adding ContentScaleFactor support to dc - defaulting to 1.0

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

diff --git a/src/common/gifdecod.cpp b/src/common/gifdecod.cpp
index 828afb82c8e864ac7c115a3c29499e905205b97e..b853ee97a987f11e9e4eee57b8292318e3927f11 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


@@ -8,46 +8,93 @@
 // 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/intl.h"
+    #include "wx/log.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"

 
 

+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
+};
+
+#define GetFrame(n)     ((GIFImage*)m_frames[n])
+
+//---------------------------------------------------------------------------
+// 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
+    wxString comment;
+
+    wxDECLARE_NO_COPY_CLASS(GIFImage);
+};
+
+wxDECLARE_SCOPED_PTR(GIFImage, GIFImagePtr)
+wxDEFINE_SCOPED_PTR(GIFImage, GIFImagePtr)
+
+
+//---------------------------------------------------------------------------
+// GIFImage constructor
+//---------------------------------------------------------------------------
+GIFImage::GIFImage()
+{
+    w = 0;
+    h = 0;
+    left = 0;
+    top = 0;
+    transparent = 0;
+    disposal = wxANIM_DONOTREMOVE;
+    delay = -1;
+    p = (unsigned char *) NULL;
+    pal = (unsigned char *) 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()


@@ -57,24 +104,17 @@ 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;

 }
 
 
 }
 
 


@@ -84,30 +124,32 @@ 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())
-        return FALSE;
+    if (!image->IsOk())
+        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) &&


@@ -124,32 +166,39 @@ 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
+    unsigned char r[256];
+    unsigned char g[256];
+    unsigned char b[256];

 
 

-    if (pal)
+    for (i = 0; i < 256; i++)

     {
     {

-        unsigned char* r = new unsigned char[256];
-        unsigned char* g = new unsigned char[256];
-        unsigned char* b = new unsigned char[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));
-        delete[] r; delete[] g; delete[] b;
+        r[i] = pal[3*i + 0];
+        g[i] = pal[3*i + 1];
+        b[i] = pal[3*i + 2];

     }
 
     }
 

-    /* copy image data */
-    for (i = 0; i < (GetWidth() * GetHeight()); i++, src++)
+    image->SetPalette(wxPalette(GetNcolours(frame), r, g, b));
+#endif // wxUSE_PALETTE
+
+    // 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;
+    wxString comment = GetFrame(frame)->comment;
+    if ( !comment.empty() )
+    {
+        image->SetOption(wxIMAGE_OPTION_GIF_COMMENT, comment);
+    }
+
+    return true;

 }
 
 
 }
 
 


@@ -159,113 +208,43 @@ bool wxGIFDecoder::ConvertToImage(wxImage *image) const
 
 // Get data for current frame
 
 
 // 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
-
-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); }
-
-
-//---------------------------------------------------------------------------
-// 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;
-}

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


@@ -275,23 +254,22 @@ 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 = 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


@@ -304,22 +282,27 @@ int wxGIFDecoder::getcode(int bits, int ab_fin)
                 break;
             }
 
                 break;
             }
 

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

             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;


@@ -329,34 +312,49 @@ int wxGIFDecoder::getcode(int bits, int ab_fin)
 // dgif:
 //  GIF decoding function. The initial code size (aka root size)
 //  is 'bits'. Supports interlaced images (interl == 1).
 // dgif:
 //  GIF decoding function. The initial code size (aka root size)
 //  is 'bits'. Supports interlaced images (interl == 1).

-//
-int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
+//  Returns wxGIF_OK (== 0) on success, or an error code if something
+// fails (see header file for details)
+wxGIFErrorCode
+wxGIFDecoder::dgif(wxInputStream& stream, GIFImage *img, int interl, int bits)

 {
 {

-#ifdef __WXMAC__
-    int *ab_prefix = new int[4096];        /* alphabet (prefixes) */
-    int *ab_tail = new int[4096];          /* alphabet (tails) */
-    int *stack = new int[4096];            /* decompression stack */
-#else
-    int ab_prefix[4096];        /* alphabet (prefixes) */
-    int ab_tail[4096];          /* alphabet (tails) */
-    int stack[4096];            /* decompression stack */
-#endif
-    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 */
+    static const int allocSize = 4096 + 1;
+    int *ab_prefix = new int[allocSize]; // alphabet (prefixes)
+    if (ab_prefix == NULL)
+    {
+        return wxGIF_MEMERR;
+    }
+
+    int *ab_tail = new int[allocSize];   // alphabet (tails)
+    if (ab_tail == NULL)
+    {
+        delete[] ab_prefix;
+        return wxGIF_MEMERR;
+    }
+
+    int *stack = new int[allocSize];     // decompression stack
+    if (stack == NULL)
+    {
+        delete[] ab_prefix;
+        delete[] ab_tail;
+        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 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 process

     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;


@@ -365,52 +363,91 @@ 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];
             code         = ab_prefix[code];
         while (code > ab_clr)
         {
             stack[pos++] = ab_tail[code];
             code         = ab_prefix[code];

+
+            // Don't overflow. This shouldn't happen with normal
+            // GIF files, the allocSize of 4096+1 is enough. This
+            // will only happen with badly formed GIFs.
+            if (pos >= allocSize)
+            {
+                delete[] ab_prefix;
+                delete[] ab_tail;
+                delete[] stack;
+                return wxGIF_INVFORMAT;
+            }
+        }
+
+        if (pos >= allocSize)
+        {
+            delete[] ab_prefix;
+            delete[] ab_tail;
+            delete[] stack;
+            return wxGIF_INVFORMAT;

         }
         }

-        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) */
+        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)

         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++;


@@ -422,10 +459,11 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
             }
         }
 
             }
         }
 

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

         while (pos >= 0)
         {
         while (pos >= 0)
         {

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

 
             if (++x >= (img->w))
             {
 
             if (++x >= (img->w))
             {


@@ -433,7 +471,7 @@ 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;


@@ -441,20 +479,97 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
                         case 3: y += 4; break;
                         case 4: y += 2; break;
                     }
                         case 3: y += 4; break;
                         case 4: y += 2; break;
                     }

-                    if (y >= (img->h))
+
+                    /* 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 successfully
+                    decoded).
+                    If we don't loop, but merely set y to some other
+                    value, that new value might still be invalid depending
+                    on the height of the image. This would cause out of
+                    bounds writing.
+                    */
+                    while (y >= (img->h))

                     {
                         switch (++pass)
                         {
                             case 2: y = 4; break;
                             case 3: y = 2; break;
                             case 4: y = 1; break;
                     {
                         switch (++pass)
                         {
                             case 2: y = 4; break;
                             case 3: y = 2; break;
                             case 4: y = 1; break;

+
+                            default:
+                                /*
+                                It's possible we arrive here. For example this
+                                happens when the image is interlaced, and the
+                                height is 1. Looking at the above cases, the
+                                lowest possible y is 1. While the only valid
+                                one would be 0 for an image of height 1. So
+                                'eventually' the loop will arrive here.
+                                This case makes sure this while loop is
+                                exited, as well as the 2 other ones.
+                                */
+
+                                // Set y to a valid coordinate so the local
+                                // while loop will be exited. (y = 0 always
+                                // is >= img->h since if img->h == 0 the
+                                // image is never decoded)
+                                y = 0;
+
+                                // This will exit the other outer while loop
+                                pos = -1;
+
+                                // This will halt image decoding.
+                                code = ab_fin;
+
+                                break;

                         }
                     }
                 }
                 else
                 {
                         }
                     }
                 }
                 else
                 {

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

                     y++;
                     y++;

+/*
+Normally image decoding is finished when an End of Information code is
+encountered (code == ab_fin) however some broken encoders write wrong
+"block byte counts" (The first byte value after the "code size" byte),
+being one value too high. It might very well be possible other variants
+of this problem occur as well. The only sensible solution seems to
+be to check for clipping.
+Example of wrong encoding:
+(1 * 1 B/W image, raster data stream follows in hex bytes)
+
+02  << B/W images have a code size of 2
+02  << Block byte count
+44  << LZW packed
+00  << Zero byte count (terminates data stream)
+
+Because the block byte count is 2, the zero byte count is used in the
+decoding process, and decoding is continued after this byte. (While it
+should signal an end of image)
+
+It should be:
+02
+02
+44
+01  << When decoded this correctly includes the End of Information code
+00
+
+Or (Worse solution):
+02
+01
+44
+00
+(The 44 doesn't include an End of Information code, but at least the
+decoder correctly skips to 00 now after decoding, and signals this
+as an End of Information itself)
+*/
+                    if (y >= img->h)
+                    {
+                        code = ab_fin;
+                        break;
+                    }

                 }
             }
         }
                 }
             }
         }


@@ -464,30 +579,29 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
     }
     while (code != ab_fin);
 
     }
     while (code != ab_fin);
 

-#ifdef __WXMAC__

     delete [] ab_prefix ;
     delete [] ab_tail ;
     delete [] stack ;
     delete [] ab_prefix ;
     delete [] ab_tail ;
     delete [] stack ;

-#endif
-    return 0;
+
+    return wxGIF_OK;

 }
 
 
 // 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::DoCanRead(wxInputStream &stream) const

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

-    m_f->Read(buf, 3);
-    m_f->SeekI(-3, wxFromCurrent);
+    if ( !stream.Read(buf, WXSIZEOF(buf)) )
+        return false;

 
 

-    return (memcmp(buf, "GIF", 3) == 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


@@ -496,201 +610,355 @@ 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)

 {
 {

-    int           ncolors, 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) */
-    m_f->Read(buf, 6);
+    // check for animated GIF support (ver. >= 89a)
+
+    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)
 
     if (memcmp(buf + 3, "89a", 3) < 0)

-        m_anim = FALSE;
+    {
+        anim = false;
+    }

 
 

-    /* read logical screen descriptor block (LSDB) */
-    m_f->Read(buf, 7);
-    m_screenw = buf[0] + 256 * buf[1];
-    m_screenh = buf[2] + 256 * buf[3];
+    // 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;
+    }
+
+    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];
+
+        global_ncolors = 2 << (buf[4] & 0x07);
+        unsigned int numBytes = 3 * global_ncolors;
+        stream.Read(pal, numBytes);
+        if (stream.LastRead() != numBytes)
+        {
+            return wxGIF_INVFORMAT;
+        }

 
 

-        ncolors = 2 << (buf[4] & 0x07);
-        m_f->Read(pal, 3 * ncolors);
+        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;

+    wxString comment;

 
 

-    /* 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();
-
-        /* end of data? */
-        if (type == 0x3B)
+        type = stream.GetC();
+
+        /*
+        If the end of file has been reached (or an error) and a ";"
+        (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
+        possible here since some init code is done after this loop.
+        */
+        if (stream.Eof())// || !stream.IsOk())

         {
         {

-            done = TRUE;
+            /*
+            type is set to some bogus value, so there's no
+            need to continue evaluating it.
+            */
+            break; // Alternative : "return wxGIF_INVFORMAT;"

         }
         }

-        else
-        /* extension block? */
-        if (type == 0x21)
+
+        switch (type)

         {
         {

-            if (((unsigned char)m_f->GetC()) == 0xF9)
-            /* graphics control extension, parse it */
-            {
-                m_f->Read(buf, 6);
+            case GIF_MARKER_ENDOFDATA:
+                done = true;
+                break;
+            case GIF_MARKER_EXT:
+                switch (stream.GetC())
+                {
+                    case GIF_MARKER_EXT_GRAPHICS_CONTROL:
+                    {
+                        // graphics control extension, parse it

 
 

-                /* read delay and convert from 1/100 of a second to ms */
-                delay = 10 * (buf[2] + 256 * buf[3]);
+                        static const unsigned int gceSize = 6;
+                        stream.Read(buf, gceSize);
+                        if (stream.LastRead() != gceSize)
+                        {
+                            Destroy();
+                            return wxGIF_INVFORMAT;
+                        }

 
 

-                /* read transparent colour index, if used */
-                if (buf[1] & 0x01)
-                    transparent = buf[4];
+                        // read delay and convert from 1/100 of a second to ms
+                        delay = 10 * (buf[2] + 256 * buf[3]);

 
 

-                /* read disposal method */
-                disposal = (buf[1] & 0x1C) - 1;
-            }
-            else
-            /* other extension, skip */
+                        // read transparent colour index, if used
+                        transparent = buf[1] & 0x01 ? buf[4] : -1;
+
+                        // read disposal method
+                        disposal = (wxAnimationDisposal)(((buf[1] & 0x1C) >> 2) - 1);
+                        break;
+                    }
+                    case GIF_MARKER_EXT_COMMENT:
+                    {
+                        int len = stream.GetC();
+                        while (len)
+                        {
+                            if ( stream.Eof() )
+                            {
+                                done = true;
+                                break;
+                            }
+
+                            wxCharBuffer charbuf(len);
+                            stream.Read(charbuf.data(), len);
+                            if ( (int) stream.LastRead() != len )
+                            {
+                                done = true;
+                                break;
+                            }
+
+                            comment += wxConvertMB2WX(charbuf.data());
+
+                            len = stream.GetC();
+                        }
+
+                        break;
+                    }
+                    default:
+                        // other extension, skip
+                        while ((i = stream.GetC()) != 0)
+                        {
+                            if (stream.Eof() || (stream.LastRead() == 0) ||
+                                stream.SeekI(i, wxFromCurrent) == wxInvalidOffset)
+                            {
+                                done = true;
+                                break;
+                            }
+                        }
+                        break;
+                }
+                break;
+            case GIF_MARKER_SEP:

             {
             {

-                while ((i = (unsigned char)m_f->GetC()) != 0)
+                // 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->comment = comment;
+                comment.clear();
+                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 )

                 {
                 {

-                    m_f->SeekI(i, wxFromCurrent);
+                    // 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;
+                        }
+                    }

                 }
                 }

-            }
-        }
-        else
-        /* image descriptor block? */
-        if (type == 0x2C)
-        {
-            /* allocate memory for IMAGEN struct */
-            pimg = (*ppimg) = new GIFImage();

 
 

-            if (pimg == NULL)
-            {
-                Destroy();
-                return wxGIF_MEMERR;
-            }
+                interl = ((buf[8] & 0x40)? 1 : 0);
+                size = pimg->w * pimg->h;

 
 

-            /* fill in the data */
-            m_f->Read(buf, 9);
-            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];
-            interl = ((buf[8] & 0x40)? 1 : 0);
-            size = pimg->w * pimg->h;
-
-            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);
-            pimg->pal = (unsigned char *) malloc(768);
-
-            if ((!pimg->p) || (!pimg->pal))
-            {
-                Destroy();
-                return wxGIF_MEMERR;
-            }
+                pimg->transparent = transparent;
+                pimg->disposal = disposal;
+                pimg->delay = delay;

 
 

-            /* load local color map if available, else use global map */
-            if ((buf[8] & 0x80) == 0x80)
-            {
-                ncolors = 2 << (buf[8] & 0x07);
-                m_f->Read(pimg->pal, 3 * ncolors);
-            }
-            else
-                memcpy(pimg->pal, pal, 768);
+                // 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;

 
 

-            /* get initial code size from first byte in raster data */
-            bits = (unsigned char)m_f->GetC();
+                // decode image
+                wxGIFErrorCode result = dgif(stream, pimg.get(), interl, bits);
+                if (result != wxGIF_OK)
+                    return result;

 
 

-            /* decode image */
-            dgif(pimg, interl, bits);
-            m_nimages++;
+                guardDestroy.Dismiss();

 
 

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

         }
     }
 
         }
     }
 

-    /* setup image pointers */
-    if (m_nimages != 0)
+    if (m_nFrames <= 0)

     {
     {

-        m_image = 1;
-        m_plast = pimg;
-        m_pimage = m_pfirst;
+        Destroy();
+        return wxGIF_INVFORMAT;

     }
 
     }
 

-    /* try to read to the end of the stream */
-    while (type != 0x3B)
+    // try to read to the end of the stream
+    while (type != GIF_MARKER_ENDOFDATA)

     {
     {

-        type = (unsigned char)m_f->GetC();
+        if (!stream.IsOk())
+            return wxGIF_TRUNCATED;

 
 

-        if (type == 0x21)
-        {
-            /* extension type */
-            (void) m_f->GetC();
+        type = stream.GetC();

 
 

-            /* skip all data */
-            while ((i = (unsigned char)m_f->GetC()) != 0)
-            {
-                m_f->SeekI(i, wxFromCurrent);
-            }
-        }
-        else if (type == 0x2C)
+        switch (type)

         {
         {

-            /* image descriptor block */
-            m_f->Read(buf, 9);
+            case GIF_MARKER_EXT:
+                // extension type
+                (void) stream.GetC();

 
 

-            /* local color map */
-            if ((buf[8] & 0x80) == 0x80)
+                // 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:

             {
             {

-                ncolors = 2 << (buf[8] & 0x07);
-                m_f->SeekI(3 * ncolors, wxFromCurrent);
-            }
+                // 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;
+                }

 
 

-            /* initial code size */
-            (void) m_f->GetC();
+                // 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;
+                    }
+                }

 
 

-            /* skip all data */
-            while ((i = (unsigned char)m_f->GetC()) != 0)
-            {
-                m_f->SeekI(i, wxFromCurrent);
+                // initial code size
+                (void) stream.GetC();
+                if (stream.Eof() || (stream.LastRead() == 0))
+                {
+                    Destroy();
+                    return wxGIF_INVFORMAT;
+                }
+
+                // skip all data
+                while ((i = stream.GetC()) != 0)
+                {
+                    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;

         }
     }
 
         }
     }