cc/trees/property_tree_builder.cc

   1 // Copyright 2014 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/property_tree_builder.h"
   6
   7 #include <map>
   8 #include <set>
   9
  10 #include "cc/base/math_util.h"
  11 #include "cc/layers/layer.h"
  12 #include "cc/layers/layer_impl.h"
  13 #include "cc/trees/layer_tree_host.h"
  14 #include "ui/gfx/geometry/point_f.h"
  15 #include "ui/gfx/geometry/vector2d_conversions.h"
  16
  17 namespace cc {
  18
  19 class LayerTreeHost;
  20
  21 namespace {
  22
  23 static const int kInvalidPropertyTreeNodeId = -1;
  24 static const int kRootPropertyTreeNodeId = 0;
  25 static const int kUnclippedRootClipTreeNodeId = 0;
  26
  27 template <typename LayerType>
  28 struct DataForRecursion {
  29   TransformTree* transform_tree;
  30   ClipTree* clip_tree;
  31   EffectTree* effect_tree;
  32   LayerType* transform_tree_parent;
  33   LayerType* transform_fixed_parent;
  34   LayerType* render_target;
  35   int clip_tree_parent;
  36   int effect_tree_parent;
  37   const LayerType* page_scale_layer;
  38   const LayerType* inner_viewport_scroll_layer;
  39   const LayerType* outer_viewport_scroll_layer;
  40   float page_scale_factor;
  41   float device_scale_factor;
  42   bool in_subtree_of_page_scale_layer;
  43   bool affected_by_inner_viewport_bounds_delta;
  44   bool affected_by_outer_viewport_bounds_delta;
  45   bool should_flatten;
  46   bool ancestor_clips_subtree;
  47   const gfx::Transform* device_transform;
  48   gfx::Vector2dF scroll_compensation_adjustment;
  49   int sequence_number;
  50 };
  51
  52 template <typename LayerType>
  53 static LayerType* GetTransformParent(const DataForRecursion<LayerType>& data,
  54                                      LayerType* layer) {
  55   return layer->position_constraint().is_fixed_position()
  56              ? data.transform_fixed_parent
  57              : data.transform_tree_parent;
  58 }
  59
  60 template <typename LayerType>
  61 static ClipNode* GetClipParent(const DataForRecursion<LayerType>& data,
  62                                LayerType* layer) {
  63   const bool inherits_clip = !layer->parent() || !layer->clip_parent();
  64   const int id = inherits_clip ? data.clip_tree_parent
  65                                : layer->clip_parent()->clip_tree_index();
  66   return data.clip_tree->Node(id);
  67 }
  68
  69 template <typename LayerType>
  70 static bool RequiresClipNode(LayerType* layer,
  71                              const DataForRecursion<LayerType>& data,
  72                              int parent_transform_id,
  73                              bool is_clipped) {
  74   const bool render_surface_applies_clip =
  75       layer->has_render_surface() && is_clipped;
  76   const bool render_surface_may_grow_due_to_clip_children =
  77       layer->has_render_surface() && layer->num_unclipped_descendants() > 0;
  78
  79   if (layer->masks_to_bounds() || layer->mask_layer() ||
  80       render_surface_may_grow_due_to_clip_children)
  81     return true;
  82
  83   if (!render_surface_applies_clip)
  84     return false;
  85
  86   return true;
  87 }
  88
  89 template <typename LayerType>
  90 static bool LayerClipsSubtree(LayerType* layer) {
  91   return layer->masks_to_bounds() || layer->mask_layer();
  92 }
  93
  94 template <typename LayerType>
  95 void AddClipNodeIfNeeded(const DataForRecursion<LayerType>& data_from_ancestor,
  96                          LayerType* layer,
  97                          bool created_transform_node,
  98                          DataForRecursion<LayerType>* data_for_children) {
  99   ClipNode* parent = GetClipParent(data_from_ancestor, layer);
 100   int parent_id = parent->id;
 101
 102   bool ancestor_clips_subtree =
 103       data_from_ancestor.ancestor_clips_subtree ||
 104       (layer->clip_parent() && layer->clip_parent()->is_clipped());
 105
 106   data_for_children->ancestor_clips_subtree = false;
 107   bool has_unclipped_surface = false;
 108
 109   if (layer->has_render_surface()) {
 110     if (ancestor_clips_subtree && layer->num_unclipped_descendants() > 0)
 111       data_for_children->ancestor_clips_subtree = true;
 112     else if (!ancestor_clips_subtree && !layer->num_unclipped_descendants())
 113       has_unclipped_surface = true;
 114   } else {
 115     data_for_children->ancestor_clips_subtree = ancestor_clips_subtree;
 116   }
 117
 118   bool layer_clips_subtree = LayerClipsSubtree(layer);
 119   if (layer_clips_subtree)
 120     data_for_children->ancestor_clips_subtree = true;
 121
 122   if (has_unclipped_surface)
 123     parent_id = kUnclippedRootClipTreeNodeId;
 124
 125   if (!RequiresClipNode(layer, data_from_ancestor, parent->data.transform_id,
 126                         ancestor_clips_subtree)) {
 127     // Unclipped surfaces reset the clip rect.
 128     data_for_children->clip_tree_parent = parent_id;
 129   } else {
 130     LayerType* transform_parent = data_for_children->transform_tree_parent;
 131     if (layer->position_constraint().is_fixed_position() &&
 132         !created_transform_node) {
 133       transform_parent = data_for_children->transform_fixed_parent;
 134     }
 135     ClipNode node;
 136     node.data.clip = gfx::RectF(
 137         gfx::PointF() + layer->offset_to_transform_parent(), layer->bounds());
 138     node.data.transform_id = transform_parent->transform_tree_index();
 139     node.data.target_id =
 140         data_for_children->render_target->transform_tree_index();
 141     node.owner_id = layer->id();
 142     node.data.inherit_parent_target_space_clip = !layer_clips_subtree &&
 143                                                  layer->has_render_surface() &&
 144                                                  ancestor_clips_subtree;
 145     node.data.requires_tight_clip_rect =
 146         ancestor_clips_subtree &&
 147         (!layer->has_render_surface() ||
 148          (!layer_clips_subtree && layer->num_unclipped_descendants()));
 149
 150     node.data.render_surface_is_clipped = layer->has_render_surface() &&
 151                                           ancestor_clips_subtree &&
 152                                           !layer->num_unclipped_descendants();
 153
 154     data_for_children->clip_tree_parent =
 155         data_for_children->clip_tree->Insert(node, parent_id);
 156   }
 157
 158   layer->SetClipTreeIndex(data_for_children->clip_tree_parent);
 159
 160   layer->set_is_clipped(data_for_children->ancestor_clips_subtree);
 161
 162   // TODO(awoloszyn): Right now when we hit a node with a replica, we reset the
 163   // clip for all children since we may need to draw. We need to figure out a
 164   // better way, since we will need both the clipped and unclipped versions.
 165 }
 166
 167 template <typename LayerType>
 168 bool AddTransformNodeIfNeeded(
 169     const DataForRecursion<LayerType>& data_from_ancestor,
 170     LayerType* layer,
 171     DataForRecursion<LayerType>* data_for_children) {
 172   const bool is_root = !layer->parent();
 173   const bool is_page_scale_layer = layer == data_from_ancestor.page_scale_layer;
 174   const bool is_scrollable = layer->scrollable();
 175   const bool is_fixed = layer->position_constraint().is_fixed_position();
 176
 177   const bool has_significant_transform =
 178       !layer->transform().IsIdentityOr2DTranslation();
 179
 180   const bool has_potentially_animated_transform =
 181       layer->HasPotentiallyRunningTransformAnimation();
 182
 183   // A transform node is needed even for a finished animation, since differences
 184   // in the timing of animation state updates can mean that an animation that's
 185   // in the Finished state at tree-building time on the main thread is still in
 186   // the Running state right after commit on the compositor thread.
 187   const bool has_any_transform_animation =
 188       layer->HasAnyAnimationTargetingProperty(Animation::TRANSFORM);
 189
 190   const bool has_surface = layer->has_render_surface();
 191
 192   bool requires_node = is_root || is_scrollable || has_significant_transform ||
 193                        has_any_transform_animation || has_surface || is_fixed ||
 194                        is_page_scale_layer;
 195
 196   LayerType* transform_parent = GetTransformParent(data_from_ancestor, layer);
 197   DCHECK_IMPLIES(!is_root, transform_parent);
 198
 199   int parent_index = kRootPropertyTreeNodeId;
 200   if (transform_parent)
 201     parent_index = transform_parent->transform_tree_index();
 202
 203   int source_index = parent_index;
 204
 205   gfx::Vector2dF source_offset;
 206   if (transform_parent) {
 207     if (layer->scroll_parent()) {
 208       LayerType* source = layer->parent();
 209       source_offset += source->offset_to_transform_parent();
 210       source_index = source->transform_tree_index();
 211     } else if (!is_fixed) {
 212       source_offset = transform_parent->offset_to_transform_parent();
 213     } else {
 214       source_offset = data_from_ancestor.transform_tree_parent
 215                           ->offset_to_transform_parent();
 216       source_index =
 217           data_from_ancestor.transform_tree_parent->transform_tree_index();
 218       source_offset += data_from_ancestor.scroll_compensation_adjustment;
 219     }
 220   }
 221
 222   if (layer->IsContainerForFixedPositionLayers() || is_root) {
 223     data_for_children->affected_by_inner_viewport_bounds_delta =
 224         layer == data_from_ancestor.inner_viewport_scroll_layer;
 225     data_for_children->affected_by_outer_viewport_bounds_delta =
 226         layer == data_from_ancestor.outer_viewport_scroll_layer;
 227     if (is_scrollable) {
 228       DCHECK(!is_root);
 229       DCHECK(layer->transform().IsIdentity());
 230       data_for_children->transform_fixed_parent = layer->parent();
 231     } else {
 232       data_for_children->transform_fixed_parent = layer;
 233     }
 234   }
 235   data_for_children->transform_tree_parent = layer;
 236
 237   if (layer->IsContainerForFixedPositionLayers() || is_fixed)
 238     data_for_children->scroll_compensation_adjustment = gfx::Vector2dF();
 239
 240   if (!requires_node) {
 241     data_for_children->should_flatten |= layer->should_flatten_transform();
 242     gfx::Vector2dF local_offset = layer->position().OffsetFromOrigin() +
 243                                   layer->transform().To2dTranslation();
 244     gfx::Vector2dF source_to_parent;
 245     if (source_index != parent_index) {
 246       gfx::Transform to_parent;
 247       data_from_ancestor.transform_tree->ComputeTransform(
 248           source_index, parent_index, &to_parent);
 249       source_to_parent = to_parent.To2dTranslation();
 250     }
 251     layer->set_offset_to_transform_parent(source_offset + source_to_parent +
 252                                           local_offset);
 253     layer->set_should_flatten_transform_from_property_tree(
 254         data_from_ancestor.should_flatten);
 255     layer->SetTransformTreeIndex(parent_index);
 256     return false;
 257   }
 258
 259   data_for_children->transform_tree->Insert(TransformNode(), parent_index);
 260
 261   TransformNode* node = data_for_children->transform_tree->back();
 262   layer->SetTransformTreeIndex(node->id);
 263
 264   node->data.scrolls = is_scrollable;
 265   node->data.flattens_inherited_transform = data_for_children->should_flatten;
 266
 267   // Surfaces inherently flatten transforms.
 268   data_for_children->should_flatten =
 269       layer->should_flatten_transform() || has_surface;
 270   node->data.target_id =
 271       data_from_ancestor.render_target->transform_tree_index();
 272   node->data.content_target_id =
 273       data_for_children->render_target->transform_tree_index();
 274   DCHECK_NE(node->data.target_id, kInvalidPropertyTreeNodeId);
 275   node->data.is_animated = has_potentially_animated_transform;
 276   if (has_potentially_animated_transform) {
 277     float maximum_animation_target_scale = 0.f;
 278     if (layer->MaximumTargetScale(&maximum_animation_target_scale)) {
 279       node->data.local_maximum_animation_target_scale =
 280           maximum_animation_target_scale;
 281     }
 282
 283     float starting_animation_scale = 0.f;
 284     if (layer->AnimationStartScale(&starting_animation_scale)) {
 285       node->data.local_starting_animation_scale = starting_animation_scale;
 286     }
 287
 288     node->data.has_only_translation_animations =
 289         layer->HasOnlyTranslationTransforms();
 290   }
 291
 292   float post_local_scale_factor = 1.0f;
 293   if (is_root) {
 294     node->data.post_local = *data_from_ancestor.device_transform;
 295     post_local_scale_factor = data_from_ancestor.device_scale_factor;
 296   }
 297
 298   if (is_page_scale_layer)
 299     post_local_scale_factor *= data_from_ancestor.page_scale_factor;
 300
 301   if (has_surface && !is_root) {
 302     node->data.needs_sublayer_scale = true;
 303     node->data.layer_scale_factor = data_from_ancestor.device_scale_factor;
 304     if (data_from_ancestor.in_subtree_of_page_scale_layer)
 305       node->data.layer_scale_factor *= data_from_ancestor.page_scale_factor;
 306   }
 307
 308   node->data.source_node_id = source_index;
 309   if (is_root) {
 310     node->data.post_local.Scale(post_local_scale_factor,
 311                                 post_local_scale_factor);
 312     node->data.post_local.Translate(layer->position().x(),
 313                                     layer->position().y());
 314   } else {
 315     node->data.post_local_scale_factor = post_local_scale_factor;
 316     node->data.source_offset = source_offset;
 317     node->data.update_post_local_transform(layer->position(),
 318                                            layer->transform_origin());
 319   }
 320
 321   if (!layer->scroll_parent())
 322     node->data.scroll_offset = layer->CurrentScrollOffset();
 323
 324   if (is_fixed) {
 325     if (data_from_ancestor.affected_by_inner_viewport_bounds_delta) {
 326       node->data.affected_by_inner_viewport_bounds_delta_x =
 327           layer->position_constraint().is_fixed_to_right_edge();
 328       node->data.affected_by_inner_viewport_bounds_delta_y =
 329           layer->position_constraint().is_fixed_to_bottom_edge();
 330       if (node->data.affected_by_inner_viewport_bounds_delta_x ||
 331           node->data.affected_by_inner_viewport_bounds_delta_y) {
 332         data_for_children->transform_tree
 333             ->AddNodeAffectedByInnerViewportBoundsDelta(node->id);
 334       }
 335     } else if (data_from_ancestor.affected_by_outer_viewport_bounds_delta) {
 336       node->data.affected_by_outer_viewport_bounds_delta_x =
 337           layer->position_constraint().is_fixed_to_right_edge();
 338       node->data.affected_by_outer_viewport_bounds_delta_y =
 339           layer->position_constraint().is_fixed_to_bottom_edge();
 340       if (node->data.affected_by_outer_viewport_bounds_delta_x ||
 341           node->data.affected_by_outer_viewport_bounds_delta_y) {
 342         data_for_children->transform_tree
 343             ->AddNodeAffectedByOuterViewportBoundsDelta(node->id);
 344       }
 345     }
 346   }
 347
 348   node->data.local = layer->transform();
 349   node->data.update_pre_local_transform(layer->transform_origin());
 350
 351   node->data.needs_local_transform_update = true;
 352   data_from_ancestor.transform_tree->UpdateTransforms(node->id);
 353
 354   layer->set_offset_to_transform_parent(gfx::Vector2dF());
 355
 356   // Flattening (if needed) will be handled by |node|.
 357   layer->set_should_flatten_transform_from_property_tree(false);
 358
 359   data_for_children->scroll_compensation_adjustment +=
 360       layer->ScrollCompensationAdjustment() - node->data.scroll_snap;
 361
 362   node->owner_id = layer->id();
 363
 364   return true;
 365 }
 366
 367 bool IsAnimatingOpacity(Layer* layer) {
 368   return layer->HasPotentiallyRunningOpacityAnimation() ||
 369          layer->OpacityCanAnimateOnImplThread();
 370 }
 371
 372 bool IsAnimatingOpacity(LayerImpl* layer) {
 373   return layer->HasPotentiallyRunningOpacityAnimation();
 374 }
 375
 376 template <typename LayerType>
 377 void AddEffectNodeIfNeeded(
 378     const DataForRecursion<LayerType>& data_from_ancestor,
 379     LayerType* layer,
 380     DataForRecursion<LayerType>* data_for_children) {
 381   const bool is_root = !layer->parent();
 382   const bool has_transparency = layer->opacity() != 1.f;
 383   const bool has_animated_opacity = IsAnimatingOpacity(layer);
 384   bool requires_node = is_root || has_transparency || has_animated_opacity;
 385
 386   int parent_id = data_from_ancestor.effect_tree_parent;
 387
 388   if (!requires_node) {
 389     layer->SetEffectTreeIndex(parent_id);
 390     data_for_children->effect_tree_parent = parent_id;
 391     return;
 392   }
 393
 394   EffectNode node;
 395   node.owner_id = layer->id();
 396   node.data.opacity = layer->opacity();
 397   node.data.screen_space_opacity = layer->opacity();
 398   if (!is_root)
 399     node.data.screen_space_opacity *=
 400         data_from_ancestor.effect_tree->Node(parent_id)
 401             ->data.screen_space_opacity;
 402   data_for_children->effect_tree_parent =
 403       data_for_children->effect_tree->Insert(node, parent_id);
 404   layer->SetEffectTreeIndex(data_for_children->effect_tree_parent);
 405 }
 406
 407 template <typename LayerType>
 408 void BuildPropertyTreesInternal(
 409     LayerType* layer,
 410     const DataForRecursion<LayerType>& data_from_parent) {
 411   layer->set_property_tree_sequence_number(data_from_parent.sequence_number);
 412   DataForRecursion<LayerType> data_for_children(data_from_parent);
 413   if (layer->has_render_surface()) {
 414     data_for_children.render_target = layer;
 415     layer->set_draw_blend_mode(SkXfermode::kSrcOver_Mode);
 416   } else {
 417     layer->set_draw_blend_mode(layer->blend_mode());
 418   }
 419
 420   bool created_transform_node =
 421       AddTransformNodeIfNeeded(data_from_parent, layer, &data_for_children);
 422   AddClipNodeIfNeeded(data_from_parent, layer, created_transform_node,
 423                       &data_for_children);
 424   AddEffectNodeIfNeeded(data_from_parent, layer, &data_for_children);
 425
 426   if (layer == data_from_parent.page_scale_layer)
 427     data_for_children.in_subtree_of_page_scale_layer = true;
 428
 429   for (size_t i = 0; i < layer->children().size(); ++i) {
 430     if (!layer->child_at(i)->scroll_parent()) {
 431       BuildPropertyTreesInternal(layer->child_at(i), data_for_children);
 432     } else {
 433       // The child should be included in its scroll parent's list of scroll
 434       // children.
 435       DCHECK(layer->child_at(i)->scroll_parent()->scroll_children()->count(
 436           layer->child_at(i)));
 437     }
 438   }
 439
 440   if (layer->scroll_children()) {
 441     for (LayerType* scroll_child : *layer->scroll_children()) {
 442       DCHECK_EQ(scroll_child->scroll_parent(), layer);
 443       BuildPropertyTreesInternal(scroll_child, data_for_children);
 444     }
 445   }
 446
 447   if (layer->has_replica())
 448     BuildPropertyTreesInternal(layer->replica_layer(), data_for_children);
 449 }
 450
 451 }  // namespace
 452
 453 template <typename LayerType>
 454 void BuildPropertyTreesTopLevelInternal(
 455     LayerType* root_layer,
 456     const LayerType* page_scale_layer,
 457     const LayerType* inner_viewport_scroll_layer,
 458     const LayerType* outer_viewport_scroll_layer,
 459     float page_scale_factor,
 460     float device_scale_factor,
 461     const gfx::Rect& viewport,
 462     const gfx::Transform& device_transform,
 463     PropertyTrees* property_trees) {
 464   if (!property_trees->needs_rebuild)
 465     return;
 466
 467   property_trees->sequence_number++;
 468
 469   DataForRecursion<LayerType> data_for_recursion;
 470   data_for_recursion.transform_tree = &property_trees->transform_tree;
 471   data_for_recursion.clip_tree = &property_trees->clip_tree;
 472   data_for_recursion.effect_tree = &property_trees->effect_tree;
 473   data_for_recursion.transform_tree_parent = nullptr;
 474   data_for_recursion.transform_fixed_parent = nullptr;
 475   data_for_recursion.render_target = root_layer;
 476   data_for_recursion.clip_tree_parent = kUnclippedRootClipTreeNodeId;
 477   data_for_recursion.effect_tree_parent = kInvalidPropertyTreeNodeId;
 478   data_for_recursion.page_scale_layer = page_scale_layer;
 479   data_for_recursion.inner_viewport_scroll_layer = inner_viewport_scroll_layer;
 480   data_for_recursion.outer_viewport_scroll_layer = outer_viewport_scroll_layer;
 481   data_for_recursion.page_scale_factor = page_scale_factor;
 482   data_for_recursion.device_scale_factor = device_scale_factor;
 483   data_for_recursion.in_subtree_of_page_scale_layer = false;
 484   data_for_recursion.affected_by_inner_viewport_bounds_delta = false;
 485   data_for_recursion.affected_by_outer_viewport_bounds_delta = false;
 486   data_for_recursion.should_flatten = false;
 487   data_for_recursion.ancestor_clips_subtree = true;
 488   data_for_recursion.device_transform = &device_transform;
 489
 490   data_for_recursion.transform_tree->clear();
 491   data_for_recursion.clip_tree->clear();
 492   data_for_recursion.effect_tree->clear();
 493   data_for_recursion.sequence_number = property_trees->sequence_number;
 494
 495   ClipNode root_clip;
 496   root_clip.data.clip = gfx::RectF(viewport);
 497   root_clip.data.transform_id = kRootPropertyTreeNodeId;
 498   data_for_recursion.clip_tree_parent = data_for_recursion.clip_tree->Insert(
 499       root_clip, kUnclippedRootClipTreeNodeId);
 500   BuildPropertyTreesInternal(root_layer, data_for_recursion);
 501   property_trees->needs_rebuild = false;
 502
 503   // The transform tree is kept up-to-date as it is built, but the
 504   // combined_clips stored in the clip tree aren't computed during tree
 505   // building.
 506   property_trees->transform_tree.set_needs_update(false);
 507   property_trees->clip_tree.set_needs_update(true);
 508   property_trees->effect_tree.set_needs_update(false);
 509 }
 510
 511 void PropertyTreeBuilder::BuildPropertyTrees(
 512     Layer* root_layer,
 513     const Layer* page_scale_layer,
 514     const Layer* inner_viewport_scroll_layer,
 515     const Layer* outer_viewport_scroll_layer,
 516     float page_scale_factor,
 517     float device_scale_factor,
 518     const gfx::Rect& viewport,
 519     const gfx::Transform& device_transform,
 520     PropertyTrees* property_trees) {
 521   BuildPropertyTreesTopLevelInternal(
 522       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 523       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 524       viewport, device_transform, property_trees);
 525 }
 526
 527 void PropertyTreeBuilder::BuildPropertyTrees(
 528     LayerImpl* root_layer,
 529     const LayerImpl* page_scale_layer,
 530     const LayerImpl* inner_viewport_scroll_layer,
 531     const LayerImpl* outer_viewport_scroll_layer,
 532     float page_scale_factor,
 533     float device_scale_factor,
 534     const gfx::Rect& viewport,
 535     const gfx::Transform& device_transform,
 536     PropertyTrees* property_trees) {
 537   BuildPropertyTreesTopLevelInternal(
 538       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 539       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 540       viewport, device_transform, property_trees);
 541 }
 542
 543 }  // namespace cc