YUV and color xforms

src/codec/SkJpegCodec.cpp

Index: src/codec/SkJpegCodec.cpp
diff --git a/src/codec/SkJpegCodec.cpp b/src/codec/SkJpegCodec.cpp
index d2f7cdb0fa382db95a0e69c9ca9dea607a691f3b..7af0e51a8dfaf2b35d07b87d017a2dfbb7c8d624 100644
--- a/src/codec/SkJpegCodec.cpp
+++ b/src/codec/SkJpegCodec.cpp
@@ -535,7 +535,7 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
                                          void* dst, size_t dstRowBytes,
                                          const Options& options, SkPMColor*, int*,
                                          int* rowsDecoded) {
-    if (options.fSubset) {
+/*    if (options.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
     }
@@ -577,6 +577,102 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
     }
 
     return kSuccess;
+*/
+
+    this->initializeColorXform(dstInfo);
+
+    // This will check is_yuv_supported(), so we don't need to here.
+    SkYUVSizeInfo yuvInfo;
+    if (!this->onQueryYUV8(&yuvInfo, nullptr)) {
+        return fDecoderMgr->returnFailure("onQueryYUV8", kInvalidInput);
+    }
+
+    // Set the jump location for libjpeg errors
+    if (setjmp(fDecoderMgr->getJmpBuf())) {
+        return fDecoderMgr->returnFailure("setjmp", kInvalidInput);
+    }
+
+    // Get a pointer to the decompress info since we will use it quite frequently
+    jpeg_decompress_struct* dinfo = fDecoderMgr->dinfo();
+
+    dinfo->raw_data_out = TRUE;
+    if (!jpeg_start_decompress(dinfo)) {
+        return fDecoderMgr->returnFailure("startDecompress", kInvalidInput);
+    }
+
+    // Currently, we require that the Y plane dimensions match the image dimensions
+    // and that the U and V planes are the same dimensions.
+    SkASSERT(yuvInfo.fSizes[SkYUVSizeInfo::kU] == yuvInfo.fSizes[SkYUVSizeInfo::kV]);
+    SkASSERT((uint32_t) yuvInfo.fSizes[SkYUVSizeInfo::kY].width() == dinfo->output_width &&
+            (uint32_t) yuvInfo.fSizes[SkYUVSizeInfo::kY].height() == dinfo->output_height);
+
+    // Build a JSAMPIMAGE to handle output from libjpeg-turbo.  A JSAMPIMAGE has
+    // a 2-D array of pixels for each of the components (Y, U, V) in the image.
+    // Cheat Sheet:
+    //     JSAMPIMAGE == JSAMPLEARRAY* == JSAMPROW** == JSAMPLE***
+    JSAMPARRAY yuv[3];
+
+    // Set aside enough space for pointers to rows of Y, U, and V.
+    JSAMPROW rowptrs[2 * DCTSIZE + DCTSIZE + DCTSIZE];
+    yuv[0] = &rowptrs[0];           // Y rows (DCTSIZE or 2 * DCTSIZE)
+    yuv[1] = &rowptrs[1 /******/* DCTSIZE]; // U rows (DCTSIZE)
+    yuv[2] = &rowptrs[2 /*******/* DCTSIZE]; // V rows (DCTSIZE)
+
+    // Initialize rowptrs.
+    SkASSERT(yuvInfo.fWidthBytes[0] == yuvInfo.fWidthBytes[1] && yuvInfo.fWidthBytes[0] == yuvInfo.fWidthBytes[2]);
+    SkAutoTMalloc<uint8_t> storage(3 * DCTSIZE * yuvInfo.fWidthBytes[0]);
+    int numYRowsPerBlock = DCTSIZE * dinfo->comp_info[0].v_samp_factor;
+    SkASSERT(DCTSIZE == numYRowsPerBlock);
+    JSAMPLE* storagePtr = (JSAMPLE*) storage.get();
+    for (int i = 0; i < numYRowsPerBlock; i++) {
+        rowptrs[i] = storagePtr;
+        storagePtr += yuvInfo.fWidthBytes[0];
+    }
+    for (int i = 0; i < numYRowsPerBlock; i++) {
+        rowptrs[DCTSIZE + i] = storagePtr;
+        storagePtr += yuvInfo.fWidthBytes[0];
+    }
+    for (int i = 0; i < numYRowsPerBlock; i++) {
+        rowptrs[DCTSIZE + DCTSIZE + i] = storagePtr;
+        storagePtr += yuvInfo.fWidthBytes[0];
+    }
+
+    uint32_t numRowsPerBlock = numYRowsPerBlock;
+
+    // We intentionally round down here, as this first loop will only handle
+    // full block rows.  As a special case at the end, we will handle any
+    // remaining rows that do not make up a full block.
+    const int numIters = dinfo->output_height / numRowsPerBlock;
+    for (int i = 0; i < numIters; i++) {
+        JDIMENSION linesRead = jpeg_read_raw_data(dinfo, yuv, numRowsPerBlock);
+        if (linesRead < numRowsPerBlock) {
+            // FIXME: Handle incomplete YUV decodes without signalling an error.
+            return kInvalidInput;
+        }
+
+        for (uint32_t j = 0; j < DCTSIZE; j++) {
+            fColorXform->applyYUV(dst, yuv[0][j], yuv[1][j], yuv[2][j], dstInfo.width());
+            dst = SkTAddOffset<void>(dst, dstRowBytes);
+        }
+    }
+
+    uint32_t remainingRows = dinfo->output_height - dinfo->output_scanline;
+    SkASSERT(remainingRows == dinfo->output_height % numRowsPerBlock);
+    SkASSERT(dinfo->output_scanline == numIters * numRowsPerBlock);
+    if (remainingRows > 0) {
+        JDIMENSION linesRead = jpeg_read_raw_data(dinfo, yuv, numRowsPerBlock);
+        if (linesRead < remainingRows) {
+            // FIXME: Handle incomplete YUV decodes without signalling an error.
+            return kInvalidInput;
+        }
+
+        for (uint32_t j = 0; j < remainingRows; j++) {
+            fColorXform->applyYUV(dst, yuv[0][j], yuv[1][j], yuv[2][j], dstInfo.width());
+            dst = SkTAddOffset<void>(dst, dstRowBytes);
+        }
+    }
+
+    return kSuccess;
 }
 
 void SkJpegCodec::allocateStorage(const SkImageInfo& dstInfo) {