X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/464122b639263c81fcbd698bae3826313d2165a2..07cf98cb8eb7625eeffc95e407a9fa1ad863b451:/src/common/gifdecod.cpp

diff --git a/src/common/gifdecod.cpp b/src/common/gifdecod.cpp
index 047189cc51..e8fcdc7514 100644
--- a/src/common/gifdecod.cpp
+++ b/src/common/gifdecod.cpp
@@ -2,8 +2,8 @@
 // Name:        gifdecod.cpp
 // Purpose:     wxGIFDecoder, GIF reader for wxImage and wxAnimation
 // Author:      Guillermo Rodriguez Garcia <guille@iies.es>
-// Version:     3.01
-// Last rev:    1999/08/14
+// Version:     3.03
+// RCS-ID:      
 // Copyright:   (c) Guillermo Rodriguez Garcia
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
@@ -20,14 +20,13 @@
 #endif
 
 #ifndef WX_PRECOMP
-#  include "wx/setup.h"
+#  include "wx/defs.h"
 #endif
 
-#if wxUSE_STREAMS
+#if wxUSE_STREAMS && wxUSE_GIF
 
 #include <stdlib.h>
 #include <string.h>
-#include "wx/defs.h"
 #include "wx/gifdecod.h"
  
 
@@ -85,6 +84,9 @@ bool wxGIFDecoder::ConvertToImage(wxImage *image) const
     unsigned long i;
     int      transparent;
 
+    /* just in case... */
+    image->Destroy();
+
     /* create the image */
     image->Create(GetWidth(), GetHeight());
 
@@ -436,6 +438,23 @@ int wxGIFDecoder::dgif(IMAGEN *img, int interl, int bits)
 }
 
 
+// CanRead:
+//  Returns TRUE if the file looks like a valid GIF, FALSE otherwise.
+//
+bool wxGIFDecoder::CanRead()
+{
+    unsigned char buf[3];
+    off_t pos;
+
+    pos = m_f->TellI();
+    m_f->SeekI(0, wxFromStart);
+    m_f->Read(buf, 3);
+    m_f->SeekI(pos, wxFromStart);
+
+    return (memcmp(buf, "GIF", 3) == 0);
+}
+
+
 // ReadGIF:
 //  Reads and decodes one or more GIF images, depending on whether
 //  animated GIF support is enabled. Can read GIFs with any bit
@@ -455,13 +474,14 @@ int wxGIFDecoder::ReadGIF()
     unsigned char buf[16];
     IMAGEN        **ppimg, *pimg, *pprev;
 
+    /* check GIF signature */
+    if (!CanRead())
+        return E_FORMATO;
 
-    /* check GIF signature and animated GIF support (ver. >= 89a) */
+    /* check for and animated GIF support (ver. >= 89a) */
+    m_f->SeekI(0, wxFromStart);
     m_f->Read(buf, 6);
 
-    if (memcmp(buf, "GIF", 3) != 0)
-        return E_FORMATO;
-
     if (memcmp(buf + 3, "89a", 3) < 0)
         m_anim = FALSE;
 
@@ -523,8 +543,10 @@ int wxGIFDecoder::ReadGIF()
                     /* This line should not be neccessary!
                      * Some images are not loaded correctly
                      * without it. A bug in wxStream?
+                     * Yes. Fixed now.
                      */
                     // m_f->SeekI(m_f->TellI(), wxFromStart);
+
                     m_f->SeekI(i, wxFromCurrent);
                 }
             }
@@ -603,4 +625,4 @@ int wxGIFDecoder::ReadGIF()
     return E_OK;
 }
 
-#endif // wxUSE_STREAM
+#endif // wxUSE_STREAMS && wxUSE_GIF