jpegimagedecoder.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * Copyright (C) 2006 Apple Computer, Inc.
 * Copyright (C) 2008, 2009 Google, Inc.
 *
 * Portions are Copyright (C) 2001-6 mozilla.org
 *
 * Other contributors:
 *   Stuart Parmenter <[e-mail]>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Alternatively, the contents of this file may be used under the terms
 * of either the Mozilla Public License Version 1.1, found at
 * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
 * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
 * (the "GPL"), in which case the provisions of the MPL or the GPL are
 * applicable instead of those above.  If you wish to allow use of your
 * version of this file only under the terms of one of those two
 * licenses (the MPL or the GPL) and not to allow others to use your
 * version of this file under the LGPL, indicate your decision by
 * deletingthe provisions above and replace them with the notice and
 * other provisions required by the MPL or the GPL, as the case may be.
 * If you do not delete the provisions above, a recipient may use your
 * version of this file under any of the LGPL, the MPL or the GPL.
 */

#include "config.h"
#include "JPEGImageDecoder.h"
#include <assert.h>

extern "C" {
#include "jpeglib.h"
}

#include <setjmp.h>

namespace WebCore {

struct decoder_error_mgr {
    struct jpeg_error_mgr pub;  /* "public" fields for IJG library*/
    jmp_buf setjmp_buffer;      /* For handling catastropic errors */
};

enum jstate {
    JPEG_HEADER,                          /* Reading JFIF headers */
    JPEG_START_DECOMPRESS,
    JPEG_DECOMPRESS_PROGRESSIVE,          /* Output progressive pixels */
    JPEG_DECOMPRESS_SEQUENTIAL,           /* Output sequential pixels */
    JPEG_DONE,
    JPEG_SINK_NON_JPEG_TRAILER,          /* Some image files have a */
                                         /* non-JPEG trailer */
    JPEG_ERROR    
};

void init_source(j_decompress_ptr jd);
boolean fill_input_buffer(j_decompress_ptr jd);
void skip_input_data(j_decompress_ptr jd, long num_bytes);
void term_source(j_decompress_ptr jd);
void error_exit(j_common_ptr cinfo);

/*
 *  Implementation of a JPEG src object that understands our state machine
 */
struct decoder_source_mgr {
  /* public fields; must be first in this struct! */
  struct jpeg_source_mgr pub;

  JPEGImageReader *decoder;
};

class JPEGImageReader
{
public:
    JPEGImageReader(JPEGImageDecoder* decoder)
        : m_decoder(decoder)
        , m_bufferLength(0)
        , m_bytesToSkip(0)
        , m_state(JPEG_HEADER)
        , m_samples(0)
    {
        memset(&m_info, 0, sizeof(jpeg_decompress_struct));
 
        /* We set up the normal JPEG error routines, then override error_exit. */
        m_info.err = jpeg_std_error(&m_err.pub);
        m_err.pub.error_exit = error_exit;

        /* Allocate and initialize JPEG decompression object */
        jpeg_create_decompress(&m_info);
  
        decoder_source_mgr* src = NULL;
        if (!m_info.src) {
            src = (decoder_source_mgr*)fastCalloc(sizeof(decoder_source_mgr), 1);
            if (!src) {
                m_state = JPEG_ERROR;
                return;
            }
        }

        m_info.src = (jpeg_source_mgr*)src;

        /* Set up callback functions. */
        src->pub.init_source = init_source;
        src->pub.fill_input_buffer = fill_input_buffer;
        src->pub.skip_input_data = skip_input_data;
        src->pub.resync_to_restart = jpeg_resync_to_restart;
        src->pub.term_source = term_source;
        src->decoder = this;
    }

    ~JPEGImageReader()
    {
        close();
    }

    void close() {
        decoder_source_mgr* src = (decoder_source_mgr*)m_info.src;
        if (src)
            fastFree(src);
        m_info.src = 0;

        jpeg_destroy_decompress(&m_info);
    }

    void skipBytes(long num_bytes) {
        decoder_source_mgr* src = (decoder_source_mgr*)m_info.src;
        long bytesToSkip = std::min(num_bytes, (long)src->pub.bytes_in_buffer);
        src->pub.bytes_in_buffer -= (size_t)bytesToSkip;
        src->pub.next_input_byte += bytesToSkip;
    
        if (num_bytes > bytesToSkip)
            m_bytesToSkip = (size_t)(num_bytes - bytesToSkip);
        else
            m_bytesToSkip = 0;
    }

    bool decode(const Vector<char>& data, bool sizeOnly) {
        m_decodingSizeOnly = sizeOnly;
        
        unsigned newByteCount = data.size() - m_bufferLength;
        unsigned readOffset = m_bufferLength - m_info.src->bytes_in_buffer;

        m_info.src->bytes_in_buffer += newByteCount;
        m_info.src->next_input_byte = (JOCTET*)(data.data()) + readOffset;
        
        // If we still have bytes to skip, try to skip those now.
        if (m_bytesToSkip)
            skipBytes(m_bytesToSkip);

        m_bufferLength = data.size();
        
        // We need to do the setjmp here. Otherwise bad things will happen
        if (setjmp(m_err.setjmp_buffer)) {
            m_state = JPEG_SINK_NON_JPEG_TRAILER;
            close();
            return false;
        }

        switch (m_state) {
            case JPEG_HEADER:
            {
                /* Read file parameters with jpeg_read_header() */
                if (jpeg_read_header(&m_info, true) == JPEG_SUSPENDED)
                    return true; /* I/O suspension */

                /* let libjpeg take care of gray->RGB and YCbCr->RGB conversions */
                switch (m_info.jpeg_color_space) {
                    case JCS_GRAYSCALE:
                    case JCS_RGB:
                    case JCS_YCbCr:
                        m_info.out_color_space = JCS_RGB;
                        break;
                    case JCS_CMYK:
                    case JCS_YCCK:
                    default:
                        m_state = JPEG_ERROR;
                        return false;
                }

                /*
                 * Don't allocate a giant and superfluous memory buffer
                 * when the image is a sequential JPEG.
                 */
                m_info.buffered_image = jpeg_has_multiple_scans(&m_info);

                /* Used to set up image size so arrays can be allocated */
                jpeg_calc_output_dimensions(&m_info);

                /*
                 * Make a one-row-high sample array that will go away
                 * when done with image. Always make it big enough to
                 * hold an RGB row.  Since this uses the IJG memory
                 * manager, it must be allocated before the call to
                 * jpeg_start_compress().
                 */
                int row_stride = m_info.output_width * 4; // RGBA buffer


                m_samples = (*m_info.mem->alloc_sarray)((j_common_ptr) &m_info,
                                           JPOOL_IMAGE,
                                           row_stride, 1);

                m_state = JPEG_START_DECOMPRESS;

                // We can fill in the size now that the header is available.
                if (!m_decoder->setSize(m_info.image_width, m_info.image_height)) {
                    m_state = JPEG_ERROR;
                    return false;
                }

                if (m_decodingSizeOnly) {
                    // We can stop here.
                    // Reduce our buffer length and available data.
                    m_bufferLength -= m_info.src->bytes_in_buffer;
                    m_info.src->bytes_in_buffer = 0;
                    return true;
                }
            }

            case JPEG_START_DECOMPRESS:
            {
                /* Set parameters for decompression */
                /* FIXME -- Should reset dct_method and dither mode
                 * for final pass of progressive JPEG
                 */
                m_info.dct_method =  JDCT_ISLOW;
                m_info.dither_mode = JDITHER_FS;
                m_info.do_fancy_upsampling = true;
                m_info.enable_2pass_quant = false;
                m_info.do_block_smoothing = true;

                /* Start decompressor */
                if (!jpeg_start_decompress(&m_info))
                    return true; /* I/O suspension */

                /* If this is a progressive JPEG ... */
                m_state = (m_info.buffered_image) ? JPEG_DECOMPRESS_PROGRESSIVE : JPEG_DECOMPRESS_SEQUENTIAL;
            }
    
            case JPEG_DECOMPRESS_SEQUENTIAL:
            {
                if (m_state == JPEG_DECOMPRESS_SEQUENTIAL) {
      
                    if (!m_decoder->outputScanlines())
                        return true; /* I/O suspension */