Add R-Tree data structure.
Review URL: https://codereview.appspot.com/6489055 git-svn-id: http://skia.googlecode.com/svn/trunk@5401 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
rileya@google.com
parent
d6bbbf8a83
commit
1f45e934b6
@ -14,6 +14,7 @@
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'<(skia_src_path)/core/SkAdvancedTypefaceMetrics.cpp',
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'<(skia_src_path)/core/SkAlphaRuns.cpp',
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'<(skia_src_path)/core/SkAntiRun.h',
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'<(skia_src_path)/core/SkBBoxHierarchy.h',
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'<(skia_src_path)/core/SkBitmap.cpp',
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'<(skia_src_path)/core/SkBitmapHeap.cpp',
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'<(skia_src_path)/core/SkBitmapHeap.h',
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@ -127,6 +128,8 @@
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'<(skia_src_path)/core/SkRegion.cpp',
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'<(skia_src_path)/core/SkRegionPriv.h',
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'<(skia_src_path)/core/SkRegion_path.cpp',
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'<(skia_src_path)/core/SkRTree.h',
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'<(skia_src_path)/core/SkRTree.cpp',
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'<(skia_src_path)/core/SkScalar.cpp',
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'<(skia_src_path)/core/SkScalerContext.cpp',
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'<(skia_src_path)/core/SkScan.cpp',
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@ -75,6 +75,7 @@
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'../tests/RefCntTest.cpp',
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'../tests/RefDictTest.cpp',
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'../tests/RegionTest.cpp',
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'../tests/RTreeTest.cpp',
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'../tests/ScalarTest.cpp',
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'../tests/ShaderOpacityTest.cpp',
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'../tests/Sk64Test.cpp',
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53
src/core/SkBBoxHierarchy.h
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53
src/core/SkBBoxHierarchy.h
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@ -0,0 +1,53 @@
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/*
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* Copyright 2012 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkBBoxHierarchy_DEFINED
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#define SkBBoxHierarchy_DEFINED
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#include "SkRect.h"
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#include "SkTDArray.h"
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/**
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* Interface for a spatial data structure that associates user data pointers with axis-aligned
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* bounding boxes, and allows efficient retrieval of intersections with query rectangles.
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*/
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class SkBBoxHierarchy {
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public:
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virtual ~SkBBoxHierarchy() { }
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/**
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* Insert a data pointer and corresponding bounding box
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* @param data The data pointer, may be NULL
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* @param bounds The bounding box, should not be empty
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* @param defer Whether or not it is acceptable to delay insertion of this element (building up
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* an entire spatial data structure at once is often faster and produces better
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* structures than repeated inserts) until flushDeferredInserts is called or the first
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* search.
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*/
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virtual void insert(void* data, const SkIRect& bounds, bool defer = false) = 0;
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/**
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* If any insertions have been deferred, this forces them to be inserted
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*/
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virtual void flushDeferredInserts() = 0;
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/**
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* Populate 'results' with data pointers corresponding to bounding boxes that intersect 'query'
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*/
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virtual void search(const SkIRect& query, SkTDArray<void*>* results) = 0;
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virtual void clear() = 0;
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/**
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* Gets the number of insertions
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*/
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virtual int getCount() const = 0;
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};
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#endif
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470
src/core/SkRTree.cpp
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470
src/core/SkRTree.cpp
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@ -0,0 +1,470 @@
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/*
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* Copyright 2012 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "SkRTree.h"
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#include "SkTSort.h"
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static inline uint32_t get_area(const SkIRect& rect);
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static inline uint32_t get_overlap(const SkIRect& rect1, const SkIRect& rect2);
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static inline uint32_t get_margin(const SkIRect& rect);
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static inline uint32_t get_overlap_increase(const SkIRect& rect1, const SkIRect& rect2,
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SkIRect expandBy);
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static inline uint32_t get_area_increase(const SkIRect& rect1, SkIRect rect2);
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static inline void join_no_empty_check(const SkIRect& joinWith, SkIRect* out);
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///////////////////////////////////////////////////////////////////////////////////////////////////
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SkRTree* SkRTree::Create(int minChildren, int maxChildren) {
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if (minChildren < maxChildren && (maxChildren + 1) / 2 >= minChildren &&
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minChildren > 0 && maxChildren < static_cast<int>(SK_MaxU16)) {
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return new SkRTree(minChildren, maxChildren);
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}
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return NULL;
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}
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SkRTree::SkRTree(int minChildren, int maxChildren)
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: fMinChildren(minChildren)
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, fMaxChildren(maxChildren)
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, fNodeSize(sizeof(Node) + sizeof(Branch) * maxChildren)
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, fCount(0)
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, fNodes(fNodeSize * 256) {
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SkASSERT(minChildren < maxChildren && minChildren > 0 && maxChildren <
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static_cast<int>(SK_MaxU16));
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SkASSERT((maxChildren + 1) / 2 >= minChildren);
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this->validate();
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}
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SkRTree::~SkRTree() {
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this->clear();
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}
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void SkRTree::insert(void* data, const SkIRect& bounds, bool defer) {
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this->validate();
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if (bounds.isEmpty()) {
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SkASSERT(false);
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return;
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}
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Branch newBranch;
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newBranch.fBounds = bounds;
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newBranch.fChild.data = data;
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if (this->isEmpty()) {
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// since a bulk-load into an existing tree is as of yet unimplemented (and arguably not
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// of vital importance right now), we only batch up inserts if the tree is empty.
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if (defer) {
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fDeferredInserts.push(newBranch);
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return;
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} else {
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fRoot.fChild.subtree = allocateNode(0);
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fRoot.fChild.subtree->fNumChildren = 0;
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}
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}
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Branch* newSibling = insert(fRoot.fChild.subtree, &newBranch);
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fRoot.fBounds = this->computeBounds(fRoot.fChild.subtree);
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if (NULL != newSibling) {
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Node* oldRoot = fRoot.fChild.subtree;
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Node* newRoot = this->allocateNode(oldRoot->fLevel + 1);
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newRoot->fNumChildren = 2;
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*newRoot->child(0) = fRoot;
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*newRoot->child(1) = *newSibling;
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fRoot.fChild.subtree = newRoot;
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fRoot.fBounds = this->computeBounds(fRoot.fChild.subtree);
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}
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++fCount;
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this->validate();
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}
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void SkRTree::flushDeferredInserts() {
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this->validate();
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if (this->isEmpty() && fDeferredInserts.count() > 0) {
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fCount = fDeferredInserts.count();
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if (1 == fCount) {
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fRoot.fChild.subtree = allocateNode(0);
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fRoot.fChild.subtree->fNumChildren = 0;
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this->insert(fRoot.fChild.subtree, &fDeferredInserts[0]);
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fRoot.fBounds = fDeferredInserts[0].fBounds;
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} else {
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fRoot = this->bulkLoad(&fDeferredInserts);
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}
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} else {
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// TODO: some algorithm for bulk loading into an already populated tree
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SkASSERT(0 == fDeferredInserts.count());
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}
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fDeferredInserts.rewind();
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this->validate();
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}
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void SkRTree::search(const SkIRect& query, SkTDArray<void*>* results) {
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this->validate();
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if (0 != fDeferredInserts.count()) {
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this->flushDeferredInserts();
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}
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if (!this->isEmpty() && SkIRect::IntersectsNoEmptyCheck(fRoot.fBounds, query)) {
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this->search(fRoot.fChild.subtree, query, results);
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}
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this->validate();
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}
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void SkRTree::clear() {
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this->validate();
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fNodes.reset();
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fDeferredInserts.rewind();
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fCount = 0;
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this->validate();
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}
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SkRTree::Node* SkRTree::allocateNode(uint16_t level) {
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Node* out = static_cast<Node*>(fNodes.allocThrow(fNodeSize));
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out->fNumChildren = 0;
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out->fLevel = level;
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return out;
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}
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SkRTree::Branch* SkRTree::insert(Node* root, Branch* branch, uint16_t level) {
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Branch* toInsert = branch;
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if (root->fLevel != level) {
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int childIndex = this->chooseSubtree(root, branch);
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toInsert = this->insert(root->child(childIndex)->fChild.subtree, branch, level);
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root->child(childIndex)->fBounds = this->computeBounds(
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root->child(childIndex)->fChild.subtree);
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}
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if (NULL != toInsert) {
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if (root->fNumChildren == fMaxChildren) {
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// handle overflow by splitting. TODO: opportunistic reinsertion
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// decide on a distribution to divide with
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Node* newSibling = this->allocateNode(root->fLevel);
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Branch* toDivide = SkNEW_ARRAY(Branch, fMaxChildren + 1);
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for (int i = 0; i < fMaxChildren; ++i) {
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toDivide[i] = *root->child(i);
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}
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toDivide[fMaxChildren] = *toInsert;
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int splitIndex = this->distributeChildren(toDivide);
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// divide up the branches
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root->fNumChildren = splitIndex;
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newSibling->fNumChildren = fMaxChildren + 1 - splitIndex;
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for (int i = 0; i < splitIndex; ++i) {
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*root->child(i) = toDivide[i];
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}
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for (int i = splitIndex; i < fMaxChildren + 1; ++i) {
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*newSibling->child(i - splitIndex) = toDivide[i];
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}
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SkDELETE_ARRAY(toDivide);
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// pass the new sibling branch up to the parent
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branch->fChild.subtree = newSibling;
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branch->fBounds = this->computeBounds(newSibling);
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return branch;
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} else {
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*root->child(root->fNumChildren) = *toInsert;
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++root->fNumChildren;
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return NULL;
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}
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}
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return NULL;
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}
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int SkRTree::chooseSubtree(Node* root, Branch* branch) {
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SkASSERT(!root->isLeaf());
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if (1 < root->fLevel) {
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// root's child pointers do not point to leaves, so minimize area increase
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int32_t minAreaIncrease = SK_MaxS32;
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int32_t minArea = SK_MaxS32;
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int32_t bestSubtree = -1;
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for (int i = 0; i < root->fNumChildren; ++i) {
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const SkIRect& subtreeBounds = root->child(i)->fBounds;
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int32_t areaIncrease = get_area_increase(subtreeBounds, branch->fBounds);
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// break ties in favor of subtree with smallest area
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if (areaIncrease < minAreaIncrease || (areaIncrease == minAreaIncrease &&
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static_cast<int32_t>(get_area(subtreeBounds)) < minArea)) {
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minAreaIncrease = areaIncrease;
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minArea = get_area(subtreeBounds);
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bestSubtree = i;
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}
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}
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SkASSERT(-1 != bestSubtree);
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return bestSubtree;
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} else if (1 == root->fLevel) {
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// root's child pointers do point to leaves, so minimize overlap increase
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int32_t minOverlapIncrease = SK_MaxS32;
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int32_t minAreaIncrease = SK_MaxS32;
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int32_t bestSubtree = -1;
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for (int32_t i = 0; i < root->fNumChildren; ++i) {
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const SkIRect& subtreeBounds = root->child(i)->fBounds;
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SkIRect expandedBounds = subtreeBounds;
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join_no_empty_check(branch->fBounds, &expandedBounds);
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int32_t overlap = 0;
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for (int32_t j = 0; j < root->fNumChildren; ++j) {
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if (j == i) continue;
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// Note: this would be more correct if we subtracted the original pre-expanded
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// overlap, but computing overlaps is expensive and omitting it doesn't seem to
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// hurt query performance. See get_overlap_increase()
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overlap += get_overlap(expandedBounds, root->child(j)->fBounds);
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}
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// break ties with lowest area increase
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if (overlap < minOverlapIncrease || (overlap == minOverlapIncrease &&
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static_cast<int32_t>(get_area_increase(branch->fBounds, subtreeBounds)) <
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minAreaIncrease)) {
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minOverlapIncrease = overlap;
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minAreaIncrease = get_area_increase(branch->fBounds, subtreeBounds);
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bestSubtree = i;
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}
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}
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return bestSubtree;
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} else {
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SkASSERT(false);
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return 0;
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}
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}
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SkIRect SkRTree::computeBounds(Node* n) {
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SkIRect r = n->child(0)->fBounds;
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for (int i = 1; i < n->fNumChildren; ++i) {
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join_no_empty_check(n->child(i)->fBounds, &r);
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}
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return r;
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}
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int SkRTree::distributeChildren(Branch* children) {
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// We have two sides to sort by on each of two axes:
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const static SortSide sorts[2][2] = {
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{&SkIRect::fLeft, &SkIRect::fRight},
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{&SkIRect::fTop, &SkIRect::fBottom}
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};
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// We want to choose an axis to split on, then a distribution along that axis; we'll need
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// three pieces of info: the split axis, the side to sort by on that axis, and the index
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// to split the sorted array on.
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int32_t sortSide = -1;
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int32_t k = -1;
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int32_t axis = -1;
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int32_t bestS = SK_MaxS32;
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// Evaluate each axis, we want the min summed margin-value (s) over all distributions
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for (int i = 0; i < 2; ++i) {
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int32_t minOverlap = SK_MaxS32;
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int32_t minArea = SK_MaxS32;
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int32_t axisBestK = 0;
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int32_t axisBestSide = 0;
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int32_t s = 0;
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// Evaluate each sort
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for (int j = 0; j < 2; ++j) {
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SkQSort(sorts[i][j], children, children + fMaxChildren, &RectLessThan);
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// Evaluate each split index
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for (int32_t k = 1; k <= fMaxChildren - 2 * fMinChildren + 2; ++k) {
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SkIRect r1 = children[0].fBounds;
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SkIRect r2 = children[fMinChildren + k - 1].fBounds;
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for (int32_t l = 1; l < fMinChildren - 1 + k; ++l) {
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join_no_empty_check(children[l].fBounds, &r1);
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}
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for (int32_t l = fMinChildren + k; l < fMaxChildren + 1; ++l) {
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join_no_empty_check(children[l].fBounds, &r2);
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}
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int32_t area = get_area(r1) + get_area(r2);
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int32_t overlap = get_overlap(r1, r2);
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s += get_margin(r1) + get_margin(r2);
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if (overlap < minOverlap || (overlap == minOverlap && area < minArea)) {
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minOverlap = overlap;
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minArea = area;
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axisBestSide = j;
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axisBestK = k;
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}
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}
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}
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if (s < bestS) {
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bestS = s;
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axis = i;
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sortSide = axisBestSide;
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k = axisBestK;
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}
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}
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// replicate the sort of the winning distribution, (we can skip this if the last
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// sort ended up being best)
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if (!(axis == 1 && sortSide == 1)) {
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SkQSort(sorts[axis][sortSide], children, children + fMaxChildren, &RectLessThan);
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}
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return fMinChildren - 1 + k;
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}
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void SkRTree::search(Node* root, const SkIRect query, SkTDArray<void*>* results) const {
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for (int i = 0; i < root->fNumChildren; ++i) {
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if (SkIRect::IntersectsNoEmptyCheck(root->child(i)->fBounds, query)) {
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if (root->isLeaf()) {
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results->push(root->child(i)->fChild.data);
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} else {
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this->search(root->child(i)->fChild.subtree, query, results);
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}
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}
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}
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}
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SkRTree::Branch SkRTree::bulkLoad(SkTDArray<Branch>* branches, int level) {
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if (branches->count() == 1) {
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// Only one branch: it will be the root
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Branch out = (*branches)[0];
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branches->rewind();
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return out;
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} else {
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// First we sort the whole list by y coordinates
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SkQSort<int, Branch>(level, branches->begin(), branches->end() - 1, &RectLessY);
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int numBranches = branches->count() / fMaxChildren;
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int remainder = branches->count() % fMaxChildren;
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int newBranches = 0;
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if (0 != remainder) {
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++numBranches;
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// If the remainder isn't enough to fill a node, we'll need to add fewer nodes to
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// some other branches to make up for it
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if (remainder >= fMinChildren) {
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remainder = 0;
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} else {
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remainder = fMinChildren - remainder;
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}
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}
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int numStrips = SkScalarCeil(SkScalarSqrt(SkIntToScalar(numBranches)));
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int currentBranch = 0;
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for (int i = 0; i < numStrips; ++i) {
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int begin = currentBranch;
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int end = currentBranch + numStrips * fMaxChildren - SkMin32(remainder,
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(fMaxChildren - fMinChildren) * numStrips);
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if (end > branches->count()) {
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end = branches->count();
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}
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// Now we sort horizontal strips of rectangles by their x coords
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SkQSort<int, Branch>(level, branches->begin() + begin, branches->begin() + end - 1,
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&RectLessX);
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for (int j = 0; j < numStrips && currentBranch < branches->count(); ++j) {
|
||||
int incrementBy = fMaxChildren;
|
||||
if (remainder != 0) {
|
||||
// if need be, omit some nodes to make up for remainder
|
||||
if (remainder <= fMaxChildren - fMinChildren) {
|
||||
incrementBy -= remainder;
|
||||
remainder = 0;
|
||||
} else {
|
||||
incrementBy = fMinChildren;
|
||||
remainder -= fMaxChildren - fMinChildren;
|
||||
}
|
||||
}
|
||||
Node* n = allocateNode(level);
|
||||
n->fNumChildren = 1;
|
||||
*n->child(0) = (*branches)[currentBranch];
|
||||
Branch b;
|
||||
b.fBounds = (*branches)[currentBranch].fBounds;
|
||||
b.fChild.subtree = n;
|
||||
++currentBranch;
|
||||
for (int k = 1; k < incrementBy && currentBranch < branches->count(); ++k) {
|
||||
b.fBounds.join((*branches)[currentBranch].fBounds);
|
||||
*n->child(k) = (*branches)[currentBranch];
|
||||
++n->fNumChildren;
|
||||
++currentBranch;
|
||||
}
|
||||
(*branches)[newBranches] = b;
|
||||
++newBranches;
|
||||
}
|
||||
}
|
||||
branches->setCount(newBranches);
|
||||
return this->bulkLoad(branches, level + 1);
|
||||
}
|
||||
}
|
||||
|
||||
void SkRTree::validate() {
|
||||
#ifdef SK_DEBUG
|
||||
if (this->isEmpty()) {
|
||||
return;
|
||||
}
|
||||
SkASSERT(fCount == this->validateSubtree(fRoot.fChild.subtree, fRoot.fBounds, true));
|
||||
#endif
|
||||
}
|
||||
|
||||
int SkRTree::validateSubtree(Node* root, SkIRect bounds, bool isRoot) {
|
||||
// make sure the pointer is pointing to a valid place
|
||||
SkASSERT(fNodes.contains(static_cast<void*>(root)));
|
||||
|
||||
if (isRoot) {
|
||||
// If the root of this subtree is the overall root, we have looser standards:
|
||||
if (root->isLeaf()) {
|
||||
SkASSERT(root->fNumChildren >= 1 && root->fNumChildren <= fMaxChildren);
|
||||
} else {
|
||||
SkASSERT(root->fNumChildren >= 2 && root->fNumChildren <= fMaxChildren);
|
||||
}
|
||||
} else {
|
||||
SkASSERT(root->fNumChildren >= fMinChildren && root->fNumChildren <= fMaxChildren);
|
||||
}
|
||||
|
||||
for (int i = 0; i < root->fNumChildren; ++i) {
|
||||
SkASSERT(bounds.contains(root->child(i)->fBounds));
|
||||
}
|
||||
|
||||
if (root->isLeaf()) {
|
||||
SkASSERT(0 == root->fLevel);
|
||||
return root->fNumChildren;
|
||||
} else {
|
||||
int childCount = 0;
|
||||
for (int i = 0; i < root->fNumChildren; ++i) {
|
||||
SkASSERT(root->child(i)->fChild.subtree->fLevel == root->fLevel - 1);
|
||||
childCount += this->validateSubtree(root->child(i)->fChild.subtree,
|
||||
root->child(i)->fBounds);
|
||||
}
|
||||
return childCount;
|
||||
}
|
||||
}
|
||||
|
||||
///////////////////////////////////////////////////////////////////////////////////////////////////
|
||||
|
||||
static inline uint32_t get_area(const SkIRect& rect) {
|
||||
return rect.width() * rect.height();
|
||||
}
|
||||
|
||||
static inline uint32_t get_overlap(const SkIRect& rect1, const SkIRect& rect2) {
|
||||
// I suspect there's a more efficient way of computing this...
|
||||
return SkMax32(0, SkMin32(rect1.fRight, rect2.fRight) - SkMax32(rect1.fLeft, rect2.fLeft)) *
|
||||
SkMax32(0, SkMin32(rect1.fBottom, rect2.fBottom) - SkMax32(rect1.fTop, rect2.fTop));
|
||||
}
|
||||
|
||||
// Get the margin (aka perimeter)
|
||||
static inline uint32_t get_margin(const SkIRect& rect) {
|
||||
return 2 * (rect.width() + rect.height());
|
||||
}
|
||||
|
||||
static inline uint32_t get_overlap_increase(const SkIRect& rect1, const SkIRect& rect2,
|
||||
SkIRect expandBy) {
|
||||
join_no_empty_check(rect1, &expandBy);
|
||||
return get_overlap(expandBy, rect2) - get_overlap(rect1, rect2);
|
||||
}
|
||||
|
||||
static inline uint32_t get_area_increase(const SkIRect& rect1, SkIRect rect2) {
|
||||
join_no_empty_check(rect1, &rect2);
|
||||
return get_area(rect2) - get_area(rect1);
|
||||
}
|
||||
|
||||
// Expand 'out' to include 'joinWith'
|
||||
static inline void join_no_empty_check(const SkIRect& joinWith, SkIRect* out) {
|
||||
// since we check for empty bounds on insert, we know we'll never have empty rects
|
||||
// and we can save the empty check that SkIRect::join requires
|
||||
if (joinWith.fLeft < out->fLeft) { out->fLeft = joinWith.fLeft; }
|
||||
if (joinWith.fTop < out->fTop) { out->fTop = joinWith.fTop; }
|
||||
if (joinWith.fRight > out->fRight) { out->fRight = joinWith.fRight; }
|
||||
if (joinWith.fBottom > out->fBottom) { out->fBottom = joinWith.fBottom; }
|
||||
}
|
||||
|
||||
177
src/core/SkRTree.h
Normal file
177
src/core/SkRTree.h
Normal file
@ -0,0 +1,177 @@
|
||||
|
||||
/*
|
||||
* Copyright 2012 Google Inc.
|
||||
*
|
||||
* Use of this source code is governed by a BSD-style license that can be
|
||||
* found in the LICENSE file.
|
||||
*/
|
||||
|
||||
#ifndef SkRTree_DEFINED
|
||||
#define SkRTree_DEFINED
|
||||
|
||||
#include "SkRect.h"
|
||||
#include "SkTDArray.h"
|
||||
#include "SkChunkAlloc.h"
|
||||
#include "SkBBoxHierarchy.h"
|
||||
|
||||
/**
|
||||
* An R-Tree implementation. In short, it is a balanced n-ary tree containing a hierarchy of
|
||||
* bounding rectangles.
|
||||
*
|
||||
* Much like a B-Tree it maintains balance by enforcing minimum and maximum child counts, and
|
||||
* splitting nodes when they become overfull. Unlike B-trees, however, we're using spatial data; so
|
||||
* there isn't a canonical ordering to use when choosing insertion locations and splitting
|
||||
* distributions. A variety of heuristics have been proposed for these problems; here, we're using
|
||||
* something resembling an R*-tree, which attempts to minimize area and overlap during insertion,
|
||||
* and aims to minimize a combination of margin, overlap, and area when splitting.
|
||||
*
|
||||
* One detail that is thus far unimplemented that may improve tree quality is attempting to remove
|
||||
* and reinsert nodes when they become full, instead of immediately splitting (nodes that may have
|
||||
* been placed well early on may hurt the tree later when more nodes have been added; removing
|
||||
* and reinserting nodes generally helps reduce overlap and make a better tree). Deletion of nodes
|
||||
* is also unimplemented.
|
||||
*
|
||||
* For more details see:
|
||||
*
|
||||
* Beckmann, N.; Kriegel, H. P.; Schneider, R.; Seeger, B. (1990). "The R*-tree:
|
||||
* an efficient and robust access method for points and rectangles"
|
||||
*
|
||||
* It also supports bulk-loading from a batch of bounds and values; if you don't require the tree
|
||||
* to be usable in its intermediate states while it is being constructed, this is significantly
|
||||
* quicker than individual insertions and produces more consistent trees.
|
||||
*/
|
||||
class SkRTree : public SkBBoxHierarchy {
|
||||
public:
|
||||
|
||||
/**
|
||||
* Create a new R-Tree with specified min/max child counts.
|
||||
* The child counts are valid iff:
|
||||
* - (max + 1) / 2 >= min (splitting an overfull node must be enough to populate 2 nodes)
|
||||
* - min < max
|
||||
* - min > 0
|
||||
* - max < SK_MaxU16
|
||||
*/
|
||||
static SkRTree* Create(int minChildren, int maxChildren);
|
||||
virtual ~SkRTree();
|
||||
|
||||
/**
|
||||
* Insert a node, consisting of bounds and a data value into the tree, if we don't immediately
|
||||
* need to use the tree; we may allow the insert to be deferred (this can allow us to bulk-load
|
||||
* a large batch of nodes at once, which tends to be faster and produce a better tree).
|
||||
* @param data The data value
|
||||
* @param bounds The corresponding bounding box
|
||||
* @param defer Can this insert be deferred? (this may be ignored)
|
||||
*/
|
||||
virtual void insert(void* data, const SkIRect& bounds, bool defer = false);
|
||||
|
||||
/**
|
||||
* If any inserts have been deferred, this will add them into the tree
|
||||
*/
|
||||
virtual void flushDeferredInserts();
|
||||
|
||||
/**
|
||||
* Given a query rectangle, populates the passed-in array with the elements it intersects
|
||||
*/
|
||||
virtual void search(const SkIRect& query, SkTDArray<void*>* results);
|
||||
|
||||
virtual void clear();
|
||||
bool isEmpty() const { return 0 == fCount; }
|
||||
int getDepth() const { return this->isEmpty() ? 0 : fRoot.fChild.subtree->fLevel + 1; }
|
||||
|
||||
/**
|
||||
* This gets the insertion count (rather than the node count)
|
||||
*/
|
||||
virtual int getCount() const { return fCount; }
|
||||
|
||||
private:
|
||||
|
||||
struct Node;
|
||||
|
||||
/**
|
||||
* A branch of the tree, this may contain a pointer to another interior node, or a data value
|
||||
*/
|
||||
struct Branch {
|
||||
union {
|
||||
Node* subtree;
|
||||
void* data;
|
||||
} fChild;
|
||||
SkIRect fBounds;
|
||||
};
|
||||
|
||||
/**
|
||||
* A node in the tree, has between fMinChildren and fMaxChildren (the root is a special case)
|
||||
*/
|
||||
struct Node {
|
||||
uint16_t fNumChildren;
|
||||
uint16_t fLevel;
|
||||
bool isLeaf() { return 0 == fLevel; }
|
||||
// Since we want to be able to pick min/max child counts at runtime, we assume the creator
|
||||
// has allocated sufficient space directly after us in memory, and index into that space
|
||||
Branch* child(size_t index) {
|
||||
return reinterpret_cast<Branch*>(this + 1) + index;
|
||||
}
|
||||
};
|
||||
|
||||
typedef int32_t SkIRect::*SortSide;
|
||||
|
||||
// Helper for sorting our children arrays by sides of their rects
|
||||
static bool RectLessThan(SortSide const& side, const Branch lhs, const Branch rhs) {
|
||||
return lhs.fBounds.*side < rhs.fBounds.*side;
|
||||
}
|
||||
|
||||
static bool RectLessX(int&, const Branch lhs, const Branch rhs) {
|
||||
return ((lhs.fBounds.fRight - lhs.fBounds.fLeft) >> 1) <
|
||||
((rhs.fBounds.fRight - lhs.fBounds.fLeft) >> 1);
|
||||
}
|
||||
|
||||
static bool RectLessY(int&, const Branch lhs, const Branch rhs) {
|
||||
return ((lhs.fBounds.fBottom - lhs.fBounds.fTop) >> 1) <
|
||||
((rhs.fBounds.fBottom - lhs.fBounds.fTop) >> 1);
|
||||
}
|
||||
|
||||
SkRTree(int minChildren, int maxChildren);
|
||||
|
||||
/**
|
||||
* Recursively descend the tree to find an insertion position for 'branch', updates
|
||||
* bounding boxes on the way up.
|
||||
*/
|
||||
Branch* insert(Node* root, Branch* branch, uint16_t level = 0);
|
||||
|
||||
int chooseSubtree(Node* root, Branch* branch);
|
||||
SkIRect computeBounds(Node* n);
|
||||
int distributeChildren(Branch* children);
|
||||
void search(Node* root, const SkIRect query, SkTDArray<void*>* results) const;
|
||||
|
||||
/**
|
||||
* This performs a bottom-up bulk load using the STR (sort-tile-recursive) algorithm, this
|
||||
* seems to generally produce better, more consistent trees at significantly lower cost than
|
||||
* repeated insertions.
|
||||
*
|
||||
* This consumes the input array.
|
||||
*
|
||||
* TODO: Experiment with other bulk-load algorithms (in particular the Hilbert pack variant,
|
||||
* which groups rects by position on the Hilbert curve, is probably worth a look). There also
|
||||
* exist top-down bulk load variants (VAMSplit, TopDownGreedy, etc).
|
||||
*/
|
||||
Branch bulkLoad(SkTDArray<Branch>* branches, int level = 0);
|
||||
|
||||
void validate();
|
||||
int validateSubtree(Node* root, SkIRect bounds, bool isRoot = false);
|
||||
|
||||
const int fMinChildren;
|
||||
const int fMaxChildren;
|
||||
const size_t fNodeSize;
|
||||
|
||||
// This is the count of data elements (rather than total nodes in the tree)
|
||||
size_t fCount;
|
||||
|
||||
Branch fRoot;
|
||||
SkChunkAlloc fNodes;
|
||||
SkTDArray<Branch> fDeferredInserts;
|
||||
|
||||
Node* allocateNode(uint16_t level);
|
||||
|
||||
};
|
||||
|
||||
#endif
|
||||
|
||||
144
tests/RTreeTest.cpp
Normal file
144
tests/RTreeTest.cpp
Normal file
@ -0,0 +1,144 @@
|
||||
|
||||
/*
|
||||
* Copyright 2012 Google Inc.
|
||||
*
|
||||
* Use of this source code is governed by a BSD-style license that can be
|
||||
* found in the LICENSE file.
|
||||
*/
|
||||
|
||||
#include "Test.h"
|
||||
#include "SkRandom.h"
|
||||
#include "SkRTree.h"
|
||||
#include "SkTSort.h"
|
||||
|
||||
static const size_t MIN_CHILDREN = 6;
|
||||
static const size_t MAX_CHILDREN = 11;
|
||||
|
||||
static const size_t NUM_RECTS = 200;
|
||||
static const size_t NUM_ITERATIONS = 100;
|
||||
static const size_t NUM_QUERIES = 50;
|
||||
|
||||
struct DataRect {
|
||||
SkIRect rect;
|
||||
void* data;
|
||||
};
|
||||
|
||||
static SkIRect random_rect(SkRandom& rand) {
|
||||
SkIRect rect = {0,0,0,0};
|
||||
while (rect.isEmpty()) {
|
||||
rect.fLeft = rand.nextS() % 1000;
|
||||
rect.fRight = rand.nextS() % 1000;
|
||||
rect.fTop = rand.nextS() % 1000;
|
||||
rect.fBottom = rand.nextS() % 1000;
|
||||
rect.sort();
|
||||
}
|
||||
return rect;
|
||||
}
|
||||
|
||||
static void random_data_rects(SkRandom& rand, DataRect out[], int n) {
|
||||
for (int i = 0; i < n; ++i) {
|
||||
out[i].rect = random_rect(rand);
|
||||
out[i].data = reinterpret_cast<void*>(i);
|
||||
}
|
||||
}
|
||||
|
||||
static bool verify_query(SkIRect query, DataRect rects[],
|
||||
SkTDArray<void*>& found) {
|
||||
SkTDArray<void*> expected;
|
||||
// manually intersect with every rectangle
|
||||
for (int i = 0; i < NUM_RECTS; ++i) {
|
||||
if (SkIRect::IntersectsNoEmptyCheck(query, rects[i].rect)) {
|
||||
expected.push(rects[i].data);
|
||||
}
|
||||
}
|
||||
|
||||
if (expected.count() != found.count()) {
|
||||
return false;
|
||||
}
|
||||
|
||||
if (0 == expected.count()) {
|
||||
return true;
|
||||
}
|
||||
|
||||
// Just cast to long since sorting by the value of the void*'s was being problematic...
|
||||
SkTQSort(reinterpret_cast<long*>(expected.begin()),
|
||||
reinterpret_cast<long*>(expected.end() - 1));
|
||||
SkTQSort(reinterpret_cast<long*>(found.begin()),
|
||||
reinterpret_cast<long*>(found.end() - 1));
|
||||
return found == expected;
|
||||
}
|
||||
|
||||
static void runQueries(skiatest::Reporter* reporter, SkRandom& rand, DataRect rects[],
|
||||
SkRTree& tree) {
|
||||
for (int i = 0; i < NUM_QUERIES; ++i) {
|
||||
SkTDArray<void*> hits;
|
||||
SkIRect query = random_rect(rand);
|
||||
tree.search(query, &hits);
|
||||
REPORTER_ASSERT(reporter, verify_query(query, rects, hits));
|
||||
}
|
||||
}
|
||||
|
||||
static void TestRTree(skiatest::Reporter* reporter) {
|
||||
DataRect rects[NUM_RECTS];
|
||||
SkRandom rand;
|
||||
SkRTree* rtree = SkRTree::Create(MIN_CHILDREN, MAX_CHILDREN);
|
||||
REPORTER_ASSERT(reporter, NULL != rtree);
|
||||
|
||||
int expectedDepthMin = -1;
|
||||
int expectedDepthMax = -1;
|
||||
|
||||
int tmp = NUM_RECTS;
|
||||
while (tmp > 0) {
|
||||
tmp -= static_cast<int>(pow(static_cast<double>(MAX_CHILDREN),
|
||||
static_cast<double>(expectedDepthMin + 1)));
|
||||
++expectedDepthMin;
|
||||
}
|
||||
|
||||
tmp = NUM_RECTS;
|
||||
while (tmp > 0) {
|
||||
tmp -= static_cast<int>(pow(static_cast<double>(MIN_CHILDREN),
|
||||
static_cast<double>(expectedDepthMax + 1)));
|
||||
++expectedDepthMax;
|
||||
}
|
||||
|
||||
for (int i = 0; i < NUM_ITERATIONS; ++i) {
|
||||
random_data_rects(rand, rects, NUM_RECTS);
|
||||
|
||||
// First try bulk-loaded inserts
|
||||
for (int i = 0; i < NUM_RECTS; ++i) {
|
||||
rtree->insert(rects[i].data, rects[i].rect, true);
|
||||
}
|
||||
rtree->flushDeferredInserts();
|
||||
runQueries(reporter, rand, rects, *rtree);
|
||||
REPORTER_ASSERT(reporter, NUM_RECTS == rtree->getCount());
|
||||
REPORTER_ASSERT(reporter, expectedDepthMin <= rtree->getDepth() &&
|
||||
expectedDepthMax >= rtree->getDepth());
|
||||
rtree->clear();
|
||||
REPORTER_ASSERT(reporter, 0 == rtree->getCount());
|
||||
|
||||
// Then try immediate inserts
|
||||
for (int i = 0; i < NUM_RECTS; ++i) {
|
||||
rtree->insert(rects[i].data, rects[i].rect);
|
||||
}
|
||||
runQueries(reporter, rand, rects, *rtree);
|
||||
REPORTER_ASSERT(reporter, NUM_RECTS == rtree->getCount());
|
||||
REPORTER_ASSERT(reporter, expectedDepthMin <= rtree->getDepth() &&
|
||||
expectedDepthMax >= rtree->getDepth());
|
||||
rtree->clear();
|
||||
REPORTER_ASSERT(reporter, 0 == rtree->getCount());
|
||||
|
||||
// And for good measure try immediate inserts, but in reversed order
|
||||
for (int i = NUM_RECTS - 1; i >= 0; --i) {
|
||||
rtree->insert(rects[i].data, rects[i].rect);
|
||||
}
|
||||
runQueries(reporter, rand, rects, *rtree);
|
||||
REPORTER_ASSERT(reporter, NUM_RECTS == rtree->getCount());
|
||||
REPORTER_ASSERT(reporter, expectedDepthMin <= rtree->getDepth() &&
|
||||
expectedDepthMax >= rtree->getDepth());
|
||||
rtree->clear();
|
||||
REPORTER_ASSERT(reporter, 0 == rtree->getCount());
|
||||
}
|
||||
}
|
||||
|
||||
#include "TestClassDef.h"
|
||||
DEFINE_TESTCLASS("RTree", RTreeTestClass, TestRTree)
|
||||
Loading…
Reference in New Issue
Block a user