Add support for compressed alpha ktx files
R=robertphillips@google.com
Author: krajcevski@google.com
Review URL: https://codereview.chromium.org/447283002
diff --git a/src/images/SkImageDecoder_ktx.cpp b/src/images/SkImageDecoder_ktx.cpp
index c06450c..64a37d9 100644
--- a/src/images/SkImageDecoder_ktx.cpp
+++ b/src/images/SkImageDecoder_ktx.cpp
@@ -91,12 +91,39 @@
}
}
- // Set the config...
- bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(), alphaType));
+ // Search through the compressed formats to see if the KTX file is holding
+ // compressed data
+ bool ktxIsCompressed = false;
+ SkTextureCompressor::Format ktxCompressedFormat;
+ for (int i = 0; i < SkTextureCompressor::kFormatCnt; ++i) {
+ SkTextureCompressor::Format fmt = static_cast<SkTextureCompressor::Format>(i);
+ if (ktxFile.isCompressedFormat(fmt)) {
+ ktxIsCompressed = true;
+ ktxCompressedFormat = fmt;
+ break;
+ }
+ }
+
+ // If the compressed format is a grayscale image, then setup the bitmap properly...
+ bool isCompressedAlpha = ktxIsCompressed &&
+ ((SkTextureCompressor::kLATC_Format == ktxCompressedFormat) ||
+ (SkTextureCompressor::kR11_EAC_Format == ktxCompressedFormat));
+
+ // Set the image dimensions and underlying pixel type.
+ if (isCompressedAlpha) {
+ const int w = sampler.scaledWidth();
+ const int h = sampler.scaledHeight();
+ bm->setInfo(SkImageInfo::MakeA8(w, h));
+ } else {
+ const int w = sampler.scaledWidth();
+ const int h = sampler.scaledHeight();
+ bm->setInfo(SkImageInfo::MakeN32(w, h, alphaType));
+ }
+
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
return true;
}
-
+
// If we've made it this far, then we know how to grok the data.
if (!this->allocPixelRef(bm, NULL)) {
return false;
@@ -105,7 +132,36 @@
// Lock the pixels, since we're about to write to them...
SkAutoLockPixels alp(*bm);
- if (ktxFile.isCompressedFormat(SkTextureCompressor::kETC1_Format)) {
+ if (isCompressedAlpha) {
+ if (!sampler.begin(bm, SkScaledBitmapSampler::kGray, *this)) {
+ return false;
+ }
+
+ // Alpha data is only a single byte per pixel.
+ int nPixels = width * height;
+ SkAutoMalloc outRGBData(nPixels);
+ uint8_t *outRGBDataPtr = reinterpret_cast<uint8_t *>(outRGBData.get());
+
+ // Decode the compressed format
+ const uint8_t *buf = reinterpret_cast<const uint8_t *>(ktxFile.pixelData());
+ if (!SkTextureCompressor::DecompressBufferFromFormat(
+ outRGBDataPtr, width, buf, width, height, ktxCompressedFormat)) {
+ return false;
+ }
+
+ // Set each of the pixels...
+ const int srcRowBytes = width;
+ const int dstHeight = sampler.scaledHeight();
+ const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBDataPtr);
+ srcRow += sampler.srcY0() * srcRowBytes;
+ for (int y = 0; y < dstHeight; ++y) {
+ sampler.next(srcRow);
+ srcRow += sampler.srcDY() * srcRowBytes;
+ }
+
+ return true;
+
+ } else if (ktxFile.isCompressedFormat(SkTextureCompressor::kETC1_Format)) {
if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
return false;
}
