bool SkCreateBitmapFromCGImage(SkBitmap* dst, CGImageRef image, SkISize* scaleToFit) {
const int width = scaleToFit ? scaleToFit->width() : SkToInt(CGImageGetWidth(image));
const int height = scaleToFit ? scaleToFit->height() : SkToInt(CGImageGetHeight(image));
SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
SkBitmap tmp;
if (!tmp.allocPixels(info)) {
return false;
}
if (!SkCopyPixelsFromCGImage(tmp.info(), tmp.rowBytes(), tmp.getPixels(), image)) {
return false;
}
CGImageAlphaInfo cgInfo = CGImageGetAlphaInfo(image);
switch (cgInfo) {
case kCGImageAlphaNone:
case kCGImageAlphaNoneSkipLast:
case kCGImageAlphaNoneSkipFirst:
SkASSERT(SkBitmap::ComputeIsOpaque(tmp));
tmp.setAlphaType(kOpaque_SkAlphaType);
break;
default:
// we don't know if we're opaque or not, so compute it.
if (SkBitmap::ComputeIsOpaque(tmp)) {
tmp.setAlphaType(kOpaque_SkAlphaType);
}
}
*dst = tmp;
return true;
}
bool SkImageDecoder_CG::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
CGImageSourceRef imageSrc = SkStreamToCGImageSource(stream);
if (NULL == imageSrc) {
return false;
}
SkAutoTCallVProc<const void, CFRelease> arsrc(imageSrc);
CGImageRef image = CGImageSourceCreateImageAtIndex(imageSrc, 0, NULL);
if (NULL == image) {
return false;
}
SkAutoTCallVProc<CGImage, CGImageRelease> arimage(image);
const int width = SkToInt(CGImageGetWidth(image));
const int height = SkToInt(CGImageGetHeight(image));
bm->setInfo(SkImageInfo::MakeN32Premul(width, height));
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
return true;
}
if (!this->allocPixelRef(bm, NULL)) {
return false;
}
SkAutoLockPixels alp(*bm);
if (!SkCopyPixelsFromCGImage(bm->info(), bm->rowBytes(), bm->getPixels(), image)) {
return false;
}
CGImageAlphaInfo info = CGImageGetAlphaInfo(image);
switch (info) {
case kCGImageAlphaNone:
case kCGImageAlphaNoneSkipLast:
case kCGImageAlphaNoneSkipFirst:
SkASSERT(SkBitmap::ComputeIsOpaque(*bm));
bm->setAlphaType(kOpaque_SkAlphaType);
break;
default:
// we don't know if we're opaque or not, so compute it.
if (SkBitmap::ComputeIsOpaque(*bm)) {
bm->setAlphaType(kOpaque_SkAlphaType);
}
}
if (!bm->isOpaque() && this->getRequireUnpremultipliedColors()) {
// CGBitmapContext does not support unpremultiplied, so the image has been premultiplied.
// Convert to unpremultiplied.
for (int i = 0; i < width; ++i) {
for (int j = 0; j < height; ++j) {
uint32_t* addr = bm->getAddr32(i, j);
*addr = SkUnPreMultiply::UnPreMultiplyPreservingByteOrder(*addr);
}
}
bm->setAlphaType(kUnpremul_SkAlphaType);
}
return true;
}
bool SkImageGeneratorCG::onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
SkPMColor ctable[], int* ctableCount) {
if (kN32_SkColorType != info.colorType()) {
// FIXME: Support other colorTypes.
return false;
}
switch (info.alphaType()) {
case kOpaque_SkAlphaType:
if (kOpaque_SkAlphaType != this->getInfo().alphaType()) {
return false;
}
break;
case kPremul_SkAlphaType:
break;
default:
return false;
}
CGImageRef image = CGImageSourceCreateImageAtIndex((CGImageSourceRef) fImageSrc.get(), 0,
nullptr);
if (!image) {
return false;
}
SkAutoTCallVProc<CGImage, CGImageRelease> autoImage(image);
// FIXME: Using this function (as opposed to swizzling ourselves) greatly
// restricts the color and alpha types that we support. If we
// swizzle ourselves, we can add support for:
// kUnpremul_SkAlphaType
// 16-bit per component RGBA
// kGray_8_SkColorType
// kIndex_8_SkColorType
// Additionally, it would be interesting to compare the performance
// of SkSwizzler with CG's built in swizzler.
if (!SkCopyPixelsFromCGImage(info, rowBytes, pixels, image)) {
return false;
}
return true;
}
