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Cleaned up wxGIFDecoder.

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Applied patch by troelsk which mostly makes the GIF decoder more readable by using named constants instead of magic numbers. Left out the edits that changed unsigned char to wxUint8. In addition removed unnecessary casts around wxInputStream.GetC() calls.

Closes #12506.



git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66566 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Dimitri Schoolwerth
2011-01-04 11:47:53 +00:00
parent 6e45339c29
commit 90e10cd1be
1 changed files with 197 additions and 186 deletions
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383
src/common/gifdecod.cpp
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@@ -29,7 +29,16 @@
#include "wx/scopedptr.h"
#include "wx/scopeguard.h"
enum
{
GIF_MARKER_EXT = '!', // 0x21
GIF_MARKER_SEP = ',', // 0x2C
GIF_MARKER_ENDOFDATA = ';', // 0x3B
GIF_MARKER_EXT_GRAPHICS_CONTROL = 0xF9,
GIF_MARKER_EXT_COMMENT = 0xFE,
GIF_MARKER_EXT_APP = 0xFF
};
//---------------------------------------------------------------------------
// GIFImage
@@ -254,7 +263,7 @@ int wxGIFDecoder::getcode(wxInputStream& stream, int bits, int ab_fin)
// if no bytes left in this block, read the next block
if (m_restbyte == 0)
{
m_restbyte = (unsigned char)stream.GetC();
m_restbyte = stream.GetC();
/* Some encoders are a bit broken: instead of issuing
* an end-of-image symbol (ab_fin) they come up with
@@ -667,11 +676,11 @@ wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream)
bool done = false;
while (!done)
{
type = (unsigned char)stream.GetC();
type = stream.GetC();
/*
If the end of file has been reached (or an error) and a ";"
(0x3B) hasn't been encountered yet, exit the loop. (Without this
(GIF_MARKER_ENDOFDATA) hasn't been encountered yet, exit the loop. (Without this
check the while loop would loop endlessly.) Later on, in the next while
loop, the file will be treated as being truncated (But still
be decoded as far as possible). returning wxGIF_TRUNCATED is not
@@ -686,150 +695,147 @@ wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream)
break; // Alternative : "return wxGIF_INVFORMAT;"
}
// end of data?
if (type == 0x3B)
switch (type)
{
done = true;
}
else
// extension block?
if (type == 0x21)
{
if (((unsigned char)stream.GetC()) == 0xF9)
// graphics control extension, parse it
{
static const unsigned int gceSize = 6;
stream.Read(buf, gceSize);
if (stream.LastRead() != gceSize)
case GIF_MARKER_ENDOFDATA:
done = true;
break;
case GIF_MARKER_EXT:
if (stream.GetC() == GIF_MARKER_EXT_GRAPHICS_CONTROL)
// graphics control extension, parse it
{
Destroy();
return wxGIF_INVFORMAT;
}
// read delay and convert from 1/100 of a second to ms
delay = 10 * (buf[2] + 256 * buf[3]);
// read transparent colour index, if used
transparent = buf[1] & 0x01 ? buf[4] : -1;
// read disposal method
disposal = (wxAnimationDisposal)(((buf[1] & 0x1C) >> 2) - 1);
}
else
// other extension, skip
{
while ((i = (unsigned char)stream.GetC()) != 0)
{
if (stream.Eof() || (stream.LastRead() == 0) ||
stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
static const unsigned int gceSize = 6;
stream.Read(buf, gceSize);
if (stream.LastRead() != gceSize)
{
done = true;
break;
}
}
}
}
else
// image descriptor block?
if (type == 0x2C)
{
// allocate memory for IMAGEN struct
GIFImagePtr pimg(new GIFImage());
wxScopeGuard guardDestroy = wxMakeObjGuard(*this, &wxGIFDecoder::Destroy);
if ( !pimg.get() )
return wxGIF_MEMERR;
// fill in the data
static const unsigned int idbSize = (2 + 2 + 2 + 2 + 1);
stream.Read(buf, idbSize);
if (stream.LastRead() != idbSize)
return wxGIF_INVFORMAT;
pimg->left = buf[0] + 256 * buf[1];
pimg->top = buf[2] + 256 * buf[3];
/*
pimg->left = buf[4] + 256 * buf[5];
pimg->top = buf[4] + 256 * buf[5];
*/
pimg->w = buf[4] + 256 * buf[5];
pimg->h = buf[6] + 256 * buf[7];
if ( anim )
{
// some GIF images specify incorrect animation size but we can
// still open them if we fix up the animation size, see #9465
if ( m_nFrames == 0 )
{
if ( pimg->w > (unsigned)m_szAnimation.x )
m_szAnimation.x = pimg->w;
if ( pimg->h > (unsigned)m_szAnimation.y )
m_szAnimation.y = pimg->h;
}
else // subsequent frames
{
// check that we have valid size
if ( (!pimg->w || pimg->w > (unsigned)m_szAnimation.x) ||
(!pimg->h || pimg->h > (unsigned)m_szAnimation.y) )
{
wxLogError(_("Incorrect GIF frame size (%u, %d) for "
"the frame #%u"),
pimg->w, pimg->h, m_nFrames);
Destroy();
return wxGIF_INVFORMAT;
}
// read delay and convert from 1/100 of a second to ms
delay = 10 * (buf[2] + 256 * buf[3]);
// read transparent colour index, if used
transparent = buf[1] & 0x01 ? buf[4] : -1;
// read disposal method
disposal = (wxAnimationDisposal)(((buf[1] & 0x1C) >> 2) - 1);
}
}
interl = ((buf[8] & 0x40)? 1 : 0);
size = pimg->w * pimg->h;
pimg->transparent = transparent;
pimg->disposal = disposal;
pimg->delay = delay;
// allocate memory for image and palette
pimg->p = (unsigned char *) malloc((unsigned int)size);
pimg->pal = (unsigned char *) malloc(768);
if ((!pimg->p) || (!pimg->pal))
return wxGIF_MEMERR;
// load local color map if available, else use global map
if ((buf[8] & 0x80) == 0x80)
else
// other extension, skip
{
while ((i = stream.GetC()) != 0)
{
if (stream.Eof() || (stream.LastRead() == 0) ||
stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
{
done = true;
break;
}
}
}
break;
case GIF_MARKER_SEP:
{
unsigned int local_ncolors = 2 << (buf[8] & 0x07);
unsigned int numBytes = 3 * local_ncolors;
stream.Read(pimg->pal, numBytes);
pimg->ncolours = local_ncolors;
if (stream.LastRead() != numBytes)
// allocate memory for IMAGEN struct
GIFImagePtr pimg(new GIFImage());
wxScopeGuard guardDestroy = wxMakeObjGuard(*this, &wxGIFDecoder::Destroy);
if ( !pimg.get() )
return wxGIF_MEMERR;
// fill in the data
static const unsigned int idbSize = (2 + 2 + 2 + 2 + 1);
stream.Read(buf, idbSize);
if (stream.LastRead() != idbSize)
return wxGIF_INVFORMAT;
pimg->left = buf[0] + 256 * buf[1];
pimg->top = buf[2] + 256 * buf[3];
/*
pimg->left = buf[4] + 256 * buf[5];
pimg->top = buf[4] + 256 * buf[5];
*/
pimg->w = buf[4] + 256 * buf[5];
pimg->h = buf[6] + 256 * buf[7];
if ( anim )
{
// some GIF images specify incorrect animation size but we can
// still open them if we fix up the animation size, see #9465
if ( m_nFrames == 0 )
{
if ( pimg->w > (unsigned)m_szAnimation.x )
m_szAnimation.x = pimg->w;
if ( pimg->h > (unsigned)m_szAnimation.y )
m_szAnimation.y = pimg->h;
}
else // subsequent frames
{
// check that we have valid size
if ( (!pimg->w || pimg->w > (unsigned)m_szAnimation.x) ||
(!pimg->h || pimg->h > (unsigned)m_szAnimation.y) )
{
wxLogError(_("Incorrect GIF frame size (%u, %d) for "
"the frame #%u"),
pimg->w, pimg->h, m_nFrames);
return wxGIF_INVFORMAT;
}
}
}
interl = ((buf[8] & 0x40)? 1 : 0);
size = pimg->w * pimg->h;
pimg->transparent = transparent;
pimg->disposal = disposal;
pimg->delay = delay;
// allocate memory for image and palette
pimg->p = (unsigned char *) malloc((unsigned int)size);
pimg->pal = (unsigned char *) malloc(768);
if ((!pimg->p) || (!pimg->pal))
return wxGIF_MEMERR;
// load local color map if available, else use global map
if ((buf[8] & 0x80) == 0x80)
{
unsigned int local_ncolors = 2 << (buf[8] & 0x07);
unsigned int numBytes = 3 * local_ncolors;
stream.Read(pimg->pal, numBytes);
pimg->ncolours = local_ncolors;
if (stream.LastRead() != numBytes)
return wxGIF_INVFORMAT;
}
else
{
memcpy(pimg->pal, pal, 768);
pimg->ncolours = global_ncolors;
}
// get initial code size from first byte in raster data
bits = stream.GetC();
if (bits == 0)
return wxGIF_INVFORMAT;
// decode image
wxGIFErrorCode result = dgif(stream, pimg.get(), interl, bits);
if (result != wxGIF_OK)
return result;
guardDestroy.Dismiss();
// add the image to our frame array
m_frames.Add(pimg.release());
m_nFrames++;
// if this is not an animated GIF, exit after first image
if (!anim)
done = true;
break;
}
else
{
memcpy(pimg->pal, pal, 768);
pimg->ncolours = global_ncolors;
}
// get initial code size from first byte in raster data
bits = (unsigned char)stream.GetC();
if (bits == 0)
return wxGIF_INVFORMAT;
// decode image
wxGIFErrorCode result = dgif(stream, pimg.get(), interl, bits);
if (result != wxGIF_OK)
return result;
guardDestroy.Dismiss();
// add the image to our frame array
m_frames.Add(pimg.release());
m_nFrames++;
// if this is not an animated GIF, exit after first image
if (!anim)
done = true;
}
}
@@ -840,75 +846,80 @@ wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream)
}
// try to read to the end of the stream
while (type != 0x3B)
while (type != GIF_MARKER_ENDOFDATA)
{
if (!stream.IsOk())
return wxGIF_TRUNCATED;
type = (unsigned char)stream.GetC();
type = stream.GetC();
if (type == 0x21)
switch (type)
{
// extension type
(void) stream.GetC();
case GIF_MARKER_EXT:
// extension type
(void) stream.GetC();
// skip all data
while ((i = (unsigned char)stream.GetC()) != 0)
// skip all data
while ((i = stream.GetC()) != 0)
{
if (stream.Eof() || (stream.LastRead() == 0) ||
stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
{
Destroy();
return wxGIF_INVFORMAT;
}
}
break;
case GIF_MARKER_SEP:
{
if (stream.Eof() || (stream.LastRead() == 0) ||
stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
// image descriptor block
static const unsigned int idbSize = (2 + 2 + 2 + 2 + 1);
stream.Read(buf, idbSize);
if (stream.LastRead() != idbSize)
{
Destroy();
return wxGIF_INVFORMAT;
}
}
}
else if (type == 0x2C)
{
// image descriptor block
static const unsigned int idbSize = (2 + 2 + 2 + 2 + 1);
stream.Read(buf, idbSize);
if (stream.LastRead() != idbSize)
{
Destroy();
return wxGIF_INVFORMAT;
}
// local color map
if ((buf[8] & 0x80) == 0x80)
{
unsigned int local_ncolors = 2 << (buf[8] & 0x07);
wxFileOffset numBytes = 3 * local_ncolors;
if (stream.SeekI(numBytes, wxFromCurrent) == wxInvalidOffset)
// local color map
if ((buf[8] & 0x80) == 0x80)
{
unsigned int local_ncolors = 2 << (buf[8] & 0x07);
wxFileOffset numBytes = 3 * local_ncolors;
if (stream.SeekI(numBytes, wxFromCurrent) == wxInvalidOffset)
{
Destroy();
return wxGIF_INVFORMAT;
}
}
// initial code size
(void) stream.GetC();
if (stream.Eof() || (stream.LastRead() == 0))
{
Destroy();
return wxGIF_INVFORMAT;
}
}
// initial code size
(void) stream.GetC();
if (stream.Eof() || (stream.LastRead() == 0))
{
Destroy();
return wxGIF_INVFORMAT;
}
// skip all data
while ((i = (unsigned char)stream.GetC()) != 0)
{
if (stream.Eof() || (stream.LastRead() == 0) ||
stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
// skip all data
while ((i = stream.GetC()) != 0)
{
Destroy();
return wxGIF_INVFORMAT;
if (stream.Eof() || (stream.LastRead() == 0) ||
stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
{
Destroy();
return wxGIF_INVFORMAT;
}
}
break;
}
}
else if ((type != 0x3B) && (type != 00)) // testing
{
// images are OK, but couldn't read to the end of the stream
return wxGIF_TRUNCATED;
default:
if ((type != GIF_MARKER_ENDOFDATA) && (type != 00)) // testing
{
// images are OK, but couldn't read to the end of the stream
return wxGIF_TRUNCATED;
}
break;
}
}