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GnashImageGif.cpp
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GnashImageGif.cpp
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// GnashImageGif.cpp: gif_lib wrapper for Gnash.
//
// Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
//
#ifdef HAVE_CONFIG_H
#include "gnashconfig.h"
#endif
#include "utility.h"
#include "GnashImageGif.h"
#include "log.h"
#include "GnashException.h"
#include "IOChannel.h"
#include <sstream>
#include <cstring> // std::memcpy
#include <boost/scoped_array.hpp>
extern "C" {
#include <gif_lib.h>
}
namespace gnash {
static int
readData(GifFileType* ft, GifByteType* data, int length)
{
// Do not read until opened.
assert(ft);
IOChannel* in = reinterpret_cast<IOChannel*>(ft->UserData);
return in->read(reinterpret_cast<char*>(data), length);
}
GifImageInput::GifImageInput(boost::shared_ptr<IOChannel> in) :
ImageInput(in),
_gif(NULL),
_currentRow(0)
{
}
GifImageInput::~GifImageInput()
{
// Clean up allocated data.
DGifCloseFile(_gif);
}
size_t
GifImageInput::getHeight() const
{
assert (_gif);
return _gif->SHeight;
}
size_t
GifImageInput::getWidth() const
{
assert (_gif);
return _gif->SWidth;
}
void
GifImageInput::readScanline(unsigned char* rgbData)
{
ColorMapObject* colormap = (_gif->Image.ColorMap) ?
_gif->Image.ColorMap :
_gif->SColorMap;
assert(colormap);
unsigned char* ptr = rgbData;
for (size_t i = 0, e = getWidth(); i < e; ++i)
{
GifColorType* mapentry = &colormap->Colors[_gifData[_currentRow][i]];
*ptr++ = mapentry->Red;
*ptr++ = mapentry->Green;
*ptr++ = mapentry->Blue;
}
_currentRow++;
}
void
GifImageInput::read()
{
_gif = DGifOpen(_inStream.get(), &readData);
GifRecordType record;
// Parse the (first?) image into memory.
// Is there a multi-dimensional smart array? It's silly to
// have to allocate each row separately and can mean a lot
// of reallocation.
do
{
if (DGifGetRecordType(_gif, &record) != GIF_OK)
{
throw ParserException(_("GIF: Error retrieving record type"));
}
switch (record)
{
case IMAGE_DESC_RECORD_TYPE:
{
// Fill the _gif->Image fields
if (DGifGetImageDesc(_gif) != GIF_OK)
{
throw ParserException(_("GIF: Error retrieving image description"));
}
const int backgroundColor = _gif->SBackGroundColor;
// Set the height dimension of the array
_gifData.reset(new PixelRow[getHeight()]);
// The GIF 'screen' width and height
const size_t screenWidth = getWidth();
const size_t screenHeight = getHeight();
// Set all the pixels to the background colour.
for (size_t i = 0; i < screenHeight; ++i)
{
// Set the width dimension of the array
_gifData[i].reset(new GifPixelType[screenWidth]);
// Fill all the pixels with the background color.
std::memset(_gifData[i].get(), backgroundColor, screenWidth);
}
// The position of the image on the GIF 'screen'
const size_t imageHeight = _gif->Image.Height;
const size_t imageWidth = _gif->Image.Width;
const size_t imageTop = _gif->Image.Top;
const size_t imageLeft = _gif->Image.Left;
if (imageHeight + imageTop > screenHeight ||
imageWidth + imageLeft > screenWidth)
{
throw ParserException(_("GIF: invalid image data (bounds outside GIF screen)"));
}
// Handle interlaced data in four passes.
if (_gif->Image.Interlace)
{
log_debug(_("Found interlaced GIF (%d x %d)"), screenWidth, screenHeight);
// The order of interlaced GIFs.
static const int interlacedOffsets[] =
{ 0, 4, 2, 1 };
static const int interlacedJumps[] =
{ 8, 8, 4, 2 };
for (size_t i = 0; i < 4; ++i)
{
for (size_t j = imageTop + interlacedOffsets[i];
j < imageTop + imageHeight;
j += interlacedJumps[i])
{
if (DGifGetLine(_gif, &_gifData[j][imageLeft], imageWidth) != GIF_OK)
{
throw ParserException(_("GIF: failed reading pixel data"));
}
}
}
break;
}
// Non-interlaced data.
log_debug(_("Found non-interlaced GIF (%d x %d)"), screenWidth, screenHeight);
for (size_t i = imageTop; i < imageHeight; ++i)
{
// Read the gif data into the gif array.
if (DGifGetLine(_gif, &_gifData[i][imageLeft], imageWidth) != GIF_OK)
{
throw ParserException(_("GIF: failed reading pixel data"));
}
}
break;
}
case EXTENSION_RECORD_TYPE:
// Skip all extension records.
GifByteType* extension;
int extCode;
DGifGetExtension(_gif, &extCode, &extension);
while (extension)
{
if (DGifGetExtensionNext(_gif, &extension) == GIF_ERROR)
{
break;
}
}
break;
default:
break;
}
} while (record != TERMINATE_RECORD_TYPE);
// Set the type to RGB
// TODO: implement RGBA!
_type = GNASH_IMAGE_RGB;
}
} // namespace gnash
// Local Variables:
// mode: C++
// c-basic-offset: 8
// tab-width: 8
// indent-tabs-mode: t
// End: