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   bool axis_aligned_with_respect_to_parent =
  83       data.transform_tree->Are2DAxisAligned(layer->transform_tree_index(),
  84                                             parent_transform_id);
  85
  86   return !axis_aligned_with_respect_to_parent;
  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   if (LayerClipsSubtree(layer))
 119     data_for_children->ancestor_clips_subtree = true;
 120
 121   if (has_unclipped_surface)
 122     parent_id = 0;
 123
 124   if (!RequiresClipNode(layer, data_from_ancestor, parent->data.transform_id,
 125                         data_for_children->ancestor_clips_subtree)) {
 126     // Unclipped surfaces reset the clip rect.
 127     data_for_children->clip_tree_parent = parent_id;
 128   } else {
 129     LayerType* transform_parent = data_for_children->transform_tree_parent;
 130     if (layer->position_constraint().is_fixed_position() &&
 131         !created_transform_node) {
 132       transform_parent = data_for_children->transform_fixed_parent;
 133     }
 134     ClipNode node;
 135     node.data.clip = gfx::RectF(
 136         gfx::PointF() + layer->offset_to_transform_parent(), layer->bounds());
 137     node.data.transform_id = transform_parent->transform_tree_index();
 138     node.data.target_id =
 139         data_for_children->render_target->transform_tree_index();
 140     node.owner_id = layer->id();
 141
 142     data_for_children->clip_tree_parent =
 143         data_for_children->clip_tree->Insert(node, parent_id);
 144   }
 145
 146   layer->SetClipTreeIndex(
 147       has_unclipped_surface ? 0 : data_for_children->clip_tree_parent);
 148
 149   layer->set_is_clipped(data_for_children->ancestor_clips_subtree);
 150
 151   // TODO(awoloszyn): Right now when we hit a node with a replica, we reset the
 152   // clip for all children since we may need to draw. We need to figure out a
 153   // better way, since we will need both the clipped and unclipped versions.
 154 }
 155
 156 template <typename LayerType>
 157 bool AddTransformNodeIfNeeded(
 158     const DataForRecursion<LayerType>& data_from_ancestor,
 159     LayerType* layer,
 160     DataForRecursion<LayerType>* data_for_children) {
 161   const bool is_root = !layer->parent();
 162   const bool is_page_scale_layer = layer == data_from_ancestor.page_scale_layer;
 163   const bool is_scrollable = layer->scrollable();
 164   const bool is_fixed = layer->position_constraint().is_fixed_position();
 165
 166   const bool has_significant_transform =
 167       !layer->transform().IsIdentityOr2DTranslation();
 168
 169   const bool has_potentially_animated_transform =
 170       layer->HasPotentiallyRunningTransformAnimation();
 171
 172   const bool has_surface = !!layer->render_surface();
 173
 174   bool requires_node = is_root || is_scrollable || has_significant_transform ||
 175                        has_potentially_animated_transform || has_surface ||
 176                        is_fixed || is_page_scale_layer;
 177
 178   LayerType* transform_parent = GetTransformParent(data_from_ancestor, layer);
 179   DCHECK_IMPLIES(!is_root, transform_parent);
 180
 181   int parent_index = 0;
 182   if (transform_parent)
 183     parent_index = transform_parent->transform_tree_index();
 184
 185   int source_index = parent_index;
 186
 187   gfx::Vector2dF source_offset;
 188   if (transform_parent) {
 189     if (layer->scroll_parent()) {
 190       LayerType* source = layer->parent();
 191       source_offset += source->offset_to_transform_parent();
 192       source_index = source->transform_tree_index();
 193     } else if (!is_fixed) {
 194       source_offset = transform_parent->offset_to_transform_parent();
 195     } else {
 196       source_offset = data_from_ancestor.transform_tree_parent
 197                           ->offset_to_transform_parent();
 198       source_index =
 199           data_from_ancestor.transform_tree_parent->transform_tree_index();
 200       source_offset += data_from_ancestor.scroll_compensation_adjustment;
 201     }
 202   }
 203
 204   if (layer->IsContainerForFixedPositionLayers() || is_root) {
 205     data_for_children->affected_by_inner_viewport_bounds_delta =
 206         layer == data_from_ancestor.inner_viewport_scroll_layer;
 207     data_for_children->affected_by_outer_viewport_bounds_delta =
 208         layer == data_from_ancestor.outer_viewport_scroll_layer;
 209     if (is_scrollable) {
 210       DCHECK(!is_root);
 211       DCHECK(layer->transform().IsIdentity());
 212       data_for_children->transform_fixed_parent = layer->parent();
 213     } else {
 214       data_for_children->transform_fixed_parent = layer;
 215     }
 216   }
 217   data_for_children->transform_tree_parent = layer;
 218
 219   if (layer->IsContainerForFixedPositionLayers() || is_fixed)
 220     data_for_children->scroll_compensation_adjustment = gfx::Vector2dF();
 221
 222   if (!requires_node) {
 223     data_for_children->should_flatten |= layer->should_flatten_transform();
 224     gfx::Vector2dF local_offset = layer->position().OffsetFromOrigin() +
 225                                   layer->transform().To2dTranslation();
 226     gfx::Vector2dF source_to_parent;
 227     if (source_index != parent_index) {
 228       gfx::Transform to_parent;
 229       data_from_ancestor.transform_tree->ComputeTransform(
 230           source_index, parent_index, &to_parent);
 231       source_to_parent = to_parent.To2dTranslation();
 232     }
 233     layer->set_offset_to_transform_parent(source_offset + source_to_parent +
 234                                           local_offset);
 235     layer->set_should_flatten_transform_from_property_tree(
 236         data_from_ancestor.should_flatten);
 237     layer->SetTransformTreeIndex(parent_index);
 238     return false;
 239   }
 240
 241   data_for_children->transform_tree->Insert(TransformNode(), parent_index);
 242
 243   TransformNode* node = data_for_children->transform_tree->back();
 244   layer->SetTransformTreeIndex(node->id);
 245
 246   node->data.scrolls = is_scrollable;
 247   node->data.flattens_inherited_transform = data_for_children->should_flatten;
 248
 249   // Surfaces inherently flatten transforms.
 250   data_for_children->should_flatten =
 251       layer->should_flatten_transform() || has_surface;
 252   node->data.target_id =
 253       data_from_ancestor.render_target->transform_tree_index();
 254   node->data.content_target_id =
 255       data_for_children->render_target->transform_tree_index();
 256   DCHECK_NE(node->data.target_id, -1);
 257   node->data.is_animated = has_potentially_animated_transform;
 258
 259   float post_local_scale_factor = 1.0f;
 260   if (is_root) {
 261     node->data.post_local = *data_from_ancestor.device_transform;
 262     post_local_scale_factor = data_from_ancestor.device_scale_factor;
 263   }
 264
 265   if (is_page_scale_layer)
 266     post_local_scale_factor *= data_from_ancestor.page_scale_factor;
 267
 268   if (has_surface && !is_root) {
 269     node->data.needs_sublayer_scale = true;
 270     node->data.layer_scale_factor = data_from_ancestor.device_scale_factor;
 271     if (data_from_ancestor.in_subtree_of_page_scale_layer)
 272       node->data.layer_scale_factor *= data_from_ancestor.page_scale_factor;
 273   }
 274
 275   node->data.source_node_id = source_index;
 276   if (is_root) {
 277     node->data.post_local.Scale(post_local_scale_factor,
 278                                 post_local_scale_factor);
 279     node->data.post_local.Translate(layer->position().x(),
 280                                     layer->position().y());
 281   } else {
 282     node->data.post_local_scale_factor = post_local_scale_factor;
 283     node->data.source_offset = source_offset;
 284     node->data.update_post_local_transform(layer->position(),
 285                                            layer->transform_origin());
 286   }
 287
 288   if (!layer->scroll_parent())
 289     node->data.scroll_offset = layer->CurrentScrollOffset();
 290
 291   if (is_fixed) {
 292     if (data_from_ancestor.affected_by_inner_viewport_bounds_delta) {
 293       node->data.affected_by_inner_viewport_bounds_delta_x =
 294           layer->position_constraint().is_fixed_to_right_edge();
 295       node->data.affected_by_inner_viewport_bounds_delta_y =
 296           layer->position_constraint().is_fixed_to_bottom_edge();
 297       if (node->data.affected_by_inner_viewport_bounds_delta_x ||
 298           node->data.affected_by_inner_viewport_bounds_delta_y) {
 299         data_for_children->transform_tree
 300             ->AddNodeAffectedByInnerViewportBoundsDelta(node->id);
 301       }
 302     } else if (data_from_ancestor.affected_by_outer_viewport_bounds_delta) {
 303       node->data.affected_by_outer_viewport_bounds_delta_x =
 304           layer->position_constraint().is_fixed_to_right_edge();
 305       node->data.affected_by_outer_viewport_bounds_delta_y =
 306           layer->position_constraint().is_fixed_to_bottom_edge();
 307       if (node->data.affected_by_outer_viewport_bounds_delta_x ||
 308           node->data.affected_by_outer_viewport_bounds_delta_y) {
 309         data_for_children->transform_tree
 310             ->AddNodeAffectedByOuterViewportBoundsDelta(node->id);
 311       }
 312     }
 313   }
 314
 315   node->data.local = layer->transform();
 316   node->data.update_pre_local_transform(layer->transform_origin());
 317
 318   node->data.needs_local_transform_update = true;
 319   data_from_ancestor.transform_tree->UpdateTransforms(node->id);
 320
 321   layer->set_offset_to_transform_parent(gfx::Vector2dF());
 322
 323   // Flattening (if needed) will be handled by |node|.
 324   layer->set_should_flatten_transform_from_property_tree(false);
 325
 326   data_for_children->scroll_compensation_adjustment +=
 327       layer->ScrollCompensationAdjustment() - node->data.scroll_snap;
 328
 329   node->owner_id = layer->id();
 330
 331   return true;
 332 }
 333
 334 bool IsAnimatingOpacity(Layer* layer) {
 335   return layer->HasPotentiallyRunningOpacityAnimation() ||
 336          layer->OpacityCanAnimateOnImplThread();
 337 }
 338
 339 bool IsAnimatingOpacity(LayerImpl* layer) {
 340   return layer->HasPotentiallyRunningOpacityAnimation();
 341 }
 342
 343 template <typename LayerType>
 344 void AddOpacityNodeIfNeeded(
 345     const DataForRecursion<LayerType>& data_from_ancestor,
 346     LayerType* layer,
 347     DataForRecursion<LayerType>* data_for_children) {
 348   const bool is_root = !layer->parent();
 349   const bool has_transparency = layer->opacity() != 1.f;
 350   const bool has_animated_opacity = IsAnimatingOpacity(layer);
 351   bool requires_node = is_root || has_transparency || has_animated_opacity;
 352
 353   int parent_id = data_from_ancestor.opacity_tree_parent;
 354
 355   if (!requires_node) {
 356     layer->SetOpacityTreeIndex(parent_id);
 357     data_for_children->opacity_tree_parent = parent_id;
 358     return;
 359   }
 360
 361   OpacityNode node;
 362   node.owner_id = layer->id();
 363   node.data.opacity = layer->opacity();
 364   node.data.screen_space_opacity = layer->opacity();
 365   if (!is_root)
 366     node.data.screen_space_opacity *=
 367         data_from_ancestor.opacity_tree->Node(parent_id)
 368             ->data.screen_space_opacity;
 369   data_for_children->opacity_tree_parent =
 370       data_for_children->opacity_tree->Insert(node, parent_id);
 371   layer->SetOpacityTreeIndex(data_for_children->opacity_tree_parent);
 372 }
 373
 374 template <typename LayerType>
 375 void BuildPropertyTreesInternal(
 376     LayerType* layer,
 377     const DataForRecursion<LayerType>& data_from_parent) {
 378   layer->set_property_tree_sequence_number(data_from_parent.sequence_number);
 379   DataForRecursion<LayerType> data_for_children(data_from_parent);
 380   if (layer->render_surface())
 381     data_for_children.render_target = layer;
 382
 383   bool created_transform_node =
 384       AddTransformNodeIfNeeded(data_from_parent, layer, &data_for_children);
 385   AddClipNodeIfNeeded(data_from_parent, layer, created_transform_node,
 386                       &data_for_children);
 387
 388   if (data_from_parent.opacity_tree)
 389     AddOpacityNodeIfNeeded(data_from_parent, layer, &data_for_children);
 390
 391   if (layer == data_from_parent.page_scale_layer)
 392     data_for_children.in_subtree_of_page_scale_layer = true;
 393
 394   for (size_t i = 0; i < layer->children().size(); ++i) {
 395     if (!layer->child_at(i)->scroll_parent()) {
 396       BuildPropertyTreesInternal(layer->child_at(i), data_for_children);
 397     } else {
 398       // The child should be included in its scroll parent's list of scroll
 399       // children.
 400       DCHECK(layer->child_at(i)->scroll_parent()->scroll_children()->count(
 401           layer->child_at(i)));
 402     }
 403   }
 404
 405   if (layer->scroll_children()) {
 406     for (LayerType* scroll_child : *layer->scroll_children()) {
 407       DCHECK_EQ(scroll_child->scroll_parent(), layer);
 408       BuildPropertyTreesInternal(scroll_child, data_for_children);
 409     }
 410   }
 411
 412   if (layer->has_replica())
 413     BuildPropertyTreesInternal(layer->replica_layer(), data_for_children);
 414 }
 415
 416 }  // namespace
 417
 418 template <typename LayerType>
 419 void BuildPropertyTreesTopLevelInternal(
 420     LayerType* root_layer,
 421     const LayerType* page_scale_layer,
 422     const LayerType* inner_viewport_scroll_layer,
 423     const LayerType* outer_viewport_scroll_layer,
 424     float page_scale_factor,
 425     float device_scale_factor,
 426     const gfx::Rect& viewport,
 427     const gfx::Transform& device_transform,
 428     PropertyTrees* property_trees) {
 429   if (!property_trees->needs_rebuild)
 430     return;
 431
 432   property_trees->sequence_number++;
 433
 434   DataForRecursion<LayerType> data_for_recursion;
 435   data_for_recursion.transform_tree = &property_trees->transform_tree;
 436   data_for_recursion.clip_tree = &property_trees->clip_tree;
 437   data_for_recursion.opacity_tree = &property_trees->opacity_tree;
 438   data_for_recursion.transform_tree_parent = nullptr;
 439   data_for_recursion.transform_fixed_parent = nullptr;
 440   data_for_recursion.render_target = root_layer;
 441   data_for_recursion.clip_tree_parent = 0;
 442   data_for_recursion.opacity_tree_parent = -1;
 443   data_for_recursion.page_scale_layer = page_scale_layer;
 444   data_for_recursion.inner_viewport_scroll_layer = inner_viewport_scroll_layer;
 445   data_for_recursion.outer_viewport_scroll_layer = outer_viewport_scroll_layer;
 446   data_for_recursion.page_scale_factor = page_scale_factor;
 447   data_for_recursion.device_scale_factor = device_scale_factor;
 448   data_for_recursion.in_subtree_of_page_scale_layer = false;
 449   data_for_recursion.affected_by_inner_viewport_bounds_delta = false;
 450   data_for_recursion.affected_by_outer_viewport_bounds_delta = false;
 451   data_for_recursion.should_flatten = false;
 452   data_for_recursion.ancestor_clips_subtree = true;
 453   data_for_recursion.device_transform = &device_transform;
 454
 455   data_for_recursion.transform_tree->clear();
 456   data_for_recursion.clip_tree->clear();
 457   data_for_recursion.opacity_tree->clear();
 458   data_for_recursion.sequence_number = property_trees->sequence_number;
 459
 460   ClipNode root_clip;
 461   root_clip.data.clip = viewport;
 462   root_clip.data.transform_id = 0;
 463   data_for_recursion.clip_tree_parent =
 464       data_for_recursion.clip_tree->Insert(root_clip, 0);
 465   BuildPropertyTreesInternal(root_layer, data_for_recursion);
 466   property_trees->needs_rebuild = false;
 467
 468   // The transform tree is kept up-to-date as it is built, but the
 469   // combined_clips stored in the clip tree aren't computed during tree
 470   // building.
 471   property_trees->transform_tree.set_needs_update(false);
 472   property_trees->clip_tree.set_needs_update(true);
 473   property_trees->opacity_tree.set_needs_update(false);
 474 }
 475
 476 void PropertyTreeBuilder::BuildPropertyTrees(
 477     Layer* root_layer,
 478     const Layer* page_scale_layer,
 479     const Layer* inner_viewport_scroll_layer,
 480     const Layer* outer_viewport_scroll_layer,
 481     float page_scale_factor,
 482     float device_scale_factor,
 483     const gfx::Rect& viewport,
 484     const gfx::Transform& device_transform,
 485     PropertyTrees* property_trees) {
 486   BuildPropertyTreesTopLevelInternal(
 487       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 488       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 489       viewport, device_transform, property_trees);
 490 }
 491
 492 void PropertyTreeBuilder::BuildPropertyTrees(
 493     LayerImpl* root_layer,
 494     const LayerImpl* page_scale_layer,
 495     const LayerImpl* inner_viewport_scroll_layer,
 496     const LayerImpl* outer_viewport_scroll_layer,
 497     float page_scale_factor,
 498     float device_scale_factor,
 499     const gfx::Rect& viewport,
 500     const gfx::Transform& device_transform,
 501     PropertyTrees* property_trees) {
 502   BuildPropertyTreesTopLevelInternal(
 503       root_layer, page_scale_layer, inner_viewport_scroll_layer,
 504       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
 505       viewport, device_transform, property_trees);
 506 }
 507
 508 }  // namespace cc