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 = !resourceless_software_draw();
 460
 461     ++render_surface_layer_list_id_;
 462     LayerTreeHostCommon::CalcDrawPropsImplInputs inputs(
 463         root_layer(),
 464         DrawViewportSize(),
 465         layer_tree_host_impl_->DrawTransform(),
 466         device_scale_factor(),
 467         total_page_scale_factor(),
 468         page_scale_layer,
 469         MaxTextureSize(),
 470         settings().can_use_lcd_text,
 471         can_render_to_separate_surface,
 472         settings().layer_transforms_should_scale_layer_contents,
 473         &render_surface_layer_list_,
 474         render_surface_layer_list_id_);
 475     LayerTreeHostCommon::CalculateDrawProperties(&inputs);
 476   }
 477
 478   {
 479     TRACE_EVENT2("cc",
 480                  "LayerTreeImpl::UpdateTilePriorities",
 481                  "IsActive",
 482                  IsActiveTree(),
 483                  "SourceFrameNumber",
 484                  source_frame_number_);
 485     scoped_ptr<OcclusionTracker<LayerImpl> > occlusion_tracker;
 486     if (settings().use_occlusion_for_tile_prioritization) {
 487       occlusion_tracker.reset(new OcclusionTracker<LayerImpl>(
 488           root_layer()->render_surface()->content_rect()));
 489       occlusion_tracker->set_minimum_tracking_size(
 490           settings().minimum_occlusion_tracking_size);
 491     }
 492
 493     // LayerIterator is used here instead of CallFunctionForSubtree to only
 494     // UpdateTilePriorities on layers that will be visible (and thus have valid
 495     // draw properties) and not because any ordering is required.
 496     typedef LayerIterator<LayerImpl> LayerIteratorType;
 497     LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
 498     for (LayerIteratorType it =
 499              LayerIteratorType::Begin(&render_surface_layer_list_);
 500          it != end;
 501          ++it) {
 502       if (occlusion_tracker)
 503         occlusion_tracker->EnterLayer(it);
 504
 505       LayerImpl* layer = *it;
 506       if (it.represents_itself())
 507         layer->UpdateTiles(occlusion_tracker.get());
 508
 509       if (!it.represents_contributing_render_surface()) {
 510         if (occlusion_tracker)
 511           occlusion_tracker->LeaveLayer(it);
 512         continue;
 513       }
 514
 515       if (layer->mask_layer())
 516         layer->mask_layer()->UpdateTiles(occlusion_tracker.get());
 517       if (layer->replica_layer() && layer->replica_layer()->mask_layer())
 518         layer->replica_layer()->mask_layer()->UpdateTiles(
 519             occlusion_tracker.get());
 520
 521       if (occlusion_tracker)
 522         occlusion_tracker->LeaveLayer(it);
 523     }
 524   }
 525
 526   DCHECK(!needs_update_draw_properties_) <<
 527       "CalcDrawProperties should not set_needs_update_draw_properties()";
 528   return true;
 529 }
 530
 531 const LayerImplList& LayerTreeImpl::RenderSurfaceLayerList() const {
 532   // If this assert triggers, then the list is dirty.
 533   DCHECK(!needs_update_draw_properties_);
 534   return render_surface_layer_list_;
 535 }
 536
 537 gfx::Size LayerTreeImpl::ScrollableSize() const {
 538   LayerImpl* root_scroll_layer = OuterViewportScrollLayer()
 539                                      ? OuterViewportScrollLayer()
 540                                      : InnerViewportScrollLayer();
 541   if (!root_scroll_layer || root_scroll_layer->children().empty())
 542     return gfx::Size();
 543   return root_scroll_layer->children()[0]->bounds();
 544 }
 545
 546 LayerImpl* LayerTreeImpl::LayerById(int id) {
 547   LayerIdMap::iterator iter = layer_id_map_.find(id);
 548   return iter != layer_id_map_.end() ? iter->second : NULL;
 549 }
 550
 551 void LayerTreeImpl::RegisterLayer(LayerImpl* layer) {
 552   DCHECK(!LayerById(layer->id()));
 553   layer_id_map_[layer->id()] = layer;
 554 }
 555
 556 void LayerTreeImpl::UnregisterLayer(LayerImpl* layer) {
 557   DCHECK(LayerById(layer->id()));
 558   layer_id_map_.erase(layer->id());
 559 }
 560
 561 size_t LayerTreeImpl::NumLayers() {
 562   return layer_id_map_.size();
 563 }
 564
 565 void LayerTreeImpl::PushPersistedState(LayerTreeImpl* pending_tree) {
 566   pending_tree->SetCurrentlyScrollingLayer(
 567       LayerTreeHostCommon::FindLayerInSubtree(pending_tree->root_layer(),
 568           currently_scrolling_layer_ ? currently_scrolling_layer_->id() : 0));
 569 }
 570
 571 static void DidBecomeActiveRecursive(LayerImpl* layer) {
 572   layer->DidBecomeActive();
 573   if (layer->mask_layer())
 574     layer->mask_layer()->DidBecomeActive();
 575   if (layer->replica_layer() && layer->replica_layer()->mask_layer())
 576     layer->replica_layer()->mask_layer()->DidBecomeActive();
 577
 578   for (size_t i = 0; i < layer->children().size(); ++i)
 579     DidBecomeActiveRecursive(layer->children()[i]);
 580 }
 581
 582 void LayerTreeImpl::DidBecomeActive() {
 583   if (next_activation_forces_redraw_) {
 584     layer_tree_host_impl_->SetFullRootLayerDamage();
 585     next_activation_forces_redraw_ = false;
 586   }
 587
 588   if (scrolling_layer_id_from_previous_tree_) {
 589     currently_scrolling_layer_ = LayerTreeHostCommon::FindLayerInSubtree(
 590         root_layer(), scrolling_layer_id_from_previous_tree_);
 591   }
 592
 593   // Always reset this flag on activation, as we would only have activated
 594   // if we were in a good state.
 595   ResetRequiresHighResToDraw();
 596
 597   if (root_layer())
 598     DidBecomeActiveRecursive(root_layer());
 599
 600   devtools_instrumentation::DidActivateLayerTree(layer_tree_host_impl_->id(),
 601                                                  source_frame_number_);
 602 }
 603
 604 bool LayerTreeImpl::ContentsTexturesPurged() const {
 605   return contents_textures_purged_;
 606 }
 607
 608 void LayerTreeImpl::SetContentsTexturesPurged() {
 609   if (contents_textures_purged_)
 610     return;
 611   contents_textures_purged_ = true;
 612   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 613 }
 614
 615 void LayerTreeImpl::ResetContentsTexturesPurged() {
 616   if (!contents_textures_purged_)
 617     return;
 618   contents_textures_purged_ = false;
 619   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 620 }
 621
 622 void LayerTreeImpl::SetRequiresHighResToDraw() {
 623   requires_high_res_to_draw_ = true;
 624 }
 625
 626 void LayerTreeImpl::ResetRequiresHighResToDraw() {
 627   requires_high_res_to_draw_ = false;
 628 }
 629
 630 bool LayerTreeImpl::RequiresHighResToDraw() const {
 631   return requires_high_res_to_draw_;
 632 }
 633
 634 bool LayerTreeImpl::ViewportSizeInvalid() const {
 635   return viewport_size_invalid_;
 636 }
 637
 638 void LayerTreeImpl::SetViewportSizeInvalid() {
 639   viewport_size_invalid_ = true;
 640   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 641 }
 642
 643 void LayerTreeImpl::ResetViewportSizeInvalid() {
 644   viewport_size_invalid_ = false;
 645   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 646 }
 647
 648 Proxy* LayerTreeImpl::proxy() const {
 649   return layer_tree_host_impl_->proxy();
 650 }
 651
 652 const LayerTreeSettings& LayerTreeImpl::settings() const {
 653   return layer_tree_host_impl_->settings();
 654 }
 655
 656 const RendererCapabilitiesImpl& LayerTreeImpl::GetRendererCapabilities() const {
 657   return layer_tree_host_impl_->GetRendererCapabilities();
 658 }
 659
 660 ContextProvider* LayerTreeImpl::context_provider() const {
 661   return output_surface()->context_provider();
 662 }
 663
 664 OutputSurface* LayerTreeImpl::output_surface() const {
 665   return layer_tree_host_impl_->output_surface();
 666 }
 667
 668 ResourceProvider* LayerTreeImpl::resource_provider() const {
 669   return layer_tree_host_impl_->resource_provider();
 670 }
 671
 672 TileManager* LayerTreeImpl::tile_manager() const {
 673   return layer_tree_host_impl_->tile_manager();
 674 }
 675
 676 FrameRateCounter* LayerTreeImpl::frame_rate_counter() const {
 677   return layer_tree_host_impl_->fps_counter();
 678 }
 679
 680 PaintTimeCounter* LayerTreeImpl::paint_time_counter() const {
 681   return layer_tree_host_impl_->paint_time_counter();
 682 }
 683
 684 MemoryHistory* LayerTreeImpl::memory_history() const {
 685   return layer_tree_host_impl_->memory_history();
 686 }
 687
 688 bool LayerTreeImpl::resourceless_software_draw() const {
 689   return layer_tree_host_impl_->GetDrawMode() ==
 690          DRAW_MODE_RESOURCELESS_SOFTWARE;
 691 }
 692
 693 gfx::Size LayerTreeImpl::device_viewport_size() const {
 694   return layer_tree_host_impl_->device_viewport_size();
 695 }
 696
 697 bool LayerTreeImpl::IsActiveTree() const {
 698   return layer_tree_host_impl_->active_tree() == this;
 699 }
 700
 701 bool LayerTreeImpl::IsPendingTree() const {
 702   return layer_tree_host_impl_->pending_tree() == this;
 703 }
 704
 705 bool LayerTreeImpl::IsRecycleTree() const {
 706   return layer_tree_host_impl_->recycle_tree() == this;
 707 }
 708
 709 LayerImpl* LayerTreeImpl::FindActiveTreeLayerById(int id) {
 710   LayerTreeImpl* tree = layer_tree_host_impl_->active_tree();
 711   if (!tree)
 712     return NULL;
 713   return tree->LayerById(id);
 714 }
 715
 716 LayerImpl* LayerTreeImpl::FindPendingTreeLayerById(int id) {
 717   LayerTreeImpl* tree = layer_tree_host_impl_->pending_tree();
 718   if (!tree)
 719     return NULL;
 720   return tree->LayerById(id);
 721 }
 722
 723 LayerImpl* LayerTreeImpl::FindRecycleTreeLayerById(int id) {
 724   LayerTreeImpl* tree = layer_tree_host_impl_->recycle_tree();
 725   if (!tree)
 726     return NULL;
 727   return tree->LayerById(id);
 728 }
 729
 730 int LayerTreeImpl::MaxTextureSize() const {
 731   return layer_tree_host_impl_->GetRendererCapabilities().max_texture_size;
 732 }
 733
 734 bool LayerTreeImpl::PinchGestureActive() const {
 735   return layer_tree_host_impl_->pinch_gesture_active();
 736 }
 737
 738 BeginFrameArgs LayerTreeImpl::CurrentBeginFrameArgs() const {
 739   return layer_tree_host_impl_->CurrentBeginFrameArgs();
 740 }
 741
 742 base::TimeDelta LayerTreeImpl::begin_impl_frame_interval() const {
 743   return layer_tree_host_impl_->begin_impl_frame_interval();
 744 }
 745
 746 void LayerTreeImpl::SetNeedsCommit() {
 747   layer_tree_host_impl_->SetNeedsCommit();
 748 }
 749
 750 gfx::Rect LayerTreeImpl::DeviceViewport() const {
 751   return layer_tree_host_impl_->DeviceViewport();
 752 }
 753
 754 gfx::Size LayerTreeImpl::DrawViewportSize() const {
 755   return layer_tree_host_impl_->DrawViewportSize();
 756 }
 757
 758 const gfx::Rect LayerTreeImpl::ViewportRectForTilePriority() const {
 759   return layer_tree_host_impl_->ViewportRectForTilePriority();
 760 }
 761
 762 scoped_ptr<ScrollbarAnimationController>
 763 LayerTreeImpl::CreateScrollbarAnimationController(LayerImpl* scrolling_layer) {
 764   DCHECK(settings().scrollbar_fade_delay_ms);
 765   DCHECK(settings().scrollbar_fade_duration_ms);
 766   base::TimeDelta delay =
 767       base::TimeDelta::FromMilliseconds(settings().scrollbar_fade_delay_ms);
 768   base::TimeDelta duration =
 769       base::TimeDelta::FromMilliseconds(settings().scrollbar_fade_duration_ms);
 770   switch (settings().scrollbar_animator) {
 771     case LayerTreeSettings::LinearFade: {
 772       return ScrollbarAnimationControllerLinearFade::Create(
 773                  scrolling_layer, layer_tree_host_impl_, delay, duration)
 774           .PassAs<ScrollbarAnimationController>();
 775     }
 776     case LayerTreeSettings::Thinning: {
 777       return ScrollbarAnimationControllerThinning::Create(
 778                  scrolling_layer, layer_tree_host_impl_, delay, duration)
 779           .PassAs<ScrollbarAnimationController>();
 780     }
 781     case LayerTreeSettings::NoAnimator:
 782       NOTREACHED();
 783       break;
 784   }
 785   return scoped_ptr<ScrollbarAnimationController>();
 786 }
 787
 788 void LayerTreeImpl::DidAnimateScrollOffset() {
 789   layer_tree_host_impl_->DidAnimateScrollOffset();
 790 }
 791
 792 bool LayerTreeImpl::use_gpu_rasterization() const {
 793   return layer_tree_host_impl_->use_gpu_rasterization();
 794 }
 795
 796 bool LayerTreeImpl::create_low_res_tiling() const {
 797   return layer_tree_host_impl_->create_low_res_tiling();
 798 }
 799
 800 void LayerTreeImpl::SetNeedsRedraw() {
 801   layer_tree_host_impl_->SetNeedsRedraw();
 802 }
 803
 804 const LayerTreeDebugState& LayerTreeImpl::debug_state() const {
 805   return layer_tree_host_impl_->debug_state();
 806 }
 807
 808 float LayerTreeImpl::device_scale_factor() const {
 809   return layer_tree_host_impl_->device_scale_factor();
 810 }
 811
 812 DebugRectHistory* LayerTreeImpl::debug_rect_history() const {
 813   return layer_tree_host_impl_->debug_rect_history();
 814 }
 815
 816 AnimationRegistrar* LayerTreeImpl::animationRegistrar() const {
 817   return layer_tree_host_impl_->animation_registrar();
 818 }
 819
 820 void LayerTreeImpl::AsValueInto(base::debug::TracedValue* state) const {
 821   TracedValue::MakeDictIntoImplicitSnapshot(state, "cc::LayerTreeImpl", this);
 822   state->SetInteger("source_frame_number", source_frame_number_);
 823
 824   state->BeginDictionary("root_layer");
 825   root_layer_->AsValueInto(state);
 826   state->EndDictionary();
 827
 828   state->BeginArray("render_surface_layer_list");
 829   typedef LayerIterator<LayerImpl> LayerIteratorType;
 830   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
 831   for (LayerIteratorType it = LayerIteratorType::Begin(
 832            &render_surface_layer_list_); it != end; ++it) {
 833     if (!it.represents_itself())
 834       continue;
 835     TracedValue::AppendIDRef(*it, state);
 836   }
 837   state->EndArray();
 838 }
 839
 840 void LayerTreeImpl::SetRootLayerScrollOffsetDelegate(
 841     LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) {
 842   if (root_layer_scroll_offset_delegate_ == root_layer_scroll_offset_delegate)
 843     return;
 844
 845   if (!root_layer_scroll_offset_delegate) {
 846     // Make sure we remove the proxies from their layers before
 847     // releasing them.
 848     if (InnerViewportScrollLayer())
 849       InnerViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
 850     if (OuterViewportScrollLayer())
 851       OuterViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
 852     inner_viewport_scroll_delegate_proxy_.reset();
 853     outer_viewport_scroll_delegate_proxy_.reset();
 854   }
 855
 856   root_layer_scroll_offset_delegate_ = root_layer_scroll_offset_delegate;
 857
 858   if (root_layer_scroll_offset_delegate_) {
 859     root_layer_scroll_offset_delegate_->UpdateRootLayerState(
 860         TotalScrollOffset(),
 861         TotalMaxScrollOffset(),
 862         ScrollableSize(),
 863         total_page_scale_factor(),
 864         min_page_scale_factor(),
 865         max_page_scale_factor());
 866
 867     if (inner_viewport_scroll_layer_) {
 868       inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 869           new LayerScrollOffsetDelegateProxy(InnerViewportScrollLayer(),
 870                                              root_layer_scroll_offset_delegate_,
 871                                              this));
 872       inner_viewport_scroll_layer_->SetScrollOffsetDelegate(
 873           inner_viewport_scroll_delegate_proxy_.get());
 874     }
 875
 876     if (outer_viewport_scroll_layer_) {
 877       outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 878           new LayerScrollOffsetDelegateProxy(OuterViewportScrollLayer(),
 879                                              root_layer_scroll_offset_delegate_,
 880                                              this));
 881       outer_viewport_scroll_layer_->SetScrollOffsetDelegate(
 882           outer_viewport_scroll_delegate_proxy_.get());
 883     }
 884   }
 885 }
 886
 887 void LayerTreeImpl::UpdateScrollOffsetDelegate() {
 888   DCHECK(InnerViewportScrollLayer());
 889   DCHECK(root_layer_scroll_offset_delegate_);
 890
 891   gfx::Vector2dF offset =
 892       inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 893
 894   if (OuterViewportScrollLayer())
 895     offset += outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 896
 897   root_layer_scroll_offset_delegate_->UpdateRootLayerState(
 898       offset,
 899       TotalMaxScrollOffset(),
 900       ScrollableSize(),
 901       total_page_scale_factor(),
 902       min_page_scale_factor(),
 903       max_page_scale_factor());
 904 }
 905
 906 gfx::Vector2dF LayerTreeImpl::GetDelegatedScrollOffset(LayerImpl* layer) {
 907   DCHECK(root_layer_scroll_offset_delegate_);
 908   DCHECK(InnerViewportScrollLayer());
 909   if (layer == InnerViewportScrollLayer() && !OuterViewportScrollLayer())
 910     return root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
 911
 912   // If we get here, we have both inner/outer viewports, and need to distribute
 913   // the scroll offset between them.
 914   DCHECK(inner_viewport_scroll_delegate_proxy_);
 915   DCHECK(outer_viewport_scroll_delegate_proxy_);
 916   gfx::Vector2dF inner_viewport_offset =
 917       inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 918   gfx::Vector2dF outer_viewport_offset =
 919       outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
 920
 921   // It may be nothing has changed.
 922   gfx::Vector2dF delegate_offset =
 923       root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
 924   if (inner_viewport_offset + outer_viewport_offset == delegate_offset) {
 925     if (layer == InnerViewportScrollLayer())
 926       return inner_viewport_offset;
 927     else
 928       return outer_viewport_offset;
 929   }
 930
 931   gfx::Vector2d max_outer_viewport_scroll_offset =
 932       OuterViewportScrollLayer()->MaxScrollOffset();
 933
 934   outer_viewport_offset = delegate_offset - inner_viewport_offset;
 935   outer_viewport_offset.SetToMin(max_outer_viewport_scroll_offset);
 936   outer_viewport_offset.SetToMax(gfx::Vector2d());
 937
 938   if (layer == OuterViewportScrollLayer())
 939     return outer_viewport_offset;
 940
 941   inner_viewport_offset = delegate_offset - outer_viewport_offset;
 942
 943   return inner_viewport_offset;
 944 }
 945
 946 void LayerTreeImpl::QueueSwapPromise(scoped_ptr<SwapPromise> swap_promise) {
 947   DCHECK(swap_promise);
 948   swap_promise_list_.push_back(swap_promise.Pass());
 949 }
 950
 951 void LayerTreeImpl::PassSwapPromises(
 952     ScopedPtrVector<SwapPromise>* new_swap_promise) {
 953   swap_promise_list_.insert_and_take(swap_promise_list_.end(),
 954                                      *new_swap_promise);
 955   new_swap_promise->clear();
 956 }
 957
 958 void LayerTreeImpl::FinishSwapPromises(CompositorFrameMetadata* metadata) {
 959   for (size_t i = 0; i < swap_promise_list_.size(); i++)
 960     swap_promise_list_[i]->DidSwap(metadata);
 961   swap_promise_list_.clear();
 962 }
 963
 964 void LayerTreeImpl::BreakSwapPromises(SwapPromise::DidNotSwapReason reason) {
 965   for (size_t i = 0; i < swap_promise_list_.size(); i++)
 966     swap_promise_list_[i]->DidNotSwap(reason);
 967   swap_promise_list_.clear();
 968 }
 969
 970 void LayerTreeImpl::DidModifyTilePriorities() {
 971   layer_tree_host_impl_->DidModifyTilePriorities();
 972 }
 973
 974 void LayerTreeImpl::set_ui_resource_request_queue(
 975     const UIResourceRequestQueue& queue) {
 976   ui_resource_request_queue_ = queue;
 977 }
 978
 979 ResourceProvider::ResourceId LayerTreeImpl::ResourceIdForUIResource(
 980     UIResourceId uid) const {
 981   return layer_tree_host_impl_->ResourceIdForUIResource(uid);
 982 }
 983
 984 bool LayerTreeImpl::IsUIResourceOpaque(UIResourceId uid) const {
 985   return layer_tree_host_impl_->IsUIResourceOpaque(uid);
 986 }
 987
 988 void LayerTreeImpl::ProcessUIResourceRequestQueue() {
 989   while (ui_resource_request_queue_.size() > 0) {
 990     UIResourceRequest req = ui_resource_request_queue_.front();
 991     ui_resource_request_queue_.pop_front();
 992
 993     switch (req.GetType()) {
 994       case UIResourceRequest::UIResourceCreate:
 995         layer_tree_host_impl_->CreateUIResource(req.GetId(), req.GetBitmap());
 996         break;
 997       case UIResourceRequest::UIResourceDelete:
 998         layer_tree_host_impl_->DeleteUIResource(req.GetId());
 999         break;
1000       case UIResourceRequest::UIResourceInvalidRequest:
1001         NOTREACHED();
1002         break;
1003     }
1004   }
1005
1006   // If all UI resource evictions were not recreated by processing this queue,
1007   // then another commit is required.
1008   if (layer_tree_host_impl_->EvictedUIResourcesExist())
1009     layer_tree_host_impl_->SetNeedsCommit();
1010 }
1011
1012 void LayerTreeImpl::AddLayerWithCopyOutputRequest(LayerImpl* layer) {
1013   // Only the active tree needs to know about layers with copy requests, as
1014   // they are aborted if not serviced during draw.
1015   DCHECK(IsActiveTree());
1016
1017   // DCHECK(std::find(layers_with_copy_output_request_.begin(),
1018   //                 layers_with_copy_output_request_.end(),
1019   //                 layer) == layers_with_copy_output_request_.end());
1020   // TODO(danakj): Remove this once crash is found crbug.com/309777
1021   for (size_t i = 0; i < layers_with_copy_output_request_.size(); ++i) {
1022     CHECK(layers_with_copy_output_request_[i] != layer)
1023         << i << " of " << layers_with_copy_output_request_.size();
1024   }
1025   layers_with_copy_output_request_.push_back(layer);
1026 }
1027
1028 void LayerTreeImpl::RemoveLayerWithCopyOutputRequest(LayerImpl* layer) {
1029   // Only the active tree needs to know about layers with copy requests, as
1030   // they are aborted if not serviced during draw.
1031   DCHECK(IsActiveTree());
1032
1033   std::vector<LayerImpl*>::iterator it = std::find(
1034       layers_with_copy_output_request_.begin(),
1035       layers_with_copy_output_request_.end(),
1036       layer);
1037   DCHECK(it != layers_with_copy_output_request_.end());
1038   layers_with_copy_output_request_.erase(it);
1039
1040   // TODO(danakj): Remove this once crash is found crbug.com/309777
1041   for (size_t i = 0; i < layers_with_copy_output_request_.size(); ++i) {
1042     CHECK(layers_with_copy_output_request_[i] != layer)
1043         << i << " of " << layers_with_copy_output_request_.size();
1044   }
1045 }
1046
1047 const std::vector<LayerImpl*>& LayerTreeImpl::LayersWithCopyOutputRequest()
1048     const {
1049   // Only the active tree needs to know about layers with copy requests, as
1050   // they are aborted if not serviced during draw.
1051   DCHECK(IsActiveTree());
1052
1053   return layers_with_copy_output_request_;
1054 }
1055
1056 void LayerTreeImpl::ReleaseResourcesRecursive(LayerImpl* current) {
1057   DCHECK(current);
1058   current->ReleaseResources();
1059   if (current->mask_layer())
1060     ReleaseResourcesRecursive(current->mask_layer());
1061   if (current->replica_layer())
1062     ReleaseResourcesRecursive(current->replica_layer());
1063   for (size_t i = 0; i < current->children().size(); ++i)
1064     ReleaseResourcesRecursive(current->children()[i]);
1065 }
1066
1067 template <typename LayerType>
1068 static inline bool LayerClipsSubtree(LayerType* layer) {
1069   return layer->masks_to_bounds() || layer->mask_layer();
1070 }
1071
1072 static bool PointHitsRect(
1073     const gfx::PointF& screen_space_point,
1074     const gfx::Transform& local_space_to_screen_space_transform,
1075     const gfx::RectF& local_space_rect,
1076     float* distance_to_camera) {
1077   // If the transform is not invertible, then assume that this point doesn't hit
1078   // this rect.
1079   gfx::Transform inverse_local_space_to_screen_space(
1080       gfx::Transform::kSkipInitialization);
1081   if (!local_space_to_screen_space_transform.GetInverse(
1082           &inverse_local_space_to_screen_space))
1083     return false;
1084
1085   // Transform the hit test point from screen space to the local space of the
1086   // given rect.
1087   bool clipped = false;
1088   gfx::Point3F planar_point = MathUtil::ProjectPoint3D(
1089       inverse_local_space_to_screen_space, screen_space_point, &clipped);
1090   gfx::PointF hit_test_point_in_local_space =
1091       gfx::PointF(planar_point.x(), planar_point.y());
1092
1093   // If ProjectPoint could not project to a valid value, then we assume that
1094   // this point doesn't hit this rect.
1095   if (clipped)
1096     return false;
1097
1098   if (!local_space_rect.Contains(hit_test_point_in_local_space))
1099     return false;
1100
1101   if (distance_to_camera) {
1102     // To compute the distance to the camera, we have to take the planar point
1103     // and pull it back to world space and compute the displacement along the
1104     // z-axis.
1105     gfx::Point3F planar_point_in_screen_space(planar_point);
1106     local_space_to_screen_space_transform.TransformPoint(
1107         &planar_point_in_screen_space);
1108     *distance_to_camera = planar_point_in_screen_space.z();
1109   }
1110
1111   return true;
1112 }
1113
1114 static bool PointHitsRegion(const gfx::PointF& screen_space_point,
1115                             const gfx::Transform& screen_space_transform,
1116                             const Region& layer_space_region,
1117                             float layer_content_scale_x,
1118                             float layer_content_scale_y) {
1119   // If the transform is not invertible, then assume that this point doesn't hit
1120   // this region.
1121   gfx::Transform inverse_screen_space_transform(
1122       gfx::Transform::kSkipInitialization);
1123   if (!screen_space_transform.GetInverse(&inverse_screen_space_transform))
1124     return false;
1125
1126   // Transform the hit test point from screen space to the local space of the
1127   // given region.
1128   bool clipped = false;
1129   gfx::PointF hit_test_point_in_content_space = MathUtil::ProjectPoint(
1130       inverse_screen_space_transform, screen_space_point, &clipped);
1131   gfx::PointF hit_test_point_in_layer_space =
1132       gfx::ScalePoint(hit_test_point_in_content_space,
1133                       1.f / layer_content_scale_x,
1134                       1.f / layer_content_scale_y);
1135
1136   // If ProjectPoint could not project to a valid value, then we assume that
1137   // this point doesn't hit this region.
1138   if (clipped)
1139     return false;
1140
1141   return layer_space_region.Contains(
1142       gfx::ToRoundedPoint(hit_test_point_in_layer_space));
1143 }
1144
1145 static const LayerImpl* GetNextClippingLayer(const LayerImpl* layer) {
1146   if (layer->scroll_parent())
1147     return layer->scroll_parent();
1148   if (layer->clip_parent())
1149     return layer->clip_parent();
1150   return layer->parent();
1151 }
1152
1153 static bool PointIsClippedBySurfaceOrClipRect(
1154     const gfx::PointF& screen_space_point,
1155     const LayerImpl* layer) {
1156   // Walk up the layer tree and hit-test any render_surfaces and any layer
1157   // clip rects that are active.
1158   for (; layer; layer = GetNextClippingLayer(layer)) {
1159     if (layer->render_surface() &&
1160         !PointHitsRect(screen_space_point,
1161                        layer->render_surface()->screen_space_transform(),
1162                        layer->render_surface()->content_rect(),
1163                        NULL))
1164       return true;
1165
1166     if (LayerClipsSubtree(layer) &&
1167         !PointHitsRect(screen_space_point,
1168                        layer->screen_space_transform(),
1169                        gfx::Rect(layer->content_bounds()),
1170                        NULL))
1171       return true;
1172   }
1173
1174   // If we have finished walking all ancestors without having already exited,
1175   // then the point is not clipped by any ancestors.
1176   return false;
1177 }
1178
1179 static bool PointHitsLayer(const LayerImpl* layer,
1180                            const gfx::PointF& screen_space_point,
1181                            float* distance_to_intersection) {
1182   gfx::RectF content_rect(layer->content_bounds());
1183   if (!PointHitsRect(screen_space_point,
1184                      layer->screen_space_transform(),
1185                      content_rect,
1186                      distance_to_intersection))
1187     return false;
1188
1189   // At this point, we think the point does hit the layer, but we need to walk
1190   // up the parents to ensure that the layer was not clipped in such a way
1191   // that the hit point actually should not hit the layer.
1192   if (PointIsClippedBySurfaceOrClipRect(screen_space_point, layer))
1193     return false;
1194
1195   // Skip the HUD layer.
1196   if (layer == layer->layer_tree_impl()->hud_layer())
1197     return false;
1198
1199   return true;
1200 }
1201
1202 struct FindClosestMatchingLayerDataForRecursion {
1203   FindClosestMatchingLayerDataForRecursion()
1204       : closest_match(NULL),
1205         closest_distance(-std::numeric_limits<float>::infinity()) {}
1206   LayerImpl* closest_match;
1207   // Note that the positive z-axis points towards the camera, so bigger means
1208   // closer in this case, counterintuitively.
1209   float closest_distance;
1210 };
1211
1212 template <typename Functor>
1213 static void FindClosestMatchingLayer(
1214     const gfx::PointF& screen_space_point,
1215     LayerImpl* layer,
1216     const Functor& func,
1217     FindClosestMatchingLayerDataForRecursion* data_for_recursion) {
1218   for (int i = layer->children().size() - 1; i >= 0; --i) {
1219     FindClosestMatchingLayer(
1220         screen_space_point, layer->children()[i], func, data_for_recursion);
1221   }
1222
1223   float distance_to_intersection = 0.f;
1224   if (func(layer) &&
1225       PointHitsLayer(layer, screen_space_point, &distance_to_intersection) &&
1226       ((!data_for_recursion->closest_match ||
1227         distance_to_intersection > data_for_recursion->closest_distance))) {
1228     data_for_recursion->closest_distance = distance_to_intersection;
1229     data_for_recursion->closest_match = layer;
1230   }
1231 }
1232
1233 static bool ScrollsAnyDrawnRenderSurfaceLayerListMember(LayerImpl* layer) {
1234   if (!layer->scrollable())
1235     return false;
1236   if (layer->IsDrawnRenderSurfaceLayerListMember())
1237     return true;
1238   if (!layer->scroll_children())
1239     return false;
1240   for (std::set<LayerImpl*>::const_iterator it =
1241            layer->scroll_children()->begin();
1242        it != layer->scroll_children()->end();
1243        ++it) {
1244     if ((*it)->IsDrawnRenderSurfaceLayerListMember())
1245       return true;
1246   }
1247   return false;
1248 }
1249
1250 struct FindScrollingLayerFunctor {
1251   bool operator()(LayerImpl* layer) const {
1252     return ScrollsAnyDrawnRenderSurfaceLayerListMember(layer);
1253   }
1254 };
1255
1256 LayerImpl* LayerTreeImpl::FindFirstScrollingLayerThatIsHitByPoint(
1257     const gfx::PointF& screen_space_point) {
1258   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1259   FindClosestMatchingLayer(screen_space_point,
1260                            root_layer(),
1261                            FindScrollingLayerFunctor(),
1262                            &data_for_recursion);
1263   return data_for_recursion.closest_match;
1264 }
1265
1266 struct HitTestVisibleScrollableOrTouchableFunctor {
1267   bool operator()(LayerImpl* layer) const {
1268     return layer->IsDrawnRenderSurfaceLayerListMember() ||
1269            ScrollsAnyDrawnRenderSurfaceLayerListMember(layer) ||
1270            !layer->touch_event_handler_region().IsEmpty() ||
1271            layer->have_wheel_event_handlers();
1272   }
1273 };
1274
1275 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPoint(
1276     const gfx::PointF& screen_space_point) {
1277   if (!root_layer())
1278     return NULL;
1279   if (!UpdateDrawProperties())
1280     return NULL;
1281   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1282   FindClosestMatchingLayer(screen_space_point,
1283                            root_layer(),
1284                            HitTestVisibleScrollableOrTouchableFunctor(),
1285                            &data_for_recursion);
1286   return data_for_recursion.closest_match;
1287 }
1288
1289 static bool LayerHasTouchEventHandlersAt(const gfx::PointF& screen_space_point,
1290                                          LayerImpl* layer_impl) {
1291   if (layer_impl->touch_event_handler_region().IsEmpty())
1292     return false;
1293
1294   if (!PointHitsRegion(screen_space_point,
1295                        layer_impl->screen_space_transform(),
1296                        layer_impl->touch_event_handler_region(),
1297                        layer_impl->contents_scale_x(),
1298                        layer_impl->contents_scale_y()))
1299     return false;
1300
1301   // At this point, we think the point does hit the touch event handler region
1302   // on the layer, but we need to walk up the parents to ensure that the layer
1303   // was not clipped in such a way that the hit point actually should not hit
1304   // the layer.
1305   if (PointIsClippedBySurfaceOrClipRect(screen_space_point, layer_impl))
1306     return false;
1307
1308   return true;
1309 }
1310
1311 struct FindTouchEventLayerFunctor {
1312   bool operator()(LayerImpl* layer) const {
1313     return LayerHasTouchEventHandlersAt(screen_space_point, layer);
1314   }
1315   const gfx::PointF screen_space_point;
1316 };
1317
1318 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
1319     const gfx::PointF& screen_space_point) {
1320   if (!root_layer())
1321     return NULL;
1322   if (!UpdateDrawProperties())
1323     return NULL;
1324   FindTouchEventLayerFunctor func = {screen_space_point};
1325   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1326   FindClosestMatchingLayer(
1327       screen_space_point, root_layer(), func, &data_for_recursion);
1328   return data_for_recursion.closest_match;
1329 }
1330
1331 void LayerTreeImpl::RegisterSelection(const LayerSelectionBound& start,
1332                                       const LayerSelectionBound& end) {
1333   selection_start_ = start;
1334   selection_end_ = end;
1335 }
1336
1337 static ViewportSelectionBound ComputeViewportSelection(
1338     const LayerSelectionBound& layer_bound,
1339     LayerImpl* layer,
1340     float device_scale_factor) {
1341   ViewportSelectionBound viewport_bound;
1342   viewport_bound.type = layer_bound.type;
1343
1344   if (!layer || layer_bound.type == SELECTION_BOUND_EMPTY)
1345     return viewport_bound;
1346
1347   gfx::PointF layer_scaled_top = gfx::ScalePoint(layer_bound.edge_top,
1348                                                  layer->contents_scale_x(),
1349                                                  layer->contents_scale_y());
1350   gfx::PointF layer_scaled_bottom = gfx::ScalePoint(layer_bound.edge_bottom,
1351                                                     layer->contents_scale_x(),
1352                                                     layer->contents_scale_y());
1353
1354   bool clipped = false;
1355   gfx::PointF screen_top = MathUtil::MapPoint(
1356       layer->screen_space_transform(), layer_scaled_top, &clipped);
1357   gfx::PointF screen_bottom = MathUtil::MapPoint(
1358       layer->screen_space_transform(), layer_scaled_bottom, &clipped);
1359
1360   const float inv_scale = 1.f / device_scale_factor;
1361   viewport_bound.edge_top = gfx::ScalePoint(screen_top, inv_scale);
1362   viewport_bound.edge_bottom = gfx::ScalePoint(screen_bottom, inv_scale);
1363
1364   // The bottom edge point is used for visibility testing as it is the logical
1365   // focal point for bound selection handles (this may change in the future).
1366   // Shifting the visibility point fractionally inward ensures that neighboring
1367   // or logically coincident layers aligned to integral DPI coordinates will not
1368   // spuriously occlude the bound.
1369   gfx::Vector2dF visibility_offset = layer_scaled_top - layer_scaled_bottom;
1370   visibility_offset.Scale(device_scale_factor / visibility_offset.Length());
1371   gfx::PointF visibility_point = layer_scaled_bottom + visibility_offset;
1372   if (visibility_point.x() <= 0)
1373     visibility_point.set_x(visibility_point.x() + device_scale_factor);
1374   visibility_point = MathUtil::MapPoint(
1375       layer->screen_space_transform(), visibility_point, &clipped);
1376
1377   float intersect_distance = 0.f;
1378   viewport_bound.visible =
1379       PointHitsLayer(layer, visibility_point, &intersect_distance);
1380
1381   return viewport_bound;
1382 }
1383
1384 void LayerTreeImpl::GetViewportSelection(ViewportSelectionBound* start,
1385                                          ViewportSelectionBound* end) {
1386   DCHECK(start);
1387   DCHECK(end);
1388
1389   *start = ComputeViewportSelection(
1390       selection_start_,
1391       selection_start_.layer_id ? LayerById(selection_start_.layer_id) : NULL,
1392       device_scale_factor());
1393   if (start->type == SELECTION_BOUND_CENTER ||
1394       start->type == SELECTION_BOUND_EMPTY) {
1395     *end = *start;
1396   } else {
1397     *end = ComputeViewportSelection(
1398         selection_end_,
1399         selection_end_.layer_id ? LayerById(selection_end_.layer_id) : NULL,
1400         device_scale_factor());
1401   }
1402 }
1403
1404 void LayerTreeImpl::RegisterPictureLayerImpl(PictureLayerImpl* layer) {
1405   layer_tree_host_impl_->RegisterPictureLayerImpl(layer);
1406 }
1407
1408 void LayerTreeImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
1409   layer_tree_host_impl_->UnregisterPictureLayerImpl(layer);
1410 }
1411
1412 void LayerTreeImpl::InputScrollAnimationFinished() {
1413   layer_tree_host_impl_->ScrollEnd();
1414 }
1415
1416 }  // namespace cc