fixed wxXmlResource::Load's detection of filenames to be done as early as possible

[wxWidgets.git] / src / common / gifdecod.cpp

diff --git a/src/common/gifdecod.cpp b/src/common/gifdecod.cpp
index 229050812f200b935d9cee6a648858e3edb8386f..1566f40bddff71423b3fbc74a9f67e6735bfec01 100644 (file)
--- a/src/common/gifdecod.cpp
+++ b/src/common/gifdecod.cpp
@@ -1,5 +1,5 @@
 /////////////////////////////////////////////////////////////////////////////
 /////////////////////////////////////////////////////////////////////////////

-// Name:        gifdecod.cpp
+// Name:        src/common/gifdecod.cpp

 // Purpose:     wxGIFDecoder, GIF reader for wxImage and wxAnimation
 // Author:      Guillermo Rodriguez Garcia <guille@iies.es>
 // Version:     3.04
 // Purpose:     wxGIFDecoder, GIF reader for wxImage and wxAnimation
 // Author:      Guillermo Rodriguez Garcia <guille@iies.es>
 // Version:     3.04


@@ -8,27 +8,54 @@
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 

-#ifdef __GNUG__
-#pragma implementation "gifdecod.h"
-#endif
-

 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__

-#  pragma hdrstop
+    #pragma hdrstop

 #endif
 
 #endif
 

+#if wxUSE_STREAMS && wxUSE_GIF
+

 #ifndef WX_PRECOMP
 #ifndef WX_PRECOMP

-#  include "wx/defs.h"
-#  include "wx/palette.h"
+    #include "wx/palette.h"

 #endif
 
 #endif
 

-#if wxUSE_STREAMS && wxUSE_GIF
-

 #include <stdlib.h>
 #include <string.h>
 #include "wx/gifdecod.h"
 #include <stdlib.h>
 #include <string.h>
 #include "wx/gifdecod.h"

+#include "wx/scopedptr.h"
+#include "wx/scopeguard.h"
+
+
+
+//---------------------------------------------------------------------------
+// GIFImage
+//---------------------------------------------------------------------------
+
+// internal class for storing GIF image data
+class GIFImage
+{
+public:
+    // def ctor
+    GIFImage();
+
+    unsigned int w;                 // width
+    unsigned int h;                 // height
+    unsigned int left;              // x coord (in logical screen)
+    unsigned int top;               // y coord (in logical screen)
+    int transparent;                // transparent color index (-1 = none)
+    wxAnimationDisposal disposal;   // disposal method
+    long delay;                     // delay in ms (-1 = unused)
+    unsigned char *p;               // bitmap
+    unsigned char *pal;             // palette
+    unsigned int ncolours;          // number of colours
+
+    wxDECLARE_NO_COPY_CLASS(GIFImage);
+};
+
+wxDECLARE_SCOPED_PTR(GIFImage, GIFImagePtr)
+wxDEFINE_SCOPED_PTR(GIFImage, GIFImagePtr)

 
 
 //---------------------------------------------------------------------------
 
 
 //---------------------------------------------------------------------------


@@ -41,32 +68,19 @@ GIFImage::GIFImage()
     left = 0;
     top = 0;
     transparent = 0;
     left = 0;
     top = 0;
     transparent = 0;

-    disposal = 0;
+    disposal = wxANIM_DONOTREMOVE;

     delay = -1;
     p = (unsigned char *) NULL;
     pal = (unsigned char *) NULL;
     delay = -1;
     p = (unsigned char *) NULL;
     pal = (unsigned char *) NULL;

-    next = (GIFImage *) NULL;
-    prev = (GIFImage *) NULL;
+    ncolours = 0;

 }
 
 //---------------------------------------------------------------------------
 // wxGIFDecoder constructor and destructor
 //---------------------------------------------------------------------------
 
 }
 
 //---------------------------------------------------------------------------
 // wxGIFDecoder constructor and destructor
 //---------------------------------------------------------------------------
 

-wxGIFDecoder::wxGIFDecoder(wxInputStream *s, bool anim)
+wxGIFDecoder::wxGIFDecoder()

 {
 {

-    m_f    = s;
-    m_anim = anim;
-
-    m_background = -1;
-    m_screenw = 0;
-    m_screenh = 0;
-
-    m_pimage  = NULL;
-    m_pfirst  = NULL;
-    m_plast   = NULL;
-    m_image   = 0;
-    m_nimages = 0;

 }
 
 wxGIFDecoder::~wxGIFDecoder()
 }
 
 wxGIFDecoder::~wxGIFDecoder()


@@ -76,24 +90,17 @@ wxGIFDecoder::~wxGIFDecoder()
 
 void wxGIFDecoder::Destroy()
 {
 
 void wxGIFDecoder::Destroy()
 {

-    GIFImage *pimg, *paux;
-
-    pimg = m_pfirst;
-
-    while (pimg != NULL)
+    wxASSERT(m_nFrames==m_frames.GetCount());
+    for (unsigned int i=0; i<m_nFrames; i++)

     {
     {

-        paux = pimg->next;
-        free(pimg->p);
-        free(pimg->pal);
-        delete pimg;
-        pimg = paux;
+        GIFImage *f = (GIFImage*)m_frames[i];
+        free(f->p);
+        free(f->pal);
+        delete f;

     }
 
     }
 

-    m_pimage  = NULL;
-    m_pfirst  = NULL;
-    m_plast   = NULL;
-    m_image   = 0;
-    m_nimages = 0;
+    m_frames.Clear();
+    m_nFrames = 0;

 }
 
 
 }
 
 


@@ -103,30 +110,32 @@ void wxGIFDecoder::Destroy()
 
 // This function was designed by Vaclav Slavik
 
 
 // This function was designed by Vaclav Slavik
 

-bool wxGIFDecoder::ConvertToImage(wxImage *image) const
+bool wxGIFDecoder::ConvertToImage(unsigned int frame, wxImage *image) const

 {
     unsigned char *src, *dst, *pal;
     unsigned long i;
     int      transparent;
 
 {
     unsigned char *src, *dst, *pal;
     unsigned long i;
     int      transparent;
 

-    /* just in case... */
+    // just in case...

     image->Destroy();
 
     image->Destroy();
 

-    /* create the image */
-    image->Create(GetWidth(), GetHeight());
+    // create the image
+    wxSize sz = GetFrameSize(frame);
+    image->Create(sz.GetWidth(), sz.GetHeight());
+    image->SetType(wxBITMAP_TYPE_GIF);

 
     if (!image->Ok())
 
     if (!image->Ok())

-        return FALSE;
+        return false;

 
 

-    pal = GetPalette();
-    src = GetData();
+    pal = GetPalette(frame);
+    src = GetData(frame);

     dst = image->GetData();
     dst = image->GetData();

-    transparent = GetTransparentColour();
+    transparent = GetTransparentColourIndex(frame);

 
 

-    /* set transparent colour mask */
+    // set transparent colour mask

     if (transparent != -1)
     {
     if (transparent != -1)
     {

-        for (i = 0; i < 256; i++)
+        for (i = 0; i < GetNcolours(frame); i++)

         {
             if ((pal[3 * i + 0] == 255) &&
                 (pal[3 * i + 1] == 0) &&
         {
             if ((pal[3 * i + 0] == 255) &&
                 (pal[3 * i + 1] == 0) &&


@@ -143,35 +152,33 @@ bool wxGIFDecoder::ConvertToImage(wxImage *image) const
         image->SetMaskColour(255, 0, 255);
     }
     else
         image->SetMaskColour(255, 0, 255);
     }
     else

-        image->SetMask(FALSE);
+        image->SetMask(false);

 
 #if wxUSE_PALETTE
 
 #if wxUSE_PALETTE

-    if (pal)
-    {
-        unsigned char r[256];
-        unsigned char g[256];
-        unsigned char b[256];
+    unsigned char r[256];
+    unsigned char g[256];
+    unsigned char b[256];

 
 

-        for (i = 0; i < 256; i++)
-        {
-            r[i] = pal[3*i + 0];
-            g[i] = pal[3*i + 1];
-            b[i] = pal[3*i + 2];
-        }
-
-        image->SetPalette(wxPalette(256, r, g, b));
+    for (i = 0; i < 256; i++)
+    {
+        r[i] = pal[3*i + 0];
+        g[i] = pal[3*i + 1];
+        b[i] = pal[3*i + 2];

     }
     }

+
+    image->SetPalette(wxPalette(GetNcolours(frame), r, g, b));

 #endif // wxUSE_PALETTE
 
 #endif // wxUSE_PALETTE
 

-    /* copy image data */
-    for (i = 0; i < (GetWidth() * GetHeight()); i++, src++)
+    // copy image data
+    unsigned long npixel = sz.GetWidth() * sz.GetHeight();
+    for (i = 0; i < npixel; i++, src++)

     {
         *(dst++) = pal[3 * (*src) + 0];
         *(dst++) = pal[3 * (*src) + 1];
         *(dst++) = pal[3 * (*src) + 2];
     }
 
     {
         *(dst++) = pal[3 * (*src) + 0];
         *(dst++) = pal[3 * (*src) + 1];
         *(dst++) = pal[3 * (*src) + 2];
     }
 

-    return TRUE;
+    return true;

 }
 
 
 }
 
 


@@ -179,115 +186,48 @@ bool wxGIFDecoder::ConvertToImage(wxImage *image) const
 // Data accessors
 //---------------------------------------------------------------------------
 
 // Data accessors
 //---------------------------------------------------------------------------
 

-// Get data for current frame
-
-int wxGIFDecoder::GetFrameIndex() const         { return m_image; }
-unsigned char* wxGIFDecoder::GetData() const    { return (m_pimage->p); }
-unsigned char* wxGIFDecoder::GetPalette() const { return (m_pimage->pal); }
-unsigned int wxGIFDecoder::GetWidth() const     { return (m_pimage->w); }
-unsigned int wxGIFDecoder::GetHeight() const    { return (m_pimage->h); }
-unsigned int wxGIFDecoder::GetTop() const       { return (m_pimage->top); }
-unsigned int wxGIFDecoder::GetLeft() const      { return (m_pimage->left); }
-int wxGIFDecoder::GetTransparentColour() const  { return (m_pimage->transparent); }
-int wxGIFDecoder::GetDisposalMethod() const     { return (m_pimage->disposal); }
-long wxGIFDecoder::GetDelay() const             { return (m_pimage->delay); }
-
-// Get global data
+#define GetFrame(n)     ((GIFImage*)m_frames[n])

 
 

-unsigned int wxGIFDecoder::GetLogicalScreenWidth() const    { return m_screenw; }
-unsigned int wxGIFDecoder::GetLogicalScreenHeight() const   { return m_screenh; }
-int wxGIFDecoder::GetBackgroundColour() const   { return m_background; }
-int wxGIFDecoder::GetNumberOfFrames() const     { return m_nimages; }
-bool wxGIFDecoder::IsAnimation() const          { return (m_nimages > 1); }

 
 

+// Get data for current frame

 
 

-//---------------------------------------------------------------------------
-// Functions to move through the animation
-//---------------------------------------------------------------------------
-
-bool wxGIFDecoder::GoFirstFrame()
+wxSize wxGIFDecoder::GetFrameSize(unsigned int frame) const

 {
 {

-    if (!IsAnimation())
-        return FALSE;
-
-    m_image = 1;
-    m_pimage = m_pfirst;
-    return TRUE;
+    return wxSize(GetFrame(frame)->w, GetFrame(frame)->h);

 }
 
 }
 

-bool wxGIFDecoder::GoLastFrame()
+wxPoint wxGIFDecoder::GetFramePosition(unsigned int frame) const

 {
 {

-    if (!IsAnimation())
-        return FALSE;
-
-    m_image = m_nimages;
-    m_pimage = m_plast;
-    return TRUE;
+    return wxPoint(GetFrame(frame)->left, GetFrame(frame)->top);

 }
 
 }
 

-bool wxGIFDecoder::GoNextFrame(bool cyclic)
+wxAnimationDisposal wxGIFDecoder::GetDisposalMethod(unsigned int frame) const

 {
 {

-    if (!IsAnimation())
-        return FALSE;
-
-    if ((m_image < m_nimages) || (cyclic))
-    {
-        m_pimage = m_pimage->next;
-        m_image++;
-
-        if (!m_pimage)
-        {
-            m_image = 1;
-            m_pimage = m_pfirst;
-        }
-
-        return TRUE;
-    }
-    else
-        return FALSE;
+    return GetFrame(frame)->disposal;

 }
 
 }
 

-bool wxGIFDecoder::GoPrevFrame(bool cyclic)
+long wxGIFDecoder::GetDelay(unsigned int frame) const

 {
 {

-    if (!IsAnimation())
-        return FALSE;
-
-    if ((m_image > 1) || (cyclic))
-    {
-        m_pimage = m_pimage->prev;
-        m_image--;
-
-        if (!m_pimage)
-        {
-            m_image = m_nimages;
-            m_pimage = m_plast;
-        }
-
-        return TRUE;
-    }
-    else
-        return FALSE;
+    return GetFrame(frame)->delay;

 }
 
 }
 

-bool wxGIFDecoder::GoFrame(int which)
+wxColour wxGIFDecoder::GetTransparentColour(unsigned int frame) const

 {
 {

-    int i;
+    unsigned char *pal = GetFrame(frame)->pal;
+    int n = GetFrame(frame)->transparent;
+    if (n == -1)
+        return wxNullColour;
+
+    return wxColour(pal[n*3 + 0],
+                    pal[n*3 + 1],
+                    pal[n*3 + 2]);
+}

 
 

-    if (!IsAnimation())
-        return FALSE;
+unsigned char* wxGIFDecoder::GetData(unsigned int frame) const    { return (GetFrame(frame)->p); }
+unsigned char* wxGIFDecoder::GetPalette(unsigned int frame) const { return (GetFrame(frame)->pal); }
+unsigned int wxGIFDecoder::GetNcolours(unsigned int frame) const  { return (GetFrame(frame)->ncolours); }
+int wxGIFDecoder::GetTransparentColourIndex(unsigned int frame) const  { return (GetFrame(frame)->transparent); }

 
 

-    if ((which >= 1) && (which <= m_nimages))
-    {
-        m_pimage = m_pfirst;
-
-        for (i = 1; i < which; i++)
-            m_pimage = m_pimage->next;
-
-        return TRUE;
-    }
-    else
-        return FALSE;
-}

 
 
 //---------------------------------------------------------------------------
 
 
 //---------------------------------------------------------------------------


@@ -297,23 +237,22 @@ bool wxGIFDecoder::GoFrame(int which)
 // getcode:
 //  Reads the next code from the file stream, with size 'bits'
 //
 // getcode:
 //  Reads the next code from the file stream, with size 'bits'
 //

-int wxGIFDecoder::getcode(int bits, int ab_fin)
+int wxGIFDecoder::getcode(wxInputStream& stream, int bits, int ab_fin)

 {
 {

-    unsigned int mask;          /* bit mask */
-    unsigned int code;          /* code (result) */
+    unsigned int mask;          // bit mask
+    unsigned int code;          // code (result)

 
 

-
-    /* get remaining bits from last byte read */
+    // get remaining bits from last byte read

     mask = (1 << bits) - 1;
     code = (m_lastbyte >> (8 - m_restbits)) & mask;
 
     mask = (1 << bits) - 1;
     code = (m_lastbyte >> (8 - m_restbits)) & mask;
 

-    /* keep reading new bytes while needed */
+    // keep reading new bytes while needed

     while (bits > m_restbits)
     {
     while (bits > m_restbits)
     {

-        /* if no bytes left in this block, read the next block */
+        // if no bytes left in this block, read the next block

         if (m_restbyte == 0)
         {
         if (m_restbyte == 0)
         {

-            m_restbyte = (unsigned char)m_f->GetC();
+            m_restbyte = (unsigned char)stream.GetC();

 
             /* Some encoders are a bit broken: instead of issuing
              * an end-of-image symbol (ab_fin) they come up with
 
             /* Some encoders are a bit broken: instead of issuing
              * an end-of-image symbol (ab_fin) they come up with


@@ -326,9 +265,9 @@ int wxGIFDecoder::getcode(int bits, int ab_fin)
                 break;
             }
 
                 break;
             }
 

-            /* prefetch data */
-            m_f->Read((void *) m_buffer, m_restbyte);
-            if (m_f->LastRead() != m_restbyte)
+            // prefetch data
+            stream.Read((void *) m_buffer, m_restbyte);
+            if (stream.LastRead() != m_restbyte)

             {
                 code = ab_fin;
                 return code;
             {
                 code = ab_fin;
                 return code;


@@ -336,17 +275,17 @@ int wxGIFDecoder::getcode(int bits, int ab_fin)
             m_bufp = m_buffer;
         }
 
             m_bufp = m_buffer;
         }
 

-        /* read next byte and isolate the bits we need */
+        // read next byte and isolate the bits we need

         m_lastbyte = (unsigned char) (*m_bufp++);
         mask       = (1 << (bits - m_restbits)) - 1;
         code       = code + ((m_lastbyte & mask) << m_restbits);
         m_restbyte--;
 
         m_lastbyte = (unsigned char) (*m_bufp++);
         mask       = (1 << (bits - m_restbits)) - 1;
         code       = code + ((m_lastbyte & mask) << m_restbits);
         m_restbyte--;
 

-        /* adjust total number of bits extracted from the buffer */
+        // adjust total number of bits extracted from the buffer

         m_restbits = m_restbits + 8;
     }
 
         m_restbits = m_restbits + 8;
     }
 

-    /* find number of bits remaining for next code */
+    // find number of bits remaining for next code

     m_restbits = (m_restbits - bits);
 
     return code;
     m_restbits = (m_restbits - bits);
 
     return code;


@@ -358,23 +297,24 @@ int wxGIFDecoder::getcode(int bits, int ab_fin)
 //  is 'bits'. Supports interlaced images (interl == 1).
 //  Returns wxGIF_OK (== 0) on success, or an error code if something
 // fails (see header file for details)
 //  is 'bits'. Supports interlaced images (interl == 1).
 //  Returns wxGIF_OK (== 0) on success, or an error code if something
 // fails (see header file for details)

-int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
+wxGIFErrorCode
+wxGIFDecoder::dgif(wxInputStream& stream, GIFImage *img, int interl, int bits)

 {
     static const int allocSize = 4096 + 1;
 {
     static const int allocSize = 4096 + 1;

-    int *ab_prefix = new int[allocSize]; /* alphabet (prefixes) */
+    int *ab_prefix = new int[allocSize]; // alphabet (prefixes)

     if (ab_prefix == NULL)
     {
         return wxGIF_MEMERR;
     }
 
     if (ab_prefix == NULL)
     {
         return wxGIF_MEMERR;
     }
 

-    int *ab_tail = new int[allocSize];   /* alphabet (tails) */
+    int *ab_tail = new int[allocSize];   // alphabet (tails)

     if (ab_tail == NULL)
     {
         delete[] ab_prefix;
         return wxGIF_MEMERR;
     }
 
     if (ab_tail == NULL)
     {
         delete[] ab_prefix;
         return wxGIF_MEMERR;
     }
 

-    int *stack = new int[allocSize];     /* decompression stack */
+    int *stack = new int[allocSize];     // decompression stack

     if (stack == NULL)
     {
         delete[] ab_prefix;
     if (stack == NULL)
     {
         delete[] ab_prefix;


@@ -382,22 +322,22 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
         return wxGIF_MEMERR;
     }
 
         return wxGIF_MEMERR;
     }
 

-    int ab_clr;                     /* clear code */
-    int ab_fin;                     /* end of info code */
-    int ab_bits;                    /* actual symbol width, in bits */
-    int ab_free;                    /* first free position in alphabet */
-    int ab_max;                     /* last possible character in alphabet */
-    int pass;                       /* pass number in interlaced images */
-    int pos;                        /* index into decompresion stack */
-    unsigned int x, y;              /* position in image buffer */
+    int ab_clr;                     // clear code
+    int ab_fin;                     // end of info code
+    int ab_bits;                    // actual symbol width, in bits
+    int ab_free;                    // first free position in alphabet
+    int ab_max;                     // last possible character in alphabet
+    int pass;                       // pass number in interlaced images
+    int pos;                        // index into decompresion stack
+    unsigned int x, y;              // position in image buffer

 
     int code, readcode, lastcode, abcabca;
 
 
     int code, readcode, lastcode, abcabca;
 

-    /* these won't change */
+    // these won't change

     ab_clr = (1 << bits);
     ab_fin = (1 << bits) + 1;
 
     ab_clr = (1 << bits);
     ab_fin = (1 << bits) + 1;
 

-    /* these will change through the decompression proccess */
+    // these will change through the decompression proccess

     ab_bits  = bits + 1;
     ab_free  = (1 << bits) + 2;
     ab_max   = (1 << ab_bits) - 1;
     ab_bits  = bits + 1;
     ab_free  = (1 << bits) + 2;
     ab_max   = (1 << ab_bits) - 1;


@@ -406,41 +346,41 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
     pass     = 1;
     pos = x = y = 0;
 
     pass     = 1;
     pos = x = y = 0;
 

-    /* reset decoder vars */
+    // reset decoder vars

     m_restbits = 0;
     m_restbyte = 0;
     m_lastbyte = 0;
 
     do
     {
     m_restbits = 0;
     m_restbyte = 0;
     m_lastbyte = 0;
 
     do
     {

-        /* get next code */
-        readcode = code = getcode(ab_bits, ab_fin);
+        // get next code
+        readcode = code = getcode(stream, ab_bits, ab_fin);

 
 

-        /* end of image? */
+        // end of image?

         if (code == ab_fin) break;
 
         if (code == ab_fin) break;
 

-        /* reset alphabet? */
+        // reset alphabet?

         if (code == ab_clr)
         {
         if (code == ab_clr)
         {

-            /* reset main variables */
+            // reset main variables

             ab_bits  = bits + 1;
             ab_free  = (1 << bits) + 2;
             ab_max   = (1 << ab_bits) - 1;
             lastcode = -1;
             abcabca  = -1;
 
             ab_bits  = bits + 1;
             ab_free  = (1 << bits) + 2;
             ab_max   = (1 << ab_bits) - 1;
             lastcode = -1;
             abcabca  = -1;
 

-            /* skip to next code */
+            // skip to next code

             continue;
         }
 
             continue;
         }
 

-        /* unknown code: special case (like in ABCABCA) */
+        // unknown code: special case (like in ABCABCA)

         if (code >= ab_free)
         {
         if (code >= ab_free)
         {

-            code = lastcode;            /* take last string */
-            stack[pos++] = abcabca;     /* add first character */
+            code = lastcode;            // take last string
+            stack[pos++] = abcabca;     // add first character

         }
 
         }
 

-        /* build the string for this code in the stack */
+        // build the string for this code in the stack

         while (code > ab_clr)
         {
             stack[pos++] = ab_tail[code];
         while (code > ab_clr)
         {
             stack[pos++] = ab_tail[code];


@@ -466,12 +406,31 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
             return wxGIF_INVFORMAT;
         }
 
             return wxGIF_INVFORMAT;
         }
 

-        stack[pos] = code;              /* push last code into the stack */
-        abcabca    = code;              /* save for special case */
+        stack[pos] = code;              // push last code into the stack
+        abcabca    = code;              // save for special case

 
 

-        /* make new entry in alphabet (only if NOT just cleared) */
+        // make new entry in alphabet (only if NOT just cleared)

         if (lastcode != -1)
         {
         if (lastcode != -1)
         {

+            // Normally, after the alphabet is full and can't grow any
+            // further (ab_free == 4096), encoder should (must?) emit CLEAR
+            // to reset it. This checks whether we really got it, otherwise
+            // the GIF is damaged.
+            if (ab_free > ab_max)
+            {
+                delete[] ab_prefix;
+                delete[] ab_tail;
+                delete[] stack;
+                return wxGIF_INVFORMAT;
+            }
+
+            // This assert seems unnecessary since the condition above
+            // eliminates the only case in which it went false. But I really
+            // don't like being forced to ask "Who in .text could have
+            // written there?!" And I wouldn't have been forced to ask if
+            // this line had already been here.
+            wxASSERT(ab_free < allocSize);
+

             ab_prefix[ab_free] = lastcode;
             ab_tail[ab_free]   = code;
             ab_free++;
             ab_prefix[ab_free] = lastcode;
             ab_tail[ab_free]   = code;
             ab_free++;


@@ -483,7 +442,7 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
             }
         }
 
             }
         }
 

-        /* dump stack data to the image buffer */
+        // dump stack data to the image buffer

         while (pos >= 0)
         {
             (img->p)[x + (y * (img->w))] = (char) stack[pos];
         while (pos >= 0)
         {
             (img->p)[x + (y * (img->w))] = (char) stack[pos];


@@ -495,7 +454,7 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
 
                 if (interl)
                 {
 
                 if (interl)
                 {

-                    /* support for interlaced images */
+                    // support for interlaced images

                     switch (pass)
                     {
                         case 1: y += 8; break;
                     switch (pass)
                     {
                         case 1: y += 8; break;


@@ -507,7 +466,7 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
                     /* loop until a valid y coordinate has been
                     found, Or if the maximum number of passes has
                     been reached, exit the loop, and stop image
                     /* loop until a valid y coordinate has been
                     found, Or if the maximum number of passes has
                     been reached, exit the loop, and stop image

-                    decoding (At this point the image is succesfully
+                    decoding (At this point the image is successfully

                     decoded).
                     If we don't loop, but merely set y to some other
                     value, that new value might still be invalid depending
                     decoded).
                     If we don't loop, but merely set y to some other
                     value, that new value might still be invalid depending


@@ -552,7 +511,7 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
                 }
                 else
                 {
                 }
                 else
                 {

-                    /* non-interlaced */
+                    // non-interlaced

                     y++;
 /*
 Normally image decoding is finished when an End of Information code is
                     y++;
 /*
 Normally image decoding is finished when an End of Information code is


@@ -612,22 +571,23 @@ as an End of Information itself)
 
 
 // CanRead:
 
 
 // CanRead:

-//  Returns TRUE if the file looks like a valid GIF, FALSE otherwise.
+//  Returns true if the file looks like a valid GIF, false otherwise.

 //
 //

-bool wxGIFDecoder::CanRead()
+bool wxGIFDecoder::CanRead(wxInputStream &stream) const

 {
     unsigned char buf[3];
 
 {
     unsigned char buf[3];
 

-    if ( !m_f->Read(buf, WXSIZEOF(buf)) )
-        return FALSE;
+    if ( !stream.Read(buf, WXSIZEOF(buf)) )
+        return false;

 
 

-    m_f->SeekI(-(off_t)WXSIZEOF(buf), wxFromCurrent);
+    if (stream.SeekI(-(wxFileOffset)WXSIZEOF(buf), wxFromCurrent) == wxInvalidOffset)
+        return false;       // this happens e.g. for non-seekable streams

 
     return memcmp(buf, "GIF", WXSIZEOF(buf)) == 0;
 }
 
 
 
     return memcmp(buf, "GIF", WXSIZEOF(buf)) == 0;
 }
 
 

-// ReadGIF:
+// LoadGIF:

 //  Reads and decodes one or more GIF images, depending on whether
 //  animated GIF support is enabled. Can read GIFs with any bit
 //  size (color depth), but the output images are always expanded
 //  Reads and decodes one or more GIF images, depending on whether
 //  animated GIF support is enabled. Can read GIFs with any bit
 //  size (color depth), but the output images are always expanded


@@ -636,76 +596,79 @@ bool wxGIFDecoder::CanRead()
 //  (== 0) on success, or an error code if something fails (see
 //  header file for details)
 //
 //  (== 0) on success, or an error code if something fails (see
 //  header file for details)
 //

-int wxGIFDecoder::ReadGIF()
+wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream)

 {
 {

-    unsigned int ncolors;
-    int           bits, interl, transparent, disposal, i;
+    unsigned int  global_ncolors = 0;
+    int           bits, interl, i;
+    wxAnimationDisposal disposal;

     long          size;
     long          delay;
     unsigned char type = 0;
     unsigned char pal[768];
     unsigned char buf[16];
     long          size;
     long          delay;
     unsigned char type = 0;
     unsigned char pal[768];
     unsigned char buf[16];

-    GIFImage      **ppimg;
-    GIFImage      *pimg, *pprev;
+    bool anim = true;

 
 

-    /* check GIF signature */
-    if (!CanRead())
+    // check GIF signature
+    if (!CanRead(stream))

         return wxGIF_INVFORMAT;
 
         return wxGIF_INVFORMAT;
 

-    /* check for animated GIF support (ver. >= 89a) */
+    // check for animated GIF support (ver. >= 89a)

 
 

-    static const size_t headerSize = (3 + 3);
-    m_f->Read(buf, headerSize);
-    if (m_f->LastRead() != headerSize)
+    static const unsigned int headerSize = (3 + 3);
+    stream.Read(buf, headerSize);
+    if (stream.LastRead() != headerSize)

     {
         return wxGIF_INVFORMAT;
     }
 
     if (memcmp(buf + 3, "89a", 3) < 0)
     {
     {
         return wxGIF_INVFORMAT;
     }
 
     if (memcmp(buf + 3, "89a", 3) < 0)
     {

-        m_anim = FALSE;
+        anim = false;

     }
 
     }
 

-    /* read logical screen descriptor block (LSDB) */
-    static const size_t lsdbSize = (2 + 2 + 1 + 1 + 1);
-    m_f->Read(buf, lsdbSize);
-    if (m_f->LastRead() != lsdbSize)
+    // read logical screen descriptor block (LSDB)
+    static const unsigned int lsdbSize = (2 + 2 + 1 + 1 + 1);
+    stream.Read(buf, lsdbSize);
+    if (stream.LastRead() != lsdbSize)

     {
         return wxGIF_INVFORMAT;
     }
 
     {
         return wxGIF_INVFORMAT;
     }
 

-    m_screenw = buf[0] + 256 * buf[1];
-    m_screenh = buf[2] + 256 * buf[3];
+    m_szAnimation.SetWidth( buf[0] + 256 * buf[1] );
+    m_szAnimation.SetHeight( buf[2] + 256 * buf[3] );

 
 

-    /* load global color map if available */
+    if (anim && ((m_szAnimation.GetWidth() == 0) || (m_szAnimation.GetHeight() == 0)))
+    {
+        return wxGIF_INVFORMAT;
+    }
+
+    // load global color map if available

     if ((buf[4] & 0x80) == 0x80)
     {
     if ((buf[4] & 0x80) == 0x80)
     {

-        m_background = buf[5];
+        int backgroundColIndex = buf[5];

 
 

-        ncolors = 2 << (buf[4] & 0x07);
-        size_t numBytes = 3 * ncolors;
-        m_f->Read(pal, numBytes);
-        if (m_f->LastRead() != numBytes)
+        global_ncolors = 2 << (buf[4] & 0x07);
+        unsigned int numBytes = 3 * global_ncolors;
+        stream.Read(pal, numBytes);
+        if (stream.LastRead() != numBytes)

         {
             return wxGIF_INVFORMAT;
         }
         {
             return wxGIF_INVFORMAT;
         }

+
+        m_background.Set(pal[backgroundColIndex*3 + 0],
+                         pal[backgroundColIndex*3 + 1],
+                         pal[backgroundColIndex*3 + 2]);

     }
 
     }
 

-    /* transparent colour, disposal method and delay default to unused */
-    transparent = -1;
-    disposal = -1;
+    // transparent colour, disposal method and delay default to unused
+    int transparent = -1;
+    disposal = wxANIM_UNSPECIFIED;

     delay = -1;
 
     delay = -1;
 

-    /* read images */
-    ppimg = &m_pfirst;
-    pprev = NULL;
-    pimg  = NULL;
-
-    bool done = FALSE;
-
-    while(!done)
+    bool done = false;
+    while (!done)

     {
     {

-        type = (unsigned char)m_f->GetC();
+        type = (unsigned char)stream.GetC();

 
         /*
         If the end of file has been reached (or an error) and a ";"
 
         /*
         If the end of file has been reached (or an error) and a ";"


@@ -715,7 +678,7 @@ int wxGIFDecoder::ReadGIF()
         be decoded as far as possible). returning wxGIF_TRUNCATED is not
         possible here since some init code is done after this loop.
         */
         be decoded as far as possible). returning wxGIF_TRUNCATED is not
         possible here since some init code is done after this loop.
         */

-        if (m_f->Eof())// || !m_f->IsOk())
+        if (stream.Eof())// || !stream.IsOk())

         {
             /*
             type is set to some bogus value, so there's no
         {
             /*
             type is set to some bogus value, so there's no


@@ -724,71 +687,66 @@ int wxGIFDecoder::ReadGIF()
             break; // Alternative : "return wxGIF_INVFORMAT;"
         }
 
             break; // Alternative : "return wxGIF_INVFORMAT;"
         }
 

-        /* end of data? */
+        // end of data?

         if (type == 0x3B)
         {
         if (type == 0x3B)
         {

-            done = TRUE;
+            done = true;

         }
         else
         }
         else

-        /* extension block? */
+        // extension block?

         if (type == 0x21)
         {
         if (type == 0x21)
         {

-            if (((unsigned char)m_f->GetC()) == 0xF9)
-            /* graphics control extension, parse it */
+            if (((unsigned char)stream.GetC()) == 0xF9)
+            // graphics control extension, parse it

             {
             {

-                static const size_t gceSize = 6;
-                m_f->Read(buf, gceSize);
-                if (m_f->LastRead() != gceSize)
+                static const unsigned int gceSize = 6;
+                stream.Read(buf, gceSize);
+                if (stream.LastRead() != gceSize)

                 {
                     Destroy();
                     return wxGIF_INVFORMAT;
                 }
 
                 {
                     Destroy();
                     return wxGIF_INVFORMAT;
                 }
 

-                /* read delay and convert from 1/100 of a second to ms */
+                // read delay and convert from 1/100 of a second to ms

                 delay = 10 * (buf[2] + 256 * buf[3]);
 
                 delay = 10 * (buf[2] + 256 * buf[3]);
 

-                /* read transparent colour index, if used */
-                if (buf[1] & 0x01)
-                    transparent = buf[4];
+                // read transparent colour index, if used
+                transparent = buf[1] & 0x01 ? buf[4] : -1;

 
 

-                /* read disposal method */
-                disposal = (buf[1] & 0x1C) - 1;
+                // read disposal method
+                disposal = (wxAnimationDisposal)(((buf[1] & 0x1C) >> 2) - 1);

             }
             else
             }
             else

-            /* other extension, skip */
+            // other extension, skip

             {
             {

-                while ((i = (unsigned char)m_f->GetC()) != 0)
+                while ((i = (unsigned char)stream.GetC()) != 0)

                 {
                 {

-                    m_f->SeekI(i, wxFromCurrent);
-                    if (m_f->Eof())
+                    if (stream.Eof() || (stream.LastRead() == 0) ||
+                        stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)

                     {
                     {

-                        done = TRUE;
+                        done = true;

                         break;
                     }
                 }
             }
         }
         else
                         break;
                     }
                 }
             }
         }
         else

-        /* image descriptor block? */
+        // image descriptor block?

         if (type == 0x2C)
         {
         if (type == 0x2C)
         {

-            /* allocate memory for IMAGEN struct */
-            pimg = (*ppimg) = new GIFImage();
+            // allocate memory for IMAGEN struct
+            GIFImagePtr pimg(new GIFImage());

 
 

-            if (pimg == NULL)
-            {
-                Destroy();
+            wxScopeGuard guardDestroy = wxMakeObjGuard(*this, &wxGIFDecoder::Destroy);
+
+            if ( !pimg.get() )

                 return wxGIF_MEMERR;
                 return wxGIF_MEMERR;

-            }

 
 

-            /* fill in the data */
-            static const size_t idbSize = (2 + 2 + 2 + 2 + 1);
-            m_f->Read(buf, idbSize);
-            if (m_f->LastRead() != idbSize)
-            {
-                Destroy();
+            // 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;
                 return wxGIF_INVFORMAT;

-            }

 
             pimg->left = buf[0] + 256 * buf[1];
             pimg->top = buf[2] + 256 * buf[3];
 
             pimg->left = buf[0] + 256 * buf[1];
             pimg->top = buf[2] + 256 * buf[3];


@@ -799,11 +757,9 @@ int wxGIFDecoder::ReadGIF()
             pimg->w = buf[4] + 256 * buf[5];
             pimg->h = buf[6] + 256 * buf[7];
 
             pimg->w = buf[4] + 256 * buf[5];
             pimg->h = buf[6] + 256 * buf[7];
 

-            if (pimg->w == 0 || pimg->h == 0)
-            {
-                Destroy();
+            if ( anim && ((pimg->w == 0) || (pimg->w > (unsigned int)m_szAnimation.GetWidth()) ||
+                  (pimg->h == 0) || (pimg->h > (unsigned int)m_szAnimation.GetHeight())) )

                 return wxGIF_INVFORMAT;
                 return wxGIF_INVFORMAT;

-            }

 
             interl = ((buf[8] & 0x40)? 1 : 0);
             size = pimg->w * pimg->h;
 
             interl = ((buf[8] & 0x40)? 1 : 0);
             size = pimg->w * pimg->h;


@@ -811,123 +767,127 @@ int wxGIFDecoder::ReadGIF()
             pimg->transparent = transparent;
             pimg->disposal = disposal;
             pimg->delay = delay;
             pimg->transparent = transparent;
             pimg->disposal = disposal;
             pimg->delay = delay;

-            pimg->next = NULL;
-            pimg->prev = pprev;
-            pprev = pimg;
-            ppimg = &pimg->next;

 
 

-            /* allocate memory for image and palette */
-            pimg->p   = (unsigned char *) malloc((size_t)size);
+            // 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))
             pimg->pal = (unsigned char *) malloc(768);
 
             if ((!pimg->p) || (!pimg->pal))

-            {
-                Destroy();

                 return wxGIF_MEMERR;
                 return wxGIF_MEMERR;

-            }

 
 

-            /* load local color map if available, else use global map */
+            // load local color map if available, else use global map

             if ((buf[8] & 0x80) == 0x80)
             {
             if ((buf[8] & 0x80) == 0x80)
             {

-                ncolors = 2 << (buf[8] & 0x07);
-                size_t numBytes = 3 * ncolors;
-                m_f->Read(pimg->pal, numBytes);
-                if (m_f->LastRead() != numBytes)
-                {
-                    Destroy();
+                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;
                     return wxGIF_INVFORMAT;

-                }

             }
             else
             {
                 memcpy(pimg->pal, pal, 768);
             }
             else
             {
                 memcpy(pimg->pal, pal, 768);

+                pimg->ncolours = global_ncolors;

             }
 
             }
 

-            /* get initial code size from first byte in raster data */
-            bits = (unsigned char)m_f->GetC();
+            // get initial code size from first byte in raster data
+            bits = (unsigned char)stream.GetC();
+            if (bits == 0)
+                return wxGIF_INVFORMAT;

 
 

-            /* decode image */
-            int result = dgif(pimg, interl, bits);
+            // decode image
+            wxGIFErrorCode result = dgif(stream, pimg.get(), interl, bits);

             if (result != wxGIF_OK)
             if (result != wxGIF_OK)

-            {
-                Destroy();

                 return result;
                 return result;

-            }
-            m_nimages++;

 
 

-            /* if this is not an animated GIF, exit after first image */
-            if (!m_anim)
-                done = TRUE;
+            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;

         }
     }
 
         }
     }
 

-    if (m_nimages == 0)
+    if (m_nFrames <= 0)

     {
         Destroy();
         return wxGIF_INVFORMAT;
     }
 
     {
         Destroy();
         return wxGIF_INVFORMAT;
     }
 

-    /* setup image pointers */
-    m_image = 1;
-    m_plast = pimg;
-    m_pimage = m_pfirst;
-
-    /* try to read to the end of the stream */
+    // try to read to the end of the stream

     while (type != 0x3B)
     {
     while (type != 0x3B)
     {

-        if (!m_f->IsOk())
+        if (!stream.IsOk())

             return wxGIF_TRUNCATED;
 
             return wxGIF_TRUNCATED;
 

-        type = (unsigned char)m_f->GetC();
+        type = (unsigned char)stream.GetC();

 
         if (type == 0x21)
         {
 
         if (type == 0x21)
         {

-            /* extension type */
-            (void) m_f->GetC();
+            // extension type
+            (void) stream.GetC();

 
 

-            /* skip all data */
-            while ((i = (unsigned char)m_f->GetC()) != 0)
+            // skip all data
+            while ((i = (unsigned char)stream.GetC()) != 0)

             {
             {

-                m_f->SeekI(i, wxFromCurrent);
+                if (stream.Eof() || (stream.LastRead() == 0) ||
+                    stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
+                {
+                    Destroy();
+                    return wxGIF_INVFORMAT;
+                }

             }
         }
         else if (type == 0x2C)
         {
             }
         }
         else if (type == 0x2C)
         {

-            /* image descriptor block */
-            static const size_t idbSize = (2 + 2 + 2 + 2 + 1);
-            m_f->Read(buf, idbSize);
-            if (m_f->LastRead() != idbSize)
+            // 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;
             }
 
             {
                 Destroy();
                 return wxGIF_INVFORMAT;
             }
 

-            /* local color map */
+            // local color map

             if ((buf[8] & 0x80) == 0x80)
             {
             if ((buf[8] & 0x80) == 0x80)
             {

-                ncolors = 2 << (buf[8] & 0x07);
-                off_t pos = m_f->TellI();
-                off_t numBytes = 3 * ncolors;
-                m_f->SeekI(numBytes, wxFromCurrent);
-                if (m_f->TellI() != (pos + numBytes))
+                unsigned int local_ncolors = 2 << (buf[8] & 0x07);
+                wxFileOffset numBytes = 3 * local_ncolors;
+                if (stream.SeekI(numBytes, wxFromCurrent) == wxInvalidOffset)

                 {
                     Destroy();
                     return wxGIF_INVFORMAT;
                 }
             }
 
                 {
                     Destroy();
                     return wxGIF_INVFORMAT;
                 }
             }
 

-            /* initial code size */
-            (void) m_f->GetC();
+            // initial code size
+            (void) stream.GetC();
+            if (stream.Eof() || (stream.LastRead() == 0))
+            {
+                Destroy();
+                return wxGIF_INVFORMAT;
+            }

 
 

-            /* skip all data */
-            while ((i = (unsigned char)m_f->GetC()) != 0)
+            // skip all data
+            while ((i = (unsigned char)stream.GetC()) != 0)

             {
             {

-                m_f->SeekI(i, wxFromCurrent);
+                if (stream.Eof() || (stream.LastRead() == 0) ||
+                    stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
+                {
+                    Destroy();
+                    return wxGIF_INVFORMAT;
+                }

             }
         }
             }
         }

-        else if ((type != 0x3B) && (type != 00)) /* testing */
+        else if ((type != 0x3B) && (type != 00)) // testing

         {
         {

-            /* images are OK, but couldn't read to the end of the stream */
+            // images are OK, but couldn't read to the end of the stream

             return wxGIF_TRUNCATED;
         }
     }
             return wxGIF_TRUNCATED;
         }
     }