JPEG YUV Decoding

src/images/SkImageDecoder_libjpeg.cpp

Index: src/images/SkImageDecoder_libjpeg.cpp
diff --git a/src/images/SkImageDecoder_libjpeg.cpp b/src/images/SkImageDecoder_libjpeg.cpp
index 99401e6b627cdc9fd023b304a6c40789c3fbec3d..6459f4237d8d21e04a332adc6070efef7ab93d1b 100644
--- a/src/images/SkImageDecoder_libjpeg.cpp
+++ b/src/images/SkImageDecoder_libjpeg.cpp
@@ -54,6 +54,22 @@ SK_CONF_DECLARE(bool, c_suppressJPEGImageDecoderErrors,
                 "Suppress most JPG error messages when decode "
                 "function fails.");
 
+// Enum for YUV decoding
+enum YUVSubsampling {
+    kUNKNOWN_YUVSubsampling,
+    k410_YUVSubsampling,
+    k411_YUVSubsampling,
+    k420_YUVSubsampling,
+    k422_YUVSubsampling,
+    k440_YUVSubsampling,
+    k444_YUVSubsampling
+};
+
+enum SizeType {
+    kSizeForMemoryAllocation_SizeType,
+    kActualSize_SizeType
+};
+
 //////////////////////////////////////////////////////////////////////////
 //////////////////////////////////////////////////////////////////////////
 
@@ -102,6 +118,66 @@ static void initialize_info(jpeg_decompress_struct* cinfo, skjpeg_source_mgr* sr
     }
 }
 
+static SkISize compute_yuv_size(const jpeg_decompress_struct& info, int component,
+                                SizeType sizeType)
+{
+    if (sizeType == kSizeForMemoryAllocation_SizeType) {
+        return SkISize::Make(info.cur_comp_info[component]->width_in_blocks * DCTSIZE,
+                             info.cur_comp_info[component]->height_in_blocks * DCTSIZE);
+    }
+    return SkISize::Make(info.cur_comp_info[component]->downsampled_width,
+                         info.cur_comp_info[component]->downsampled_height);
+}
+
+static YUVSubsampling yuv_subsampling(const jpeg_decompress_struct& info)
+{
+    if ((DCTSIZE == 8)
+        && (info.num_components == 3)
+        && (info.comps_in_scan >= info.num_components)
+        && (info.scale_denom <= 8)
+        && (info.cur_comp_info[0])
+        && (info.cur_comp_info[1])
+        && (info.cur_comp_info[2])
+        && (info.cur_comp_info[1]->h_samp_factor == 1)
+        && (info.cur_comp_info[1]->v_samp_factor == 1)
+        && (info.cur_comp_info[2]->h_samp_factor == 1)
+        && (info.cur_comp_info[2]->v_samp_factor == 1)) {
+        int h = info.cur_comp_info[0]->h_samp_factor;
+        int v = info.cur_comp_info[0]->v_samp_factor;
+        // 4:4:4 : (h == 1) && (v == 1)
+        // 4:4:0 : (h == 1) && (v == 2)
+        // 4:2:2 : (h == 2) && (v == 1)
+        // 4:2:0 : (h == 2) && (v == 2)
+        // 4:1:1 : (h == 4) && (v == 1)
+        // 4:1:0 : (h == 4) && (v == 2)
+        if (v == 1) {
+            switch (h) {
+            case 1:
+                return k444_YUVSubsampling;
+            case 2:
+                return k422_YUVSubsampling;
+            case 4:
+                return k411_YUVSubsampling;
+            default:
+                break;
+            }
+        } else if (v == 2) {
+            switch (h) {
+            case 1:
+                return k440_YUVSubsampling;
+            case 2:
+                return k420_YUVSubsampling;
+            case 4:
+                return k410_YUVSubsampling;
+            default:
+                break;
+            }
+        }
+    }
+
+    return kUNKNOWN_YUVSubsampling;
+}
+
 #ifdef SK_BUILD_FOR_ANDROID
 class SkJPEGImageIndex {
 public:
@@ -239,6 +315,8 @@ protected:
     virtual bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) SK_OVERRIDE;
 #endif
     virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
+    virtual bool onDecodeToYUV(SkStream* stream, SkISize componentSizes[3],
+                               SkImagePlanes* imagePlanes) SK_OVERRIDE;
 
 private:
 #ifdef SK_BUILD_FOR_ANDROID
@@ -325,16 +403,21 @@ static bool skip_src_rows_tile(jpeg_decompress_struct* cinfo,
 // This guy exists just to aid in debugging, as it allows debuggers to just
 // set a break-point in one place to see all error exists.
 static bool return_false(const jpeg_decompress_struct& cinfo,
-                         const SkBitmap& bm, const char caller[]) {
+                         int width, int height, const char caller[]) {
     if (!(c_suppressJPEGImageDecoderErrors)) {
         char buffer[JMSG_LENGTH_MAX];
         cinfo.err->format_message((const j_common_ptr)&cinfo, buffer);
         SkDebugf("libjpeg error %d <%s> from %s [%d %d]\n",
-                 cinfo.err->msg_code, buffer, caller, bm.width(), bm.height());
+                 cinfo.err->msg_code, buffer, caller, width, height);
     }
     return false;   // must always return false
 }
 
+static bool return_false(const jpeg_decompress_struct& cinfo,
+                         const SkBitmap& bm, const char caller[]) {
+    return return_false(cinfo, bm.width(), bm.height(), caller);
+}
+
 // Convert a scanline of CMYK samples to RGBX in place. Note that this
 // method moves the "scanline" pointer in its processing
 static void convert_CMYK_to_RGB(uint8_t* scanline, unsigned int width) {
@@ -726,6 +809,165 @@ bool SkJPEGImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
     return true;
 }
 
+static void update_components_sizes(const jpeg_decompress_struct& cinfo, SkISize componentSizes[3],
+                                    SizeType sizeType) {
+    for (int i = 0; i < 3; ++i) {
+        componentSizes[i] = compute_yuv_size(cinfo, i, sizeType);
+    }
+}
+
+static bool output_raw_data(jpeg_decompress_struct& cinfo, SkImagePlanes* imagePlanes) {
+	// U size and V size have to be the same if we're calling output_raw_data()
+	SkISize uvSize = compute_yuv_size(cinfo, 1, kSizeForMemoryAllocation_SizeType);
+    SkASSERT(uvSize == compute_yuv_size(cinfo, 2, kSizeForMemoryAllocation_SizeType));
+
+    JSAMPARRAY bufferraw[3];
+    JSAMPROW bufferraw2[32];
+    bufferraw[0] = &bufferraw2[0]; // Y channel rows (8 or 16)
+    bufferraw[1] = &bufferraw2[16]; // U channel rows (8)
+    bufferraw[2] = &bufferraw2[24]; // V channel rows (8)
+    int yWidth = cinfo.output_width;
+    int yHeight = cinfo.output_height;
+    int yMaxH = yHeight - 1;
+    int v = cinfo.cur_comp_info[0]->v_samp_factor;
+    int uvMaxH = uvSize.height() - 1;
+    JSAMPROW outputY = static_cast<JSAMPROW>(imagePlanes->plane(0));
+    JSAMPROW outputU = static_cast<JSAMPROW>(imagePlanes->plane(1));
+    JSAMPROW outputV = static_cast<JSAMPROW>(imagePlanes->plane(2));
+    size_t rowBytesY = imagePlanes->rowBytes(0);
+    size_t rowBytesU = imagePlanes->rowBytes(1);
+    size_t rowBytesV = imagePlanes->rowBytes(2);
+
+    int yScanlinesToRead = DCTSIZE * v;
+    SkAutoMalloc lastRowStorage(yWidth * 8);
+    JSAMPROW yLastRow = (JSAMPROW)lastRowStorage.get();
+    JSAMPROW uLastRow = yLastRow + 2 * yWidth;
+    JSAMPROW vLastRow = uLastRow + 2 * yWidth;
+    JSAMPROW dummyRow = vLastRow + 2 * yWidth;
+
+    while (cinfo.output_scanline < cinfo.output_height) {
+        // Request 8 or 16 scanlines: returns 0 or more scanlines.
+        bool hasYLastRow(false), hasUVLastRow(false);
+        // Assign 8 or 16 rows of memory to read the Y channel.
+        for (int i = 0; i < yScanlinesToRead; ++i) {
+            int scanline = (cinfo.output_scanline + i);
+            if (scanline < yMaxH) {
+                bufferraw2[i] = &outputY[scanline * rowBytesY];
+            } else if (scanline == yMaxH) {
+                bufferraw2[i] = yLastRow;
+                hasYLastRow = true;
+            } else {
+                bufferraw2[i] = dummyRow;
+            }
+        }
+        int scaledScanline = cinfo.output_scanline / v;
+        // Assign 8 rows of memory to read the U and V channels.
+        for (int i = 0; i < 8; ++i) {
+            int scanline = (scaledScanline + i);
+            if (scanline < uvMaxH) {
+                bufferraw2[16 + i] = &outputU[scanline * rowBytesU];
+                bufferraw2[24 + i] = &outputV[scanline * rowBytesV];
+            } else if (scanline == uvMaxH) {
+                bufferraw2[16 + i] = uLastRow;
+                bufferraw2[24 + i] = vLastRow;
+                hasUVLastRow = true;
+            } else {
+                bufferraw2[16 + i] = dummyRow;
+                bufferraw2[24 + i] = dummyRow;
+            }
+        }
+        JDIMENSION scanlinesRead = jpeg_read_raw_data(&cinfo, bufferraw, yScanlinesToRead);
+
+        if (scanlinesRead == 0)
+            return false;
+
+        if (hasYLastRow) {
+            memcpy(&outputY[yMaxH * rowBytesY], yLastRow, yWidth);
+        }
+        if (hasUVLastRow) {
+            memcpy(&outputU[uvMaxH * rowBytesU], uLastRow, uvSize.width());
+            memcpy(&outputV[uvMaxH * rowBytesV], vLastRow, uvSize.width());
+        }
+    }
+
+    cinfo.output_scanline = SkMin32(cinfo.output_scanline, cinfo.output_height);
+
+    return true;
+}
+
+bool SkJPEGImageDecoder::onDecodeToYUV(SkStream* stream, SkISize componentSizes[3],
+                                       SkImagePlanes* imagePlanes) {
+#ifdef TIME_DECODE
+    SkAutoTime atm("JPEG Decode");
+#endif
+
+    if (this->getSampleSize() != 1) {
+        return false; // Resizing not supported
+    }
+
+    JPEGAutoClean autoClean;
+
+    jpeg_decompress_struct  cinfo;
+    skjpeg_source_mgr       srcManager(stream, this);
+
+    skjpeg_error_mgr errorManager;
+    set_error_mgr(&cinfo, &errorManager);
+
+    // All objects need to be instantiated before this setjmp call so that
+    // they will be cleaned up properly if an error occurs.
+    if (setjmp(errorManager.fJmpBuf)) {
+        return return_false(cinfo, 0, 0, "setjmp");
+    }
+
+    initialize_info(&cinfo, &srcManager);
+    autoClean.set(&cinfo);
+
+    int status = jpeg_read_header(&cinfo, true);
+    if (status != JPEG_HEADER_OK) {
+        return return_false(cinfo, 0, 0, "read_header");
+    }
+
+    if (cinfo.jpeg_color_space != JCS_YCbCr) {
+        // It's not an error to not be encoded in YUV, so no need to use return_false()
+        return false;
+    }
+
+    cinfo.out_color_space = JCS_YCbCr;
+    cinfo.raw_data_out = TRUE;
+
+    if (NULL == imagePlanes) { // Compute size only
+        update_components_sizes(cinfo, componentSizes, kSizeForMemoryAllocation_SizeType);
+        return true;
+    }
+
+    set_dct_method(*this, &cinfo);
+
+    SkASSERT(1 == cinfo.scale_num);
+    cinfo.scale_denom = 1;
+
+    turn_off_visual_optimizations(&cinfo);
+
+#ifdef ANDROID_RGB
+    cinfo.dither_mode = JDITHER_NONE;
+#endif
+
+    /*  image_width and image_height are the original dimensions, available
+        after jpeg_read_header(). To see the scaled dimensions, we have to call
+        jpeg_start_decompress(), and then read output_width and output_height.
+    */
+    if (!jpeg_start_decompress(&cinfo)) {
+        return return_false(cinfo, 0, 0, "start_decompress");
+    }
+
+    if (!output_raw_data(cinfo, imagePlanes)) {
+        return return_false(cinfo, 0, 0, "output_raw_data");
+    }
+
+    update_components_sizes(cinfo, componentSizes, kActualSize_SizeType);
+    jpeg_finish_decompress(&cinfo);
+    return true;
+}
+
 #ifdef SK_BUILD_FOR_ANDROID
 bool SkJPEGImageDecoder::onBuildTileIndex(SkStreamRewindable* stream, int *width, int *height) {