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(has_unclipped_surface
 159                               ? kUnclippedRootClipTreeNodeId
 160                               : data_for_children->clip_tree_parent);
 161
 162   layer->set_is_clipped(data_for_children->ancestor_clips_subtree);
 163
 164   // TODO(awoloszyn): Right now when we hit a node with a replica, we reset the
 165   // clip for all children since we may need to draw. We need to figure out a
 166   // better way, since we will need both the clipped and unclipped versions.
 167 }
 168
 169 template <typename LayerType>
 170 bool AddTransformNodeIfNeeded(
 171     const DataForRecursion<LayerType>& data_from_ancestor,
 172     LayerType* layer,
 173     DataForRecursion<LayerType>* data_for_children) {
 174   const bool is_root = !layer->parent();
 175   const bool is_page_scale_layer = layer == data_from_ancestor.page_scale_layer;
 176   const bool is_scrollable = layer->scrollable();
 177   const bool is_fixed = layer->position_constraint().is_fixed_position();
 178
 179   const bool has_significant_transform =
 180       !layer->transform().IsIdentityOr2DTranslation();
 181
 182   const bool has_potentially_animated_transform =
 183       layer->HasPotentiallyRunningTransformAnimation();
 184
 185   // A transform node is needed even for a finished animation, since differences
 186   // in the timing of animation state updates can mean that an animation that's
 187   // in the Finished state at tree-building time on the main thread is still in
 188   // the Running state right after commit on the compositor thread.
 189   const bool has_any_transform_animation =
 190       layer->HasAnyAnimationTargetingProperty(Animation::TRANSFORM);
 191
 192   const bool has_surface = layer->has_render_surface();
 193
 194   bool requires_node = is_root || is_scrollable || has_significant_transform ||
 195                        has_any_transform_animation || has_surface || is_fixed ||
 196                        is_page_scale_layer;
 197
 198   LayerType* transform_parent = GetTransformParent(data_from_ancestor, layer);
 199   DCHECK_IMPLIES(!is_root, transform_parent);
 200
 201   int parent_index = kRootPropertyTreeNodeId;
 202   if (transform_parent)
 203     parent_index = transform_parent->transform_tree_index();
 204
 205   int source_index = parent_index;
 206
 207   gfx::Vector2dF source_offset;
 208   if (transform_parent) {
 209     if (layer->scroll_parent()) {
 210       LayerType* source = layer->parent();
 211       source_offset += source->offset_to_transform_parent();
 212       source_index = source->transform_tree_index();
 213     } else if (!is_fixed) {
 214       source_offset = transform_parent->offset_to_transform_parent();
 215     } else {
 216       source_offset = data_from_ancestor.transform_tree_parent
 217                           ->offset_to_transform_parent();
 218       source_index =
 219           data_from_ancestor.transform_tree_parent->transform_tree_index();
 220       source_offset += data_from_ancestor.scroll_compensation_adjustment;
 221     }
 222   }
 223
 224   if (layer->IsContainerForFixedPositionLayers() || is_root) {
 225     data_for_children->affected_by_inner_viewport_bounds_delta =
 226         layer == data_from_ancestor.inner_viewport_scroll_layer;
 227     data_for_children->affected_by_outer_viewport_bounds_delta =
 228         layer == data_from_ancestor.outer_viewport_scroll_layer;
 229     if (is_scrollable) {
 230       DCHECK(!is_root);
 231       DCHECK(layer->transform().IsIdentity());
 232       data_for_children->transform_fixed_parent = layer->parent();
 233     } else {
 234       data_for_children->transform_fixed_parent = layer;
 235     }
 236   }
 237   data_for_children->transform_tree_parent = layer;
 238
 239   if (layer->IsContainerForFixedPositionLayers() || is_fixed)
 240     data_for_children->scroll_compensation_adjustment = gfx::Vector2dF();
 241
 242   if (!requires_node) {
 243     data_for_children->should_flatten |= layer->should_flatten_transform();
 244     gfx::Vector2dF local_offset = layer->position().OffsetFromOrigin() +
 245                                   layer->transform().To2dTranslation();
 246     gfx::Vector2dF source_to_parent;
 247     if (source_index != parent_index) {
 248       gfx::Transform to_parent;
 249       data_from_ancestor.transform_tree->ComputeTransform(
 250           source_index, parent_index, &to_parent);
 251       source_to_parent = to_parent.To2dTranslation();
 252     }
 253     layer->set_offset_to_transform_parent(source_offset + source_to_parent +
 254                                           local_offset);
 255     layer->set_should_flatten_transform_from_property_tree(
 256         data_from_ancestor.should_flatten);
 257     layer->SetTransformTreeIndex(parent_index);
 258     return false;
 259   }
 260
 261   data_for_children->transform_tree->Insert(TransformNode(), parent_index);
 262
 263   TransformNode* node = data_for_children->transform_tree->back();
 264   layer->SetTransformTreeIndex(node->id);
 265
 266   node->data.scrolls = is_scrollable;
 267   node->data.flattens_inherited_transform = data_for_children->should_flatten;
 268
 269   // Surfaces inherently flatten transforms.
 270   data_for_children->should_flatten =
 271       layer->should_flatten_transform() || has_surface;
 272   node->data.target_id =
 273       data_from_ancestor.render_target->transform_tree_index();
 274   node->data.content_target_id =
 275       data_for_children->render_target->transform_tree_index();
 276   DCHECK_NE(node->data.target_id, kInvalidPropertyTreeNodeId);
 277   node->data.is_animated = has_potentially_animated_transform;
 278   if (has_potentially_animated_transform) {
 279     float maximum_animation_target_scale = 0.f;
 280     if (layer->MaximumTargetScale(&maximum_animation_target_scale)) {
 281       node->data.local_maximum_animation_target_scale =
 282           maximum_animation_target_scale;
 283     }
 284
 285     float starting_animation_scale = 0.f;
 286     if (layer->AnimationStartScale(&starting_animation_scale)) {
 287       node->data.local_starting_animation_scale = starting_animation_scale;
 288     }
 289
 290     node->data.has_only_translation_animations =
 291         layer->HasOnlyTranslationTransforms();
 292   }
 293
 294   float post_local_scale_factor = 1.0f;
 295   if (is_root) {
 296     node->data.post_local = *data_from_ancestor.device_transform;
 297     post_local_scale_factor = data_from_ancestor.device_scale_factor;
 298   }
 299
 300   if (is_page_scale_layer)
 301     post_local_scale_factor *= data_from_ancestor.page_scale_factor;
 302
 303   if (has_surface && !is_root) {
 304     node->data.needs_sublayer_scale = true;
 305     node->data.layer_scale_factor = data_from_ancestor.device_scale_factor;
 306     if (data_from_ancestor.in_subtree_of_page_scale_layer)
 307       node->data.layer_scale_factor *= data_from_ancestor.page_scale_factor;
 308   }
 309
 310   node->data.source_node_id = source_index;
 311   if (is_root) {
 312     node->data.post_local.Scale(post_local_scale_factor,
 313                                 post_local_scale_factor);
 314     node->data.post_local.Translate(layer->position().x(),
 315                                     layer->position().y());
 316   } else {
 317     node->data.post_local_scale_factor = post_local_scale_factor;
 318     node->data.source_offset = source_offset;
 319     node->data.update_post_local_transform(layer->position(),
 320                                            layer->transform_origin());
 321   }
 322
 323   if (!layer->scroll_parent())
 324     node->data.scroll_offset = layer->CurrentScrollOffset();
 325
 326   if (is_fixed) {
 327     if (data_from_ancestor.affected_by_inner_viewport_bounds_delta) {
 328       node->data.affected_by_inner_viewport_bounds_delta_x =
 329           layer->position_constraint().is_fixed_to_right_edge();
 330       node->data.affected_by_inner_viewport_bounds_delta_y =
 331           layer->position_constraint().is_fixed_to_bottom_edge();
 332       if (node->data.affected_by_inner_viewport_bounds_delta_x ||
 333           node->data.affected_by_inner_viewport_bounds_delta_y) {
 334         data_for_children->transform_tree
 335             ->AddNodeAffectedByInnerViewportBoundsDelta(node->id);
 336       }
 337     } else if (data_from_ancestor.affected_by_outer_viewport_bounds_delta) {
 338       node->data.affected_by_outer_viewport_bounds_delta_x =
 339           layer->position_constraint().is_fixed_to_right_edge();
 340       node->data.affected_by_outer_viewport_bounds_delta_y =
 341           layer->position_constraint().is_fixed_to_bottom_edge();
 342       if (node->data.affected_by_outer_viewport_bounds_delta_x ||
 343           node->data.affected_by_outer_viewport_bounds_delta_y) {
 344         data_for_children->transform_tree
 345             ->AddNodeAffectedByOuterViewportBoundsDelta(node->id);
 346       }
 347     }
 348   }
 349
 350   node->data.local = layer->transform();
 351   node->data.update_pre_local_transform(layer->transform_origin());
 352
 353   node->data.needs_local_transform_update = true;
 354   data_from_ancestor.transform_tree->UpdateTransforms(node->id);
 355
 356   layer->set_offset_to_transform_parent(gfx::Vector2dF());
 357
 358   // Flattening (if needed) will be handled by |node|.
 359   layer->set_should_flatten_transform_from_property_tree(false);
 360
 361   data_for_children->scroll_compensation_adjustment +=
 362       layer->ScrollCompensationAdjustment() - node->data.scroll_snap;
 363
 364   node->owner_id = layer->id();
 365
 366   return true;
 367 }
 368
 369 bool IsAnimatingOpacity(Layer* layer) {
 370   return layer->HasPotentiallyRunningOpacityAnimation() ||
 371          layer->OpacityCanAnimateOnImplThread();
 372 }
 373
 374 bool IsAnimatingOpacity(LayerImpl* layer) {
 375   return layer->HasPotentiallyRunningOpacityAnimation();
 376 }
 377
 378 template <typename LayerType>
 379 void AddEffectNodeIfNeeded(
 380     const DataForRecursion<LayerType>& data_from_ancestor,
 381     LayerType* layer,
 382     DataForRecursion<LayerType>* data_for_children) {
 383   const bool is_root = !layer->parent();
 384   const bool has_transparency = layer->opacity() != 1.f;
 385   const bool has_animated_opacity = IsAnimatingOpacity(layer);
 386   bool requires_node = is_root || has_transparency || has_animated_opacity;
 387
 388   int parent_id = data_from_ancestor.effect_tree_parent;
 389
 390   if (!requires_node) {
 391     layer->SetEffectTreeIndex(parent_id);
 392     data_for_children->effect_tree_parent = parent_id;
 393     return;
 394   }
 395
 396   EffectNode node;
 397   node.owner_id = layer->id();
 398   node.data.opacity = layer->opacity();
 399   node.data.screen_space_opacity = layer->opacity();
 400   if (!is_root)
 401     node.data.screen_space_opacity *=
 402         data_from_ancestor.effect_tree->Node(parent_id)
 403             ->data.screen_space_opacity;
 404   data_for_children->effect_tree_parent =
 405       data_for_children->effect_tree->Insert(node, parent_id);
 406   layer->SetEffectTreeIndex(data_for_children->effect_tree_parent);
 407 }
 408
 409 template <typename LayerType>
 410 void BuildPropertyTreesInternal(
 411     LayerType* layer,
 412     const DataForRecursion<LayerType>& data_from_parent) {
 413   layer->set_property_tree_sequence_number(data_from_parent.sequence_number);
 414   DataForRecursion<LayerType> data_for_children(data_from_parent);
 415   if (layer->has_render_surface()) {
 416     data_for_children.render_target = layer;
 417     layer->set_draw_blend_mode(SkXfermode::kSrcOver_Mode);
 418   } else {
 419     layer->set_draw_blend_mode(layer->blend_mode());
 420   }
 421
 422   bool created_transform_node =
 423       AddTransformNodeIfNeeded(data_from_parent, layer, &data_for_children);
 424   AddClipNodeIfNeeded(data_from_parent, layer, created_transform_node,
 425                       &data_for_children);
 426   AddEffectNodeIfNeeded(data_from_parent, layer, &data_for_children);
 427
 428   if (layer == data_from_parent.page_scale_layer)
 429     data_for_children.in_subtree_of_page_scale_layer = true;
 430
 431   for (size_t i = 0; i < layer->children().size(); ++i) {
 432     if (!layer->child_at(i)->scroll_parent()) {
 433       BuildPropertyTreesInternal(layer->child_at(i), data_for_children);
 434     } else {
 435       // The child should be included in its scroll parent's list of scroll
 436       // children.
 437       DCHECK(layer->child_at(i)->scroll_parent()->scroll_children()->count(
 438           layer->child_at(i)));
 439     }
 440   }
 441
 442   if (layer->scroll_children()) {
 443     for (LayerType* scroll_child : *layer->scroll_children()) {
 444       DCHECK_EQ(scroll_child->scroll_parent(), layer);
 445       BuildPropertyTreesInternal(scroll_child, data_for_children);
 446     }
 447   }
 448
 449   if (layer->has_replica())
 450     BuildPropertyTreesInternal(layer->replica_layer(), data_for_children);
 451 }
 452
 453 }  // namespace
 454
 455 template <typename LayerType>
 456 void BuildPropertyTreesTopLevelInternal(
 457     LayerType* root_layer,
 458     const LayerType* page_scale_layer,
 459     const LayerType* inner_viewport_scroll_layer,
 460     const LayerType* outer_viewport_scroll_layer,
 461     float page_scale_factor,
 462     float device_scale_factor,
 463     const gfx::Rect& viewport,
 464     const gfx::Transform& device_transform,
 465     PropertyTrees* property_trees) {
 466   if (!property_trees->needs_rebuild)
 467     return;
 468
 469   property_trees->sequence_number++;
 470
 471   DataForRecursion<LayerType> data_for_recursion;
 472   data_for_recursion.transform_tree = &property_trees->transform_tree;
 473   data_for_recursion.clip_tree = &property_trees->clip_tree;
 474   data_for_recursion.effect_tree = &property_trees->effect_tree;
 475   data_for_recursion.transform_tree_parent = nullptr;
 476   data_for_recursion.transform_fixed_parent = nullptr;
 477   data_for_recursion.render_target = root_layer;
 478   data_for_recursion.clip_tree_parent = kUnclippedRootClipTreeNodeId;
 479   data_for_recursion.effect_tree_parent = kInvalidPropertyTreeNodeId;
 480   data_for_recursion.page_scale_layer = page_scale_layer;
 481   data_for_recursion.inner_viewport_scroll_layer = inner_viewport_scroll_layer;
 482   data_for_recursion.outer_viewport_scroll_layer = outer_viewport_scroll_layer;
 483   data_for_recursion.page_scale_factor = page_scale_factor;
 484   data_for_recursion.device_scale_factor = device_scale_factor;
 485   data_for_recursion.in_subtree_of_page_scale_layer = false;
 486   data_for_recursion.affected_by_inner_viewport_bounds_delta = false;
 487   data_for_recursion.affected_by_outer_viewport_bounds_delta = false;
 488   data_for_recursion.should_flatten = false;
 489   data_for_recursion.ancestor_clips_subtree = true;
 490   data_for_recursion.device_transform = &device_transform;
 491
 492   data_for_recursion.transform_tree->clear();
 493   data_for_recursion.clip_tree->clear();
 494   data_for_recursion.effect_tree->clear();
 495   data_for_recursion.sequence_number = property_trees->sequence_number;
 496
 497   ClipNode root_clip;
 498   root_clip.data.clip = viewport;
 499   root_clip.data.transform_id = kRootPropertyTreeNodeId;
 500   data_for_recursion.clip_tree_parent = data_for_recursion.clip_tree->Insert(
 501       root_clip, kUnclippedRootClipTreeNodeId);
 502   BuildPropertyTreesInternal(root_layer, data_for_recursion);
 503   property_trees->needs_rebuild = false;
 504
 505   // The transform tree is kept up-to-date as it is built, but the
 506   // combined_clips stored in the clip tree aren't computed during tree
 507   // building.
 508   property_trees->transform_tree.set_needs_update(false);
 509   property_trees->clip_tree.set_needs_update(true);
 510   property_trees->effect_tree.set_needs_update(false);
 511 }
 512
 513 void PropertyTreeBuilder::BuildPropertyTrees(
 514     Layer* root_layer,
 515     const Layer* page_scale_layer,
 516     const Layer* inner_viewport_scroll_layer,
 517     const Layer* outer_viewport_scroll_layer,
 518     float page_scale_factor,
 519     float device_scale_factor,
 520     const gfx::Rect& viewport,
 521     const gfx::Transform& device_transform,
 522     PropertyTrees* property_trees) {
 523   BuildPropertyTreesTopLevelInternal(
 524       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 525       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 526       viewport, device_transform, property_trees);
 527 }
 528
 529 void PropertyTreeBuilder::BuildPropertyTrees(
 530     LayerImpl* root_layer,
 531     const LayerImpl* page_scale_layer,
 532     const LayerImpl* inner_viewport_scroll_layer,
 533     const LayerImpl* outer_viewport_scroll_layer,
 534     float page_scale_factor,
 535     float device_scale_factor,
 536     const gfx::Rect& viewport,
 537     const gfx::Transform& device_transform,
 538     PropertyTrees* property_trees) {
 539   BuildPropertyTreesTopLevelInternal(
 540       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 541       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 542       viewport, device_transform, property_trees);
 543 }
 544
 545 }  // namespace cc