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->render_surface() && is_clipped;
  76   const bool render_surface_may_grow_due_to_clip_children =
  77       layer->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->render_surface() ||
 148          (layer->has_render_surface() && !layer_clips_subtree &&
 149           layer->num_unclipped_descendants()));
 150
 151     node.data.render_surface_is_clipped = layer->has_render_surface() &&
 152                                           ancestor_clips_subtree &&
 153                                           !layer->num_unclipped_descendants();
 154
 155     data_for_children->clip_tree_parent =
 156         data_for_children->clip_tree->Insert(node, parent_id);
 157   }
 158
 159   layer->SetClipTreeIndex(has_unclipped_surface
 160                               ? kUnclippedRootClipTreeNodeId
 161                               : data_for_children->clip_tree_parent);
 162
 163   layer->set_is_clipped(data_for_children->ancestor_clips_subtree);
 164
 165   // TODO(awoloszyn): Right now when we hit a node with a replica, we reset the
 166   // clip for all children since we may need to draw. We need to figure out a
 167   // better way, since we will need both the clipped and unclipped versions.
 168 }
 169
 170 template <typename LayerType>
 171 bool AddTransformNodeIfNeeded(
 172     const DataForRecursion<LayerType>& data_from_ancestor,
 173     LayerType* layer,
 174     DataForRecursion<LayerType>* data_for_children) {
 175   const bool is_root = !layer->parent();
 176   const bool is_page_scale_layer = layer == data_from_ancestor.page_scale_layer;
 177   const bool is_scrollable = layer->scrollable();
 178   const bool is_fixed = layer->position_constraint().is_fixed_position();
 179
 180   const bool has_significant_transform =
 181       !layer->transform().IsIdentityOr2DTranslation();
 182
 183   const bool has_potentially_animated_transform =
 184       layer->HasPotentiallyRunningTransformAnimation();
 185
 186   // A transform node is needed even for a finished animation, since differences
 187   // in the timing of animation state updates can mean that an animation that's
 188   // in the Finished state at tree-building time on the main thread is still in
 189   // the Running state right after commit on the compositor thread.
 190   const bool has_any_transform_animation =
 191       layer->HasAnyAnimationTargetingProperty(Animation::TRANSFORM);
 192
 193   const bool has_surface = !!layer->render_surface();
 194
 195   bool requires_node = is_root || is_scrollable || has_significant_transform ||
 196                        has_any_transform_animation || has_surface || is_fixed ||
 197                        is_page_scale_layer;
 198
 199   LayerType* transform_parent = GetTransformParent(data_from_ancestor, layer);
 200   DCHECK_IMPLIES(!is_root, transform_parent);
 201
 202   int parent_index = kRootPropertyTreeNodeId;
 203   if (transform_parent)
 204     parent_index = transform_parent->transform_tree_index();
 205
 206   int source_index = parent_index;
 207
 208   gfx::Vector2dF source_offset;
 209   if (transform_parent) {
 210     if (layer->scroll_parent()) {
 211       LayerType* source = layer->parent();
 212       source_offset += source->offset_to_transform_parent();
 213       source_index = source->transform_tree_index();
 214     } else if (!is_fixed) {
 215       source_offset = transform_parent->offset_to_transform_parent();
 216     } else {
 217       source_offset = data_from_ancestor.transform_tree_parent
 218                           ->offset_to_transform_parent();
 219       source_index =
 220           data_from_ancestor.transform_tree_parent->transform_tree_index();
 221       source_offset += data_from_ancestor.scroll_compensation_adjustment;
 222     }
 223   }
 224
 225   if (layer->IsContainerForFixedPositionLayers() || is_root) {
 226     data_for_children->affected_by_inner_viewport_bounds_delta =
 227         layer == data_from_ancestor.inner_viewport_scroll_layer;
 228     data_for_children->affected_by_outer_viewport_bounds_delta =
 229         layer == data_from_ancestor.outer_viewport_scroll_layer;
 230     if (is_scrollable) {
 231       DCHECK(!is_root);
 232       DCHECK(layer->transform().IsIdentity());
 233       data_for_children->transform_fixed_parent = layer->parent();
 234     } else {
 235       data_for_children->transform_fixed_parent = layer;
 236     }
 237   }
 238   data_for_children->transform_tree_parent = layer;
 239
 240   if (layer->IsContainerForFixedPositionLayers() || is_fixed)
 241     data_for_children->scroll_compensation_adjustment = gfx::Vector2dF();
 242
 243   if (!requires_node) {
 244     data_for_children->should_flatten |= layer->should_flatten_transform();
 245     gfx::Vector2dF local_offset = layer->position().OffsetFromOrigin() +
 246                                   layer->transform().To2dTranslation();
 247     gfx::Vector2dF source_to_parent;
 248     if (source_index != parent_index) {
 249       gfx::Transform to_parent;
 250       data_from_ancestor.transform_tree->ComputeTransform(
 251           source_index, parent_index, &to_parent);
 252       source_to_parent = to_parent.To2dTranslation();
 253     }
 254     layer->set_offset_to_transform_parent(source_offset + source_to_parent +
 255                                           local_offset);
 256     layer->set_should_flatten_transform_from_property_tree(
 257         data_from_ancestor.should_flatten);
 258     layer->SetTransformTreeIndex(parent_index);
 259     return false;
 260   }
 261
 262   data_for_children->transform_tree->Insert(TransformNode(), parent_index);
 263
 264   TransformNode* node = data_for_children->transform_tree->back();
 265   layer->SetTransformTreeIndex(node->id);
 266
 267   node->data.scrolls = is_scrollable;
 268   node->data.flattens_inherited_transform = data_for_children->should_flatten;
 269
 270   // Surfaces inherently flatten transforms.
 271   data_for_children->should_flatten =
 272       layer->should_flatten_transform() || has_surface;
 273   node->data.target_id =
 274       data_from_ancestor.render_target->transform_tree_index();
 275   node->data.content_target_id =
 276       data_for_children->render_target->transform_tree_index();
 277   DCHECK_NE(node->data.target_id, kInvalidPropertyTreeNodeId);
 278   node->data.is_animated = has_potentially_animated_transform;
 279
 280   float post_local_scale_factor = 1.0f;
 281   if (is_root) {
 282     node->data.post_local = *data_from_ancestor.device_transform;
 283     post_local_scale_factor = data_from_ancestor.device_scale_factor;
 284   }
 285
 286   if (is_page_scale_layer)
 287     post_local_scale_factor *= data_from_ancestor.page_scale_factor;
 288
 289   if (has_surface && !is_root) {
 290     node->data.needs_sublayer_scale = true;
 291     node->data.layer_scale_factor = data_from_ancestor.device_scale_factor;
 292     if (data_from_ancestor.in_subtree_of_page_scale_layer)
 293       node->data.layer_scale_factor *= data_from_ancestor.page_scale_factor;
 294   }
 295
 296   node->data.source_node_id = source_index;
 297   if (is_root) {
 298     node->data.post_local.Scale(post_local_scale_factor,
 299                                 post_local_scale_factor);
 300     node->data.post_local.Translate(layer->position().x(),
 301                                     layer->position().y());
 302   } else {
 303     node->data.post_local_scale_factor = post_local_scale_factor;
 304     node->data.source_offset = source_offset;
 305     node->data.update_post_local_transform(layer->position(),
 306                                            layer->transform_origin());
 307   }
 308
 309   if (!layer->scroll_parent())
 310     node->data.scroll_offset = layer->CurrentScrollOffset();
 311
 312   if (is_fixed) {
 313     if (data_from_ancestor.affected_by_inner_viewport_bounds_delta) {
 314       node->data.affected_by_inner_viewport_bounds_delta_x =
 315           layer->position_constraint().is_fixed_to_right_edge();
 316       node->data.affected_by_inner_viewport_bounds_delta_y =
 317           layer->position_constraint().is_fixed_to_bottom_edge();
 318       if (node->data.affected_by_inner_viewport_bounds_delta_x ||
 319           node->data.affected_by_inner_viewport_bounds_delta_y) {
 320         data_for_children->transform_tree
 321             ->AddNodeAffectedByInnerViewportBoundsDelta(node->id);
 322       }
 323     } else if (data_from_ancestor.affected_by_outer_viewport_bounds_delta) {
 324       node->data.affected_by_outer_viewport_bounds_delta_x =
 325           layer->position_constraint().is_fixed_to_right_edge();
 326       node->data.affected_by_outer_viewport_bounds_delta_y =
 327           layer->position_constraint().is_fixed_to_bottom_edge();
 328       if (node->data.affected_by_outer_viewport_bounds_delta_x ||
 329           node->data.affected_by_outer_viewport_bounds_delta_y) {
 330         data_for_children->transform_tree
 331             ->AddNodeAffectedByOuterViewportBoundsDelta(node->id);
 332       }
 333     }
 334   }
 335
 336   node->data.local = layer->transform();
 337   node->data.update_pre_local_transform(layer->transform_origin());
 338
 339   node->data.needs_local_transform_update = true;
 340   data_from_ancestor.transform_tree->UpdateTransforms(node->id);
 341
 342   layer->set_offset_to_transform_parent(gfx::Vector2dF());
 343
 344   // Flattening (if needed) will be handled by |node|.
 345   layer->set_should_flatten_transform_from_property_tree(false);
 346
 347   data_for_children->scroll_compensation_adjustment +=
 348       layer->ScrollCompensationAdjustment() - node->data.scroll_snap;
 349
 350   node->owner_id = layer->id();
 351
 352   return true;
 353 }
 354
 355 bool IsAnimatingOpacity(Layer* layer) {
 356   return layer->HasPotentiallyRunningOpacityAnimation() ||
 357          layer->OpacityCanAnimateOnImplThread();
 358 }
 359
 360 bool IsAnimatingOpacity(LayerImpl* layer) {
 361   return layer->HasPotentiallyRunningOpacityAnimation();
 362 }
 363
 364 template <typename LayerType>
 365 void AddEffectNodeIfNeeded(
 366     const DataForRecursion<LayerType>& data_from_ancestor,
 367     LayerType* layer,
 368     DataForRecursion<LayerType>* data_for_children) {
 369   const bool is_root = !layer->parent();
 370   const bool has_transparency = layer->opacity() != 1.f;
 371   const bool has_animated_opacity = IsAnimatingOpacity(layer);
 372   bool requires_node = is_root || has_transparency || has_animated_opacity;
 373
 374   int parent_id = data_from_ancestor.effect_tree_parent;
 375
 376   if (!requires_node) {
 377     layer->SetEffectTreeIndex(parent_id);
 378     data_for_children->effect_tree_parent = parent_id;
 379     return;
 380   }
 381
 382   EffectNode node;
 383   node.owner_id = layer->id();
 384   node.data.opacity = layer->opacity();
 385   node.data.screen_space_opacity = layer->opacity();
 386   if (!is_root)
 387     node.data.screen_space_opacity *=
 388         data_from_ancestor.effect_tree->Node(parent_id)
 389             ->data.screen_space_opacity;
 390   data_for_children->effect_tree_parent =
 391       data_for_children->effect_tree->Insert(node, parent_id);
 392   layer->SetEffectTreeIndex(data_for_children->effect_tree_parent);
 393 }
 394
 395 template <typename LayerType>
 396 void BuildPropertyTreesInternal(
 397     LayerType* layer,
 398     const DataForRecursion<LayerType>& data_from_parent) {
 399   layer->set_property_tree_sequence_number(data_from_parent.sequence_number);
 400   DataForRecursion<LayerType> data_for_children(data_from_parent);
 401   if (layer->render_surface()) {
 402     data_for_children.render_target = layer;
 403     layer->set_draw_blend_mode(SkXfermode::kSrcOver_Mode);
 404   } else {
 405     layer->set_draw_blend_mode(layer->blend_mode());
 406   }
 407
 408   bool created_transform_node =
 409       AddTransformNodeIfNeeded(data_from_parent, layer, &data_for_children);
 410   AddClipNodeIfNeeded(data_from_parent, layer, created_transform_node,
 411                       &data_for_children);
 412   AddEffectNodeIfNeeded(data_from_parent, layer, &data_for_children);
 413
 414   if (layer == data_from_parent.page_scale_layer)
 415     data_for_children.in_subtree_of_page_scale_layer = true;
 416
 417   for (size_t i = 0; i < layer->children().size(); ++i) {
 418     if (!layer->child_at(i)->scroll_parent()) {
 419       BuildPropertyTreesInternal(layer->child_at(i), data_for_children);
 420     } else {
 421       // The child should be included in its scroll parent's list of scroll
 422       // children.
 423       DCHECK(layer->child_at(i)->scroll_parent()->scroll_children()->count(
 424           layer->child_at(i)));
 425     }
 426   }
 427
 428   if (layer->scroll_children()) {
 429     for (LayerType* scroll_child : *layer->scroll_children()) {
 430       DCHECK_EQ(scroll_child->scroll_parent(), layer);
 431       BuildPropertyTreesInternal(scroll_child, data_for_children);
 432     }
 433   }
 434
 435   if (layer->has_replica())
 436     BuildPropertyTreesInternal(layer->replica_layer(), data_for_children);
 437 }
 438
 439 }  // namespace
 440
 441 template <typename LayerType>
 442 void BuildPropertyTreesTopLevelInternal(
 443     LayerType* root_layer,
 444     const LayerType* page_scale_layer,
 445     const LayerType* inner_viewport_scroll_layer,
 446     const LayerType* outer_viewport_scroll_layer,
 447     float page_scale_factor,
 448     float device_scale_factor,
 449     const gfx::Rect& viewport,
 450     const gfx::Transform& device_transform,
 451     PropertyTrees* property_trees) {
 452   if (!property_trees->needs_rebuild)
 453     return;
 454
 455   property_trees->sequence_number++;
 456
 457   DataForRecursion<LayerType> data_for_recursion;
 458   data_for_recursion.transform_tree = &property_trees->transform_tree;
 459   data_for_recursion.clip_tree = &property_trees->clip_tree;
 460   data_for_recursion.effect_tree = &property_trees->effect_tree;
 461   data_for_recursion.transform_tree_parent = nullptr;
 462   data_for_recursion.transform_fixed_parent = nullptr;
 463   data_for_recursion.render_target = root_layer;
 464   data_for_recursion.clip_tree_parent = kUnclippedRootClipTreeNodeId;
 465   data_for_recursion.effect_tree_parent = kInvalidPropertyTreeNodeId;
 466   data_for_recursion.page_scale_layer = page_scale_layer;
 467   data_for_recursion.inner_viewport_scroll_layer = inner_viewport_scroll_layer;
 468   data_for_recursion.outer_viewport_scroll_layer = outer_viewport_scroll_layer;
 469   data_for_recursion.page_scale_factor = page_scale_factor;
 470   data_for_recursion.device_scale_factor = device_scale_factor;
 471   data_for_recursion.in_subtree_of_page_scale_layer = false;
 472   data_for_recursion.affected_by_inner_viewport_bounds_delta = false;
 473   data_for_recursion.affected_by_outer_viewport_bounds_delta = false;
 474   data_for_recursion.should_flatten = false;
 475   data_for_recursion.ancestor_clips_subtree = true;
 476   data_for_recursion.device_transform = &device_transform;
 477
 478   data_for_recursion.transform_tree->clear();
 479   data_for_recursion.clip_tree->clear();
 480   data_for_recursion.effect_tree->clear();
 481   data_for_recursion.sequence_number = property_trees->sequence_number;
 482
 483   ClipNode root_clip;
 484   root_clip.data.clip = viewport;
 485   root_clip.data.transform_id = kRootPropertyTreeNodeId;
 486   data_for_recursion.clip_tree_parent = data_for_recursion.clip_tree->Insert(
 487       root_clip, kUnclippedRootClipTreeNodeId);
 488   BuildPropertyTreesInternal(root_layer, data_for_recursion);
 489   property_trees->needs_rebuild = false;
 490
 491   // The transform tree is kept up-to-date as it is built, but the
 492   // combined_clips stored in the clip tree aren't computed during tree
 493   // building.
 494   property_trees->transform_tree.set_needs_update(false);
 495   property_trees->clip_tree.set_needs_update(true);
 496   property_trees->effect_tree.set_needs_update(false);
 497 }
 498
 499 void PropertyTreeBuilder::BuildPropertyTrees(
 500     Layer* root_layer,
 501     const Layer* page_scale_layer,
 502     const Layer* inner_viewport_scroll_layer,
 503     const Layer* outer_viewport_scroll_layer,
 504     float page_scale_factor,
 505     float device_scale_factor,
 506     const gfx::Rect& viewport,
 507     const gfx::Transform& device_transform,
 508     PropertyTrees* property_trees) {
 509   BuildPropertyTreesTopLevelInternal(
 510       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 511       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 512       viewport, device_transform, property_trees);
 513 }
 514
 515 void PropertyTreeBuilder::BuildPropertyTrees(
 516     LayerImpl* root_layer,
 517     const LayerImpl* page_scale_layer,
 518     const LayerImpl* inner_viewport_scroll_layer,
 519     const LayerImpl* outer_viewport_scroll_layer,
 520     float page_scale_factor,
 521     float device_scale_factor,
 522     const gfx::Rect& viewport,
 523     const gfx::Transform& device_transform,
 524     PropertyTrees* property_trees) {
 525   BuildPropertyTreesTopLevelInternal(
 526       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 527       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 528       viewport, device_transform, property_trees);
 529 }
 530
 531 }  // namespace cc