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GPU blit speedup: avoid texture filtering and texture domain when not necessary

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BUG=crbug.com/102284
REVIEW=http://codereview.appspot.com/5836047/
TEST=code path already covered by gm/nocolorbleed gm/bitmapfilters and others



git-svn-id: http://skia.googlecode.com/svn/trunk@3421 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
junov@chromium.org 2012-03-16 20:54:17 +00:00
parent 293a758929
commit f32a9b60ff
1 changed files with 78 additions and 8 deletions
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86
src/gpu/SkGpuDevice.cpp
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@ -55,6 +55,10 @@ enum {
// point we should probably get rid of these scaling constants and rebaseline
// all the blur tests.
#define BLUR_SIGMA_SCALE 0.6f
// This constant represents the screen alignment criterion in texels for
// requiring texture domain clamping to prevent color bleeding when drawing
// a sub region of a larger source image.
#define COLOR_BLEED_TOLERANCE SkFloatToScalar(0.001f)
///////////////////////////////////////////////////////////////////////////////
class SkGpuDevice::SkAutoCachedTexture : public ::SkNoncopyable {
@ -1254,6 +1258,49 @@ void SkGpuDevice::drawBitmap(const SkDraw& draw,
}
}
namespace {
bool hasAlignedSamples(const SkRect& srcRect, const SkRect& transformedRect) {
// detect pixel disalignment
if (SkScalarAbs(SkScalarRoundToScalar(transformedRect.left()) -
transformedRect.left()) < COLOR_BLEED_TOLERANCE &&
SkScalarAbs(SkScalarRoundToScalar(transformedRect.top()) -
transformedRect.top()) < COLOR_BLEED_TOLERANCE &&
SkScalarAbs(transformedRect.width() - srcRect.width()) <
COLOR_BLEED_TOLERANCE &&
SkScalarAbs(transformedRect.height() - srcRect.height()) <
COLOR_BLEED_TOLERANCE) {
return true;
}
return false;
}
bool mayColorBleed(const SkRect& srcRect, const SkRect& transformedRect,
const SkMatrix& m) {
// Only gets called if hasAlignedSamples returned false.
// So we can assume that sampling is axis aligned but not texel aligned.
GrAssert(!hasAlignedSamples(srcRect, transformedRect));
SkRect innerSrcRect(srcRect), innerTransformedRect,
outerTransformedRect(transformedRect);
innerSrcRect.inset(SK_ScalarHalf, SK_ScalarHalf);
m.mapRect(&innerTransformedRect, innerSrcRect);
// The gap between outerTransformedRect and innerTransformedRect
// represents the projection of the source border area, which is
// problematic for color bleeding. We must check whether any
// destination pixels sample the border area.
outerTransformedRect.inset(COLOR_BLEED_TOLERANCE, COLOR_BLEED_TOLERANCE);
innerTransformedRect.outset(COLOR_BLEED_TOLERANCE, COLOR_BLEED_TOLERANCE);
SkIRect outer, inner;
outerTransformedRect.round(&outer);
innerTransformedRect.round(&inner);
// If the inner and outer rects round to the same result, it means the
// border does not overlap any pixel centers. Yay!
return inner != outer;
}
} // unnamed namespace
/*
* This is called by drawBitmap(), which has to handle images that may be too
* large to be represented by a single texture.
@ -1300,11 +1347,35 @@ void SkGpuDevice::internalDrawBitmap(const SkDraw& draw,
SkFloatToScalar(srcRect.fRight * wInv),
SkFloatToScalar(srcRect.fBottom * hInv));
if (GrSamplerState::kNearest_Filter != sampler->getFilter() &&
(srcRect.width() < bitmap.width() ||
srcRect.height() < bitmap.height())) {
// If drawing a subrect of the bitmap and filtering is enabled,
// use a constrained texture domain to avoid color bleeding
bool needsTextureDomain = false;
if (GrSamplerState::kBilinear_Filter == sampler->getFilter())
{
// Need texture domain if drawing a sub rect.
needsTextureDomain = srcRect.width() < bitmap.width() ||
srcRect.height() < bitmap.height();
if (m.rectStaysRect() && draw.fMatrix->rectStaysRect()) {
// sampling is axis-aligned
GrRect floatSrcRect, transformedRect;
floatSrcRect.set(srcRect);
SkMatrix srcToDeviceMatrix(m);
srcToDeviceMatrix.postConcat(*draw.fMatrix);
srcToDeviceMatrix.mapRect(&transformedRect, floatSrcRect);
if (hasAlignedSamples(floatSrcRect, transformedRect)) {
// Samples are texel-aligned, so filtering is futile
sampler->setFilter(GrSamplerState::kNearest_Filter);
needsTextureDomain = false;
} else {
needsTextureDomain = needsTextureDomain &&
mayColorBleed(floatSrcRect, transformedRect, m);
}
}
}
GrRect textureDomain = GrRect::MakeEmpty();
if (needsTextureDomain) {
// Use a constrained texture domain to avoid color bleeding
GrScalar left, top, right, bottom;
if (srcRect.width() > 1) {
GrScalar border = GR_ScalarHalf / bitmap.width();
@ -1320,10 +1391,9 @@ void SkGpuDevice::internalDrawBitmap(const SkDraw& draw,
} else {
top = bottom = GrScalarHalf(paintRect.top() + paintRect.bottom());
}
GrRect textureDomain;
textureDomain.setLTRB(left, top, right, bottom);
sampler->setTextureDomain(textureDomain);
textureDomain.setLTRB(left, top, right, bottom);
}
sampler->setTextureDomain(textureDomain);
fContext->drawRectToRect(*grPaint, dstRect, paintRect, &m);
}