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Add optional aspect ratio parameter to R-Tree, this helps the bulk load algorithm create more square tiles.

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Review URL: https://codereview.appspot.com/6489102

git-svn-id: http://skia.googlecode.com/svn/trunk@5466 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
rileya@google.com 2012-09-10 17:31:05 +00:00
parent 10ef79ec95
commit b839f0f6a9
2 changed files with 18 additions and 10 deletions
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20
src/core/SkRTree.cpp
View File

@ -19,20 +19,21 @@ static inline void join_no_empty_check(const SkIRect& joinWith, SkIRect* out);
///////////////////////////////////////////////////////////////////////////////////////////////////
SkRTree* SkRTree::Create(int minChildren, int maxChildren) {
SkRTree* SkRTree::Create(int minChildren, int maxChildren, SkScalar aspectRatio) {
if (minChildren < maxChildren && (maxChildren + 1) / 2 >= minChildren &&
minChildren > 0 && maxChildren < static_cast<int>(SK_MaxU16)) {
return new SkRTree(minChildren, maxChildren);
return new SkRTree(minChildren, maxChildren, aspectRatio);
}
return NULL;
}
SkRTree::SkRTree(int minChildren, int maxChildren)
SkRTree::SkRTree(int minChildren, int maxChildren, SkScalar aspectRatio)
: fMinChildren(minChildren)
, fMaxChildren(maxChildren)
, fNodeSize(sizeof(Node) + sizeof(Branch) * maxChildren)
, fCount(0)
, fNodes(fNodeSize * 256) {
, fNodes(fNodeSize * 256)
, fAspectRatio(aspectRatio) {
SkASSERT(minChildren < maxChildren && minChildren > 0 && maxChildren <
static_cast<int>(SK_MaxU16));
SkASSERT((maxChildren + 1) / 2 >= minChildren);
@ -339,13 +340,16 @@ SkRTree::Branch SkRTree::bulkLoad(SkTDArray<Branch>* branches, int level) {
}
}
int numStrips = SkScalarCeil(SkScalarSqrt(SkIntToScalar(numBranches)));
int numStrips = SkScalarCeil(SkScalarSqrt(SkIntToScalar(numBranches) *
SkScalarInvert(fAspectRatio)));
int numTiles = SkScalarCeil(SkScalarSqrt(SkIntToScalar(numBranches) /
SkIntToScalar(numStrips)));
int currentBranch = 0;
for (int i = 0; i < numStrips; ++i) {
int begin = currentBranch;
int end = currentBranch + numStrips * fMaxChildren - SkMin32(remainder,
(fMaxChildren - fMinChildren) * numStrips);
int end = currentBranch + numTiles * fMaxChildren - SkMin32(remainder,
(fMaxChildren - fMinChildren) * numTiles);
if (end > branches->count()) {
end = branches->count();
}
@ -354,7 +358,7 @@ SkRTree::Branch SkRTree::bulkLoad(SkTDArray<Branch>* branches, int level) {
SkQSort<int, Branch>(level, branches->begin() + begin, branches->begin() + end - 1,
&RectLessX);
for (int j = 0; j < numStrips && currentBranch < branches->count(); ++j) {
for (int j = 0; j < numTiles && currentBranch < branches->count(); ++j) {
int incrementBy = fMaxChildren;
if (remainder != 0) {
// if need be, omit some nodes to make up for remainder

8
src/core/SkRTree.h
View File

@ -50,8 +50,11 @@ public:
* - min < max
* - min > 0
* - max < SK_MaxU16
* If you have some prior information about the distribution of bounds you're expecting, you
* can provide an optional aspect ratio parameter. This allows the bulk-load algorithm to create
* better proportioned tiles of rectangles.
*/
static SkRTree* Create(int minChildren, int maxChildren);
static SkRTree* Create(int minChildren, int maxChildren, SkScalar aspectRatio = 1);
virtual ~SkRTree();
/**
@ -129,7 +132,7 @@ private:
((rhs.fBounds.fBottom - lhs.fBounds.fTop) >> 1);
}
SkRTree(int minChildren, int maxChildren);
SkRTree(int minChildren, int maxChildren, SkScalar aspectRatio);
/**
* Recursively descend the tree to find an insertion position for 'branch', updates
@ -168,6 +171,7 @@ private:
Branch fRoot;
SkChunkAlloc fNodes;
SkTDArray<Branch> fDeferredInserts;
SkScalar fAspectRatio;
Node* allocateNode(uint16_t level);