bool GrDrawTarget::setupDstReadIfNecessary(const GrPipelineBuilder& pipelineBuilder,
const GrPipelineOptimizations& optimizations,
GrXferProcessor::DstTexture* dstTexture,
const SkRect& batchBounds) {
SkRect bounds = batchBounds;
bounds.outset(0.5f, 0.5f);
if (!pipelineBuilder.willXPNeedDstTexture(*this->caps(), optimizations)) {
return true;
}
GrRenderTarget* rt = pipelineBuilder.getRenderTarget();
if (this->caps()->textureBarrierSupport()) {
if (GrTexture* rtTex = rt->asTexture()) {
// The render target is a texture, so we can read from it directly in the shader. The XP
// will be responsible to detect this situation and request a texture barrier.
dstTexture->setTexture(rtTex);
dstTexture->setOffset(0, 0);
return true;
}
}
SkIRect copyRect;
pipelineBuilder.clip().getConservativeBounds(rt->width(), rt->height(), ©Rect);
SkIRect drawIBounds;
bounds.roundOut(&drawIBounds);
if (!copyRect.intersect(drawIBounds)) {
#ifdef SK_DEBUG
GrCapsDebugf(this->caps(), "Missed an early reject. "
"Bailing on draw from setupDstReadIfNecessary.\n");
#endif
return false;
}
// MSAA consideration: When there is support for reading MSAA samples in the shader we could
// have per-sample dst values by making the copy multisampled.
GrSurfaceDesc desc;
if (!fGpu->initCopySurfaceDstDesc(rt, &desc)) {
desc.fOrigin = kDefault_GrSurfaceOrigin;
desc.fFlags = kRenderTarget_GrSurfaceFlag;
desc.fConfig = rt->config();
}
desc.fWidth = copyRect.width();
desc.fHeight = copyRect.height();
static const uint32_t kFlags = 0;
SkAutoTUnref<GrTexture> copy(fResourceProvider->createApproxTexture(desc, kFlags));
if (!copy) {
SkDebugf("Failed to create temporary copy of destination texture.\n");
return false;
}
SkIPoint dstPoint = {0, 0};
this->copySurface(copy, rt, copyRect, dstPoint);
dstTexture->setTexture(copy);
dstTexture->setOffset(copyRect.fLeft, copyRect.fTop);
return true;
}
