[PATCH] OLE macintosh (PICT image header)

[prahal]

http://www.openflow.org/documents/OpenFlow_2011.pps is of format macintosh and has its thumbnail as "pict". Extracted with libgsf (gnome) gsf-office-thumbnailer use convert from imagemagick to make it a png. But convert fails on two issues:

• - seems that macintosh ole embed PICT without a platform header but instead use "PICT" as header.
  - builtin BMP magic from imagemagick match "PI" offset 0

This patch fixes both though I am not confident removing the match from "BMP" to "PI" is right. But the list of builting magic is sorted alphabetically thus this match always happens first :/

Code: Select all

--- a/magick/magic.c	2011-12-19 02:54:26.000000000 +0100
+++ b/magick/magic.c	2012-11-12 09:43:11.553998032 +0100
@@ -93,7 +93,7 @@
     { "BMP", 0, MagickString("CI") },
     { "BMP", 0, MagickString("CP") },
     { "BMP", 0, MagickString("IC") },
-    { "BMP", 0, MagickString("PI") },
+    //{ "BMP", 0, MagickString("PI") },
     { "CALS", 21, MagickString("version: MIL-STD-1840") },
     { "CALS", 0, MagickString("srcdocid:") },
     { "CALS", 9, MagickString("srcdocid:") },
@@ -152,6 +152,7 @@
     { "PFA", 0, MagickString("%!PS-AdobeFont-1.0") },
     { "PFB", 6, MagickString("%!PS-AdobeFont-1.0") },
     { "PGX", 0, MagickString("\050\107\020\115\046") },
+    { "PICT", 0, MagickString("PICT") },
     { "PICT", 522, MagickString("\000\021\002\377\014\000") },
     { "PNG", 0, MagickString("\211PNG\r\n\032\n") },
     { "PBM", 0, MagickString("P1") },
--- a/coders/pict.c	2012-08-30 13:41:56.000000000 +0200
+++ b/coders/pict.c	2012-11-12 08:54:36.891992713 +0100
@@ -744,6 +744,11 @@
 */
 static MagickBooleanType IsPICT(const unsigned char *magick,const size_t length)
 {
+  /* Embedded OLE2 macintosh have "PICT" instead of 512 platform header */
+  if (length < 12)
+    return(MagickFalse);
+  if (memcmp(magick,"PICT",4) == 0)
+    return(MagickTrue);
   if (length < 528)
     return(MagickFalse);
   if (memcmp(magick+522,"\000\021\002\377\014\000",6) == 0)
@@ -792,7 +797,8 @@
   ExceptionInfo *exception)
 {
   char
-    geometry[MaxTextExtent];
+    geometry[MaxTextExtent],
+    header_ole[4];
 
   Image
     *image;
@@ -863,8 +869,17 @@
   */
   pixmap.bits_per_pixel=0;
   pixmap.component_count=0;
-  for (i=0; i < 512; i++)
-    (void) ReadBlobByte(image);  /* skip header */
+  /* skip header : 512 for standard PICT and 4, ie "PICT" for OLE2 */
+  header_ole[0] = ReadBlobByte(image);
+  header_ole[1] = ReadBlobByte(image);
+  header_ole[2] = ReadBlobByte(image);
+  header_ole[3] = ReadBlobByte(image);
+  if (!((header_ole[0] == 0x50) &&
+      (header_ole[1] == 0x49) &&
+      (header_ole[2] == 0x43) &&
+      (header_ole[3] == 0x54 )))
+    for (i=0; i < 508; i++)
+      (void) ReadBlobByte(image);
   (void) ReadBlobMSBShort(image);  /* skip picture size */
   ReadRectangle(image,frame);
   while ((c=ReadBlobByte(image)) == 0) ;
--- a/config/mime.xml	2009-09-05 23:47:34.000000000 +0200
+++ b/config/mime.xml	2012-11-12 09:10:27.484276414 +0100
@@ -755,6 +755,7 @@
   <mime type="image/x-pict" description="Macintosh Quickdraw/PICT drawing" priority="100" pattern="*.pict" />
   <mime type="image/x-pict" description="Macintosh Quickdraw/PICT drawing" priority="100" pattern="*.pict1" />
   <mime type="image/x-pict" description="Macintosh Quickdraw/PICT drawing" priority="100" pattern="*.pict2" />
+  <mime type="image/x-pict" description="Macintosh Quickdraw/PICT drawing" data-type="string" offset="0" magic="PICT" priority="50" />
   <mime type="application/x-ufraw" acronym="UFRaw" description="Unidentified Flying Raw" priority="100" pattern="*.ufraw" />
   <mime type="image/x-adobe-dng" acronym="DNG" description="Digital Negative" priority="100" pattern="*.dng" />
   <mime type="image/x-canon-crw" description="Canon RaW" data-type="string" offset="0" magic="II\x1a\x00\x00\x00HEAPCCDR" priority="50" />

[magick]

Thanks, we'll get your the patch in ImageMagick by the next point release.