Initial KTX file decoder
R=bsalomon@google.com, robertphillips@google.com, halcanary@google.com, reed@google.com
Author: krajcevski@google.com
Review URL: https://codereview.chromium.org/302333002
diff --git a/src/images/SkImageDecoder_ktx.cpp b/src/images/SkImageDecoder_ktx.cpp
new file mode 100644
index 0000000..bf3445e
--- /dev/null
+++ b/src/images/SkImageDecoder_ktx.cpp
@@ -0,0 +1,179 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkColorPriv.h"
+#include "SkImageDecoder.h"
+#include "SkScaledBitmapSampler.h"
+#include "SkStream.h"
+#include "SkStreamHelpers.h"
+#include "SkTypes.h"
+
+#include "ktx.h"
+#include "etc1.h"
+
+/////////////////////////////////////////////////////////////////////////////////////////
+
+
+/////////////////////////////////////////////////////////////////////////////////////////
+
+// KTX Image decoder
+// ---
+// KTX is a general texture data storage file format ratified by the Khronos Group. As an
+// overview, a KTX file contains all of the appropriate values needed to fully specify a
+// texture in an OpenGL application, including the use of compressed data.
+//
+// This decoder is meant to be used with an SkDiscardablePixelRef so that GPU backends
+// can sniff the data before creating a texture. If they encounter a compressed format
+// that they understand, they can then upload the data directly to the GPU. Otherwise,
+// they will decode the data into a format that Skia supports.
+
+class SkKTXImageDecoder : public SkImageDecoder {
+public:
+ SkKTXImageDecoder() { }
+
+ virtual Format getFormat() const SK_OVERRIDE {
+ return kKTX_Format;
+ }
+
+protected:
+ virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
+
+private:
+ typedef SkImageDecoder INHERITED;
+};
+
+bool SkKTXImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
+ // TODO: Implement SkStream::copyToData() that's cheap for memory and file streams
+ SkAutoDataUnref data(CopyStreamToData(stream));
+ if (NULL == data) {
+ return false;
+ }
+
+ SkKTXFile ktxFile(data);
+ if (!ktxFile.valid()) {
+ return false;
+ }
+
+ const unsigned short width = ktxFile.width();
+ const unsigned short height = ktxFile.height();
+
+ // should we allow the Chooser (if present) to pick a config for us???
+ if (!this->chooseFromOneChoice(SkBitmap::kARGB_8888_Config, width, height)) {
+ return false;
+ }
+
+ // Setup the sampler...
+ SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
+
+ // Set the config...
+ bm->setConfig(SkBitmap::kARGB_8888_Config,
+ sampler.scaledWidth(), sampler.scaledHeight(),
+ 0,
+ ktxFile.isRGBA8()? kUnpremul_SkAlphaType : kOpaque_SkAlphaType);
+ 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;
+ }
+
+ // Lock the pixels, since we're about to write to them...
+ SkAutoLockPixels alp(*bm);
+
+ if (ktxFile.isETC1()) {
+ if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
+ return false;
+ }
+
+ // ETC1 Data is encoded as RGB pixels, so we should extract it as such
+ int nPixels = width * height;
+ SkAutoMalloc outRGBData(nPixels * 3);
+ etc1_byte *outRGBDataPtr = reinterpret_cast<etc1_byte *>(outRGBData.get());
+
+ // Decode ETC1
+ const etc1_byte *buf = reinterpret_cast<const etc1_byte *>(ktxFile.pixelData());
+ if (etc1_decode_image(buf, outRGBDataPtr, width, height, 3, width*3)) {
+ return false;
+ }
+
+ // Set each of the pixels...
+ const int srcRowBytes = width * 3;
+ 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.isRGB8()) {
+
+ // Uncompressed RGB data (without alpha)
+ if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
+ return false;
+ }
+
+ // Just need to read RGB pixels
+ const int srcRowBytes = width * 3;
+ const int dstHeight = sampler.scaledHeight();
+ const uint8_t *srcRow = reinterpret_cast<const uint8_t *>(ktxFile.pixelData());
+ srcRow += sampler.srcY0() * srcRowBytes;
+ for (int y = 0; y < dstHeight; ++y) {
+ sampler.next(srcRow);
+ srcRow += sampler.srcDY() * srcRowBytes;
+ }
+
+ return true;
+
+ } else if (ktxFile.isRGBA8()) {
+
+ // Uncompressed RGBA data
+ if (!sampler.begin(bm, SkScaledBitmapSampler::kRGBA, *this)) {
+ return false;
+ }
+
+ // Just need to read RGBA pixels
+ const int srcRowBytes = width * 4;
+ const int dstHeight = sampler.scaledHeight();
+ const uint8_t *srcRow = reinterpret_cast<const uint8_t *>(ktxFile.pixelData());
+ srcRow += sampler.srcY0() * srcRowBytes;
+ for (int y = 0; y < dstHeight; ++y) {
+ sampler.next(srcRow);
+ srcRow += sampler.srcDY() * srcRowBytes;
+ }
+
+ return true;
+ }
+
+ return false;
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////
+DEFINE_DECODER_CREATOR(KTXImageDecoder);
+/////////////////////////////////////////////////////////////////////////////////////////
+
+static SkImageDecoder* sk_libktx_dfactory(SkStreamRewindable* stream) {
+ if (SkKTXFile::is_ktx(stream)) {
+ return SkNEW(SkKTXImageDecoder);
+ }
+ return NULL;
+}
+
+static SkImageDecoder_DecodeReg gReg(sk_libktx_dfactory);
+
+static SkImageDecoder::Format get_format_ktx(SkStreamRewindable* stream) {
+ if (SkKTXFile::is_ktx(stream)) {
+ return SkImageDecoder::kKTX_Format;
+ }
+ return SkImageDecoder::kUnknown_Format;
+}
+
+static SkImageDecoder_FormatReg gFormatReg(get_format_ktx);