Delete dead SkImageDecoder::buildTileIndex and decodeSubset code

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 914bdea5c8b8a96f9e4b0117900831d3c797eec0..c80cd9b64f04a4a629bf3e82e346c16cac4d9d3d 100644
--- a/src/images/SkImageDecoder_libjpeg.cpp
+++ b/src/images/SkImageDecoder_libjpeg.cpp
@@ -85,154 +85,20 @@ static void initialize_info(jpeg_decompress_struct* cinfo, skjpeg_source_mgr* sr
     }
 }
 
-#ifdef SK_JPEG_INDEX_SUPPORTED
-class SkJPEGImageIndex {
-public:
-    // Takes ownership of stream.
-    SkJPEGImageIndex(SkStreamRewindable* stream, SkImageDecoder* decoder)
-        : fSrcMgr(stream, decoder)
-        , fStream(stream)
-        , fInfoInitialized(false)
-        , fHuffmanCreated(false)
-        , fDecompressStarted(false)
-        {
-            SkDEBUGCODE(fReadHeaderSucceeded = false;)
-        }
-
-    ~SkJPEGImageIndex() {
-        if (fHuffmanCreated) {
-            // Set to false before calling the libjpeg function, in case
-            // the libjpeg function calls longjmp. Our setjmp handler may
-            // attempt to delete this SkJPEGImageIndex, thus entering this
-            // destructor again. Setting fHuffmanCreated to false first
-            // prevents an infinite loop.
-            fHuffmanCreated = false;
-            jpeg_destroy_huffman_index(&fHuffmanIndex);
-        }
-        if (fDecompressStarted) {
-            // Like fHuffmanCreated, set to false before calling libjpeg
-            // function to prevent potential infinite loop.
-            fDecompressStarted = false;
-            jpeg_finish_decompress(&fCInfo);
-        }
-        if (fInfoInitialized) {
-            this->destroyInfo();
-        }
-    }
-
-    /**
-     *  Destroy the cinfo struct.
-     *  After this call, if a huffman index was already built, it
-     *  can be used after calling initializeInfoAndReadHeader
-     *  again. Must not be called after startTileDecompress except
-     *  in the destructor.
-     */
-    void destroyInfo() {
-        SkASSERT(fInfoInitialized);
-        SkASSERT(!fDecompressStarted);
-        // Like fHuffmanCreated, set to false before calling libjpeg
-        // function to prevent potential infinite loop.
-        fInfoInitialized = false;
-        jpeg_destroy_decompress(&fCInfo);
-        SkDEBUGCODE(fReadHeaderSucceeded = false;)
-    }
-
-    /**
-     *  Initialize the cinfo struct.
-     *  Calls jpeg_create_decompress, makes customizations, and
-     *  finally calls jpeg_read_header. Returns true if jpeg_read_header
-     *  returns JPEG_HEADER_OK.
-     *  If cinfo was already initialized, destroyInfo must be called to
-     *  destroy the old one. Must not be called after startTileDecompress.
-     */
-    bool initializeInfoAndReadHeader() {
-        SkASSERT(!fInfoInitialized && !fDecompressStarted);
-        initialize_info(&fCInfo, &fSrcMgr);
-        fInfoInitialized = true;
-        const bool success = (JPEG_HEADER_OK == jpeg_read_header(&fCInfo, true));
-        SkDEBUGCODE(fReadHeaderSucceeded = success;)
-        return success;
-    }
-
-    jpeg_decompress_struct* cinfo() { return &fCInfo; }
-
-    huffman_index* huffmanIndex() { return &fHuffmanIndex; }
-
-    /**
-     *  Build the index to be used for tile based decoding.
-     *  Must only be called after a successful call to
-     *  initializeInfoAndReadHeader and must not be called more
-     *  than once.
-     */
-    bool buildHuffmanIndex() {
-        SkASSERT(fReadHeaderSucceeded);
-        SkASSERT(!fHuffmanCreated);
-        jpeg_create_huffman_index(&fCInfo, &fHuffmanIndex);
-        SkASSERT(1 == fCInfo.scale_num && 1 == fCInfo.scale_denom);
-        fHuffmanCreated = jpeg_build_huffman_index(&fCInfo, &fHuffmanIndex);
-        return fHuffmanCreated;
-    }
-
-    /**
-     *  Start tile based decoding. Must only be called after a
-     *  successful call to buildHuffmanIndex, and must only be
-     *  called once.
-     */
-    bool startTileDecompress() {
-        SkASSERT(fHuffmanCreated);
-        SkASSERT(fReadHeaderSucceeded);
-        SkASSERT(!fDecompressStarted);
-        if (jpeg_start_tile_decompress(&fCInfo)) {
-            fDecompressStarted = true;
-            return true;
-        }
-        return false;
-    }
-
-private:
-    skjpeg_source_mgr  fSrcMgr;
-    SkAutoTDelete<SkStream> fStream;
-    jpeg_decompress_struct fCInfo;
-    huffman_index fHuffmanIndex;
-    bool fInfoInitialized;
-    bool fHuffmanCreated;
-    bool fDecompressStarted;
-    SkDEBUGCODE(bool fReadHeaderSucceeded;)
-};
-#endif
-
 class SkJPEGImageDecoder : public SkImageDecoder {
 public:
-#ifdef SK_JPEG_INDEX_SUPPORTED
-    SkJPEGImageDecoder() {
-        fImageIndex = nullptr;
-        fImageWidth = 0;
-        fImageHeight = 0;
-    }
-
-    virtual ~SkJPEGImageDecoder() { delete fImageIndex; }
-#endif
 
     Format getFormat() const override {
         return kJPEG_Format;
     }
 
 protected:
-#ifdef SK_JPEG_INDEX_SUPPORTED
-    bool onBuildTileIndex(SkStreamRewindable *stream, int *width, int *height) override;
-    bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) override;
-#endif
     Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
     bool onDecodeYUV8Planes(SkStream* stream, SkISize componentSizes[3],
                             void* planes[3], size_t rowBytes[3],
                             SkYUVColorSpace* colorSpace) override;
 
 private:
-#ifdef SK_JPEG_INDEX_SUPPORTED
-    SkJPEGImageIndex* fImageIndex;
-    int fImageWidth;
-    int fImageHeight;
-#endif
 
     /**
      *  Determine the appropriate bitmap colortype and out_color_space based on
@@ -295,20 +161,6 @@ static bool skip_src_rows(jpeg_decompress_struct* cinfo, void* buffer, int count
     return true;
 }
 
-#ifdef SK_JPEG_INDEX_SUPPORTED
-static bool skip_src_rows_tile(jpeg_decompress_struct* cinfo,
-                               huffman_index *index, void* buffer, int count) {
-    for (int i = 0; i < count; i++) {
-        JSAMPLE* rowptr = (JSAMPLE*)buffer;
-        int row_count = jpeg_read_tile_scanline(cinfo, index, &rowptr);
-        if (1 != row_count) {
-            return false;
-        }
-    }
-    return true;
-}
-#endif
-
 ///////////////////////////////////////////////////////////////////////////////
 
 // This guy exists just to aid in debugging, as it allows debuggers to just
@@ -329,14 +181,6 @@ static bool return_false(const jpeg_decompress_struct& cinfo,
     return false;
 }
 
-#ifdef SK_JPEG_INDEX_SUPPORTED
-static bool return_false(const jpeg_decompress_struct& cinfo,
-                         const SkBitmap& bm, const char caller[]) {
-    print_jpeg_decoder_errors(cinfo, bm.width(), bm.height(), caller);
-    return false;
-}
-#endif
-
 static SkImageDecoder::Result return_failure(const jpeg_decompress_struct& cinfo,
                                              const SkBitmap& bm, const char caller[]) {
     print_jpeg_decoder_errors(cinfo, bm.width(), bm.height(), caller);
@@ -939,240 +783,6 @@ bool SkJPEGImageDecoder::onDecodeYUV8Planes(SkStream* stream, SkISize componentS
 
 ///////////////////////////////////////////////////////////////////////////////
 
-#ifdef SK_JPEG_INDEX_SUPPORTED
-bool SkJPEGImageDecoder::onBuildTileIndex(SkStreamRewindable* stream, int *width, int *height) {
-    SkAutoTDelete<SkJPEGImageIndex> imageIndex(new SkJPEGImageIndex(stream, this));
-
-    skjpeg_error_mgr sk_err;
-    set_error_mgr(imageIndex->cinfo(), &sk_err);
-
-    // All objects need to be instantiated before this setjmp call so that
-    // they will be cleaned up properly if an error occurs.
-    if (setjmp(sk_err.fJmpBuf)) {
-        return false;
-    }
-
-    // create the cinfo used to create/build the huffmanIndex
-    if (!imageIndex->initializeInfoAndReadHeader()) {
-        return false;
-    }
-
-    if (!imageIndex->buildHuffmanIndex()) {
-        return false;
-    }
-
-    // destroy the cinfo used to create/build the huffman index
-    imageIndex->destroyInfo();
-
-    // Init decoder to image decode mode
-    if (!imageIndex->initializeInfoAndReadHeader()) {
-        return false;
-    }
-
-    jpeg_decompress_struct* cinfo = imageIndex->cinfo();
-    // We have a new cinfo, so set the error mgr again.
-    set_error_mgr(cinfo, &sk_err);
-
-    // FIXME: This sets cinfo->out_color_space, which we may change later
-    // based on the config in onDecodeSubset. This should be fine, since
-    // jpeg_init_read_tile_scanline will check out_color_space again after
-    // that change (when it calls jinit_color_deconverter).
-    (void) this->getBitmapColorType(cinfo);
-
-    turn_off_visual_optimizations(cinfo);
-
-    // instead of jpeg_start_decompress() we start a tiled decompress
-    if (!imageIndex->startTileDecompress()) {
-        return false;
-    }
-
-    SkASSERT(1 == cinfo->scale_num);
-    fImageWidth = cinfo->output_width;
-    fImageHeight = cinfo->output_height;
-
-    if (width) {
-        *width = fImageWidth;
-    }
-    if (height) {
-        *height = fImageHeight;
-    }
-
-    delete fImageIndex;
-    fImageIndex = imageIndex.detach();
-
-    return true;
-}
-
-bool SkJPEGImageDecoder::onDecodeSubset(SkBitmap* bm, const SkIRect& region) {
-    if (nullptr == fImageIndex) {
-        return false;
-    }
-    jpeg_decompress_struct* cinfo = fImageIndex->cinfo();
-
-    SkIRect rect = SkIRect::MakeWH(fImageWidth, fImageHeight);
-    if (!rect.intersect(region)) {
-        // If the requested region is entirely outside the image return false
-        return false;
-    }
-
-
-    skjpeg_error_mgr errorManager;
-    set_error_mgr(cinfo, &errorManager);
-
-    if (setjmp(errorManager.fJmpBuf)) {
-        return false;
-    }
-
-    int requestedSampleSize = this->getSampleSize();
-    cinfo->scale_denom = requestedSampleSize;
-
-    set_dct_method(*this, cinfo);
-
-    const SkColorType colorType = this->getBitmapColorType(cinfo);
-    adjust_out_color_space_and_dither(cinfo, colorType, *this);
-
-    int startX = rect.fLeft;
-    int startY = rect.fTop;
-    int width = rect.width();
-    int height = rect.height();
-
-    jpeg_init_read_tile_scanline(cinfo, fImageIndex->huffmanIndex(),
-                                 &startX, &startY, &width, &height);
-    int skiaSampleSize = recompute_sampleSize(requestedSampleSize, *cinfo);
-    int actualSampleSize = skiaSampleSize * (DCTSIZE / cinfo->min_DCT_scaled_size);
-
-    SkScaledBitmapSampler sampler(width, height, skiaSampleSize);
-
-    SkBitmap bitmap;
-    // Assume an A8 bitmap is not opaque to avoid the check of each
-    // individual pixel. It is very unlikely to be opaque, since
-    // an opaque A8 bitmap would not be very interesting.
-    // Otherwise, a jpeg image is opaque.
-    bitmap.setInfo(SkImageInfo::Make(sampler.scaledWidth(), sampler.scaledHeight(), colorType,
-                                     kAlpha_8_SkColorType == colorType ?
-                                         kPremul_SkAlphaType : kOpaque_SkAlphaType));
-
-    // Check ahead of time if the swap(dest, src) is possible or not.
-    // If yes, then we will stick to AllocPixelRef since it's cheaper with the
-    // swap happening. If no, then we will use alloc to allocate pixels to
-    // prevent garbage collection.
-    int w = rect.width() / actualSampleSize;
-    int h = rect.height() / actualSampleSize;
-    bool swapOnly = (rect == region) && bm->isNull() &&
-                    (w == bitmap.width()) && (h == bitmap.height()) &&
-                    ((startX - rect.x()) / actualSampleSize == 0) &&
-                    ((startY - rect.y()) / actualSampleSize == 0);
-    if (swapOnly) {
-        if (!this->allocPixelRef(&bitmap, nullptr)) {
-            return return_false(*cinfo, bitmap, "allocPixelRef");
-        }
-    } else {
-        if (!bitmap.tryAllocPixels()) {
-            return return_false(*cinfo, bitmap, "allocPixels");
-        }
-    }
-
-    SkAutoLockPixels alp(bitmap);
-
-#ifdef ANDROID_RGB
-    /* short-circuit the SkScaledBitmapSampler when possible, as this gives
-       a significant performance boost.
-    */
-    if (skiaSampleSize == 1 &&
-        ((kN32_SkColorType == colorType && cinfo->out_color_space == JCS_RGBA_8888) ||
-         (kRGB_565_SkColorType == colorType && cinfo->out_color_space == JCS_RGB_565)))
-    {
-        JSAMPLE* rowptr = (JSAMPLE*)bitmap.getPixels();
-        INT32 const bpr = bitmap.rowBytes();
-        int rowTotalCount = 0;
-
-        while (rowTotalCount < height) {
-            int rowCount = jpeg_read_tile_scanline(cinfo,
-                                                   fImageIndex->huffmanIndex(),
-                                                   &rowptr);
-            // if rowCount == 0, then we didn't get a scanline, so abort.
-            // onDecodeSubset() relies on onBuildTileIndex(), which
-            // needs a complete image to succeed.
-            if (0 == rowCount) {
-                return return_false(*cinfo, bitmap, "read_scanlines");
-            }
-            if (this->shouldCancelDecode()) {
-                return return_false(*cinfo, bitmap, "shouldCancelDecode");
-            }
-            rowTotalCount += rowCount;
-            rowptr += bpr;
-        }
-
-        if (swapOnly) {
-            bm->swap(bitmap);
-            return true;
-        }
-
-        return cropBitmap(bm, &bitmap, actualSampleSize, region.x(), region.y(),
-                          region.width(), region.height(), startX, startY);
-    }
-#endif
-
-    // check for supported formats
-    SkScaledBitmapSampler::SrcConfig sc;
-    int srcBytesPerPixel;
-
-    if (!get_src_config(*cinfo, &sc, &srcBytesPerPixel)) {
-        return return_false(*cinfo, *bm, "jpeg colorspace");
-    }
-
-    if (!sampler.begin(&bitmap, sc, *this)) {
-        return return_false(*cinfo, bitmap, "sampler.begin");
-    }
-
-    SkAutoMalloc  srcStorage(width * srcBytesPerPixel);
-    uint8_t* srcRow = (uint8_t*)srcStorage.get();
-
-    //  Possibly skip initial rows [sampler.srcY0]
-    if (!skip_src_rows_tile(cinfo, fImageIndex->huffmanIndex(), srcRow, sampler.srcY0())) {
-        return return_false(*cinfo, bitmap, "skip rows");
-    }
-
-    // now loop through scanlines until y == bitmap->height() - 1
-    for (int y = 0;; y++) {
-        JSAMPLE* rowptr = (JSAMPLE*)srcRow;
-        int row_count = jpeg_read_tile_scanline(cinfo, fImageIndex->huffmanIndex(), &rowptr);
-        // if row_count == 0, then we didn't get a scanline, so abort.
-        // onDecodeSubset() relies on onBuildTileIndex(), which
-        // needs a complete image to succeed.
-        if (0 == row_count) {
-            return return_false(*cinfo, bitmap, "read_scanlines");
-        }
-        if (this->shouldCancelDecode()) {
-            return return_false(*cinfo, bitmap, "shouldCancelDecode");
-        }
-
-        if (JCS_CMYK == cinfo->out_color_space) {
-            convert_CMYK_to_RGB(srcRow, width);
-        }
-
-        sampler.next(srcRow);
-        if (bitmap.height() - 1 == y) {
-            // we're done
-            break;
-        }
-
-        if (!skip_src_rows_tile(cinfo, fImageIndex->huffmanIndex(), srcRow,
-                                sampler.srcDY() - 1)) {
-            return return_false(*cinfo, bitmap, "skip rows");
-        }
-    }
-    if (swapOnly) {
-        bm->swap(bitmap);
-        return true;
-    }
-    return cropBitmap(bm, &bitmap, actualSampleSize, region.x(), region.y(),
-                      region.width(), region.height(), startX, startY);
-}
-#endif
-
-///////////////////////////////////////////////////////////////////////////////
-
 #include "SkColorPriv.h"
 
 // taken from jcolor.c in libjpeg