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