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   float page_scale_factor;
  35   float device_scale_factor;
  36   bool in_subtree_of_page_scale_layer;
  37   bool should_flatten;
  38   bool ancestor_clips_subtree;
  39   const gfx::Transform* device_transform;
  40   gfx::Vector2dF scroll_compensation_adjustment;
  41   int sequence_number;
  42 };
  43
  44 template <typename LayerType>
  45 static LayerType* GetTransformParent(const DataForRecursion<LayerType>& data,
  46                                      LayerType* layer) {
  47   return layer->position_constraint().is_fixed_position()
  48              ? data.transform_fixed_parent
  49              : data.transform_tree_parent;
  50 }
  51
  52 template <typename LayerType>
  53 static ClipNode* GetClipParent(const DataForRecursion<LayerType>& data,
  54                                LayerType* layer) {
  55   const bool inherits_clip = !layer->parent() || !layer->clip_parent();
  56   const int id = inherits_clip ? data.clip_tree_parent
  57                                : layer->clip_parent()->clip_tree_index();
  58   return data.clip_tree->Node(id);
  59 }
  60
  61 template <typename LayerType>
  62 static bool HasPotentiallyRunningAnimation(LayerType* layer,
  63                                            Animation::TargetProperty property) {
  64   if (Animation* animation =
  65           layer->layer_animation_controller()->GetAnimation(property)) {
  66     return !animation->is_finished();
  67   }
  68   return false;
  69 }
  70
  71 template <typename LayerType>
  72 static bool RequiresClipNode(LayerType* layer,
  73                              const DataForRecursion<LayerType>& data,
  74                              int parent_transform_id,
  75                              bool is_clipped) {
  76   const bool render_surface_applies_clip =
  77       layer->render_surface() && is_clipped;
  78   const bool render_surface_may_grow_due_to_clip_children =
  79       layer->render_surface() && layer->num_unclipped_descendants() > 0;
  80
  81   if (!layer->parent() || layer->masks_to_bounds() || layer->mask_layer() ||
  82       render_surface_may_grow_due_to_clip_children)
  83     return true;
  84
  85   if (!render_surface_applies_clip)
  86     return false;
  87
  88   bool axis_aligned_with_respect_to_parent =
  89       data.transform_tree->Are2DAxisAligned(layer->transform_tree_index(),
  90                                             parent_transform_id);
  91
  92   return !axis_aligned_with_respect_to_parent;
  93 }
  94
  95 template <typename LayerType>
  96 static bool LayerClipsSubtree(LayerType* layer) {
  97   return layer->masks_to_bounds() || layer->mask_layer();
  98 }
  99
 100 template <typename LayerType>
 101 void AddClipNodeIfNeeded(const DataForRecursion<LayerType>& data_from_ancestor,
 102                          LayerType* layer,
 103                          bool created_transform_node,
 104                          DataForRecursion<LayerType>* data_for_children) {
 105   ClipNode* parent = GetClipParent(data_from_ancestor, layer);
 106   int parent_id = parent->id;
 107
 108   bool ancestor_clips_subtree =
 109       data_from_ancestor.ancestor_clips_subtree || layer->clip_parent();
 110
 111   data_for_children->ancestor_clips_subtree = false;
 112   bool has_unclipped_surface = false;
 113
 114   if (layer->has_render_surface()) {
 115     if (ancestor_clips_subtree && layer->num_unclipped_descendants() > 0)
 116       data_for_children->ancestor_clips_subtree = true;
 117     else if (!ancestor_clips_subtree && !layer->num_unclipped_descendants())
 118       has_unclipped_surface = true;
 119   } else {
 120     data_for_children->ancestor_clips_subtree = ancestor_clips_subtree;
 121   }
 122
 123   if (LayerClipsSubtree(layer))
 124     data_for_children->ancestor_clips_subtree = true;
 125
 126   if (has_unclipped_surface)
 127     parent_id = 0;
 128
 129   if (!RequiresClipNode(layer, data_from_ancestor, parent->data.transform_id,
 130                         data_for_children->ancestor_clips_subtree)) {
 131     // Unclipped surfaces reset the clip rect.
 132     data_for_children->clip_tree_parent = parent_id;
 133   } else if (layer->parent()) {
 134     // Note the root clip gets handled elsewhere.
 135     LayerType* transform_parent = data_for_children->transform_tree_parent;
 136     if (layer->position_constraint().is_fixed_position() &&
 137         !created_transform_node) {
 138       transform_parent = data_for_children->transform_fixed_parent;
 139     }
 140     ClipNode node;
 141     node.data.clip = gfx::RectF(
 142         gfx::PointF() + layer->offset_to_transform_parent(), layer->bounds());
 143     node.data.transform_id = transform_parent->transform_tree_index();
 144     node.data.target_id =
 145         data_for_children->render_target->transform_tree_index();
 146     node.owner_id = layer->id();
 147
 148     data_for_children->clip_tree_parent =
 149         data_for_children->clip_tree->Insert(node, parent_id);
 150   }
 151
 152   layer->SetClipTreeIndex(
 153       has_unclipped_surface ? 0 : data_for_children->clip_tree_parent);
 154
 155   // TODO(awoloszyn): Right now when we hit a node with a replica, we reset the
 156   // clip for all children since we may need to draw. We need to figure out a
 157   // better way, since we will need both the clipped and unclipped versions.
 158 }
 159
 160 template <typename LayerType>
 161 bool AddTransformNodeIfNeeded(
 162     const DataForRecursion<LayerType>& data_from_ancestor,
 163     LayerType* layer,
 164     DataForRecursion<LayerType>* data_for_children) {
 165   const bool is_root = !layer->parent();
 166   const bool is_page_scale_layer = layer == data_from_ancestor.page_scale_layer;
 167   const bool is_scrollable = layer->scrollable();
 168   const bool is_fixed = layer->position_constraint().is_fixed_position();
 169
 170   const bool has_significant_transform =
 171       !layer->transform().IsIdentityOr2DTranslation();
 172
 173   const bool has_potentially_animated_transform =
 174       HasPotentiallyRunningAnimation(layer, Animation::TRANSFORM);
 175
 176   const bool has_animated_transform =
 177       layer->layer_animation_controller()->IsAnimatingProperty(
 178           Animation::TRANSFORM);
 179
 180   const bool has_surface = !!layer->render_surface();
 181
 182   bool requires_node = is_root || is_scrollable || has_significant_transform ||
 183                        has_potentially_animated_transform || has_surface ||
 184                        is_fixed || is_page_scale_layer;
 185
 186   LayerType* transform_parent = GetTransformParent(data_from_ancestor, layer);
 187
 188   int parent_index = 0;
 189   if (transform_parent)
 190     parent_index = transform_parent->transform_tree_index();
 191
 192   int source_index = parent_index;
 193
 194   gfx::Vector2dF source_offset;
 195   if (transform_parent) {
 196     if (layer->scroll_parent()) {
 197       LayerType* source = layer->parent();
 198       source_offset += source->offset_to_transform_parent();
 199       source_index = source->transform_tree_index();
 200     } else if (!is_fixed) {
 201       source_offset = transform_parent->offset_to_transform_parent();
 202     } else {
 203       if (data_from_ancestor.transform_tree_parent !=
 204           data_from_ancestor.transform_fixed_parent) {
 205         source_offset = data_from_ancestor.transform_tree_parent
 206                             ->offset_to_transform_parent();
 207         source_index =
 208             data_from_ancestor.transform_tree_parent->transform_tree_index();
 209       }
 210       source_offset += data_from_ancestor.scroll_compensation_adjustment;
 211     }
 212   }
 213
 214   if (layer->IsContainerForFixedPositionLayers() || is_root) {
 215     DCHECK(!is_scrollable || layer->transform().IsIdentity());
 216     data_for_children->transform_fixed_parent = layer;
 217   }
 218   data_for_children->transform_tree_parent = layer;
 219
 220   if (layer->IsContainerForFixedPositionLayers() || is_fixed)
 221     data_for_children->scroll_compensation_adjustment = gfx::Vector2dF();
 222
 223   if (!requires_node) {
 224     data_for_children->should_flatten |= layer->should_flatten_transform();
 225     gfx::Vector2dF local_offset = layer->position().OffsetFromOrigin() +
 226                                   layer->transform().To2dTranslation();
 227     gfx::Vector2dF source_to_parent;
 228     if (source_index != parent_index) {
 229       gfx::Transform to_parent;
 230       data_from_ancestor.transform_tree->ComputeTransform(
 231           source_index, parent_index, &to_parent);
 232       source_to_parent = to_parent.To2dTranslation();
 233     }
 234     layer->set_offset_to_transform_parent(source_offset + source_to_parent +
 235                                           local_offset);
 236     layer->set_should_flatten_transform_from_property_tree(
 237         data_from_ancestor.should_flatten);
 238     layer->SetTransformTreeIndex(parent_index);
 239     return false;
 240   }
 241
 242   data_for_children->transform_tree->Insert(TransformNode(), parent_index);
 243
 244   TransformNode* node = data_for_children->transform_tree->back();
 245   layer->SetTransformTreeIndex(node->id);
 246
 247   node->data.scrolls = is_scrollable;
 248   node->data.flattens_inherited_transform = data_for_children->should_flatten;
 249
 250   // Surfaces inherently flatten transforms.
 251   data_for_children->should_flatten =
 252       layer->should_flatten_transform() || has_surface;
 253   node->data.target_id =
 254       data_from_ancestor.render_target->transform_tree_index();
 255   node->data.content_target_id =
 256       data_for_children->render_target->transform_tree_index();
 257   DCHECK_NE(node->data.target_id, -1);
 258   node->data.is_animated = has_animated_transform;
 259
 260   float post_local_scale_factor = 1.0f;
 261   if (is_root) {
 262     node->data.post_local = *data_from_ancestor.device_transform;
 263     post_local_scale_factor = data_from_ancestor.device_scale_factor;
 264   }
 265
 266   if (is_page_scale_layer)
 267     post_local_scale_factor *= data_from_ancestor.page_scale_factor;
 268
 269   if (has_surface && !is_root) {
 270     node->data.needs_sublayer_scale = true;
 271     node->data.layer_scale_factor = data_from_ancestor.device_scale_factor;
 272     if (data_from_ancestor.in_subtree_of_page_scale_layer)
 273       node->data.layer_scale_factor *= data_from_ancestor.page_scale_factor;
 274   }
 275
 276   node->data.source_node_id = source_index;
 277   if (is_root) {
 278     node->data.post_local.Scale(post_local_scale_factor,
 279                                 post_local_scale_factor);
 280   } else {
 281     node->data.post_local_scale_factor = post_local_scale_factor;
 282     node->data.source_offset = source_offset;
 283     node->data.update_post_local_transform(layer->position(),
 284                                            layer->transform_origin());
 285   }
 286
 287   if (!layer->scroll_parent())
 288     node->data.scroll_offset = layer->CurrentScrollOffset();
 289
 290   node->data.local = layer->transform();
 291   node->data.update_pre_local_transform(layer->transform_origin());
 292
 293   node->data.needs_local_transform_update = true;
 294   data_from_ancestor.transform_tree->UpdateTransforms(node->id);
 295
 296   layer->set_offset_to_transform_parent(gfx::Vector2dF());
 297
 298   // Flattening (if needed) will be handled by |node|.
 299   layer->set_should_flatten_transform_from_property_tree(false);
 300
 301   data_for_children->scroll_compensation_adjustment +=
 302       layer->ScrollCompensationAdjustment() - node->data.scroll_snap;
 303
 304   node->owner_id = layer->id();
 305
 306   return true;
 307 }
 308
 309 bool IsAnimatingOpacity(Layer* layer) {
 310   return HasPotentiallyRunningAnimation(layer, Animation::OPACITY) ||
 311          layer->OpacityCanAnimateOnImplThread();
 312 }
 313
 314 bool IsAnimatingOpacity(LayerImpl* layer) {
 315   return HasPotentiallyRunningAnimation(layer, Animation::OPACITY);
 316 }
 317
 318 template <typename LayerType>
 319 void AddOpacityNodeIfNeeded(
 320     const DataForRecursion<LayerType>& data_from_ancestor,
 321     LayerType* layer,
 322     DataForRecursion<LayerType>* data_for_children) {
 323   const bool is_root = !layer->parent();
 324   const bool has_transparency = layer->opacity() != 1.f;
 325   const bool has_animated_opacity = IsAnimatingOpacity(layer);
 326   bool requires_node = is_root || has_transparency || has_animated_opacity;
 327
 328   int parent_id = data_from_ancestor.opacity_tree_parent;
 329
 330   if (!requires_node) {
 331     layer->SetOpacityTreeIndex(parent_id);
 332     data_for_children->opacity_tree_parent = parent_id;
 333     return;
 334   }
 335
 336   OpacityNode node;
 337   node.owner_id = layer->id();
 338   node.data = layer->opacity();
 339   data_for_children->opacity_tree_parent =
 340       data_for_children->opacity_tree->Insert(node, parent_id);
 341   layer->SetOpacityTreeIndex(data_for_children->opacity_tree_parent);
 342 }
 343
 344 template <typename LayerType>
 345 void BuildPropertyTreesInternal(
 346     LayerType* layer,
 347     const DataForRecursion<LayerType>& data_from_parent) {
 348   layer->set_property_tree_sequence_number(data_from_parent.sequence_number);
 349   DataForRecursion<LayerType> data_for_children(data_from_parent);
 350   if (layer->render_surface())
 351     data_for_children.render_target = layer;
 352
 353   bool created_transform_node =
 354       AddTransformNodeIfNeeded(data_from_parent, layer, &data_for_children);
 355   AddClipNodeIfNeeded(data_from_parent, layer, created_transform_node,
 356                       &data_for_children);
 357
 358   if (data_from_parent.opacity_tree)
 359     AddOpacityNodeIfNeeded(data_from_parent, layer, &data_for_children);
 360
 361   if (layer == data_from_parent.page_scale_layer)
 362     data_for_children.in_subtree_of_page_scale_layer = true;
 363
 364   for (size_t i = 0; i < layer->children().size(); ++i) {
 365     if (!layer->child_at(i)->scroll_parent())
 366       BuildPropertyTreesInternal(layer->child_at(i), data_for_children);
 367   }
 368
 369   if (layer->scroll_children()) {
 370     for (LayerType* scroll_child : *layer->scroll_children()) {
 371       BuildPropertyTreesInternal(scroll_child, data_for_children);
 372     }
 373   }
 374
 375   if (layer->has_replica())
 376     BuildPropertyTreesInternal(layer->replica_layer(), data_for_children);
 377 }
 378
 379 }  // namespace
 380
 381 template <typename LayerType>
 382 void BuildPropertyTreesTopLevelInternal(LayerType* root_layer,
 383                                         const LayerType* page_scale_layer,
 384                                         float page_scale_factor,
 385                                         float device_scale_factor,
 386                                         const gfx::Rect& viewport,
 387                                         const gfx::Transform& device_transform,
 388                                         PropertyTrees* property_trees) {
 389   property_trees->sequence_number++;
 390
 391   DataForRecursion<LayerType> data_for_recursion;
 392   data_for_recursion.transform_tree = &property_trees->transform_tree;
 393   data_for_recursion.clip_tree = &property_trees->clip_tree;
 394   data_for_recursion.opacity_tree = &property_trees->opacity_tree;
 395   data_for_recursion.transform_tree_parent = nullptr;
 396   data_for_recursion.transform_fixed_parent = nullptr;
 397   data_for_recursion.render_target = root_layer;
 398   data_for_recursion.clip_tree_parent = 0;
 399   data_for_recursion.opacity_tree_parent = -1;
 400   data_for_recursion.page_scale_layer = page_scale_layer;
 401   data_for_recursion.page_scale_factor = page_scale_factor;
 402   data_for_recursion.device_scale_factor = device_scale_factor;
 403   data_for_recursion.in_subtree_of_page_scale_layer = false;
 404   data_for_recursion.should_flatten = false;
 405   data_for_recursion.ancestor_clips_subtree = true;
 406   data_for_recursion.device_transform = &device_transform;
 407
 408   data_for_recursion.transform_tree->clear();
 409   data_for_recursion.clip_tree->clear();
 410   data_for_recursion.opacity_tree->clear();
 411   data_for_recursion.sequence_number = property_trees->sequence_number;
 412
 413   ClipNode root_clip;
 414   root_clip.data.clip = viewport;
 415   root_clip.data.transform_id = 0;
 416   data_for_recursion.clip_tree_parent =
 417       data_for_recursion.clip_tree->Insert(root_clip, 0);
 418   BuildPropertyTreesInternal(root_layer, data_for_recursion);
 419   property_trees->needs_rebuild = false;
 420
 421   // The transform tree is kept up-to-date as it is built, but the
 422   // combined_clips stored in the clip tree aren't computed during tree
 423   // building.
 424   property_trees->transform_tree.set_needs_update(false);
 425   property_trees->clip_tree.set_needs_update(true);
 426 }
 427
 428 void PropertyTreeBuilder::BuildPropertyTrees(
 429     Layer* root_layer,
 430     const Layer* page_scale_layer,
 431     float page_scale_factor,
 432     float device_scale_factor,
 433     const gfx::Rect& viewport,
 434     const gfx::Transform& device_transform,
 435     PropertyTrees* property_trees) {
 436   // TODO(enne): hoist this out of here
 437   if (!property_trees->needs_rebuild)
 438     return;
 439
 440   BuildPropertyTreesTopLevelInternal(
 441       root_layer, page_scale_layer, page_scale_factor, device_scale_factor,
 442       viewport, device_transform, property_trees);
 443 }
 444
 445 void PropertyTreeBuilder::BuildPropertyTrees(
 446     LayerImpl* root_layer,
 447     const LayerImpl* page_scale_layer,
 448     float page_scale_factor,
 449     float device_scale_factor,
 450     const gfx::Rect& viewport,
 451     const gfx::Transform& device_transform,
 452     PropertyTrees* property_trees) {
 453   BuildPropertyTreesTopLevelInternal(
 454       root_layer, page_scale_layer, page_scale_factor, device_scale_factor,
 455       viewport, device_transform, property_trees);
 456 }
 457
 458 }  // namespace cc