src/images/SkJpegUtility.cpp

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "SkJpegUtility.h"

/////////////////////////////////////////////////////////////////////
static void sk_init_source(j_decompress_ptr cinfo) {
    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;
    src->next_input_byte = (const JOCTET*)src->fBuffer;
    src->bytes_in_buffer = 0;
}

static boolean sk_fill_input_buffer(j_decompress_ptr cinfo) {
    skjpeg_source_mgr* src = (skjpeg_source_mgr*)cinfo->src;
    if (src->fDecoder != NULL && src->fDecoder->shouldCancelDecode()) {
        return FALSE;
    }
    size_t bytes = src->fStream->read(src->fBuffer, skjpeg_source_mgr::kBufferSize);
    // note that JPEG is happy with less than the full read,
    // as long as the result is non-zero
    if (bytes == 0) {
        return FALSE;
    }

    src->next_input_byte = (const JOCTET*)src->fBuffer;
    src->bytes_in_buffer = bytes;
    return TRUE;
}

static void sk_skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
    SkASSERT(num_bytes > 0);

    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;

    long bytesToSkip = num_bytes - src->bytes_in_buffer;

    // check if the skip amount exceeds the current buffer
    if (bytesToSkip > 0) {
        size_t bytes = src->fStream->skip(bytesToSkip);
        if (bytes != (size_t)bytesToSkip) {
//            SkDebugf("xxxxxxxxxxxxxx failure to skip request %d actual %d\n", bytesToSkip, bytes);
            cinfo->err->error_exit((j_common_ptr)cinfo);
        }
        src->next_input_byte = (const JOCTET*)src->fBuffer;
        src->bytes_in_buffer = 0;
    } else {
        src->next_input_byte += num_bytes;
        src->bytes_in_buffer -= num_bytes;
    }
}

static boolean sk_resync_to_restart(j_decompress_ptr cinfo, int desired) {
    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;

    // what is the desired param for???

    if (!src->fStream->rewind()) {
        SkDebugf("xxxxxxxxxxxxxx failure to rewind\n");
        cinfo->err->error_exit((j_common_ptr)cinfo);
        return FALSE;
    }
    src->next_input_byte = (const JOCTET*)src->fBuffer;
    src->bytes_in_buffer = 0;
    return TRUE;
}

static void sk_term_source(j_decompress_ptr /*cinfo*/) {}


static void skmem_init_source(j_decompress_ptr cinfo) {
    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;
    src->next_input_byte = (const JOCTET*)src->fMemoryBase;
    src->bytes_in_buffer = src->fMemoryBaseSize;
}

static boolean skmem_fill_input_buffer(j_decompress_ptr cinfo) {
    SkDebugf("xxxxxxxxxxxxxx skmem_fill_input_buffer called\n");
    return FALSE;
}

static void skmem_skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;
//    SkDebugf("xxxxxxxxxxxxxx skmem_skip_input_data called %d\n", num_bytes);
    src->next_input_byte = (const JOCTET*)((const char*)src->next_input_byte + num_bytes);
    src->bytes_in_buffer -= num_bytes;
}

static boolean skmem_resync_to_restart(j_decompress_ptr cinfo, int desired) {
    SkDebugf("xxxxxxxxxxxxxx skmem_resync_to_restart called\n");
    return TRUE;
}

static void skmem_term_source(j_decompress_ptr /*cinfo*/) {}


///////////////////////////////////////////////////////////////////////////////

skjpeg_source_mgr::skjpeg_source_mgr(SkStream* stream, SkImageDecoder* decoder) : fStream(stream) {
    fDecoder = decoder;
    const void* baseAddr = stream->getMemoryBase();
    if (baseAddr && false) {
        fMemoryBase = baseAddr;
        fMemoryBaseSize = stream->getLength();

        init_source = skmem_init_source;
        fill_input_buffer = skmem_fill_input_buffer;
        skip_input_data = skmem_skip_input_data;
        resync_to_restart = skmem_resync_to_restart;
        term_source = skmem_term_source;
    } else {
        fMemoryBase = NULL;
        fMemoryBaseSize = 0;

        init_source = sk_init_source;
        fill_input_buffer = sk_fill_input_buffer;
        skip_input_data = sk_skip_input_data;
        resync_to_restart = sk_resync_to_restart;
        term_source = sk_term_source;
    }
//    SkDebugf("**************** use memorybase %p %d\n", fMemoryBase, fMemoryBaseSize);
}

///////////////////////////////////////////////////////////////////////////////

static void sk_init_destination(j_compress_ptr cinfo) {
    skjpeg_destination_mgr* dest = (skjpeg_destination_mgr*)cinfo->dest;

    dest->next_output_byte = dest->fBuffer;
    dest->free_in_buffer = skjpeg_destination_mgr::kBufferSize;
}

static boolean sk_empty_output_buffer(j_compress_ptr cinfo) {
    skjpeg_destination_mgr* dest = (skjpeg_destination_mgr*)cinfo->dest;

//  if (!dest->fStream->write(dest->fBuffer, skjpeg_destination_mgr::kBufferSize - dest->free_in_buffer))
    if (!dest->fStream->write(dest->fBuffer,
            skjpeg_destination_mgr::kBufferSize)) {
        ERREXIT(cinfo, JERR_FILE_WRITE);
        return false;
    }

    dest->next_output_byte = dest->fBuffer;
    dest->free_in_buffer = skjpeg_destination_mgr::kBufferSize;
    return TRUE;
}

static void sk_term_destination (j_compress_ptr cinfo) {
    skjpeg_destination_mgr* dest = (skjpeg_destination_mgr*)cinfo->dest;

    size_t size = skjpeg_destination_mgr::kBufferSize - dest->free_in_buffer;
    if (size > 0) {
        if (!dest->fStream->write(dest->fBuffer, size)) {
            ERREXIT(cinfo, JERR_FILE_WRITE);
            return;
        }
    }
    dest->fStream->flush();
}

skjpeg_destination_mgr::skjpeg_destination_mgr(SkWStream* stream)
        : fStream(stream) {
    this->init_destination = sk_init_destination;
    this->empty_output_buffer = sk_empty_output_buffer;
    this->term_destination = sk_term_destination;
}

void skjpeg_error_exit(j_common_ptr cinfo) {
    skjpeg_error_mgr* error = (skjpeg_error_mgr*)cinfo->err;

    (*error->output_message) (cinfo);

    /* Let the memory manager delete any temp files before we die */
    jpeg_destroy(cinfo);

    longjmp(error->fJmpBuf, -1);
}