// Copyright 2012 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "cc/resources/picture_layer_tiling.h" #include #include #include #include "base/debug/trace_event.h" #include "cc/base/math_util.h" #include "ui/gfx/point_conversions.h" #include "ui/gfx/rect_conversions.h" #include "ui/gfx/safe_integer_conversions.h" #include "ui/gfx/size_conversions.h" namespace cc { scoped_ptr PictureLayerTiling::Create( float contents_scale, const gfx::Size& layer_bounds, PictureLayerTilingClient* client) { return make_scoped_ptr(new PictureLayerTiling(contents_scale, layer_bounds, client)); } PictureLayerTiling::PictureLayerTiling(float contents_scale, const gfx::Size& layer_bounds, PictureLayerTilingClient* client) : contents_scale_(contents_scale), layer_bounds_(layer_bounds), resolution_(NON_IDEAL_RESOLUTION), client_(client), tiling_data_(gfx::Size(), gfx::Size(), true), last_impl_frame_time_in_seconds_(0.0) { gfx::Size content_bounds = gfx::ToCeiledSize(gfx::ScaleSize(layer_bounds, contents_scale)); gfx::Size tile_size = client_->CalculateTileSize(content_bounds); DCHECK(!gfx::ToFlooredSize( gfx::ScaleSize(layer_bounds, contents_scale)).IsEmpty()) << "Tiling created with scale too small as contents become empty." << " Layer bounds: " << layer_bounds.ToString() << " Contents scale: " << contents_scale; tiling_data_.SetTotalSize(content_bounds); tiling_data_.SetMaxTextureSize(tile_size); } PictureLayerTiling::~PictureLayerTiling() { } void PictureLayerTiling::SetClient(PictureLayerTilingClient* client) { client_ = client; } gfx::Rect PictureLayerTiling::ContentRect() const { return gfx::Rect(tiling_data_.total_size()); } gfx::SizeF PictureLayerTiling::ContentSizeF() const { return gfx::ScaleSize(layer_bounds_, contents_scale_); } Tile* PictureLayerTiling::TileAt(int i, int j) const { TileMap::const_iterator iter = tiles_.find(TileMapKey(i, j)); if (iter == tiles_.end()) return NULL; return iter->second.get(); } void PictureLayerTiling::CreateTile(int i, int j, const PictureLayerTiling* twin_tiling) { TileMapKey key(i, j); DCHECK(tiles_.find(key) == tiles_.end()); gfx::Rect paint_rect = tiling_data_.TileBoundsWithBorder(i, j); gfx::Rect tile_rect = paint_rect; tile_rect.set_size(tiling_data_.max_texture_size()); // Check our twin for a valid tile. if (twin_tiling && tiling_data_.max_texture_size() == twin_tiling->tiling_data_.max_texture_size()) { if (Tile* candidate_tile = twin_tiling->TileAt(i, j)) { gfx::Rect rect = gfx::ScaleToEnclosingRect(paint_rect, 1.0f / contents_scale_); if (!client_->GetInvalidation()->Intersects(rect)) { tiles_[key] = candidate_tile; return; } } } // Create a new tile because our twin didn't have a valid one. scoped_refptr tile = client_->CreateTile(this, tile_rect); if (tile.get()) tiles_[key] = tile; } Region PictureLayerTiling::OpaqueRegionInContentRect( const gfx::Rect& content_rect) const { Region opaque_region; // TODO(enne): implement me return opaque_region; } void PictureLayerTiling::SetCanUseLCDText(bool can_use_lcd_text) { for (TileMap::iterator it = tiles_.begin(); it != tiles_.end(); ++it) it->second->set_can_use_lcd_text(can_use_lcd_text); } void PictureLayerTiling::CreateMissingTilesInLiveTilesRect() { const PictureLayerTiling* twin_tiling = client_->GetTwinTiling(this); for (TilingData::Iterator iter(&tiling_data_, live_tiles_rect_); iter; ++iter) { TileMapKey key = iter.index(); TileMap::iterator find = tiles_.find(key); if (find != tiles_.end()) continue; CreateTile(key.first, key.second, twin_tiling); } } void PictureLayerTiling::SetLayerBounds(const gfx::Size& layer_bounds) { if (layer_bounds_ == layer_bounds) return; DCHECK(!layer_bounds.IsEmpty()); gfx::Size old_layer_bounds = layer_bounds_; layer_bounds_ = layer_bounds; gfx::Size old_content_bounds = tiling_data_.total_size(); gfx::Size content_bounds = gfx::ToCeiledSize(gfx::ScaleSize(layer_bounds_, contents_scale_)); gfx::Size tile_size = client_->CalculateTileSize(content_bounds); if (tile_size != tiling_data_.max_texture_size()) { tiling_data_.SetTotalSize(content_bounds); tiling_data_.SetMaxTextureSize(tile_size); Reset(); return; } // Any tiles outside our new bounds are invalid and should be dropped. gfx::Rect bounded_live_tiles_rect(live_tiles_rect_); bounded_live_tiles_rect.Intersect(gfx::Rect(content_bounds)); SetLiveTilesRect(bounded_live_tiles_rect); tiling_data_.SetTotalSize(content_bounds); // Create tiles for newly exposed areas. Region layer_region((gfx::Rect(layer_bounds_))); layer_region.Subtract(gfx::Rect(old_layer_bounds)); Invalidate(layer_region); } void PictureLayerTiling::Invalidate(const Region& layer_region) { std::vector new_tile_keys; for (Region::Iterator iter(layer_region); iter.has_rect(); iter.next()) { gfx::Rect layer_rect = iter.rect(); gfx::Rect content_rect = gfx::ScaleToEnclosingRect(layer_rect, contents_scale_); content_rect.Intersect(live_tiles_rect_); if (content_rect.IsEmpty()) continue; for (TilingData::Iterator iter(&tiling_data_, content_rect); iter; ++iter) { TileMapKey key(iter.index()); TileMap::iterator find = tiles_.find(key); if (find == tiles_.end()) continue; tiles_.erase(find); new_tile_keys.push_back(key); } } const PictureLayerTiling* twin_tiling = client_->GetTwinTiling(this); for (size_t i = 0; i < new_tile_keys.size(); ++i) CreateTile(new_tile_keys[i].first, new_tile_keys[i].second, twin_tiling); } PictureLayerTiling::CoverageIterator::CoverageIterator() : tiling_(NULL), current_tile_(NULL), tile_i_(0), tile_j_(0), left_(0), top_(0), right_(-1), bottom_(-1) { } PictureLayerTiling::CoverageIterator::CoverageIterator( const PictureLayerTiling* tiling, float dest_scale, const gfx::Rect& dest_rect) : tiling_(tiling), dest_rect_(dest_rect), dest_to_content_scale_(0), current_tile_(NULL), tile_i_(0), tile_j_(0), left_(0), top_(0), right_(-1), bottom_(-1) { DCHECK(tiling_); if (dest_rect_.IsEmpty()) return; dest_to_content_scale_ = tiling_->contents_scale_ / dest_scale; // This is the maximum size that the dest rect can be, given the content size. gfx::Size dest_content_size = gfx::ToCeiledSize(gfx::ScaleSize( tiling_->ContentRect().size(), 1 / dest_to_content_scale_, 1 / dest_to_content_scale_)); gfx::Rect content_rect = gfx::ScaleToEnclosingRect(dest_rect_, dest_to_content_scale_, dest_to_content_scale_); // IndexFromSrcCoord clamps to valid tile ranges, so it's necessary to // check for non-intersection first. content_rect.Intersect(gfx::Rect(tiling_->tiling_data_.total_size())); if (content_rect.IsEmpty()) return; left_ = tiling_->tiling_data_.TileXIndexFromSrcCoord(content_rect.x()); top_ = tiling_->tiling_data_.TileYIndexFromSrcCoord(content_rect.y()); right_ = tiling_->tiling_data_.TileXIndexFromSrcCoord( content_rect.right() - 1); bottom_ = tiling_->tiling_data_.TileYIndexFromSrcCoord( content_rect.bottom() - 1); tile_i_ = left_ - 1; tile_j_ = top_; ++(*this); } PictureLayerTiling::CoverageIterator::~CoverageIterator() { } PictureLayerTiling::CoverageIterator& PictureLayerTiling::CoverageIterator::operator++() { if (tile_j_ > bottom_) return *this; bool first_time = tile_i_ < left_; bool new_row = false; tile_i_++; if (tile_i_ > right_) { tile_i_ = left_; tile_j_++; new_row = true; if (tile_j_ > bottom_) { current_tile_ = NULL; return *this; } } current_tile_ = tiling_->TileAt(tile_i_, tile_j_); // Calculate the current geometry rect. Due to floating point rounding // and ToEnclosingRect, tiles might overlap in destination space on the // edges. gfx::Rect last_geometry_rect = current_geometry_rect_; gfx::Rect content_rect = tiling_->tiling_data_.TileBounds(tile_i_, tile_j_); current_geometry_rect_ = gfx::ScaleToEnclosingRect(content_rect, 1 / dest_to_content_scale_, 1 / dest_to_content_scale_); current_geometry_rect_.Intersect(dest_rect_); if (first_time) return *this; // Iteration happens left->right, top->bottom. Running off the bottom-right // edge is handled by the intersection above with dest_rect_. Here we make // sure that the new current geometry rect doesn't overlap with the last. int min_left; int min_top; if (new_row) { min_left = dest_rect_.x(); min_top = last_geometry_rect.bottom(); } else { min_left = last_geometry_rect.right(); min_top = last_geometry_rect.y(); } int inset_left = std::max(0, min_left - current_geometry_rect_.x()); int inset_top = std::max(0, min_top - current_geometry_rect_.y()); current_geometry_rect_.Inset(inset_left, inset_top, 0, 0); if (!new_row) { DCHECK_EQ(last_geometry_rect.right(), current_geometry_rect_.x()); DCHECK_EQ(last_geometry_rect.bottom(), current_geometry_rect_.bottom()); DCHECK_EQ(last_geometry_rect.y(), current_geometry_rect_.y()); } return *this; } gfx::Rect PictureLayerTiling::CoverageIterator::geometry_rect() const { return current_geometry_rect_; } gfx::Rect PictureLayerTiling::CoverageIterator::full_tile_geometry_rect() const { gfx::Rect rect = tiling_->tiling_data_.TileBoundsWithBorder(tile_i_, tile_j_); rect.set_size(tiling_->tiling_data_.max_texture_size()); return rect; } gfx::RectF PictureLayerTiling::CoverageIterator::texture_rect() const { gfx::PointF tex_origin = tiling_->tiling_data_.TileBoundsWithBorder(tile_i_, tile_j_).origin(); // Convert from dest space => content space => texture space. gfx::RectF texture_rect(current_geometry_rect_); texture_rect.Scale(dest_to_content_scale_, dest_to_content_scale_); texture_rect.Offset(-tex_origin.OffsetFromOrigin()); texture_rect.Intersect(tiling_->ContentRect()); return texture_rect; } gfx::Size PictureLayerTiling::CoverageIterator::texture_size() const { return tiling_->tiling_data_.max_texture_size(); } void PictureLayerTiling::Reset() { live_tiles_rect_ = gfx::Rect(); tiles_.clear(); } void PictureLayerTiling::UpdateTilePriorities( WhichTree tree, const gfx::Size& device_viewport, const gfx::Rect& viewport_in_layer_space, const gfx::Rect& visible_layer_rect, const gfx::Size& last_layer_bounds, const gfx::Size& current_layer_bounds, float last_layer_contents_scale, float current_layer_contents_scale, const gfx::Transform& last_screen_transform, const gfx::Transform& current_screen_transform, double current_frame_time_in_seconds, size_t max_tiles_for_interest_area) { if (!NeedsUpdateForFrameAtTime(current_frame_time_in_seconds)) { // This should never be zero for the purposes of has_ever_been_updated(). DCHECK_NE(current_frame_time_in_seconds, 0.0); return; } if (ContentRect().IsEmpty()) { last_impl_frame_time_in_seconds_ = current_frame_time_in_seconds; return; } gfx::Rect viewport_in_content_space = gfx::ScaleToEnclosingRect(viewport_in_layer_space, contents_scale_); gfx::Rect visible_content_rect = gfx::ScaleToEnclosingRect(visible_layer_rect, contents_scale_); gfx::Size tile_size = tiling_data_.max_texture_size(); int64 interest_rect_area = max_tiles_for_interest_area * tile_size.width() * tile_size.height(); gfx::Rect starting_rect = visible_content_rect.IsEmpty() ? viewport_in_content_space : visible_content_rect; gfx::Rect interest_rect = ExpandRectEquallyToAreaBoundedBy( starting_rect, interest_rect_area, ContentRect(), &expansion_cache_); DCHECK(interest_rect.IsEmpty() || ContentRect().Contains(interest_rect)); SetLiveTilesRect(interest_rect); double time_delta = 0; if (last_impl_frame_time_in_seconds_ != 0.0 && last_layer_bounds == current_layer_bounds) { time_delta = current_frame_time_in_seconds - last_impl_frame_time_in_seconds_; } gfx::RectF view_rect(device_viewport); float current_scale = current_layer_contents_scale / contents_scale_; float last_scale = last_layer_contents_scale / contents_scale_; // Fast path tile priority calculation when both transforms are translations. if (last_screen_transform.IsApproximatelyIdentityOrTranslation( std::numeric_limits::epsilon()) && current_screen_transform.IsApproximatelyIdentityOrTranslation( std::numeric_limits::epsilon())) { gfx::Vector2dF current_offset( current_screen_transform.matrix().get(0, 3), current_screen_transform.matrix().get(1, 3)); gfx::Vector2dF last_offset( last_screen_transform.matrix().get(0, 3), last_screen_transform.matrix().get(1, 3)); for (TilingData::Iterator iter(&tiling_data_, interest_rect); iter; ++iter) { TileMap::iterator find = tiles_.find(iter.index()); if (find == tiles_.end()) continue; Tile* tile = find->second.get(); gfx::Rect tile_bounds = tiling_data_.TileBounds(iter.index_x(), iter.index_y()); gfx::RectF current_screen_rect = gfx::ScaleRect( tile_bounds, current_scale, current_scale) + current_offset; gfx::RectF last_screen_rect = gfx::ScaleRect( tile_bounds, last_scale, last_scale) + last_offset; float distance_to_visible_in_pixels = current_screen_rect.ManhattanInternalDistance(view_rect); float time_to_visible_in_seconds = TilePriority::TimeForBoundsToIntersect( last_screen_rect, current_screen_rect, time_delta, view_rect); TilePriority priority( resolution_, time_to_visible_in_seconds, distance_to_visible_in_pixels); tile->SetPriority(tree, priority); } } else if (!last_screen_transform.HasPerspective() && !current_screen_transform.HasPerspective()) { // Secondary fast path that can be applied for any affine transforms. // Initialize the necessary geometry in screen space, so that we can // iterate over tiles in screen space without needing a costly transform // mapping for each tile. // Apply screen space transform to the local origin point (0, 0); only the // translation component is needed and can be initialized directly. gfx::Point current_screen_space_origin( current_screen_transform.matrix().get(0, 3), current_screen_transform.matrix().get(1, 3)); gfx::Point last_screen_space_origin( last_screen_transform.matrix().get(0, 3), last_screen_transform.matrix().get(1, 3)); float current_tile_width = tiling_data_.TileSizeX(0) * current_scale; float last_tile_width = tiling_data_.TileSizeX(0) * last_scale; float current_tile_height = tiling_data_.TileSizeY(0) * current_scale; float last_tile_height = tiling_data_.TileSizeY(0) * last_scale; // Apply screen space transform to local basis vectors (tile_width, 0) and // (0, tile_height); the math simplifies and can be initialized directly. gfx::Vector2dF current_horizontal( current_screen_transform.matrix().get(0, 0) * current_tile_width, current_screen_transform.matrix().get(1, 0) * current_tile_width); gfx::Vector2dF current_vertical( current_screen_transform.matrix().get(0, 1) * current_tile_height, current_screen_transform.matrix().get(1, 1) * current_tile_height); gfx::Vector2dF last_horizontal( last_screen_transform.matrix().get(0, 0) * last_tile_width, last_screen_transform.matrix().get(1, 0) * last_tile_width); gfx::Vector2dF last_vertical( last_screen_transform.matrix().get(0, 1) * last_tile_height, last_screen_transform.matrix().get(1, 1) * last_tile_height); for (TilingData::Iterator iter(&tiling_data_, interest_rect); iter; ++iter) { TileMap::iterator find = tiles_.find(iter.index()); if (find == tiles_.end()) continue; Tile* tile = find->second.get(); int i = iter.index_x(); int j = iter.index_y(); gfx::PointF current_tile_origin = current_screen_space_origin + ScaleVector2d(current_horizontal, i) + ScaleVector2d(current_vertical, j); gfx::PointF last_tile_origin = last_screen_space_origin + ScaleVector2d(last_horizontal, i) + ScaleVector2d(last_vertical, j); gfx::RectF current_screen_rect = gfx::QuadF( current_tile_origin, current_tile_origin + current_horizontal, current_tile_origin + current_horizontal + current_vertical, current_tile_origin + current_vertical).BoundingBox(); gfx::RectF last_screen_rect = gfx::QuadF( last_tile_origin, last_tile_origin + last_horizontal, last_tile_origin + last_horizontal + last_vertical, last_tile_origin + last_vertical).BoundingBox(); float distance_to_visible_in_pixels = current_screen_rect.ManhattanInternalDistance(view_rect); float time_to_visible_in_seconds = TilePriority::TimeForBoundsToIntersect( last_screen_rect, current_screen_rect, time_delta, view_rect); TilePriority priority( resolution_, time_to_visible_in_seconds, distance_to_visible_in_pixels); tile->SetPriority(tree, priority); } } else { for (TilingData::Iterator iter(&tiling_data_, interest_rect); iter; ++iter) { TileMap::iterator find = tiles_.find(iter.index()); if (find == tiles_.end()) continue; Tile* tile = find->second.get(); gfx::Rect tile_bounds = tiling_data_.TileBounds(iter.index_x(), iter.index_y()); gfx::RectF current_layer_content_rect = gfx::ScaleRect( tile_bounds, current_scale, current_scale); gfx::RectF current_screen_rect = MathUtil::MapClippedRect( current_screen_transform, current_layer_content_rect); gfx::RectF last_layer_content_rect = gfx::ScaleRect( tile_bounds, last_scale, last_scale); gfx::RectF last_screen_rect = MathUtil::MapClippedRect( last_screen_transform, last_layer_content_rect); float distance_to_visible_in_pixels = current_screen_rect.ManhattanInternalDistance(view_rect); float time_to_visible_in_seconds = TilePriority::TimeForBoundsToIntersect( last_screen_rect, current_screen_rect, time_delta, view_rect); TilePriority priority( resolution_, time_to_visible_in_seconds, distance_to_visible_in_pixels); tile->SetPriority(tree, priority); } } last_impl_frame_time_in_seconds_ = current_frame_time_in_seconds; } void PictureLayerTiling::SetLiveTilesRect( const gfx::Rect& new_live_tiles_rect) { DCHECK(new_live_tiles_rect.IsEmpty() || ContentRect().Contains(new_live_tiles_rect)); if (live_tiles_rect_ == new_live_tiles_rect) return; // Iterate to delete all tiles outside of our new live_tiles rect. for (TilingData::DifferenceIterator iter(&tiling_data_, live_tiles_rect_, new_live_tiles_rect); iter; ++iter) { TileMapKey key(iter.index()); TileMap::iterator found = tiles_.find(key); // If the tile was outside of the recorded region, it won't exist even // though it was in the live rect. if (found != tiles_.end()) tiles_.erase(found); } const PictureLayerTiling* twin_tiling = client_->GetTwinTiling(this); // Iterate to allocate new tiles for all regions with newly exposed area. for (TilingData::DifferenceIterator iter(&tiling_data_, new_live_tiles_rect, live_tiles_rect_); iter; ++iter) { TileMapKey key(iter.index()); CreateTile(key.first, key.second, twin_tiling); } live_tiles_rect_ = new_live_tiles_rect; } void PictureLayerTiling::DidBecomeRecycled() { // DidBecomeActive below will set the active priority for tiles that are // still in the tree. Calling this first on an active tiling that is becoming // recycled takes care of tiles that are no longer in the active tree (eg. // due to a pending invalidation). for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) { it->second->SetPriority(ACTIVE_TREE, TilePriority()); } } void PictureLayerTiling::DidBecomeActive() { for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) { it->second->SetPriority(ACTIVE_TREE, it->second->priority(PENDING_TREE)); it->second->SetPriority(PENDING_TREE, TilePriority()); // Tile holds a ref onto a picture pile. If the tile never gets invalidated // and recreated, then that picture pile ref could exist indefinitely. To // prevent this, ask the client to update the pile to its own ref. This // will cause PicturePileImpls and their clones to get deleted once the // corresponding PictureLayerImpl and any in flight raster jobs go out of // scope. client_->UpdatePile(it->second.get()); } } void PictureLayerTiling::UpdateTilesToCurrentPile() { for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) { client_->UpdatePile(it->second.get()); } } scoped_ptr PictureLayerTiling::AsValue() const { scoped_ptr state(new base::DictionaryValue()); state->SetInteger("num_tiles", tiles_.size()); state->SetDouble("content_scale", contents_scale_); state->Set("content_bounds", MathUtil::AsValue(ContentRect().size()).release()); return state.PassAs(); } size_t PictureLayerTiling::GPUMemoryUsageInBytes() const { size_t amount = 0; for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) { const Tile* tile = it->second.get(); amount += tile->GPUMemoryUsageInBytes(); } return amount; } PictureLayerTiling::RectExpansionCache::RectExpansionCache() : previous_target(0) { } namespace { // This struct represents an event at which the expending rect intersects // one of its boundaries. 4 intersection events will occur during expansion. struct EdgeEvent { enum { BOTTOM, TOP, LEFT, RIGHT } edge; int* num_edges; int distance; }; // Compute the delta to expand from edges to cover target_area. int ComputeExpansionDelta(int num_x_edges, int num_y_edges, int width, int height, int64 target_area) { // Compute coefficients for the quadratic equation: // a*x^2 + b*x + c = 0 int a = num_y_edges * num_x_edges; int b = num_y_edges * width + num_x_edges * height; int64 c = static_cast(width) * height - target_area; // Compute the delta for our edges using the quadratic equation. return a == 0 ? -c / b : (-b + static_cast( std::sqrt(static_cast(b) * b - 4.0 * a * c))) / (2 * a); } } // namespace gfx::Rect PictureLayerTiling::ExpandRectEquallyToAreaBoundedBy( const gfx::Rect& starting_rect, int64 target_area, const gfx::Rect& bounding_rect, RectExpansionCache* cache) { if (starting_rect.IsEmpty()) return starting_rect; if (cache && cache->previous_start == starting_rect && cache->previous_bounds == bounding_rect && cache->previous_target == target_area) return cache->previous_result; if (cache) { cache->previous_start = starting_rect; cache->previous_bounds = bounding_rect; cache->previous_target = target_area; } DCHECK(!bounding_rect.IsEmpty()); DCHECK_GT(target_area, 0); // Expand the starting rect to cover target_area, if it is smaller than it. int delta = ComputeExpansionDelta( 2, 2, starting_rect.width(), starting_rect.height(), target_area); gfx::Rect expanded_starting_rect = starting_rect; if (delta > 0) expanded_starting_rect.Inset(-delta, -delta); gfx::Rect rect = IntersectRects(expanded_starting_rect, bounding_rect); if (rect.IsEmpty()) { // The starting_rect and bounding_rect are far away. if (cache) cache->previous_result = rect; return rect; } if (delta >= 0 && rect == expanded_starting_rect) { // The starting rect already covers the entire bounding_rect and isn't too // large for the target_area. if (cache) cache->previous_result = rect; return rect; } // Continue to expand/shrink rect to let it cover target_area. // These values will be updated by the loop and uses as the output. int origin_x = rect.x(); int origin_y = rect.y(); int width = rect.width(); int height = rect.height(); // In the beginning we will consider 2 edges in each dimension. int num_y_edges = 2; int num_x_edges = 2; // Create an event list. EdgeEvent events[] = { { EdgeEvent::BOTTOM, &num_y_edges, rect.y() - bounding_rect.y() }, { EdgeEvent::TOP, &num_y_edges, bounding_rect.bottom() - rect.bottom() }, { EdgeEvent::LEFT, &num_x_edges, rect.x() - bounding_rect.x() }, { EdgeEvent::RIGHT, &num_x_edges, bounding_rect.right() - rect.right() } }; // Sort the events by distance (closest first). if (events[0].distance > events[1].distance) std::swap(events[0], events[1]); if (events[2].distance > events[3].distance) std::swap(events[2], events[3]); if (events[0].distance > events[2].distance) std::swap(events[0], events[2]); if (events[1].distance > events[3].distance) std::swap(events[1], events[3]); if (events[1].distance > events[2].distance) std::swap(events[1], events[2]); for (int event_index = 0; event_index < 4; event_index++) { const EdgeEvent& event = events[event_index]; int delta = ComputeExpansionDelta( num_x_edges, num_y_edges, width, height, target_area); // Clamp delta to our event distance. if (delta > event.distance) delta = event.distance; // Adjust the edge count for this kind of edge. --*event.num_edges; // Apply the delta to the edges and edge events. for (int i = event_index; i < 4; i++) { switch (events[i].edge) { case EdgeEvent::BOTTOM: origin_y -= delta; height += delta; break; case EdgeEvent::TOP: height += delta; break; case EdgeEvent::LEFT: origin_x -= delta; width += delta; break; case EdgeEvent::RIGHT: width += delta; break; } events[i].distance -= delta; } // If our delta is less then our event distance, we're done. if (delta < event.distance) break; } gfx::Rect result(origin_x, origin_y, width, height); if (cache) cache->previous_result = result; return result; } } // namespace cc