296 static bool LayerHasTouchEventHandlersAt(const gfx::PointF& screen_space_point,
1297                                          LayerImpl* layer_impl) {
1298   if (layer_impl->touch_event_handler_region().IsEmpty())
1299     return false;
1300
1301   if (!PointHitsRegion(screen_space_point,
1302                        layer_impl->screen_space_transform(),
1303                        layer_impl->touch_event_handler_region(),
1304                        layer_impl->contents_scale_x(),
1305                        layer_impl->contents_scale_y()))
1306     return false;
1307
1308   // At this point, we think the point does hit the touch event handler region
1309   // on the layer, but we need to walk up the parents to ensure that the layer
1310   // was not clipped in such a way that the hit point actually should not hit
1311   // the layer.
1312   if (PointIsClippedBySurfaceOrClipRect(screen_space_point, layer_impl))
1313     return false;
1314
1315   return true;
1316 }
1317
1318 struct FindTouchEventLayerFunctor {
1319   bool operator()(LayerImpl* layer) const {
1320     return LayerHasTouchEventHandlersAt(screen_space_point, layer);
1321   }
1322   const gfx::PointF screen_space_point;
1323 };
1324
1325 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
1326     const gfx::PointF& screen_space_point) {
1327   if (!root_layer())
1328     return NULL;
1329   if (!UpdateDrawProperties())
1330     return NULL;
1331   FindTouchEventLayerFunctor func = {screen_space_point};
1332   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1333   FindClosestMatchingLayer(
1334       screen_space_point, root_layer(), func, &data_for_recursion);
1335   return data_for_recursion.closest_match;
1336 }
1337
1338 void LayerTreeImpl::RegisterSelection(const LayerSelectionBound& start,
1339                                       const LayerSelectionBound& end) {
1340   selection_start_ = start;
1341   selection_end_ = end;
1342 }
1343
1344 static ViewportSelectionBound ComputeViewportSelection(
1345     const LayerSelectionBound& layer_bound,
1346     LayerImpl* layer,
1347     float device_scale_factor) {
1348   ViewportSelectionBound viewport_bound;
1349   viewport_bound.type = layer_bound.type;
1350
1351   if (!layer || layer_bound.type == SELECTION_BOUND_EMPTY)
1352     return viewport_bound;
1353
1354   gfx::PointF layer_scaled_top = gfx::ScalePoint(layer_bound.edge_top,
1355                                                  layer->contents_scale_x(),
1356                                                  layer->contents_scale_y());
1357   gfx::PointF layer_scaled_bottom = gfx::ScalePoint(layer_bound.edge_bottom,
1358                                                     layer->contents_scale_x(),
1359                                                     layer->contents_scale_y());
1360
1361   bool clipped = false;
1362   gfx::PointF screen_top = MathUtil::MapPoint(
1363       layer->screen_space_transform(), layer_scaled_top, &clipped);
1364   gfx::PointF screen_bottom = MathUtil::MapPoint(
1365       layer->screen_space_transform(), layer_scaled_bottom, &clipped);
1366
1367   const float inv_scale = 1.f / device_scale_factor;
1368   viewport_bound.edge_top = gfx::ScalePoint(screen_top, inv_scale);
1369   viewport_bound.edge_bottom = gfx::ScalePoint(screen_bottom, inv_scale);
1370
1371   // The bottom edge point is used for visibility testing as it is the logical
1372   // focal point for bound selection handles (this may change in the future).
1373   // Shifting the visibility point fractionally inward ensures that neighboring
1374   // or logically coincident layers aligned to integral DPI coordinates will not
1375   // spuriously occlude the bound.
1376   gfx::Vector2dF visibility_offset = layer_scaled_top - layer_scaled_bottom;
1377   visibility_offset.Scale(device_scale_factor / visibility_offset.Length());
1378   gfx::PointF visibility_point = layer_scaled_bottom + visibility_offset;
1379   if (visibility_point.x() <= 0)
1380     visibility_point.set_x(visibility_point.x() + device_scale_factor);
1381   visibility_point = MathUtil::MapPoint(
1382       layer->screen_space_transform(), visibility_point, &clipped);
1383
1384   float intersect_distance = 0.f;
1385   viewport_bound.visible =
1386       PointHitsLayer(layer, visibility_point, &intersect_distance);
1387
1388   return viewport_bound;
1389 }
1390
1391 void LayerTreeImpl::GetViewportSelection(ViewportSelectionBound* start,
1392                                          ViewportSelectionBound* end) {
1393   DCHECK(start);
1394   DCHECK(end);
1395
1396   *start = ComputeViewportSelection(
1397       selection_start_,
1398       selection_start_.layer_id ? LayerById(selection_start_.layer_id) : NULL,
1399       device_scale_factor());
1400   if (start->type == SELECTION_BOUND_CENTER ||
1401       start->type == SELECTION_BOUND_EMPTY) {
1402     *end = *start;
1403   } else {
1404     *end = ComputeViewportSelection(
1405         selection_end_,
1406         selection_end_.layer_id ? LayerById(selection_end_.layer_id) : NULL,
1407         device_scale_factor());
1408   }
1409 }
1410
1411 void LayerTreeImpl::RegisterPictureLayerImpl(PictureLayerImpl* layer) {
1412   layer_tree_host_impl_->RegisterPictureLayerImpl(layer);
1413 }
1414
1415 void LayerTreeImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
1416   layer_tree_host_impl_->UnregisterPictureLayerImpl(layer);
1417 }
1418
1419 void LayerTreeImpl::InputScrollAnimationFinished() {
1420   layer_tree_host_impl_->ScrollEnd();
1421 }
1422
1423 BlockingTaskRunner* LayerTreeImpl::BlockingMainThreadTaskRunner() const {
1424   return proxy()->blocking_main_thread_task_runner();
1425 }
1426
1427 }  // namespace cc