gwenview/lib/iodevicejpegsourcemanager.cpp

   1 // vim: set tabstop=4 shiftwidth=4 noexpandtab:
   2 /*
   3 Gwenview: an image viewer
   4 Copyright 2008 Aurélien Gâteau <aurelien.gateau@free.fr>
   5
   6 This program is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU General Public License
   8 as published by the Free Software Foundation; either version 2
   9 of the License, or (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 51 Franklin Street, Fifth Floor, Cambridge, MA 02110-1301, USA.
  19
  20 */
  21 // Self
  22 #include "iodevicejpegsourcemanager.h"
  23
  24 // Qt
  25 #include <QIODevice>
  26
  27 // KDE
  28 #include <kdebug.h>
  29
  30 // libjpeg
  31 #include <stdio.h>
  32 #define XMD_H
  33 extern "C" {
  34 #include <jpeglib.h>
  35 }
  36
  37 // Local
  38
  39 namespace Gwenview {
  40 namespace IODeviceJpegSourceManager {
  41
  42 #define SOURCE_MANAGER_BUFFER_SIZE 4096
  43 struct IODeviceJpegSourceManager : public jpeg_source_mgr {
  44         QIODevice* mIODevice;
  45         JOCTET mBuffer[SOURCE_MANAGER_BUFFER_SIZE];
  46 };
  47
  48
  49 static boolean fill_input_buffer(j_decompress_ptr cinfo) {
  50         IODeviceJpegSourceManager* src = static_cast<IODeviceJpegSourceManager*>(cinfo->src);
  51         Q_ASSERT(src->mIODevice);
  52         int readSize = src->mIODevice->read((char*)src->mBuffer, SOURCE_MANAGER_BUFFER_SIZE);
  53         if (readSize > 0) {
  54                 src->next_input_byte = src->mBuffer;
  55                 src->bytes_in_buffer = readSize;
  56         } else {
  57                 /**
  58                  * JPEG file is broken. We feed the decoder with fake EOI, as specified
  59                  * in the libjpeg documentation.
  60                  */
  61                 static JOCTET fakeEOI[2] = { JOCTET(0xFF), JOCTET(JPEG_EOI)};
  62                 kWarning() << "Image is incomplete";
  63                 cinfo->src->next_input_byte = fakeEOI;
  64                 cinfo->src->bytes_in_buffer = 2;
  65         }
  66         return true;
  67 }
  68
  69
  70 static void init_source(j_decompress_ptr cinfo) {
  71         fill_input_buffer(cinfo);
  72 }
  73
  74
  75 static void skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
  76         if (num_bytes > 0) {
  77                 while (num_bytes > (long) cinfo->src->bytes_in_buffer) {
  78                         num_bytes -= (long) cinfo->src->bytes_in_buffer;
  79                         fill_input_buffer(cinfo);
  80                         /**
  81                          * we assume that fill_input_buffer will never return FALSE, so
  82                          * suspension need not be handled.
  83                          */
  84                 }
  85                 cinfo->src->next_input_byte += (size_t) num_bytes;
  86                 cinfo->src->bytes_in_buffer -= (size_t) num_bytes;
  87         }
  88 }
  89
  90
  91 static void term_source(j_decompress_ptr) {
  92 }
  93
  94
  95 void setup(j_decompress_ptr cinfo, QIODevice* ioDevice) {
  96         Q_ASSERT(!cinfo->src);
  97         IODeviceJpegSourceManager* src = (IODeviceJpegSourceManager*)
  98                 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
  99                                                                         sizeof(IODeviceJpegSourceManager));
 100         cinfo->src = src;
 101
 102         src->init_source = init_source;
 103         src->fill_input_buffer = fill_input_buffer;
 104         src->skip_input_data = skip_input_data;
 105         src->resync_to_restart = jpeg_resync_to_restart;
 106         src->term_source = term_source;
 107
 108         src->mIODevice = ioDevice;
 109 }
 110
 111
 112 } // IODeviceJpegSourceManager namespace
 113 } // Gwenview namespace