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 <algorithm>
   8 #include <limits>
   9 #include <set>
  10
  11 #include "base/trace_event/trace_event.h"
  12 #include "base/trace_event/trace_event_argument.h"
  13 #include "cc/animation/keyframed_animation_curve.h"
  14 #include "cc/animation/scrollbar_animation_controller.h"
  15 #include "cc/animation/scrollbar_animation_controller_linear_fade.h"
  16 #include "cc/animation/scrollbar_animation_controller_thinning.h"
  17 #include "cc/base/math_util.h"
  18 #include "cc/base/synced_property.h"
  19 #include "cc/base/util.h"
  20 #include "cc/debug/devtools_instrumentation.h"
  21 #include "cc/debug/traced_value.h"
  22 #include "cc/input/page_scale_animation.h"
  23 #include "cc/layers/heads_up_display_layer_impl.h"
  24 #include "cc/layers/layer.h"
  25 #include "cc/layers/layer_iterator.h"
  26 #include "cc/layers/render_surface_impl.h"
  27 #include "cc/layers/scrollbar_layer_impl_base.h"
  28 #include "cc/resources/ui_resource_request.h"
  29 #include "cc/trees/layer_tree_host_common.h"
  30 #include "cc/trees/layer_tree_host_impl.h"
  31 #include "cc/trees/occlusion_tracker.h"
  32 #include "ui/gfx/geometry/point_conversions.h"
  33 #include "ui/gfx/geometry/size_conversions.h"
  34 #include "ui/gfx/geometry/vector2d_conversions.h"
  35
  36 namespace cc {
  37
  38 // This class exists to split the LayerScrollOffsetDelegate between the
  39 // InnerViewportScrollLayer and the OuterViewportScrollLayer in a manner
  40 // that never requires the embedder or LayerImpl to know about.
  41 class LayerScrollOffsetDelegateProxy : public LayerImpl::ScrollOffsetDelegate {
  42  public:
  43   LayerScrollOffsetDelegateProxy(LayerImpl* layer,
  44                                  LayerScrollOffsetDelegate* delegate,
  45                                  LayerTreeImpl* layer_tree)
  46       : layer_(layer), delegate_(delegate), layer_tree_impl_(layer_tree) {}
  47   virtual ~LayerScrollOffsetDelegateProxy() {}
  48
  49   gfx::ScrollOffset last_set_scroll_offset() const {
  50     return last_set_scroll_offset_;
  51   }
  52
  53   // LayerScrollOffsetDelegate implementation.
  54   void SetCurrentScrollOffset(const gfx::ScrollOffset& new_offset) override {
  55     last_set_scroll_offset_ = new_offset;
  56   }
  57
  58   gfx::ScrollOffset GetCurrentScrollOffset() override {
  59     return layer_tree_impl_->GetDelegatedScrollOffset(layer_);
  60   }
  61
  62   bool IsExternalFlingActive() const override {
  63     return delegate_->IsExternalFlingActive();
  64   }
  65
  66   void Update() const override {
  67     layer_tree_impl_->UpdateScrollOffsetDelegate();
  68   }
  69
  70  private:
  71   LayerImpl* layer_;
  72   LayerScrollOffsetDelegate* delegate_;
  73   LayerTreeImpl* layer_tree_impl_;
  74   gfx::ScrollOffset last_set_scroll_offset_;
  75 };
  76
  77 LayerTreeImpl::LayerTreeImpl(
  78     LayerTreeHostImpl* layer_tree_host_impl,
  79     scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
  80     scoped_refptr<SyncedTopControls> top_controls_shown_ratio,
  81     scoped_refptr<SyncedElasticOverscroll> elastic_overscroll)
  82     : layer_tree_host_impl_(layer_tree_host_impl),
  83       source_frame_number_(-1),
  84       hud_layer_(0),
  85       currently_scrolling_layer_(NULL),
  86       root_layer_scroll_offset_delegate_(NULL),
  87       background_color_(0),
  88       has_transparent_background_(false),
  89       overscroll_elasticity_layer_(NULL),
  90       page_scale_layer_(NULL),
  91       inner_viewport_scroll_layer_(NULL),
  92       outer_viewport_scroll_layer_(NULL),
  93       page_scale_factor_(page_scale_factor),
  94       min_page_scale_factor_(0),
  95       max_page_scale_factor_(0),
  96       elastic_overscroll_(elastic_overscroll),
  97       scrolling_layer_id_from_previous_tree_(0),
  98       contents_textures_purged_(false),
  99       viewport_size_invalid_(false),
 100       needs_update_draw_properties_(true),
 101       needs_full_tree_sync_(true),
 102       next_activation_forces_redraw_(false),
 103       has_ever_been_drawn_(false),
 104       render_surface_layer_list_id_(0),
 105       top_controls_shrink_blink_size_(false),
 106       top_controls_height_(0),
 107       top_controls_shown_ratio_(top_controls_shown_ratio) {
 108 }
 109
 110 LayerTreeImpl::~LayerTreeImpl() {
 111   BreakSwapPromises(SwapPromise::SWAP_FAILS);
 112
 113   // Need to explicitly clear the tree prior to destroying this so that
 114   // the LayerTreeImpl pointer is still valid in the LayerImpl dtor.
 115   DCHECK(!root_layer_);
 116   DCHECK(layers_with_copy_output_request_.empty());
 117 }
 118
 119 void LayerTreeImpl::Shutdown() {
 120   root_layer_ = nullptr;
 121 }
 122
 123 void LayerTreeImpl::ReleaseResources() {
 124   if (root_layer_) {
 125     LayerTreeHostCommon::CallFunctionForSubtree(
 126         root_layer_.get(), [](LayerImpl* layer) { layer->ReleaseResources(); });
 127   }
 128 }
 129
 130 void LayerTreeImpl::RecreateResources() {
 131   if (root_layer_) {
 132     LayerTreeHostCommon::CallFunctionForSubtree(
 133         root_layer_.get(),
 134         [](LayerImpl* layer) { layer->RecreateResources(); });
 135   }
 136 }
 137
 138 void LayerTreeImpl::SetRootLayer(scoped_ptr<LayerImpl> layer) {
 139   if (inner_viewport_scroll_layer_)
 140     inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 141   if (outer_viewport_scroll_layer_)
 142     outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 143   inner_viewport_scroll_delegate_proxy_ = nullptr;
 144   outer_viewport_scroll_delegate_proxy_ = nullptr;
 145
 146   root_layer_ = layer.Pass();
 147   currently_scrolling_layer_ = NULL;
 148   inner_viewport_scroll_layer_ = NULL;
 149   outer_viewport_scroll_layer_ = NULL;
 150   page_scale_layer_ = NULL;
 151
 152   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 153 }
 154
 155 LayerImpl* LayerTreeImpl::InnerViewportScrollLayer() const {
 156   return inner_viewport_scroll_layer_;
 157 }
 158
 159 LayerImpl* LayerTreeImpl::OuterViewportScrollLayer() const {
 160   return outer_viewport_scroll_layer_;
 161 }
 162
 163 gfx::ScrollOffset LayerTreeImpl::TotalScrollOffset() const {
 164   gfx::ScrollOffset offset;
 165
 166   if (inner_viewport_scroll_layer_)
 167     offset += inner_viewport_scroll_layer_->CurrentScrollOffset();
 168
 169   if (outer_viewport_scroll_layer_)
 170     offset += outer_viewport_scroll_layer_->CurrentScrollOffset();
 171
 172   return offset;
 173 }
 174
 175 gfx::ScrollOffset LayerTreeImpl::TotalMaxScrollOffset() const {
 176   gfx::ScrollOffset offset;
 177
 178   if (inner_viewport_scroll_layer_)
 179     offset += inner_viewport_scroll_layer_->MaxScrollOffset();
 180
 181   if (outer_viewport_scroll_layer_)
 182     offset += outer_viewport_scroll_layer_->MaxScrollOffset();
 183
 184   return offset;
 185 }
 186
 187 scoped_ptr<LayerImpl> LayerTreeImpl::DetachLayerTree() {
 188   // Clear all data structures that have direct references to the layer tree.
 189   scrolling_layer_id_from_previous_tree_ =
 190     currently_scrolling_layer_ ? currently_scrolling_layer_->id() : 0;
 191   if (inner_viewport_scroll_layer_)
 192     inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 193   if (outer_viewport_scroll_layer_)
 194     outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
 195   inner_viewport_scroll_delegate_proxy_ = nullptr;
 196   outer_viewport_scroll_delegate_proxy_ = nullptr;
 197   inner_viewport_scroll_layer_ = NULL;
 198   outer_viewport_scroll_layer_ = NULL;
 199   page_scale_layer_ = NULL;
 200   currently_scrolling_layer_ = NULL;
 201
 202   render_surface_layer_list_.clear();
 203   set_needs_update_draw_properties();
 204   return root_layer_.Pass();
 205 }
 206
 207 void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
 208   // The request queue should have been processed and does not require a push.
 209   DCHECK_EQ(ui_resource_request_queue_.size(), 0u);
 210
 211   if (next_activation_forces_redraw_) {
 212     target_tree->ForceRedrawNextActivation();
 213     next_activation_forces_redraw_ = false;
 214   }
 215
 216   target_tree->PassSwapPromises(&swap_promise_list_);
 217
 218   target_tree->set_top_controls_shrink_blink_size(
 219       top_controls_shrink_blink_size_);
 220   target_tree->set_top_controls_height(top_controls_height_);
 221   target_tree->PushTopControls(nullptr);
 222
 223   // Active tree already shares the page_scale_factor object with pending
 224   // tree so only the limits need to be provided.
 225   target_tree->PushPageScaleFactorAndLimits(nullptr, min_page_scale_factor(),
 226                                             max_page_scale_factor());
 227   target_tree->elastic_overscroll()->PushPendingToActive();
 228
 229   target_tree->pending_page_scale_animation_ =
 230       pending_page_scale_animation_.Pass();
 231
 232   if (page_scale_layer_ && inner_viewport_scroll_layer_) {
 233     target_tree->SetViewportLayersFromIds(
 234         overscroll_elasticity_layer_ ? overscroll_elasticity_layer_->id()
 235                                      : Layer::INVALID_ID,
 236         page_scale_layer_->id(), inner_viewport_scroll_layer_->id(),
 237         outer_viewport_scroll_layer_ ? outer_viewport_scroll_layer_->id()
 238                                      : Layer::INVALID_ID);
 239   } else {
 240     target_tree->ClearViewportLayers();
 241   }
 242
 243   target_tree->RegisterSelection(selection_start_, selection_end_);
 244
 245   // This should match the property synchronization in
 246   // LayerTreeHost::finishCommitOnImplThread().
 247   target_tree->set_source_frame_number(source_frame_number());
 248   target_tree->set_background_color(background_color());
 249   target_tree->set_has_transparent_background(has_transparent_background());
 250
 251   if (ContentsTexturesPurged())
 252     target_tree->SetContentsTexturesPurged();
 253   else
 254     target_tree->ResetContentsTexturesPurged();
 255
 256   if (ViewportSizeInvalid())
 257     target_tree->SetViewportSizeInvalid();
 258   else
 259     target_tree->ResetViewportSizeInvalid();
 260
 261   if (hud_layer())
 262     target_tree->set_hud_layer(static_cast<HeadsUpDisplayLayerImpl*>(
 263         LayerTreeHostCommon::FindLayerInSubtree(
 264             target_tree->root_layer(), hud_layer()->id())));
 265   else
 266     target_tree->set_hud_layer(NULL);
 267
 268   target_tree->has_ever_been_drawn_ = false;
 269 }
 270
 271 LayerImpl* LayerTreeImpl::InnerViewportContainerLayer() const {
 272   return inner_viewport_scroll_layer_
 273              ? inner_viewport_scroll_layer_->scroll_clip_layer()
 274              : NULL;
 275 }
 276
 277 LayerImpl* LayerTreeImpl::OuterViewportContainerLayer() const {
 278   return outer_viewport_scroll_layer_
 279              ? outer_viewport_scroll_layer_->scroll_clip_layer()
 280              : NULL;
 281 }
 282
 283 LayerImpl* LayerTreeImpl::CurrentlyScrollingLayer() const {
 284   DCHECK(IsActiveTree());
 285   return currently_scrolling_layer_;
 286 }
 287
 288 void LayerTreeImpl::SetCurrentlyScrollingLayer(LayerImpl* layer) {
 289   if (currently_scrolling_layer_ == layer)
 290     return;
 291
 292   if (currently_scrolling_layer_ &&
 293       currently_scrolling_layer_->scrollbar_animation_controller())
 294     currently_scrolling_layer_->scrollbar_animation_controller()
 295         ->DidScrollEnd();
 296   currently_scrolling_layer_ = layer;
 297   if (layer && layer->scrollbar_animation_controller())
 298     layer->scrollbar_animation_controller()->DidScrollBegin();
 299 }
 300
 301 void LayerTreeImpl::ClearCurrentlyScrollingLayer() {
 302   SetCurrentlyScrollingLayer(NULL);
 303   scrolling_layer_id_from_previous_tree_ = 0;
 304 }
 305
 306 namespace {
 307
 308 void ForceScrollbarParameterUpdateAfterScaleChange(LayerImpl* current_layer) {
 309   if (!current_layer)
 310     return;
 311
 312   while (current_layer) {
 313     current_layer->ScrollbarParametersDidChange(false);
 314     current_layer = current_layer->parent();
 315   }
 316 }
 317
 318 }  // namespace
 319
 320 float LayerTreeImpl::ClampPageScaleFactorToLimits(
 321     float page_scale_factor) const {
 322   if (min_page_scale_factor_ && page_scale_factor < min_page_scale_factor_)
 323     page_scale_factor = min_page_scale_factor_;
 324   else if (max_page_scale_factor_ && page_scale_factor > max_page_scale_factor_)
 325     page_scale_factor = max_page_scale_factor_;
 326   return page_scale_factor;
 327 }
 328
 329 void LayerTreeImpl::SetPageScaleOnActiveTree(float active_page_scale) {
 330   DCHECK(IsActiveTree());
 331   if (page_scale_factor()->SetCurrent(
 332           ClampPageScaleFactorToLimits(active_page_scale)))
 333     DidUpdatePageScale();
 334 }
 335
 336 void LayerTreeImpl::PushPageScaleFromMainThread(float page_scale_factor,
 337                                                 float min_page_scale_factor,
 338                                                 float max_page_scale_factor) {
 339   PushPageScaleFactorAndLimits(&page_scale_factor, min_page_scale_factor,
 340                                max_page_scale_factor);
 341 }
 342
 343 void LayerTreeImpl::PushPageScaleFactorAndLimits(const float* page_scale_factor,
 344                                                  float min_page_scale_factor,
 345                                                  float max_page_scale_factor) {
 346   DCHECK(page_scale_factor || IsActiveTree());
 347   bool changed_page_scale = false;
 348   if (page_scale_factor) {
 349     DCHECK(!IsActiveTree() || !layer_tree_host_impl_->pending_tree());
 350     changed_page_scale |=
 351         page_scale_factor_->PushFromMainThread(*page_scale_factor);
 352   }
 353   if (IsActiveTree())
 354     changed_page_scale |= page_scale_factor_->PushPendingToActive();
 355   changed_page_scale |=
 356       SetPageScaleFactorLimits(min_page_scale_factor, max_page_scale_factor);
 357
 358   if (changed_page_scale)
 359     DidUpdatePageScale();
 360 }
 361
 362 void LayerTreeImpl::set_top_controls_shrink_blink_size(bool shrink) {
 363   if (top_controls_shrink_blink_size_ == shrink)
 364     return;
 365
 366   top_controls_shrink_blink_size_ = shrink;
 367   if (IsActiveTree())
 368     layer_tree_host_impl_->UpdateViewportContainerSizes();
 369 }
 370
 371 void LayerTreeImpl::set_top_controls_height(float top_controls_height) {
 372   if (top_controls_height_ == top_controls_height)
 373     return;
 374
 375   top_controls_height_ = top_controls_height;
 376   if (IsActiveTree())
 377     layer_tree_host_impl_->UpdateViewportContainerSizes();
 378 }
 379
 380 bool LayerTreeImpl::SetCurrentTopControlsShownRatio(float ratio) {
 381   ratio = std::max(ratio, 0.f);
 382   ratio = std::min(ratio, 1.f);
 383   return top_controls_shown_ratio_->SetCurrent(ratio);
 384 }
 385
 386 void LayerTreeImpl::PushTopControlsFromMainThread(
 387     float top_controls_shown_ratio) {
 388   PushTopControls(&top_controls_shown_ratio);
 389 }
 390
 391 void LayerTreeImpl::PushTopControls(const float* top_controls_shown_ratio) {
 392   DCHECK(top_controls_shown_ratio || IsActiveTree());
 393
 394   if (top_controls_shown_ratio) {
 395     DCHECK(!IsActiveTree() || !layer_tree_host_impl_->pending_tree());
 396     top_controls_shown_ratio_->PushFromMainThread(*top_controls_shown_ratio);
 397   }
 398   if (IsActiveTree()) {
 399     if (top_controls_shown_ratio_->PushPendingToActive())
 400       layer_tree_host_impl_->DidChangeTopControlsPosition();
 401   }
 402 }
 403
 404 bool LayerTreeImpl::SetPageScaleFactorLimits(float min_page_scale_factor,
 405                                              float max_page_scale_factor) {
 406   if (min_page_scale_factor == min_page_scale_factor_ &&
 407       max_page_scale_factor == max_page_scale_factor_)
 408     return false;
 409
 410   min_page_scale_factor_ = min_page_scale_factor;
 411   max_page_scale_factor_ = max_page_scale_factor;
 412
 413   return true;
 414 }
 415
 416 void LayerTreeImpl::DidUpdatePageScale() {
 417   if (IsActiveTree())
 418     page_scale_factor()->SetCurrent(
 419         ClampPageScaleFactorToLimits(current_page_scale_factor()));
 420
 421   set_needs_update_draw_properties();
 422
 423   if (root_layer_scroll_offset_delegate_) {
 424     root_layer_scroll_offset_delegate_->UpdateRootLayerState(
 425         TotalScrollOffset(), TotalMaxScrollOffset(), ScrollableSize(),
 426         current_page_scale_factor(), min_page_scale_factor_,
 427         max_page_scale_factor_);
 428   }
 429
 430   ForceScrollbarParameterUpdateAfterScaleChange(page_scale_layer());
 431
 432   HideInnerViewportScrollbarsIfNearMinimumScale();
 433 }
 434
 435 void LayerTreeImpl::HideInnerViewportScrollbarsIfNearMinimumScale() {
 436   if (!InnerViewportContainerLayer())
 437     return;
 438
 439   LayerImpl::ScrollbarSet* scrollbars =
 440       InnerViewportContainerLayer()->scrollbars();
 441
 442   if (!scrollbars)
 443     return;
 444
 445   for (LayerImpl::ScrollbarSet::iterator it = scrollbars->begin();
 446        it != scrollbars->end();
 447        ++it) {
 448     ScrollbarLayerImplBase* scrollbar = *it;
 449     float minimum_scale_to_show_at =
 450         min_page_scale_factor() * settings().scrollbar_show_scale_threshold;
 451     scrollbar->SetHideLayerAndSubtree(
 452         current_page_scale_factor() < minimum_scale_to_show_at);
 453   }
 454 }
 455
 456 SyncedProperty<ScaleGroup>* LayerTreeImpl::page_scale_factor() {
 457   return page_scale_factor_.get();
 458 }
 459
 460 const SyncedProperty<ScaleGroup>* LayerTreeImpl::page_scale_factor() const {
 461   return page_scale_factor_.get();
 462 }
 463
 464 gfx::SizeF LayerTreeImpl::ScrollableViewportSize() const {
 465   if (!InnerViewportContainerLayer())
 466     return gfx::SizeF();
 467
 468   return gfx::ScaleSize(InnerViewportContainerLayer()->BoundsForScrolling(),
 469                         1.0f / current_page_scale_factor());
 470 }
 471
 472 gfx::Rect LayerTreeImpl::RootScrollLayerDeviceViewportBounds() const {
 473   LayerImpl* root_scroll_layer = OuterViewportScrollLayer()
 474                                      ? OuterViewportScrollLayer()
 475                                      : InnerViewportScrollLayer();
 476   if (!root_scroll_layer || root_scroll_layer->children().empty())
 477     return gfx::Rect();
 478   LayerImpl* layer = root_scroll_layer->children()[0];
 479   return MathUtil::MapEnclosingClippedRect(layer->screen_space_transform(),
 480                                            gfx::Rect(layer->content_bounds()));
 481 }
 482
 483 void LayerTreeImpl::ApplySentScrollAndScaleDeltasFromAbortedCommit() {
 484   DCHECK(IsActiveTree());
 485
 486   page_scale_factor()->AbortCommit();
 487   top_controls_shown_ratio()->AbortCommit();
 488   elastic_overscroll()->AbortCommit();
 489
 490   if (!root_layer())
 491     return;
 492
 493   LayerTreeHostCommon::CallFunctionForSubtree(
 494       root_layer(), [](LayerImpl* layer) {
 495         layer->ApplySentScrollDeltasFromAbortedCommit();
 496       });
 497 }
 498
 499 void LayerTreeImpl::SetViewportLayersFromIds(
 500     int overscroll_elasticity_layer_id,
 501     int page_scale_layer_id,
 502     int inner_viewport_scroll_layer_id,
 503     int outer_viewport_scroll_layer_id) {
 504   overscroll_elasticity_layer_ = LayerById(overscroll_elasticity_layer_id);
 505   page_scale_layer_ = LayerById(page_scale_layer_id);
 506   DCHECK(page_scale_layer_);
 507
 508   inner_viewport_scroll_layer_ =
 509       LayerById(inner_viewport_scroll_layer_id);
 510   DCHECK(inner_viewport_scroll_layer_);
 511
 512   outer_viewport_scroll_layer_ =
 513       LayerById(outer_viewport_scroll_layer_id);
 514   DCHECK(outer_viewport_scroll_layer_ ||
 515          outer_viewport_scroll_layer_id == Layer::INVALID_ID);
 516
 517   HideInnerViewportScrollbarsIfNearMinimumScale();
 518
 519   if (!root_layer_scroll_offset_delegate_)
 520     return;
 521
 522   inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 523       new LayerScrollOffsetDelegateProxy(inner_viewport_scroll_layer_,
 524                                          root_layer_scroll_offset_delegate_,
 525                                          this));
 526
 527   if (outer_viewport_scroll_layer_)
 528     outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
 529         new LayerScrollOffsetDelegateProxy(outer_viewport_scroll_layer_,
 530                                            root_layer_scroll_offset_delegate_,
 531                                            this));
 532 }
 533
 534 void LayerTreeImpl::ClearViewportLayers() {
 535   page_scale_layer_ = NULL;
 536   inner_viewport_scroll_layer_ = NULL;
 537   outer_viewport_scroll_layer_ = NULL;
 538 }
 539
 540 bool LayerTreeImpl::UpdateDrawProperties(bool update_lcd_text) {
 541   if (!needs_update_draw_properties_)
 542     return true;
 543
 544   // Calling UpdateDrawProperties must clear this flag, so there can be no
 545   // early outs before this.
 546   needs_update_draw_properties_ = false;
 547
 548   // For max_texture_size.  When the renderer is re-created in
 549   // CreateAndSetRenderer, the needs update draw properties flag is set
 550   // again.
 551   if (!layer_tree_host_impl_->renderer())
 552     return false;
 553
 554   // Clear this after the renderer early out, as it should still be
 555   // possible to hit test even without a renderer.
 556   render_surface_layer_list_.clear();
 557
 558   if (!root_layer())
 559     return false;
 560
 561   {
 562     TRACE_EVENT2(
 563         "cc", "LayerTreeImpl::UpdateDrawProperties::CalculateDrawProperties",
 564         "IsActive", IsActiveTree(), "SourceFrameNumber", source_frame_number_);
 565     LayerImpl* page_scale_layer =
 566         page_scale_layer_ ? page_scale_layer_ : InnerViewportContainerLayer();
 567     bool can_render_to_separate_surface =
 568         (layer_tree_host_impl_->GetDrawMode() !=
 569          DRAW_MODE_RESOURCELESS_SOFTWARE);
 570
 571     ++render_surface_layer_list_id_;
 572     LayerTreeHostCommon::CalcDrawPropsImplInputs inputs(
 573         root_layer(), DrawViewportSize(),
 574         layer_tree_host_impl_->DrawTransform(), device_scale_factor(),
 575         current_page_scale_factor(), page_scale_layer,
 576         elastic_overscroll()->Current(IsActiveTree()),
 577         overscroll_elasticity_layer_, resource_provider()->max_texture_size(),
 578         settings().can_use_lcd_text, settings().layers_always_allowed_lcd_text,
 579         can_render_to_separate_surface,
 580         settings().layer_transforms_should_scale_layer_contents,
 581         settings().verify_property_trees,
 582         &render_surface_layer_list_, render_surface_layer_list_id_);
 583     LayerTreeHostCommon::CalculateDrawProperties(&inputs);
 584   }
 585
 586   {
 587     TRACE_EVENT2("cc", "LayerTreeImpl::UpdateDrawProperties::Occlusion",
 588                  "IsActive", IsActiveTree(), "SourceFrameNumber",
 589                  source_frame_number_);
 590     OcclusionTracker<LayerImpl> occlusion_tracker(
 591         root_layer()->render_surface()->content_rect());
 592     occlusion_tracker.set_minimum_tracking_size(
 593         settings().minimum_occlusion_tracking_size);
 594
 595     // LayerIterator is used here instead of CallFunctionForSubtree to only
 596     // UpdateTilePriorities on layers that will be visible (and thus have valid
 597     // draw properties) and not because any ordering is required.
 598     auto end = LayerIterator<LayerImpl>::End(&render_surface_layer_list_);
 599     for (auto it = LayerIterator<LayerImpl>::Begin(&render_surface_layer_list_);
 600          it != end; ++it) {
 601       occlusion_tracker.EnterLayer(it);
 602
 603       // There are very few render targets so this should be cheap to do for
 604       // each layer instead of something more complicated.
 605       bool inside_replica = false;
 606       LayerImpl* layer = it->render_target();
 607       while (layer && !inside_replica) {
 608         if (layer->render_target()->has_replica())
 609           inside_replica = true;
 610         layer = layer->render_target()->parent();
 611       }
 612
 613       // Don't use occlusion if a layer will appear in a replica, since the
 614       // tile raster code does not know how to look for the replica and would
 615       // consider it occluded even though the replica is visible.
 616       // Since occlusion is only used for browser compositor (i.e.
 617       // use_occlusion_for_tile_prioritization) and it won't use replicas,
 618       // this should matter not.
 619
 620       if (it.represents_itself()) {
 621         Occlusion occlusion =
 622             inside_replica ? Occlusion()
 623                            : occlusion_tracker.GetCurrentOcclusionForLayer(
 624                                  it->draw_transform());
 625         it->draw_properties().occlusion_in_content_space = occlusion;
 626       }
 627
 628       if (it.represents_contributing_render_surface()) {
 629         // Surfaces aren't used by the tile raster code, so they can have
 630         // occlusion regardless of replicas.
 631         Occlusion occlusion =
 632             occlusion_tracker.GetCurrentOcclusionForContributingSurface(
 633                 it->render_surface()->draw_transform());
 634         it->render_surface()->set_occlusion_in_content_space(occlusion);
 635         // Masks are used to draw the contributing surface, so should have
 636         // the same occlusion as the surface (nothing inside the surface
 637         // occludes them).
 638         if (LayerImpl* mask = it->mask_layer()) {
 639           Occlusion mask_occlusion =
 640               inside_replica
 641                   ? Occlusion()
 642                   : occlusion_tracker.GetCurrentOcclusionForContributingSurface(
 643                         it->render_surface()->draw_transform() *
 644                         it->draw_transform());
 645           mask->draw_properties().occlusion_in_content_space = mask_occlusion;
 646         }
 647         if (LayerImpl* replica = it->replica_layer()) {
 648           if (LayerImpl* mask = replica->mask_layer())
 649             mask->draw_properties().occlusion_in_content_space = Occlusion();
 650         }
 651       }
 652
 653       occlusion_tracker.LeaveLayer(it);
 654     }
 655
 656     unoccluded_screen_space_region_ =
 657         occlusion_tracker.ComputeVisibleRegionInScreen();
 658   }
 659
 660   // It'd be ideal if this could be done earlier, but when the raster source
 661   // is updated from the main thread during push properties, update draw
 662   // properties has not occurred yet and so it's not clear whether or not the
 663   // layer can or cannot use lcd text.  So, this is the cleanup pass to
 664   // determine if the raster source needs to be replaced with a non-lcd
 665   // raster source due to draw properties.
 666   if (update_lcd_text) {
 667     // TODO(enne): Make LTHI::sync_tree return this value.
 668     LayerTreeImpl* sync_tree =
 669         layer_tree_host_impl_->proxy()->CommitToActiveTree()
 670             ? layer_tree_host_impl_->active_tree()
 671             : layer_tree_host_impl_->pending_tree();
 672     // If this is not the sync tree, then it is not safe to update lcd text
 673     // as it causes invalidations and the tiles may be in use.
 674     DCHECK_EQ(this, sync_tree);
 675     for (const auto& layer : picture_layers_)
 676       layer->UpdateCanUseLCDTextAfterCommit();
 677   }
 678
 679   {
 680     TRACE_EVENT_BEGIN2("cc", "LayerTreeImpl::UpdateDrawProperties::UpdateTiles",
 681                        "IsActive", IsActiveTree(), "SourceFrameNumber",
 682                        source_frame_number_);
 683     const bool resourceless_software_draw =
 684         (layer_tree_host_impl_->GetDrawMode() ==
 685          DRAW_MODE_RESOURCELESS_SOFTWARE);
 686     size_t layers_updated_count = 0;
 687     bool tile_priorities_updated = false;
 688     for (PictureLayerImpl* layer : picture_layers_) {
 689       if (!layer->IsDrawnRenderSurfaceLayerListMember())
 690         continue;
 691       ++layers_updated_count;
 692       tile_priorities_updated |= layer->UpdateTiles(resourceless_software_draw);
 693     }
 694
 695     if (tile_priorities_updated)
 696       DidModifyTilePriorities();
 697
 698     TRACE_EVENT_END1("cc", "LayerTreeImpl::UpdateTilePriorities",
 699                      "layers_updated_count", layers_updated_count);
 700   }
 701
 702   DCHECK(!needs_update_draw_properties_) <<
 703       "CalcDrawProperties should not set_needs_update_draw_properties()";
 704   return true;
 705 }
 706
 707 const LayerImplList& LayerTreeImpl::RenderSurfaceLayerList() const {
 708   // If this assert triggers, then the list is dirty.
 709   DCHECK(!needs_update_draw_properties_);
 710   return render_surface_layer_list_;
 711 }
 712
 713 const Region& LayerTreeImpl::UnoccludedScreenSpaceRegion() const {
 714   // If this assert triggers, then the render_surface_layer_list_ is dirty, so
 715   // the unoccluded_screen_space_region_ is not valid anymore.
 716   DCHECK(!needs_update_draw_properties_);
 717   return unoccluded_screen_space_region_;
 718 }
 719
 720 gfx::Size LayerTreeImpl::ScrollableSize() const {
 721   LayerImpl* root_scroll_layer = OuterViewportScrollLayer()
 722                                      ? OuterViewportScrollLayer()
 723                                      : InnerViewportScrollLayer();
 724   if (!root_scroll_layer || root_scroll_layer->children().empty())
 725     return gfx::Size();
 726   return root_scroll_layer->children()[0]->bounds();
 727 }
 728
 729 LayerImpl* LayerTreeImpl::LayerById(int id) {
 730   LayerIdMap::iterator iter = layer_id_map_.find(id);
 731   return iter != layer_id_map_.end() ? iter->second : NULL;
 732 }
 733
 734 void LayerTreeImpl::RegisterLayer(LayerImpl* layer) {
 735   DCHECK(!LayerById(layer->id()));
 736   layer_id_map_[layer->id()] = layer;
 737 }
 738
 739 void LayerTreeImpl::UnregisterLayer(LayerImpl* layer) {
 740   DCHECK(LayerById(layer->id()));
 741   layer_id_map_.erase(layer->id());
 742 }
 743
 744 size_t LayerTreeImpl::NumLayers() {
 745   return layer_id_map_.size();
 746 }
 747
 748 void LayerTreeImpl::PushPersistedState(LayerTreeImpl* pending_tree) {
 749   pending_tree->SetCurrentlyScrollingLayer(
 750       LayerTreeHostCommon::FindLayerInSubtree(pending_tree->root_layer(),
 751           currently_scrolling_layer_ ? currently_scrolling_layer_->id() : 0));
 752 }
 753
 754 void LayerTreeImpl::DidBecomeActive() {
 755   if (next_activation_forces_redraw_) {
 756     layer_tree_host_impl_->SetFullRootLayerDamage();
 757     next_activation_forces_redraw_ = false;
 758   }
 759
 760   if (scrolling_layer_id_from_previous_tree_) {
 761     currently_scrolling_layer_ = LayerTreeHostCommon::FindLayerInSubtree(
 762         root_layer(), scrolling_layer_id_from_previous_tree_);
 763   }
 764
 765   // Always reset this flag on activation, as we would only have activated
 766   // if we were in a good state.
 767   layer_tree_host_impl_->ResetRequiresHighResToDraw();
 768
 769   if (root_layer()) {
 770     LayerTreeHostCommon::CallFunctionForSubtree(
 771         root_layer(), [](LayerImpl* layer) { layer->DidBecomeActive(); });
 772   }
 773
 774   devtools_instrumentation::DidActivateLayerTree(layer_tree_host_impl_->id(),
 775                                                  source_frame_number_);
 776 }
 777
 778 bool LayerTreeImpl::ContentsTexturesPurged() const {
 779   return contents_textures_purged_;
 780 }
 781
 782 void LayerTreeImpl::SetContentsTexturesPurged() {
 783   if (contents_textures_purged_)
 784     return;
 785   contents_textures_purged_ = true;
 786   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 787 }
 788
 789 void LayerTreeImpl::ResetContentsTexturesPurged() {
 790   if (!contents_textures_purged_)
 791     return;
 792   contents_textures_purged_ = false;
 793   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 794 }
 795
 796 bool LayerTreeImpl::RequiresHighResToDraw() const {
 797   return layer_tree_host_impl_->RequiresHighResToDraw();
 798 }
 799
 800 bool LayerTreeImpl::ViewportSizeInvalid() const {
 801   return viewport_size_invalid_;
 802 }
 803
 804 void LayerTreeImpl::SetViewportSizeInvalid() {
 805   viewport_size_invalid_ = true;
 806   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 807 }
 808
 809 void LayerTreeImpl::ResetViewportSizeInvalid() {
 810   viewport_size_invalid_ = false;
 811   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 812 }
 813
 814 Proxy* LayerTreeImpl::proxy() const {
 815   return layer_tree_host_impl_->proxy();
 816 }
 817
 818 const LayerTreeSettings& LayerTreeImpl::settings() const {
 819   return layer_tree_host_impl_->settings();
 820 }
 821
 822 const LayerTreeDebugState& LayerTreeImpl::debug_state() const {
 823   return layer_tree_host_impl_->debug_state();
 824 }
 825
 826 const RendererCapabilitiesImpl& LayerTreeImpl::GetRendererCapabilities() const {
 827   return layer_tree_host_impl_->GetRendererCapabilities();
 828 }
 829
 830 ContextProvider* LayerTreeImpl::context_provider() const {
 831   return output_surface()->context_provider();
 832 }
 833
 834 OutputSurface* LayerTreeImpl::output_surface() const {
 835   return layer_tree_host_impl_->output_surface();
 836 }
 837
 838 ResourceProvider* LayerTreeImpl::resource_provider() const {
 839   return layer_tree_host_impl_->resource_provider();
 840 }
 841
 842 TileManager* LayerTreeImpl::tile_manager() const {
 843   return layer_tree_host_impl_->tile_manager();
 844 }
 845
 846 FrameRateCounter* LayerTreeImpl::frame_rate_counter() const {
 847   return layer_tree_host_impl_->fps_counter();
 848 }
 849
 850 PaintTimeCounter* LayerTreeImpl::paint_time_counter() const {
 851   return layer_tree_host_impl_->paint_time_counter();
 852 }
 853
 854 MemoryHistory* LayerTreeImpl::memory_history() const {
 855   return layer_tree_host_impl_->memory_history();
 856 }
 857
 858 gfx::Size LayerTreeImpl::device_viewport_size() const {
 859   return layer_tree_host_impl_->device_viewport_size();
 860 }
 861
 862 float LayerTreeImpl::device_scale_factor() const {
 863   return layer_tree_host_impl_->device_scale_factor();
 864 }
 865
 866 DebugRectHistory* LayerTreeImpl::debug_rect_history() const {
 867   return layer_tree_host_impl_->debug_rect_history();
 868 }
 869
 870 bool LayerTreeImpl::IsActiveTree() const {
 871   return layer_tree_host_impl_->active_tree() == this;
 872 }
 873
 874 bool LayerTreeImpl::IsPendingTree() const {
 875   return layer_tree_host_impl_->pending_tree() == this;
 876 }
 877
 878 bool LayerTreeImpl::IsRecycleTree() const {
 879   return layer_tree_host_impl_->recycle_tree() == this;
 880 }
 881
 882 bool LayerTreeImpl::IsSyncTree() const {
 883   return layer_tree_host_impl_->sync_tree() == this;
 884 }
 885
 886 LayerImpl* LayerTreeImpl::FindActiveTreeLayerById(int id) {
 887   LayerTreeImpl* tree = layer_tree_host_impl_->active_tree();
 888   if (!tree)
 889     return NULL;
 890   return tree->LayerById(id);
 891 }
 892
 893 LayerImpl* LayerTreeImpl::FindPendingTreeLayerById(int id) {
 894   LayerTreeImpl* tree = layer_tree_host_impl_->pending_tree();
 895   if (!tree)
 896     return NULL;
 897   return tree->LayerById(id);
 898 }
 899
 900 bool LayerTreeImpl::PinchGestureActive() const {
 901   return layer_tree_host_impl_->pinch_gesture_active();
 902 }
 903
 904 BeginFrameArgs LayerTreeImpl::CurrentBeginFrameArgs() const {
 905   return layer_tree_host_impl_->CurrentBeginFrameArgs();
 906 }
 907
 908 base::TimeDelta LayerTreeImpl::begin_impl_frame_interval() const {
 909   return layer_tree_host_impl_->begin_impl_frame_interval();
 910 }
 911
 912 void LayerTreeImpl::SetNeedsCommit() {
 913   layer_tree_host_impl_->SetNeedsCommit();
 914 }
 915
 916 gfx::Rect LayerTreeImpl::DeviceViewport() const {
 917   return layer_tree_host_impl_->DeviceViewport();
 918 }
 919
 920 gfx::Size LayerTreeImpl::DrawViewportSize() const {
 921   return layer_tree_host_impl_->DrawViewportSize();
 922 }
 923
 924 const gfx::Rect LayerTreeImpl::ViewportRectForTilePriority() const {
 925   return layer_tree_host_impl_->ViewportRectForTilePriority();
 926 }
 927
 928 scoped_ptr<ScrollbarAnimationController>
 929 LayerTreeImpl::CreateScrollbarAnimationController(LayerImpl* scrolling_layer) {
 930   DCHECK(settings().scrollbar_fade_delay_ms);
 931   DCHECK(settings().scrollbar_fade_duration_ms);
 932   base::TimeDelta delay =
 933       base::TimeDelta::FromMilliseconds(settings().scrollbar_fade_delay_ms);
 934   base::TimeDelta resize_delay = base::TimeDelta::FromMilliseconds(
 935       settings().scrollbar_fade_resize_delay_ms);
 936   base::TimeDelta duration =
 937       base::TimeDelta::FromMilliseconds(settings().scrollbar_fade_duration_ms);
 938   switch (settings().scrollbar_animator) {
 939     case LayerTreeSettings::LINEAR_FADE: {
 940       return ScrollbarAnimationControllerLinearFade::Create(
 941           scrolling_layer,
 942           layer_tree_host_impl_,
 943           delay,
 944           resize_delay,
 945           duration);
 946     }
 947     case LayerTreeSettings::THINNING: {
 948       return ScrollbarAnimationControllerThinning::Create(scrolling_layer,
 949                                                           layer_tree_host_impl_,
 950                                                           delay,
 951                                                           resize_delay,
 952                                                           duration);
 953     }
 954     case LayerTreeSettings::NO_ANIMATOR:
 955       NOTREACHED();
 956       break;
 957   }
 958   return nullptr;
 959 }
 960
 961 void LayerTreeImpl::DidAnimateScrollOffset() {
 962   layer_tree_host_impl_->DidAnimateScrollOffset();
 963 }
 964
 965 bool LayerTreeImpl::use_gpu_rasterization() const {
 966   return layer_tree_host_impl_->use_gpu_rasterization();
 967 }
 968
 969 GpuRasterizationStatus LayerTreeImpl::GetGpuRasterizationStatus() const {
 970   return layer_tree_host_impl_->gpu_rasterization_status();
 971 }
 972
 973 bool LayerTreeImpl::create_low_res_tiling() const {
 974   return layer_tree_host_impl_->create_low_res_tiling();
 975 }
 976
 977 void LayerTreeImpl::SetNeedsRedraw() {
 978   layer_tree_host_impl_->SetNeedsRedraw();
 979 }
 980
 981 AnimationRegistrar* LayerTreeImpl::GetAnimationRegistrar() const {
 982   return layer_tree_host_impl_->animation_registrar();
 983 }
 984
 985 void LayerTreeImpl::GetAllTilesAndPrioritiesForTracing(
 986     std::map<const Tile*, TilePriority>* tile_map) const {
 987   typedef LayerIterator<LayerImpl> LayerIteratorType;
 988   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
 989   for (LayerIteratorType it =
 990            LayerIteratorType::Begin(&render_surface_layer_list_);
 991        it != end;
 992        ++it) {
 993     if (!it.represents_itself())
 994       continue;
 995     LayerImpl* layer_impl = *it;
 996     layer_impl->GetAllTilesAndPrioritiesForTracing(tile_map);
 997   }
 998 }
 999
1000 void LayerTreeImpl::AsValueInto(base::trace_event::TracedValue* state) const {
1001   TracedValue::MakeDictIntoImplicitSnapshot(state, "cc::LayerTreeImpl", this);
1002   state->SetInteger("source_frame_number", source_frame_number_);
1003
1004   state->BeginDictionary("root_layer");
1005   root_layer_->AsValueInto(state);
1006   state->EndDictionary();
1007
1008   state->BeginArray("render_surface_layer_list");
1009   typedef LayerIterator<LayerImpl> LayerIteratorType;
1010   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list_);
1011   for (LayerIteratorType it = LayerIteratorType::Begin(
1012            &render_surface_layer_list_); it != end; ++it) {
1013     if (!it.represents_itself())
1014       continue;
1015     TracedValue::AppendIDRef(*it, state);
1016   }
1017   state->EndArray();
1018
1019   state->BeginArray("swap_promise_trace_ids");
1020   for (size_t i = 0; i < swap_promise_list_.size(); i++)
1021     state->AppendDouble(swap_promise_list_[i]->TraceId());
1022   state->EndArray();
1023 }
1024
1025 void LayerTreeImpl::SetRootLayerScrollOffsetDelegate(
1026     LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) {
1027   if (root_layer_scroll_offset_delegate_ == root_layer_scroll_offset_delegate)
1028     return;
1029
1030   if (!root_layer_scroll_offset_delegate) {
1031     // Make sure we remove the proxies from their layers before
1032     // releasing them.
1033     if (InnerViewportScrollLayer())
1034       InnerViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
1035     if (OuterViewportScrollLayer())
1036       OuterViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
1037     inner_viewport_scroll_delegate_proxy_ = nullptr;
1038     outer_viewport_scroll_delegate_proxy_ = nullptr;
1039   }
1040
1041   root_layer_scroll_offset_delegate_ = root_layer_scroll_offset_delegate;
1042
1043   if (root_layer_scroll_offset_delegate_) {
1044     root_layer_scroll_offset_delegate_->UpdateRootLayerState(
1045         TotalScrollOffset(), TotalMaxScrollOffset(), ScrollableSize(),
1046         current_page_scale_factor(), min_page_scale_factor(),
1047         max_page_scale_factor());
1048
1049     if (inner_viewport_scroll_layer_) {
1050       inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
1051           new LayerScrollOffsetDelegateProxy(InnerViewportScrollLayer(),
1052                                              root_layer_scroll_offset_delegate_,
1053                                              this));
1054       inner_viewport_scroll_layer_->SetScrollOffsetDelegate(
1055           inner_viewport_scroll_delegate_proxy_.get());
1056     }
1057
1058     if (outer_viewport_scroll_layer_) {
1059       outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
1060           new LayerScrollOffsetDelegateProxy(OuterViewportScrollLayer(),
1061                                              root_layer_scroll_offset_delegate_,
1062                                              this));
1063       outer_viewport_scroll_layer_->SetScrollOffsetDelegate(
1064           outer_viewport_scroll_delegate_proxy_.get());
1065     }
1066
1067     if (inner_viewport_scroll_layer_)
1068       inner_viewport_scroll_layer_->RefreshFromScrollDelegate();
1069     if (outer_viewport_scroll_layer_)
1070       outer_viewport_scroll_layer_->RefreshFromScrollDelegate();
1071
1072     if (inner_viewport_scroll_layer_)
1073       UpdateScrollOffsetDelegate();
1074   }
1075 }
1076
1077 void LayerTreeImpl::OnRootLayerDelegatedScrollOffsetChanged() {
1078   DCHECK(root_layer_scroll_offset_delegate_);
1079   if (inner_viewport_scroll_layer_) {
1080     inner_viewport_scroll_layer_->RefreshFromScrollDelegate();
1081   }
1082   if (outer_viewport_scroll_layer_) {
1083     outer_viewport_scroll_layer_->RefreshFromScrollDelegate();
1084   }
1085 }
1086
1087 void LayerTreeImpl::UpdateScrollOffsetDelegate() {
1088   DCHECK(InnerViewportScrollLayer());
1089   DCHECK(!OuterViewportScrollLayer() || outer_viewport_scroll_delegate_proxy_);
1090   DCHECK(root_layer_scroll_offset_delegate_);
1091
1092   gfx::ScrollOffset offset =
1093       inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
1094
1095   if (OuterViewportScrollLayer())
1096     offset += outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
1097
1098   root_layer_scroll_offset_delegate_->UpdateRootLayerState(
1099       offset, TotalMaxScrollOffset(), ScrollableSize(),
1100       current_page_scale_factor(), min_page_scale_factor(),
1101       max_page_scale_factor());
1102 }
1103
1104 gfx::ScrollOffset LayerTreeImpl::GetDelegatedScrollOffset(LayerImpl* layer) {
1105   DCHECK(root_layer_scroll_offset_delegate_);
1106   DCHECK(InnerViewportScrollLayer());
1107   if (layer == InnerViewportScrollLayer() && !OuterViewportScrollLayer())
1108     return root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
1109
1110   // If we get here, we have both inner/outer viewports, and need to distribute
1111   // the scroll offset between them.
1112   DCHECK(inner_viewport_scroll_delegate_proxy_);
1113   DCHECK(outer_viewport_scroll_delegate_proxy_);
1114   gfx::ScrollOffset inner_viewport_offset =
1115       inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
1116   gfx::ScrollOffset outer_viewport_offset =
1117       outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
1118
1119   // It may be nothing has changed.
1120   gfx::ScrollOffset delegate_offset =
1121       root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
1122   if (inner_viewport_offset + outer_viewport_offset == delegate_offset) {
1123     if (layer == InnerViewportScrollLayer())
1124       return inner_viewport_offset;
1125     else
1126       return outer_viewport_offset;
1127   }
1128
1129   gfx::ScrollOffset max_outer_viewport_scroll_offset =
1130       OuterViewportScrollLayer()->MaxScrollOffset();
1131
1132   outer_viewport_offset = delegate_offset - inner_viewport_offset;
1133   outer_viewport_offset.SetToMin(max_outer_viewport_scroll_offset);
1134   outer_viewport_offset.SetToMax(gfx::ScrollOffset());
1135
1136   if (layer == OuterViewportScrollLayer())
1137     return outer_viewport_offset;
1138
1139   inner_viewport_offset = delegate_offset - outer_viewport_offset;
1140
1141   return inner_viewport_offset;
1142 }
1143
1144 void LayerTreeImpl::QueueSwapPromise(scoped_ptr<SwapPromise> swap_promise) {
1145   DCHECK(swap_promise);
1146   swap_promise_list_.push_back(swap_promise.Pass());
1147 }
1148
1149 void LayerTreeImpl::PassSwapPromises(
1150     ScopedPtrVector<SwapPromise>* new_swap_promise) {
1151   swap_promise_list_.insert_and_take(swap_promise_list_.end(),
1152                                      new_swap_promise);
1153   new_swap_promise->clear();
1154 }
1155
1156 void LayerTreeImpl::FinishSwapPromises(CompositorFrameMetadata* metadata) {
1157   for (size_t i = 0; i < swap_promise_list_.size(); i++)
1158     swap_promise_list_[i]->DidSwap(metadata);
1159   swap_promise_list_.clear();
1160 }
1161
1162 void LayerTreeImpl::BreakSwapPromises(SwapPromise::DidNotSwapReason reason) {
1163   for (size_t i = 0; i < swap_promise_list_.size(); i++)
1164     swap_promise_list_[i]->DidNotSwap(reason);
1165   swap_promise_list_.clear();
1166 }
1167
1168 void LayerTreeImpl::DidModifyTilePriorities() {
1169   layer_tree_host_impl_->DidModifyTilePriorities();
1170 }
1171
1172 void LayerTreeImpl::set_ui_resource_request_queue(
1173     const UIResourceRequestQueue& queue) {
1174   ui_resource_request_queue_ = queue;
1175 }
1176
1177 ResourceProvider::ResourceId LayerTreeImpl::ResourceIdForUIResource(
1178     UIResourceId uid) const {
1179   return layer_tree_host_impl_->ResourceIdForUIResource(uid);
1180 }
1181
1182 bool LayerTreeImpl::IsUIResourceOpaque(UIResourceId uid) const {
1183   return layer_tree_host_impl_->IsUIResourceOpaque(uid);
1184 }
1185
1186 void LayerTreeImpl::ProcessUIResourceRequestQueue() {
1187   for (const auto& req : ui_resource_request_queue_) {
1188     switch (req.GetType()) {
1189       case UIResourceRequest::UI_RESOURCE_CREATE:
1190         layer_tree_host_impl_->CreateUIResource(req.GetId(), req.GetBitmap());
1191         break;
1192       case UIResourceRequest::UI_RESOURCE_DELETE:
1193         layer_tree_host_impl_->DeleteUIResource(req.GetId());
1194         break;
1195       case UIResourceRequest::UI_RESOURCE_INVALID_REQUEST:
1196         NOTREACHED();
1197         break;
1198     }
1199   }
1200   ui_resource_request_queue_.clear();
1201
1202   // If all UI resource evictions were not recreated by processing this queue,
1203   // then another commit is required.
1204   if (layer_tree_host_impl_->EvictedUIResourcesExist())
1205     layer_tree_host_impl_->SetNeedsCommit();
1206 }
1207
1208 void LayerTreeImpl::RegisterPictureLayerImpl(PictureLayerImpl* layer) {
1209   DCHECK(std::find(picture_layers_.begin(), picture_layers_.end(), layer) ==
1210          picture_layers_.end());
1211   picture_layers_.push_back(layer);
1212 }
1213
1214 void LayerTreeImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
1215   std::vector<PictureLayerImpl*>::iterator it =
1216       std::find(picture_layers_.begin(), picture_layers_.end(), layer);
1217   DCHECK(it != picture_layers_.end());
1218   picture_layers_.erase(it);
1219 }
1220
1221 void LayerTreeImpl::AddLayerWithCopyOutputRequest(LayerImpl* layer) {
1222   // Only the active tree needs to know about layers with copy requests, as
1223   // they are aborted if not serviced during draw.
1224   DCHECK(IsActiveTree());
1225
1226   // DCHECK(std::find(layers_with_copy_output_request_.begin(),
1227   //                 layers_with_copy_output_request_.end(),
1228   //                 layer) == layers_with_copy_output_request_.end());
1229   // TODO(danakj): Remove this once crash is found crbug.com/309777
1230   for (size_t i = 0; i < layers_with_copy_output_request_.size(); ++i) {
1231     CHECK(layers_with_copy_output_request_[i] != layer)
1232         << i << " of " << layers_with_copy_output_request_.size();
1233   }
1234   layers_with_copy_output_request_.push_back(layer);
1235 }
1236
1237 void LayerTreeImpl::RemoveLayerWithCopyOutputRequest(LayerImpl* layer) {
1238   // Only the active tree needs to know about layers with copy requests, as
1239   // they are aborted if not serviced during draw.
1240   DCHECK(IsActiveTree());
1241
1242   std::vector<LayerImpl*>::iterator it = std::find(
1243       layers_with_copy_output_request_.begin(),
1244       layers_with_copy_output_request_.end(),
1245       layer);
1246   DCHECK(it != layers_with_copy_output_request_.end());
1247   layers_with_copy_output_request_.erase(it);
1248
1249   // TODO(danakj): Remove this once crash is found crbug.com/309777
1250   for (size_t i = 0; i < layers_with_copy_output_request_.size(); ++i) {
1251     CHECK(layers_with_copy_output_request_[i] != layer)
1252         << i << " of " << layers_with_copy_output_request_.size();
1253   }
1254 }
1255
1256 const std::vector<LayerImpl*>& LayerTreeImpl::LayersWithCopyOutputRequest()
1257     const {
1258   // Only the active tree needs to know about layers with copy requests, as
1259   // they are aborted if not serviced during draw.
1260   DCHECK(IsActiveTree());
1261
1262   return layers_with_copy_output_request_;
1263 }
1264
1265 template <typename LayerType>
1266 static inline bool LayerClipsSubtree(LayerType* layer) {
1267   return layer->masks_to_bounds() || layer->mask_layer();
1268 }
1269
1270 static bool PointHitsRect(
1271     const gfx::PointF& screen_space_point,
1272     const gfx::Transform& local_space_to_screen_space_transform,
1273     const gfx::RectF& local_space_rect,
1274     float* distance_to_camera) {
1275   // If the transform is not invertible, then assume that this point doesn't hit
1276   // this rect.
1277   gfx::Transform inverse_local_space_to_screen_space(
1278       gfx::Transform::kSkipInitialization);
1279   if (!local_space_to_screen_space_transform.GetInverse(
1280           &inverse_local_space_to_screen_space))
1281     return false;
1282
1283   // Transform the hit test point from screen space to the local space of the
1284   // given rect.
1285   bool clipped = false;
1286   gfx::Point3F planar_point = MathUtil::ProjectPoint3D(
1287       inverse_local_space_to_screen_space, screen_space_point, &clipped);
1288   gfx::PointF hit_test_point_in_local_space =
1289       gfx::PointF(planar_point.x(), planar_point.y());
1290
1291   // If ProjectPoint could not project to a valid value, then we assume that
1292   // this point doesn't hit this rect.
1293   if (clipped)
1294     return false;
1295
1296   if (!local_space_rect.Contains(hit_test_point_in_local_space))
1297     return false;
1298
1299   if (distance_to_camera) {
1300     // To compute the distance to the camera, we have to take the planar point
1301     // and pull it back to world space and compute the displacement along the
1302     // z-axis.
1303     gfx::Point3F planar_point_in_screen_space(planar_point);
1304     local_space_to_screen_space_transform.TransformPoint(
1305         &planar_point_in_screen_space);
1306     *distance_to_camera = planar_point_in_screen_space.z();
1307   }
1308
1309   return true;
1310 }
1311
1312 static bool PointHitsRegion(const gfx::PointF& screen_space_point,
1313                             const gfx::Transform& screen_space_transform,
1314                             const Region& layer_space_region,
1315                             float layer_content_scale_x,
1316                             float layer_content_scale_y) {
1317   // If the transform is not invertible, then assume that this point doesn't hit
1318   // this region.
1319   gfx::Transform inverse_screen_space_transform(
1320       gfx::Transform::kSkipInitialization);
1321   if (!screen_space_transform.GetInverse(&inverse_screen_space_transform))
1322     return false;
1323
1324   // Transform the hit test point from screen space to the local space of the
1325   // given region.
1326   bool clipped = false;
1327   gfx::PointF hit_test_point_in_content_space = MathUtil::ProjectPoint(
1328       inverse_screen_space_transform, screen_space_point, &clipped);
1329   gfx::PointF hit_test_point_in_layer_space =
1330       gfx::ScalePoint(hit_test_point_in_content_space,
1331                       1.f / layer_content_scale_x,
1332                       1.f / layer_content_scale_y);
1333
1334   // If ProjectPoint could not project to a valid value, then we assume that
1335   // this point doesn't hit this region.
1336   if (clipped)
1337     return false;
1338
1339   return layer_space_region.Contains(
1340       gfx::ToRoundedPoint(hit_test_point_in_layer_space));
1341 }
1342
1343 static const LayerImpl* GetNextClippingLayer(const LayerImpl* layer) {
1344   if (layer->scroll_parent())
1345     return layer->scroll_parent();
1346   if (layer->clip_parent())
1347     return layer->clip_parent();
1348   return layer->parent();
1349 }
1350
1351 static bool PointIsClippedBySurfaceOrClipRect(
1352     const gfx::PointF& screen_space_point,
1353     const LayerImpl* layer) {
1354   // Walk up the layer tree and hit-test any render_surfaces and any layer
1355   // clip rects that are active.
1356   for (; layer; layer = GetNextClippingLayer(layer)) {
1357     if (layer->render_surface() &&
1358         !PointHitsRect(screen_space_point,
1359                        layer->render_surface()->screen_space_transform(),
1360                        layer->render_surface()->content_rect(),
1361                        NULL))
1362       return true;
1363
1364     if (LayerClipsSubtree(layer) &&
1365         !PointHitsRect(screen_space_point,
1366                        layer->screen_space_transform(),
1367                        gfx::Rect(layer->content_bounds()),
1368                        NULL))
1369       return true;
1370   }
1371
1372   // If we have finished walking all ancestors without having already exited,
1373   // then the point is not clipped by any ancestors.
1374   return false;
1375 }
1376
1377 static bool PointHitsLayer(const LayerImpl* layer,
1378                            const gfx::PointF& screen_space_point,
1379                            float* distance_to_intersection) {
1380   gfx::RectF content_rect(layer->content_bounds());
1381   if (!PointHitsRect(screen_space_point,
1382                      layer->screen_space_transform(),
1383                      content_rect,
1384                      distance_to_intersection))
1385     return false;
1386
1387   // At this point, we think the point does hit the layer, but we need to walk
1388   // up the parents to ensure that the layer was not clipped in such a way
1389   // that the hit point actually should not hit the layer.
1390   if (PointIsClippedBySurfaceOrClipRect(screen_space_point, layer))
1391     return false;
1392
1393   // Skip the HUD layer.
1394   if (layer == layer->layer_tree_impl()->hud_layer())
1395     return false;
1396
1397   return true;
1398 }
1399
1400 struct FindClosestMatchingLayerDataForRecursion {
1401   FindClosestMatchingLayerDataForRecursion()
1402       : closest_match(NULL),
1403         closest_distance(-std::numeric_limits<float>::infinity()) {}
1404   LayerImpl* closest_match;
1405   // Note that the positive z-axis points towards the camera, so bigger means
1406   // closer in this case, counterintuitively.
1407   float closest_distance;
1408 };
1409
1410 template <typename Functor>
1411 static void FindClosestMatchingLayer(
1412     const gfx::PointF& screen_space_point,
1413     LayerImpl* layer,
1414     const Functor& func,
1415     FindClosestMatchingLayerDataForRecursion* data_for_recursion) {
1416   for (int i = layer->children().size() - 1; i >= 0; --i) {
1417     FindClosestMatchingLayer(
1418         screen_space_point, layer->children()[i], func, data_for_recursion);
1419   }
1420
1421   float distance_to_intersection = 0.f;
1422   if (func(layer) &&
1423       PointHitsLayer(layer, screen_space_point, &distance_to_intersection) &&
1424       ((!data_for_recursion->closest_match ||
1425         distance_to_intersection > data_for_recursion->closest_distance))) {
1426     data_for_recursion->closest_distance = distance_to_intersection;
1427     data_for_recursion->closest_match = layer;
1428   }
1429 }
1430
1431 static bool ScrollsAnyDrawnRenderSurfaceLayerListMember(LayerImpl* layer) {
1432   if (!layer->scrollable())
1433     return false;
1434   if (layer->draw_properties().layer_or_descendant_is_drawn)
1435     return true;
1436
1437   if (!layer->scroll_children())
1438     return false;
1439   for (std::set<LayerImpl*>::const_iterator it =
1440            layer->scroll_children()->begin();
1441        it != layer->scroll_children()->end();
1442        ++it) {
1443     if ((*it)->draw_properties().layer_or_descendant_is_drawn)
1444       return true;
1445   }
1446   return false;
1447 }
1448
1449 struct FindScrollingLayerFunctor {
1450   bool operator()(LayerImpl* layer) const {
1451     return ScrollsAnyDrawnRenderSurfaceLayerListMember(layer);
1452   }
1453 };
1454
1455 LayerImpl* LayerTreeImpl::FindFirstScrollingLayerThatIsHitByPoint(
1456     const gfx::PointF& screen_space_point) {
1457   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1458   FindClosestMatchingLayer(screen_space_point,
1459                            root_layer(),
1460                            FindScrollingLayerFunctor(),
1461                            &data_for_recursion);
1462   return data_for_recursion.closest_match;
1463 }
1464
1465 struct HitTestVisibleScrollableOrTouchableFunctor {
1466   bool operator()(LayerImpl* layer) const {
1467     return layer->IsDrawnRenderSurfaceLayerListMember() ||
1468            ScrollsAnyDrawnRenderSurfaceLayerListMember(layer) ||
1469            !layer->touch_event_handler_region().IsEmpty() ||
1470            layer->have_wheel_event_handlers();
1471   }
1472 };
1473
1474 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPoint(
1475     const gfx::PointF& screen_space_point) {
1476   if (!root_layer())
1477     return NULL;
1478   bool update_lcd_text = false;
1479   if (!UpdateDrawProperties(update_lcd_text))
1480     return NULL;
1481   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1482   FindClosestMatchingLayer(screen_space_point,
1483                            root_layer(),
1484                            HitTestVisibleScrollableOrTouchableFunctor(),
1485                            &data_for_recursion);
1486   return data_for_recursion.closest_match;
1487 }
1488
1489 static bool LayerHasTouchEventHandlersAt(const gfx::PointF& screen_space_point,
1490                                          LayerImpl* layer_impl) {
1491   if (layer_impl->touch_event_handler_region().IsEmpty())
1492     return false;
1493
1494   if (!PointHitsRegion(screen_space_point,
1495                        layer_impl->screen_space_transform(),
1496                        layer_impl->touch_event_handler_region(),
1497                        layer_impl->contents_scale_x(),
1498                        layer_impl->contents_scale_y()))
1499     return false;
1500
1501   // At this point, we think the point does hit the touch event handler region
1502   // on the layer, but we need to walk up the parents to ensure that the layer
1503   // was not clipped in such a way that the hit point actually should not hit
1504   // the layer.
1505   if (PointIsClippedBySurfaceOrClipRect(screen_space_point, layer_impl))
1506     return false;
1507
1508   return true;
1509 }
1510
1511 struct FindWheelEventLayerFunctor {
1512   bool operator()(LayerImpl* layer) const {
1513     return layer->have_wheel_event_handlers();
1514   }
1515 };
1516
1517 LayerImpl* LayerTreeImpl::FindLayerWithWheelHandlerThatIsHitByPoint(
1518     const gfx::PointF& screen_space_point) {
1519   if (!root_layer())
1520     return NULL;
1521   bool update_lcd_text = false;
1522   if (!UpdateDrawProperties(update_lcd_text))
1523     return NULL;
1524   FindWheelEventLayerFunctor func;
1525   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1526   FindClosestMatchingLayer(screen_space_point, root_layer(), func,
1527                            &data_for_recursion);
1528   return data_for_recursion.closest_match;
1529 }
1530
1531 struct FindTouchEventLayerFunctor {
1532   bool operator()(LayerImpl* layer) const {
1533     return LayerHasTouchEventHandlersAt(screen_space_point, layer);
1534   }
1535   const gfx::PointF screen_space_point;
1536 };
1537
1538 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
1539     const gfx::PointF& screen_space_point) {
1540   if (!root_layer())
1541     return NULL;
1542   bool update_lcd_text = false;
1543   if (!UpdateDrawProperties(update_lcd_text))
1544     return NULL;
1545   FindTouchEventLayerFunctor func = {screen_space_point};
1546   FindClosestMatchingLayerDataForRecursion data_for_recursion;
1547   FindClosestMatchingLayer(
1548       screen_space_point, root_layer(), func, &data_for_recursion);
1549   return data_for_recursion.closest_match;
1550 }
1551
1552 void LayerTreeImpl::RegisterSelection(const LayerSelectionBound& start,
1553                                       const LayerSelectionBound& end) {
1554   selection_start_ = start;
1555   selection_end_ = end;
1556 }
1557
1558 static ViewportSelectionBound ComputeViewportSelection(
1559     const LayerSelectionBound& layer_bound,
1560     LayerImpl* layer,
1561     float device_scale_factor) {
1562   ViewportSelectionBound viewport_bound;
1563   viewport_bound.type = layer_bound.type;
1564
1565   if (!layer || layer_bound.type == SELECTION_BOUND_EMPTY)
1566     return viewport_bound;
1567
1568   gfx::PointF layer_scaled_top = gfx::ScalePoint(layer_bound.edge_top,
1569                                                  layer->contents_scale_x(),
1570                                                  layer->contents_scale_y());
1571   gfx::PointF layer_scaled_bottom = gfx::ScalePoint(layer_bound.edge_bottom,
1572                                                     layer->contents_scale_x(),
1573                                                     layer->contents_scale_y());
1574
1575   bool clipped = false;
1576   gfx::PointF screen_top = MathUtil::MapPoint(
1577       layer->screen_space_transform(), layer_scaled_top, &clipped);
1578   gfx::PointF screen_bottom = MathUtil::MapPoint(
1579       layer->screen_space_transform(), layer_scaled_bottom, &clipped);
1580
1581   const float inv_scale = 1.f / device_scale_factor;
1582   viewport_bound.edge_top = gfx::ScalePoint(screen_top, inv_scale);
1583   viewport_bound.edge_bottom = gfx::ScalePoint(screen_bottom, inv_scale);
1584
1585   // The bottom edge point is used for visibility testing as it is the logical
1586   // focal point for bound selection handles (this may change in the future).
1587   // Shifting the visibility point fractionally inward ensures that neighboring
1588   // or logically coincident layers aligned to integral DPI coordinates will not
1589   // spuriously occlude the bound.
1590   gfx::Vector2dF visibility_offset = layer_scaled_top - layer_scaled_bottom;
1591   visibility_offset.Scale(device_scale_factor / visibility_offset.Length());
1592   gfx::PointF visibility_point = layer_scaled_bottom + visibility_offset;
1593   if (visibility_point.x() <= 0)
1594     visibility_point.set_x(visibility_point.x() + device_scale_factor);
1595   visibility_point = MathUtil::MapPoint(
1596       layer->screen_space_transform(), visibility_point, &clipped);
1597
1598   float intersect_distance = 0.f;
1599   viewport_bound.visible =
1600       PointHitsLayer(layer, visibility_point, &intersect_distance);
1601
1602   return viewport_bound;
1603 }
1604
1605 void LayerTreeImpl::GetViewportSelection(ViewportSelectionBound* start,
1606                                          ViewportSelectionBound* end) {
1607   DCHECK(start);
1608   DCHECK(end);
1609
1610   *start = ComputeViewportSelection(
1611       selection_start_,
1612       selection_start_.layer_id ? LayerById(selection_start_.layer_id) : NULL,
1613       device_scale_factor());
1614   if (start->type == SELECTION_BOUND_CENTER ||
1615       start->type == SELECTION_BOUND_EMPTY) {
1616     *end = *start;
1617   } else {
1618     *end = ComputeViewportSelection(
1619         selection_end_,
1620         selection_end_.layer_id ? LayerById(selection_end_.layer_id) : NULL,
1621         device_scale_factor());
1622   }
1623 }
1624
1625 void LayerTreeImpl::InputScrollAnimationFinished() {
1626   layer_tree_host_impl_->ScrollEnd();
1627 }
1628
1629 bool LayerTreeImpl::SmoothnessTakesPriority() const {
1630   return layer_tree_host_impl_->GetTreePriority() == SMOOTHNESS_TAKES_PRIORITY;
1631 }
1632
1633 BlockingTaskRunner* LayerTreeImpl::BlockingMainThreadTaskRunner() const {
1634   return proxy()->blocking_main_thread_task_runner();
1635 }
1636
1637 void LayerTreeImpl::SetPendingPageScaleAnimation(
1638     scoped_ptr<PendingPageScaleAnimation> pending_animation) {
1639   pending_page_scale_animation_ = pending_animation.Pass();
1640 }
1641
1642 scoped_ptr<PendingPageScaleAnimation>
1643     LayerTreeImpl::TakePendingPageScaleAnimation() {
1644   return pending_page_scale_animation_.Pass();
1645 }
1646
1647 }  // namespace cc