cc/trees/property_tree.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 <set>
   6 #include <vector>
   7
   8 #include "base/logging.h"
   9 #include "cc/base/math_util.h"
  10 #include "cc/trees/property_tree.h"
  11
  12 namespace cc {
  13
  14 template <typename T>
  15 PropertyTree<T>::PropertyTree()
  16     : needs_update_(false) {
  17   nodes_.push_back(T());
  18   back()->id = 0;
  19   back()->parent_id = -1;
  20 }
  21
  22 template <typename T>
  23 PropertyTree<T>::~PropertyTree() {
  24 }
  25
  26 TransformTree::TransformTree() : source_to_parent_updates_allowed_(true) {
  27 }
  28
  29 TransformTree::~TransformTree() {
  30 }
  31
  32 template <typename T>
  33 int PropertyTree<T>::Insert(const T& tree_node, int parent_id) {
  34   DCHECK_GT(nodes_.size(), 0u);
  35   nodes_.push_back(tree_node);
  36   T& node = nodes_.back();
  37   node.parent_id = parent_id;
  38   node.id = static_cast<int>(nodes_.size()) - 1;
  39   return node.id;
  40 }
  41
  42 template <typename T>
  43 void PropertyTree<T>::clear() {
  44   nodes_.clear();
  45   nodes_.push_back(T());
  46   back()->id = 0;
  47   back()->parent_id = -1;
  48 }
  49
  50 template class PropertyTree<TransformNode>;
  51 template class PropertyTree<ClipNode>;
  52 template class PropertyTree<OpacityNode>;
  53
  54 TransformNodeData::TransformNodeData()
  55     : target_id(-1),
  56       content_target_id(-1),
  57       source_node_id(-1),
  58       needs_local_transform_update(true),
  59       is_invertible(true),
  60       ancestors_are_invertible(true),
  61       is_animated(false),
  62       to_screen_is_animated(false),
  63       flattens_inherited_transform(false),
  64       node_and_ancestors_are_flat(true),
  65       node_and_ancestors_have_only_integer_translation(true),
  66       scrolls(false),
  67       needs_sublayer_scale(false),
  68       affected_by_inner_viewport_bounds_delta_x(false),
  69       affected_by_inner_viewport_bounds_delta_y(false),
  70       affected_by_outer_viewport_bounds_delta_x(false),
  71       affected_by_outer_viewport_bounds_delta_y(false),
  72       layer_scale_factor(1.0f),
  73       post_local_scale_factor(1.0f) {
  74 }
  75
  76 TransformNodeData::~TransformNodeData() {
  77 }
  78
  79 void TransformNodeData::update_pre_local_transform(
  80     const gfx::Point3F& transform_origin) {
  81   pre_local.MakeIdentity();
  82   pre_local.Translate3d(-transform_origin.x(), -transform_origin.y(),
  83                         -transform_origin.z());
  84 }
  85
  86 void TransformNodeData::update_post_local_transform(
  87     const gfx::PointF& position,
  88     const gfx::Point3F& transform_origin) {
  89   post_local.MakeIdentity();
  90   post_local.Scale(post_local_scale_factor, post_local_scale_factor);
  91   post_local.Translate3d(
  92       position.x() + source_offset.x() + transform_origin.x(),
  93       position.y() + source_offset.y() + transform_origin.y(),
  94       transform_origin.z());
  95 }
  96
  97 ClipNodeData::ClipNodeData()
  98     : transform_id(-1),
  99       target_id(-1),
 100       inherit_parent_target_space_clip(false) {}
 101
 102 OpacityNodeData::OpacityNodeData() : opacity(1.f), screen_space_opacity(1.f) {
 103 }
 104
 105 void TransformTree::clear() {
 106   PropertyTree<TransformNode>::clear();
 107
 108   nodes_affected_by_inner_viewport_bounds_delta_.clear();
 109   nodes_affected_by_outer_viewport_bounds_delta_.clear();
 110 }
 111
 112 bool TransformTree::ComputeTransform(int source_id,
 113                                      int dest_id,
 114                                      gfx::Transform* transform) const {
 115   transform->MakeIdentity();
 116
 117   if (source_id == dest_id)
 118     return true;
 119
 120   if (source_id > dest_id) {
 121     return CombineTransformsBetween(source_id, dest_id, transform);
 122   }
 123
 124   return CombineInversesBetween(source_id, dest_id, transform);
 125 }
 126
 127 bool TransformTree::ComputeTransformWithDestinationSublayerScale(
 128     int source_id,
 129     int dest_id,
 130     gfx::Transform* transform) const {
 131   bool success = ComputeTransform(source_id, dest_id, transform);
 132
 133   const TransformNode* dest_node = Node(dest_id);
 134   if (!dest_node->data.needs_sublayer_scale)
 135     return success;
 136
 137   transform->matrix().postScale(dest_node->data.sublayer_scale.x(),
 138                                 dest_node->data.sublayer_scale.y(), 1.f);
 139   return success;
 140 }
 141
 142 bool TransformTree::ComputeTransformWithSourceSublayerScale(
 143     int source_id,
 144     int dest_id,
 145     gfx::Transform* transform) const {
 146   bool success = ComputeTransform(source_id, dest_id, transform);
 147
 148   const TransformNode* source_node = Node(source_id);
 149   if (!source_node->data.needs_sublayer_scale)
 150     return success;
 151
 152   if (source_node->data.sublayer_scale.x() == 0 ||
 153       source_node->data.sublayer_scale.y() == 0)
 154     return false;
 155
 156   transform->Scale(1.f / source_node->data.sublayer_scale.x(),
 157                    1.f / source_node->data.sublayer_scale.y());
 158   return success;
 159 }
 160
 161 bool TransformTree::Are2DAxisAligned(int source_id, int dest_id) const {
 162   gfx::Transform transform;
 163   return ComputeTransform(source_id, dest_id, &transform) &&
 164          transform.Preserves2dAxisAlignment();
 165 }
 166
 167 bool TransformTree::NeedsSourceToParentUpdate(TransformNode* node) {
 168   return (source_to_parent_updates_allowed() &&
 169           node->parent_id != node->data.source_node_id);
 170 }
 171
 172 void TransformTree::UpdateTransforms(int id) {
 173   TransformNode* node = Node(id);
 174   TransformNode* parent_node = parent(node);
 175   TransformNode* target_node = Node(node->data.target_id);
 176   if (node->data.needs_local_transform_update ||
 177       NeedsSourceToParentUpdate(node))
 178     UpdateLocalTransform(node);
 179   UpdateScreenSpaceTransform(node, parent_node, target_node);
 180   UpdateSublayerScale(node);
 181   UpdateTargetSpaceTransform(node, target_node);
 182   UpdateIsAnimated(node, parent_node);
 183   UpdateSnapping(node);
 184   UpdateNodeAndAncestorsHaveIntegerTranslations(node, parent_node);
 185 }
 186
 187 bool TransformTree::IsDescendant(int desc_id, int source_id) const {
 188   while (desc_id != source_id) {
 189     if (desc_id < 0)
 190       return false;
 191     desc_id = Node(desc_id)->parent_id;
 192   }
 193   return true;
 194 }
 195
 196 bool TransformTree::CombineTransformsBetween(int source_id,
 197                                              int dest_id,
 198                                              gfx::Transform* transform) const {
 199   DCHECK(source_id > dest_id);
 200   const TransformNode* current = Node(source_id);
 201   const TransformNode* dest = Node(dest_id);
 202   // Combine transforms to and from the screen when possible. Since flattening
 203   // is a non-linear operation, we cannot use this approach when there is
 204   // non-trivial flattening between the source and destination nodes. For
 205   // example, consider the tree R->A->B->C, where B flattens its inherited
 206   // transform, and A has a non-flat transform. Suppose C is the source and A is
 207   // the destination. The expected result is C * B. But C's to_screen
 208   // transform is C * B * flattened(A * R), and A's from_screen transform is
 209   // R^{-1} * A^{-1}. If at least one of A and R isn't flat, the inverse of
 210   // flattened(A * R) won't be R^{-1} * A{-1}, so multiplying C's to_screen and
 211   // A's from_screen will not produce the correct result.
 212   if (!dest || (dest->data.ancestors_are_invertible &&
 213                 dest->data.node_and_ancestors_are_flat)) {
 214     transform->ConcatTransform(current->data.to_screen);
 215     if (dest)
 216       transform->ConcatTransform(dest->data.from_screen);
 217     return true;
 218   }
 219
 220   // Flattening is defined in a way that requires it to be applied while
 221   // traversing downward in the tree. We first identify nodes that are on the
 222   // path from the source to the destination (this is traversing upward), and
 223   // then we visit these nodes in reverse order, flattening as needed. We
 224   // early-out if we get to a node whose target node is the destination, since
 225   // we can then re-use the target space transform stored at that node. However,
 226   // we cannot re-use a stored target space transform if the destination has a
 227   // zero sublayer scale, since stored target space transforms have sublayer
 228   // scale baked in, but we need to compute an unscaled transform.
 229   std::vector<int> source_to_destination;
 230   source_to_destination.push_back(current->id);
 231   current = parent(current);
 232   bool destination_has_non_zero_sublayer_scale =
 233       dest->data.sublayer_scale.x() != 0.f &&
 234       dest->data.sublayer_scale.y() != 0.f;
 235   DCHECK(destination_has_non_zero_sublayer_scale ||
 236          !dest->data.ancestors_are_invertible);
 237   for (; current && current->id > dest_id; current = parent(current)) {
 238     if (destination_has_non_zero_sublayer_scale &&
 239         current->data.target_id == dest_id &&
 240         current->data.content_target_id == dest_id)
 241       break;
 242     source_to_destination.push_back(current->id);
 243   }
 244
 245   gfx::Transform combined_transform;
 246   if (current->id > dest_id) {
 247     combined_transform = current->data.to_target;
 248     // The stored target space transform has sublayer scale baked in, but we
 249     // need the unscaled transform.
 250     combined_transform.Scale(1.0f / dest->data.sublayer_scale.x(),
 251                              1.0f / dest->data.sublayer_scale.y());
 252   } else if (current->id < dest_id) {
 253     // We have reached the lowest common ancestor of the source and destination
 254     // nodes. This case can occur when we are transforming between a node
 255     // corresponding to a fixed-position layer (or its descendant) and the node
 256     // corresponding to the layer's render target. For example, consider the
 257     // layer tree R->T->S->F where F is fixed-position, S owns a render surface,
 258     // and T has a significant transform. This will yield the following
 259     // transform tree:
 260     //    R
 261     //    |
 262     //    T
 263     //   /|
 264     //  S F
 265     // In this example, T will have id 2, S will have id 3, and F will have id
 266     // 4. When walking up the ancestor chain from F, the first node with a
 267     // smaller id than S will be T, the lowest common ancestor of these nodes.
 268     // We compute the transform from T to S here, and then from F to T in the
 269     // loop below.
 270     DCHECK(IsDescendant(dest_id, current->id));
 271     CombineInversesBetween(current->id, dest_id, &combined_transform);
 272     DCHECK(combined_transform.IsApproximatelyIdentityOrTranslation(
 273         SkDoubleToMScalar(1e-4)));
 274   }
 275
 276   size_t source_to_destination_size = source_to_destination.size();
 277   for (size_t i = 0; i < source_to_destination_size; ++i) {
 278     size_t index = source_to_destination_size - 1 - i;
 279     const TransformNode* node = Node(source_to_destination[index]);
 280     if (node->data.flattens_inherited_transform)
 281       combined_transform.FlattenTo2d();
 282     combined_transform.PreconcatTransform(node->data.to_parent);
 283   }
 284
 285   transform->ConcatTransform(combined_transform);
 286   return true;
 287 }
 288
 289 bool TransformTree::CombineInversesBetween(int source_id,
 290                                            int dest_id,
 291                                            gfx::Transform* transform) const {
 292   DCHECK(source_id < dest_id);
 293   const TransformNode* current = Node(dest_id);
 294   const TransformNode* dest = Node(source_id);
 295   // Just as in CombineTransformsBetween, we can use screen space transforms in
 296   // this computation only when there isn't any non-trivial flattening
 297   // involved.
 298   if (current->data.ancestors_are_invertible &&
 299       current->data.node_and_ancestors_are_flat) {
 300     transform->PreconcatTransform(current->data.from_screen);
 301     if (dest)
 302       transform->PreconcatTransform(dest->data.to_screen);
 303     return true;
 304   }
 305
 306   // Inverting a flattening is not equivalent to flattening an inverse. This
 307   // means we cannot, for example, use the inverse of each node's to_parent
 308   // transform, flattening where needed. Instead, we must compute the transform
 309   // from the destination to the source, with flattening, and then invert the
 310   // result.
 311   gfx::Transform dest_to_source;
 312   CombineTransformsBetween(dest_id, source_id, &dest_to_source);
 313   gfx::Transform source_to_dest;
 314   bool all_are_invertible = dest_to_source.GetInverse(&source_to_dest);
 315   transform->PreconcatTransform(source_to_dest);
 316   return all_are_invertible;
 317 }
 318
 319 void TransformTree::UpdateLocalTransform(TransformNode* node) {
 320   gfx::Transform transform = node->data.post_local;
 321   if (NeedsSourceToParentUpdate(node)) {
 322     gfx::Transform to_parent;
 323     ComputeTransform(node->data.source_node_id, node->parent_id, &to_parent);
 324     node->data.source_to_parent = to_parent.To2dTranslation();
 325   }
 326
 327   gfx::Vector2dF fixed_position_adjustment;
 328   if (node->data.affected_by_inner_viewport_bounds_delta_x)
 329     fixed_position_adjustment.set_x(inner_viewport_bounds_delta_.x());
 330   else if (node->data.affected_by_outer_viewport_bounds_delta_x)
 331     fixed_position_adjustment.set_x(outer_viewport_bounds_delta_.x());
 332
 333   if (node->data.affected_by_inner_viewport_bounds_delta_y)
 334     fixed_position_adjustment.set_y(inner_viewport_bounds_delta_.y());
 335   else if (node->data.affected_by_outer_viewport_bounds_delta_y)
 336     fixed_position_adjustment.set_y(outer_viewport_bounds_delta_.y());
 337
 338   transform.Translate(
 339       node->data.source_to_parent.x() - node->data.scroll_offset.x() +
 340           fixed_position_adjustment.x(),
 341       node->data.source_to_parent.y() - node->data.scroll_offset.y() +
 342           fixed_position_adjustment.y());
 343   transform.PreconcatTransform(node->data.local);
 344   transform.PreconcatTransform(node->data.pre_local);
 345   node->data.set_to_parent(transform);
 346   node->data.needs_local_transform_update = false;
 347 }
 348
 349 void TransformTree::UpdateScreenSpaceTransform(TransformNode* node,
 350                                                TransformNode* parent_node,
 351                                                TransformNode* target_node) {
 352   if (!parent_node) {
 353     node->data.to_screen = node->data.to_parent;
 354     node->data.ancestors_are_invertible = true;
 355     node->data.to_screen_is_animated = false;
 356     node->data.node_and_ancestors_are_flat = node->data.to_parent.IsFlat();
 357   } else {
 358     node->data.to_screen = parent_node->data.to_screen;
 359     if (node->data.flattens_inherited_transform)
 360       node->data.to_screen.FlattenTo2d();
 361     node->data.to_screen.PreconcatTransform(node->data.to_parent);
 362     node->data.ancestors_are_invertible =
 363         parent_node->data.ancestors_are_invertible;
 364     node->data.node_and_ancestors_are_flat =
 365         parent_node->data.node_and_ancestors_are_flat &&
 366         node->data.to_parent.IsFlat();
 367   }
 368
 369   if (!node->data.to_screen.GetInverse(&node->data.from_screen))
 370     node->data.ancestors_are_invertible = false;
 371 }
 372
 373 void TransformTree::UpdateSublayerScale(TransformNode* node) {
 374   // The sublayer scale depends on the screen space transform, so update it too.
 375   node->data.sublayer_scale =
 376       node->data.needs_sublayer_scale
 377           ? MathUtil::ComputeTransform2dScaleComponents(
 378                 node->data.to_screen, node->data.layer_scale_factor)
 379           : gfx::Vector2dF(1.0f, 1.0f);
 380 }
 381
 382 void TransformTree::UpdateTargetSpaceTransform(TransformNode* node,
 383                                                TransformNode* target_node) {
 384   if (node->data.needs_sublayer_scale) {
 385     node->data.to_target.MakeIdentity();
 386     node->data.to_target.Scale(node->data.sublayer_scale.x(),
 387                                node->data.sublayer_scale.y());
 388   } else {
 389     const bool target_is_root_surface = target_node->id == 1;
 390     // In order to include the root transform for the root surface, we walk up
 391     // to the root of the transform tree in ComputeTransform.
 392     int target_id = target_is_root_surface ? 0 : target_node->id;
 393     ComputeTransformWithDestinationSublayerScale(node->id, target_id,
 394                                                  &node->data.to_target);
 395   }
 396
 397   if (!node->data.to_target.GetInverse(&node->data.from_target))
 398     node->data.ancestors_are_invertible = false;
 399 }
 400
 401 void TransformTree::UpdateIsAnimated(TransformNode* node,
 402                                      TransformNode* parent_node) {
 403   if (parent_node) {
 404     node->data.to_screen_is_animated =
 405         node->data.is_animated || parent_node->data.to_screen_is_animated;
 406   }
 407 }
 408
 409 void TransformTree::UpdateSnapping(TransformNode* node) {
 410   if (!node->data.scrolls || node->data.to_screen_is_animated ||
 411       !node->data.to_target.IsScaleOrTranslation()) {
 412     return;
 413   }
 414
 415   // Scroll snapping must be done in target space (the pixels we care about).
 416   // This means we effectively snap the target space transform. If TT is the
 417   // target space transform and TT' is TT with its translation components
 418   // rounded, then what we're after is the scroll delta X, where TT * X = TT'.
 419   // I.e., we want a transform that will realize our scroll snap. It follows
 420   // that X = TT^-1 * TT'. We cache TT and TT^-1 to make this more efficient.
 421   gfx::Transform rounded = node->data.to_target;
 422   rounded.RoundTranslationComponents();
 423   gfx::Transform delta = node->data.from_target;
 424   delta *= rounded;
 425
 426   DCHECK(delta.IsApproximatelyIdentityOrTranslation(SkDoubleToMScalar(1e-4)))
 427       << delta.ToString();
 428
 429   gfx::Vector2dF translation = delta.To2dTranslation();
 430
 431   // Now that we have our scroll delta, we must apply it to each of our
 432   // combined, to/from matrices.
 433   node->data.to_parent.Translate(translation.x(), translation.y());
 434   node->data.to_target.Translate(translation.x(), translation.y());
 435   node->data.from_target.matrix().postTranslate(-translation.x(),
 436                                                 -translation.y(), 0);
 437   node->data.to_screen.Translate(translation.x(), translation.y());
 438   node->data.from_screen.matrix().postTranslate(-translation.x(),
 439                                                 -translation.y(), 0);
 440
 441   node->data.scroll_snap = translation;
 442 }
 443
 444 void TransformTree::SetInnerViewportBoundsDelta(gfx::Vector2dF bounds_delta) {
 445   if (inner_viewport_bounds_delta_ == bounds_delta)
 446     return;
 447
 448   inner_viewport_bounds_delta_ = bounds_delta;
 449
 450   if (nodes_affected_by_inner_viewport_bounds_delta_.empty())
 451     return;
 452
 453   set_needs_update(true);
 454   for (int i : nodes_affected_by_inner_viewport_bounds_delta_)
 455     Node(i)->data.needs_local_transform_update = true;
 456 }
 457
 458 void TransformTree::SetOuterViewportBoundsDelta(gfx::Vector2dF bounds_delta) {
 459   if (outer_viewport_bounds_delta_ == bounds_delta)
 460     return;
 461
 462   outer_viewport_bounds_delta_ = bounds_delta;
 463
 464   if (nodes_affected_by_outer_viewport_bounds_delta_.empty())
 465     return;
 466
 467   set_needs_update(true);
 468   for (int i : nodes_affected_by_outer_viewport_bounds_delta_)
 469     Node(i)->data.needs_local_transform_update = true;
 470 }
 471
 472 void TransformTree::AddNodeAffectedByInnerViewportBoundsDelta(int node_id) {
 473   nodes_affected_by_inner_viewport_bounds_delta_.push_back(node_id);
 474 }
 475
 476 void TransformTree::AddNodeAffectedByOuterViewportBoundsDelta(int node_id) {
 477   nodes_affected_by_outer_viewport_bounds_delta_.push_back(node_id);
 478 }
 479
 480 bool TransformTree::HasNodesAffectedByInnerViewportBoundsDelta() const {
 481   return !nodes_affected_by_inner_viewport_bounds_delta_.empty();
 482 }
 483
 484 bool TransformTree::HasNodesAffectedByOuterViewportBoundsDelta() const {
 485   return !nodes_affected_by_outer_viewport_bounds_delta_.empty();
 486 }
 487
 488 void OpacityTree::UpdateOpacities(int id) {
 489   OpacityNode* node = Node(id);
 490   node->data.screen_space_opacity = node->data.opacity;
 491
 492   OpacityNode* parent_node = parent(node);
 493   if (parent_node)
 494     node->data.screen_space_opacity *= parent_node->data.screen_space_opacity;
 495 }
 496
 497 void TransformTree::UpdateNodeAndAncestorsHaveIntegerTranslations(
 498     TransformNode* node,
 499     TransformNode* parent_node) {
 500   node->data.node_and_ancestors_have_only_integer_translation =
 501       node->data.to_parent.IsIdentityOrIntegerTranslation();
 502   if (parent_node)
 503     node->data.node_and_ancestors_have_only_integer_translation =
 504         node->data.node_and_ancestors_have_only_integer_translation &&
 505         parent_node->data.node_and_ancestors_have_only_integer_translation;
 506 }
 507
 508 PropertyTrees::PropertyTrees() : needs_rebuild(true), sequence_number(0) {
 509 }
 510
 511 }  // namespace cc