bool SkBitmapProcState::possiblyScaleImage() {
SkASSERT(NULL == fBitmap);
fAdjustedMatrix = false;
if (fFilterLevel <= SkPaint::kLow_FilterLevel) {
return false;
}
// Check to see if the transformation matrix is simple, and if we're
// doing high quality scaling. If so, do the bitmap scale here and
// remove the (non-fractional) scaling component from the matrix.
SkScalar invScaleX = fInvMatrix.getScaleX();
SkScalar invScaleY = fInvMatrix.getScaleY();
float trueDestWidth = fOrigBitmap.width() / invScaleX;
float trueDestHeight = fOrigBitmap.height() / invScaleY;
#ifndef SK_IGNORE_PROPER_FRACTIONAL_SCALING
float roundedDestWidth = SkScalarRoundToScalar(trueDestWidth);
float roundedDestHeight = SkScalarRoundToScalar(trueDestHeight);
#else
float roundedDestWidth = trueDestWidth;
float roundedDestHeight = trueDestHeight;
#endif
if (SkPaint::kHigh_FilterLevel == fFilterLevel &&
fInvMatrix.getType() <= (SkMatrix::kScale_Mask | SkMatrix::kTranslate_Mask) &&
kN32_SkColorType == fOrigBitmap.colorType() &&
cache_size_okay(fOrigBitmap, fInvMatrix)) {
if (SkScalarNearlyEqual(invScaleX,1.0f) &&
SkScalarNearlyEqual(invScaleY,1.0f)) {
// short-circuit identity scaling; the output is supposed to
// be the same as the input, so we might as well go fast.
// Note(humper): We could also probably do this if the scales
// are close to -1 as well, since the flip doesn't require
// any fancy re-sampling...
// Set our filter level to low -- the only post-filtering this
// image might require is some interpolation if the translation
// is fractional.
fFilterLevel = SkPaint::kLow_FilterLevel;
return false;
}
if (!SkBitmapCache::Find(fOrigBitmap, roundedDestWidth, roundedDestHeight, &fScaledBitmap)) {
// All the criteria are met; let's make a new bitmap.
if (!SkBitmapScaler::Resize(&fScaledBitmap,
fOrigBitmap,
SkBitmapScaler::RESIZE_BEST,
roundedDestWidth,
roundedDestHeight,
SkResourceCache::GetAllocator())) {
// we failed to create fScaledBitmap, so just return and let
// the scanline proc handle it.
return false;
}
SkASSERT(fScaledBitmap.getPixels());
fScaledBitmap.setImmutable();
SkBitmapCache::Add(fOrigBitmap, roundedDestWidth, roundedDestHeight, fScaledBitmap);
}
SkASSERT(fScaledBitmap.getPixels());
fBitmap = &fScaledBitmap;
// set the inv matrix type to translate-only;
fInvMatrix.setTranslate(fInvMatrix.getTranslateX() / fInvMatrix.getScaleX(),
fInvMatrix.getTranslateY() / fInvMatrix.getScaleY());
#ifndef SK_IGNORE_PROPER_FRACTIONAL_SCALING
// reintroduce any fractional scaling missed by our integral scale done above.
float fractionalScaleX = roundedDestWidth/trueDestWidth;
float fractionalScaleY = roundedDestHeight/trueDestHeight;
fInvMatrix.postScale(fractionalScaleX, fractionalScaleY);
#endif
fAdjustedMatrix = true;
// Set our filter level to low -- the only post-filtering this
// image might require is some interpolation if the translation
// is fractional or if there's any remaining scaling to be done.
fFilterLevel = SkPaint::kLow_FilterLevel;
return true;
}
/*
* If High, then our special-case for scale-only did not take, and so we
* have to make a choice:
* 1. fall back on mipmaps + bilerp
* 2. fall back on scanline bicubic filter
* For now, we compute the "scale" value from the matrix, and have a
* threshold to decide when bicubic is better, and when mips are better.
* No doubt a fancier decision tree could be used uere.
*
* If Medium, then we just try to build a mipmap and select a level,
* setting the filter-level to kLow to signal that we just need bilerp
* to process the selected level.
*/
SkScalar scaleSqd = effective_matrix_scale_sqrd(fInvMatrix);
if (SkPaint::kHigh_FilterLevel == fFilterLevel) {
// Set the limit at 0.25 for the CTM... if the CTM is scaling smaller
// than this, then the mipmaps quality may be greater (certainly faster)
// so we only keep High quality if the scale is greater than this.
//
// Since we're dealing with the inverse, we compare against its inverse.
const SkScalar bicubicLimit = 4.0f;
const SkScalar bicubicLimitSqd = bicubicLimit * bicubicLimit;
if (scaleSqd < bicubicLimitSqd) { // use bicubic scanline
return false;
}
// else set the filter-level to Medium, since we're scaling down and
// want to reqeust mipmaps
fFilterLevel = SkPaint::kMedium_FilterLevel;
}
SkASSERT(SkPaint::kMedium_FilterLevel == fFilterLevel);
/**
* Medium quality means use a mipmap for down-scaling, and just bilper
* for upscaling. Since we're examining the inverse matrix, we look for
* a scale > 1 to indicate down scaling by the CTM.
*/
if (scaleSqd > SK_Scalar1) {
fCurrMip.reset(SkMipMapCache::FindAndRef(fOrigBitmap));
if (NULL == fCurrMip.get()) {
fCurrMip.reset(SkMipMap::Build(fOrigBitmap));
if (NULL == fCurrMip.get()) {
return false;
}
SkMipMapCache::Add(fOrigBitmap, fCurrMip);
}
SkScalar levelScale = SkScalarInvert(SkScalarSqrt(scaleSqd));
SkMipMap::Level level;
if (fCurrMip->extractLevel(levelScale, &level)) {
SkScalar invScaleFixup = level.fScale;
fInvMatrix.postScale(invScaleFixup, invScaleFixup);
const SkImageInfo info = fOrigBitmap.info().makeWH(level.fWidth, level.fHeight);
// todo: if we could wrap the fCurrMip in a pixelref, then we could just install
// that here, and not need to explicitly track it ourselves.
fScaledBitmap.installPixels(info, level.fPixels, level.fRowBytes);
fBitmap = &fScaledBitmap;
fFilterLevel = SkPaint::kLow_FilterLevel;
return true;
}
}
return false;
}
bool SkBitmapProcState::possiblyScaleImage() {
AutoScaledCacheUnlocker unlocker(&fScaledCacheID);
SkASSERT(NULL == fBitmap);
SkASSERT(NULL == fScaledCacheID);
if (fFilterLevel <= SkPaint::kLow_FilterLevel) {
return false;
}
// Check to see if the transformation matrix is simple, and if we're
// doing high quality scaling. If so, do the bitmap scale here and
// remove the scaling component from the matrix.
if (SkPaint::kHigh_FilterLevel == fFilterLevel &&
fInvMatrix.getType() <= (SkMatrix::kScale_Mask | SkMatrix::kTranslate_Mask) &&
kN32_SkColorType == fOrigBitmap.colorType() &&
cache_size_okay(fOrigBitmap, fInvMatrix)) {
SkScalar invScaleX = fInvMatrix.getScaleX();
SkScalar invScaleY = fInvMatrix.getScaleY();
fScaledCacheID = SkScaledImageCache::FindAndLock(fOrigBitmap,
invScaleX, invScaleY,
&fScaledBitmap);
if (fScaledCacheID) {
fScaledBitmap.lockPixels();
if (!fScaledBitmap.getPixels()) {
fScaledBitmap.unlockPixels();
// found a purged entry (discardablememory?), release it
SkScaledImageCache::Unlock(fScaledCacheID);
fScaledCacheID = NULL;
// fall through to rebuild
}
}
if (NULL == fScaledCacheID) {
float dest_width = fOrigBitmap.width() / invScaleX;
float dest_height = fOrigBitmap.height() / invScaleY;
// All the criteria are met; let's make a new bitmap.
if (!SkBitmapScaler::Resize(&fScaledBitmap,
fOrigBitmap,
SkBitmapScaler::RESIZE_BEST,
dest_width,
dest_height,
SkScaledImageCache::GetAllocator())) {
// we failed to create fScaledBitmap, so just return and let
// the scanline proc handle it.
return false;
}
SkASSERT(NULL != fScaledBitmap.getPixels());
fScaledCacheID = SkScaledImageCache::AddAndLock(fOrigBitmap,
invScaleX,
invScaleY,
fScaledBitmap);
if (!fScaledCacheID) {
fScaledBitmap.reset();
return false;
}
SkASSERT(NULL != fScaledBitmap.getPixels());
}
SkASSERT(NULL != fScaledBitmap.getPixels());
fBitmap = &fScaledBitmap;
// set the inv matrix type to translate-only;
fInvMatrix.setTranslate(fInvMatrix.getTranslateX() / fInvMatrix.getScaleX(),
fInvMatrix.getTranslateY() / fInvMatrix.getScaleY());
// no need for any further filtering; we just did it!
fFilterLevel = SkPaint::kNone_FilterLevel;
unlocker.release();
return true;
}
/*
* If High, then our special-case for scale-only did not take, and so we
* have to make a choice:
* 1. fall back on mipmaps + bilerp
* 2. fall back on scanline bicubic filter
* For now, we compute the "scale" value from the matrix, and have a
* threshold to decide when bicubic is better, and when mips are better.
* No doubt a fancier decision tree could be used uere.
*
* If Medium, then we just try to build a mipmap and select a level,
* setting the filter-level to kLow to signal that we just need bilerp
* to process the selected level.
*/
SkScalar scaleSqd = effective_matrix_scale_sqrd(fInvMatrix);
if (SkPaint::kHigh_FilterLevel == fFilterLevel) {
// Set the limit at 0.25 for the CTM... if the CTM is scaling smaller
// than this, then the mipmaps quality may be greater (certainly faster)
// so we only keep High quality if the scale is greater than this.
//
// Since we're dealing with the inverse, we compare against its inverse.
const SkScalar bicubicLimit = 4.0f;
const SkScalar bicubicLimitSqd = bicubicLimit * bicubicLimit;
if (scaleSqd < bicubicLimitSqd) { // use bicubic scanline
return false;
}
// else set the filter-level to Medium, since we're scaling down and
// want to reqeust mipmaps
fFilterLevel = SkPaint::kMedium_FilterLevel;
}
SkASSERT(SkPaint::kMedium_FilterLevel == fFilterLevel);
/**
* Medium quality means use a mipmap for down-scaling, and just bilper
* for upscaling. Since we're examining the inverse matrix, we look for
* a scale > 1 to indicate down scaling by the CTM.
*/
if (scaleSqd > SK_Scalar1) {
const SkMipMap* mip = NULL;
SkASSERT(NULL == fScaledCacheID);
fScaledCacheID = SkScaledImageCache::FindAndLockMip(fOrigBitmap, &mip);
if (!fScaledCacheID) {
SkASSERT(NULL == mip);
mip = SkMipMap::Build(fOrigBitmap);
if (mip) {
fScaledCacheID = SkScaledImageCache::AddAndLockMip(fOrigBitmap,
mip);
SkASSERT(mip->getRefCnt() > 1);
mip->unref(); // the cache took a ref
SkASSERT(fScaledCacheID);
}
} else {
SkASSERT(mip);
}
if (mip) {
SkScalar levelScale = SkScalarInvert(SkScalarSqrt(scaleSqd));
SkMipMap::Level level;
if (mip->extractLevel(levelScale, &level)) {
SkScalar invScaleFixup = level.fScale;
fInvMatrix.postScale(invScaleFixup, invScaleFixup);
SkImageInfo info = fOrigBitmap.info();
info.fWidth = level.fWidth;
info.fHeight = level.fHeight;
fScaledBitmap.installPixels(info, level.fPixels, level.fRowBytes);
fBitmap = &fScaledBitmap;
fFilterLevel = SkPaint::kLow_FilterLevel;
unlocker.release();
return true;
}
}
}
return false;
}
