Minor cleanup

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

diff --git a/src/common/gifdecod.cpp b/src/common/gifdecod.cpp
index 732557ca3b2d7fa1c623fa8f95a92ae27dcee8d4..db8ac994df84931e58513134241eece23ed39480 100644 (file)
--- a/src/common/gifdecod.cpp
+++ b/src/common/gifdecod.cpp
@@ -8,10 +8,6 @@
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
-#if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
-#pragma implementation "gifdecod.h"
-#endif
-
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
@@ -271,17 +267,19 @@ bool wxGIFDecoder::GoPrevFrame(bool cyclic)
 
 bool wxGIFDecoder::GoFrame(int which)
 {
-    int i;
-
     if (!IsAnimation())
         return false;
 
     if ((which >= 1) && (which <= m_nimages))
     {
+        m_image = 1;
         m_pimage = m_pfirst;
 
-        for (i = 0; i < which; i++)
+        while (m_image < which)
+        {
+            m_image++;
             m_pimage = m_pimage->next;
+        }
 
         return true;
     }
@@ -507,7 +505,7 @@ 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
-                    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
@@ -621,7 +619,7 @@ bool wxGIFDecoder::CanRead()
     if ( !m_f->Read(buf, WXSIZEOF(buf)) )
         return false;
 
-    m_f->SeekI(-(off_t)WXSIZEOF(buf), wxFromCurrent);
+    m_f->SeekI(-(wxFileOffset)WXSIZEOF(buf), wxFromCurrent);
 
     return memcmp(buf, "GIF", WXSIZEOF(buf)) == 0;
 }
@@ -677,6 +675,11 @@ int wxGIFDecoder::ReadGIF()
     m_screenw = buf[0] + 256 * buf[1];
     m_screenh = buf[2] + 256 * buf[3];
 
+    if ((m_screenw == 0) || (m_screenh == 0))
+    {
+        return wxGIF_INVFORMAT;
+    }
+
     /* load global color map if available */
     if ((buf[4] & 0x80) == 0x80)
     {
@@ -703,7 +706,7 @@ int wxGIFDecoder::ReadGIF()
 
     bool done = false;
 
-    while(!done)
+    while (!done)
     {
         type = (unsigned char)m_f->GetC();
 
@@ -752,7 +755,7 @@ int wxGIFDecoder::ReadGIF()
                     transparent = buf[4];
 
                 /* read disposal method */
-                disposal = (buf[1] & 0x1C) - 1;
+                disposal = ((buf[1] & 0x1C) >> 2) - 1;
             }
             else
             /* other extension, skip */
@@ -799,7 +802,7 @@ int wxGIFDecoder::ReadGIF()
             pimg->w = buf[4] + 256 * buf[5];
             pimg->h = buf[6] + 256 * buf[7];
 
-            if (pimg->w == 0 || pimg->h == 0)
+            if ((pimg->w == 0) || (pimg->w > m_screenw) || (pimg->h == 0) || (pimg->h > m_screenh))
             {
                 Destroy();
                 return wxGIF_INVFORMAT;
@@ -845,6 +848,11 @@ int wxGIFDecoder::ReadGIF()
 
             /* get initial code size from first byte in raster data */
             bits = (unsigned char)m_f->GetC();
+            if (bits == 0)
+            {
+                Destroy();
+                return wxGIF_INVFORMAT;
+            }
 
             /* decode image */
             int result = dgif(pimg, interl, bits);
@@ -861,7 +869,7 @@ int wxGIFDecoder::ReadGIF()
         }
     }
 
-    if (m_nimages == 0)
+    if (m_nimages <= 0)
     {
         Destroy();
         return wxGIF_INVFORMAT;