Re: display word wrapping

[Juanma Barranquero]

OK, here's the patch with Vimage_types containing a list of potentially
supported image types, and an internal image_type_cache serving as a
cache alist.

Questions:

 - Should image_type_cache be exported to Lisp? OOH, it is an
   implementation detail; OTOH, exporting it would allow reseting an
   entry and trying a new library without restarting Emacs (if a load
   failed, of course; there's no support for unloading image libraries).

 - I'm initializing Vimage_types in syms_of_image() instead of
   init_image(), because I have the relevant #ifdef's already in place,
   but that's no a very good reason :)  Should I move it?

 - Is any way to do a defconst from C code? (There's no DEFCONST_LISP).
   Or is it irrelevant?

David, could you please try the patch and see if it addresses your
concerns?

                                                                Juanma




--- src/xdisp.c.orig    2004-06-08 13:20:45.000000000 +0200
+++ src/xdisp.c 2004-06-08 12:47:27.000000000 +0200
@@ -22262,5 +22262,6 @@
   DEFVAR_LISP ("image-types", &Vimage_types,
     doc: /* List of supported image types.
-Each element of the list is a symbol for a supported image type.  */);
+Each element of the list is a symbol for a potentially supported image type.
+To know whether it is really supported, you must use `image-type-available-p'. 
 */);
   Vimage_types = Qnil;
 
--- src/image.c.orig    2004-06-07 13:14:55.000000000 +0200
+++ src/image.c 2004-06-08 13:09:57.000000000 +0200
@@ -606,4 +606,8 @@
 static struct image_type *image_types;
 
+/* Cache for delayed-loading image types.  */
+
+Lisp_Object image_type_cache;
+
 /* The symbol `xbm' which is used as the type symbol for XBM images.  */
 
@@ -630,5 +634,5 @@
 /* Function prototypes.  */
 
-static void define_image_type P_ ((struct image_type *type));
+static Lisp_Object define_image_type P_ ((struct image_type *type, int 
loaded));
 static struct image_type *lookup_image_type P_ ((Lisp_Object symbol));
 static void image_error P_ ((char *format, Lisp_Object, Lisp_Object));
@@ -638,19 +642,35 @@
                                       Lisp_Object));
 
+#define CACHE_IMAGE_TYPE(type, status) \
+  do { image_type_cache = Fcons (Fcons (type, status), image_type_cache); } 
while (0)
+
+#define ADD_SUPPORTED_IMAGE_TYPE(type) \
+  do { Vimage_types = Fcons (type, Vimage_types); } while (0)
 
 /* Define a new image type from TYPE.  This adds a copy of TYPE to
-   image_types and adds the symbol *TYPE->type to Vimage_types.  */
+   image_types and adds (*TYPE->type, loaded) to image_type_cache.  */
 
-static void
-define_image_type (type)
+static Lisp_Object
+define_image_type (type, loaded)
      struct image_type *type;
+     int loaded;
 {
-  /* Make a copy of TYPE to avoid a bus error in a dumped Emacs.
-     The initialized data segment is read-only.  */
-  struct image_type *p = (struct image_type *) xmalloc (sizeof *p);
-  bcopy (type, p, sizeof *p);
-  p->next = image_types;
-  image_types = p;
-  Vimage_types = Fcons (*p->type, Vimage_types);
+  Lisp_Object success;
+
+  if (!loaded)
+    success = Qnil;
+  else
+    {
+      /* Make a copy of TYPE to avoid a bus error in a dumped Emacs.
+         The initialized data segment is read-only.  */
+      struct image_type *p = (struct image_type *) xmalloc (sizeof *p);
+      bcopy (type, p, sizeof *p);
+      p->next = image_types;
+      image_types = p;
+      success = Qt;
+    }
+
+  CACHE_IMAGE_TYPE(*type->type, success);
+  return success;
 }
 
@@ -1789,4 +1809,31 @@
   }
 
+/* Load a DLL implementing an image type.
+   The `image-library-alist' variable associates a symbol,
+   identifying  an image type, to a list of possible filenames.
+   The function returns NULL if no library could be loaded for
+   the given image type, or if the library was previously loaded;
+   else the handle of the DLL.  */
+static HMODULE
+w32_dynaload (Lisp_Object libraries, Lisp_Object library_id)
+{
+  HMODULE library = NULL;
+
+  if (CONSP (libraries) && NILP (Fassq (library_id, image_type_cache)))
+    {
+      Lisp_Object dlls = Fassq (library_id, libraries);
+
+      if (CONSP (dlls))
+        for (dlls = XCDR (dlls); CONSP (dlls); dlls = XCDR (dlls))
+          {
+            CHECK_STRING_CAR (dlls);
+            if (library = LoadLibrary (SDATA (XCAR (dlls))))
+              break;
+          }
+    }
+
+  return library;
+}
+
 #endif /* HAVE_NTGUI */
 
@@ -3489,11 +3536,10 @@
 DEF_IMGLIB_FN (XImageFree);
 
-
 static int
-init_xpm_functions (void)
+init_xpm_functions (Lisp_Object libraries)
 {
   HMODULE library;
 
-  if (!(library = LoadLibrary ("libXpm.dll")))
+  if (!(library = w32_dynaload (libraries, Qxpm)))
     return 0;
 
@@ -5589,19 +5635,10 @@
 
 static int
-init_png_functions (void)
+init_png_functions (Lisp_Object libraries)
 {
   HMODULE library;
 
-  /* Ensure zlib is loaded.  Try debug version first.  */
-  if (!LoadLibrary ("zlibd.dll")
-      && !LoadLibrary ("zlib.dll"))
-    return 0;
-
   /* Try loading libpng under probable names.  */
-  if (!(library = LoadLibrary ("libpng13d.dll"))
-      && !(library = LoadLibrary ("libpng13.dll"))
-      && !(library = LoadLibrary ("libpng12d.dll"))
-      && !(library = LoadLibrary ("libpng12.dll"))
-      && !(library = LoadLibrary ("libpng.dll")))
+  if (!(library = w32_dynaload (libraries, Qpng)))
     return 0;
 
@@ -6247,11 +6284,9 @@
 
 static int
-init_jpeg_functions (void)
+init_jpeg_functions (Lisp_Object libraries)
 {
   HMODULE library;
 
-  if (!(library = LoadLibrary ("libjpeg.dll"))
-      && !(library = LoadLibrary ("jpeg-62.dll"))
-      && !(library = LoadLibrary ("jpeg.dll")))
+  if (!(library = w32_dynaload (libraries, Qjpeg)))
     return 0;
 
@@ -6684,9 +6719,9 @@
 
 static int
-init_tiff_functions (void)
+init_tiff_functions (Lisp_Object libraries)
 {
   HMODULE library;
 
-  if (!(library = LoadLibrary ("libtiff.dll")))
+  if (!(library = w32_dynaload (libraries, Qtiff)))
     return 0;
 
@@ -7104,9 +7139,9 @@
 
 static int
-init_gif_functions (void)
+init_gif_functions (Lisp_Object libraries)
 {
   HMODULE library;
 
-  if (!(library = LoadLibrary ("libungif.dll")))
+  if (!(library = w32_dynaload (libraries, Qgif)))
     return 0;
 
@@ -7881,7 +7916,70 @@
  ***********************************************************************/
 
+#ifdef HAVE_NTGUI
+/* Image types that rely on external libraries are loaded dynamically
+   if the library is available.  */
+#define CHECK_LIB_AVAILABLE(image_type, init_lib_fn) \
+  define_image_type (image_type, init_lib_fn (libraries))
+#else
+#define CHECK_LIB_AVAILABLE(image_type, init_lib_fn) \
+  define_image_type (image_type, TRUE)
+#endif /* HAVE_NTGUI */
+
+DEFUN ("init-image-library", Finit_image_library, Sinit_image_library, 2, 2, 0,
+       doc: /* Initialize image library implementing image type TYPE.
+Return non-nil if TYPE is a supported image type.
+
+Image types pbm and xbm are prebuilt; other types are loaded here.
+Libraries to load are specified in alist LIBRARIES (usually, the value
+of `image-library-alist', which see.  */)
+  (type, libraries)
+{
+  Lisp_Object tested;
+
+  /* Don't try to reload the library.  */
+  tested = Fassq (type, image_type_cache);
+  if (CONSP (tested))
+    return XCDR (tested);
+
+#if defined (HAVE_XPM) || defined (MAC_OS)
+  if (EQ (type, Qxpm))
+    return CHECK_LIB_AVAILABLE(&xpm_type, init_xpm_functions);
+#endif
+
+#if defined (HAVE_JPEG) || defined (MAC_OS)
+  if (EQ (type, Qjpeg))
+    return CHECK_LIB_AVAILABLE(&jpeg_type, init_jpeg_functions);
+#endif
+
+#if defined (HAVE_TIFF) || defined (MAC_OS)
+  if (EQ (type, Qtiff))
+    return CHECK_LIB_AVAILABLE(&tiff_type, init_tiff_functions);
+#endif
+
+#if defined (HAVE_GIF) || defined (MAC_OS)
+  if (EQ (type, Qgif))
+    return CHECK_LIB_AVAILABLE(&gif_type, init_gif_functions);
+#endif
+
+#if defined (HAVE_PNG) || defined (MAC_OS)
+  if (EQ (type, Qpng))
+    return CHECK_LIB_AVAILABLE(&png_type, init_png_functions);
+#endif
+
+#ifdef HAVE_GHOSTSCRIPT
+  if (EQ (type, Qpostscript))
+    return CHECK_LIB_AVAILABLE(&gs_type, init_gs_functions);
+#endif
+
+  /* If the type is not recognized, avoid testing it ever again.  */
+  CACHE_IMAGE_TYPE(type, Qnil);
+  return Qnil;
+}
+
 void
 syms_of_image ()
 {
+  Vimage_types = Qnil;
+
   QCascent = intern (":ascent");
   staticpro (&QCascent);
@@ -7917,4 +8015,5 @@
   staticpro (&Qpostscript);
 #ifdef HAVE_GHOSTSCRIPT
+  ADD_SUPPORTED_IMAGE_TYPE(&Qpostscript);
   QCloader = intern (":loader");
   staticpro (&QCloader);
@@ -7929,11 +8028,14 @@
   Qpbm = intern ("pbm");
   staticpro (&Qpbm);
+  ADD_SUPPORTED_IMAGE_TYPE(Qpbm);
 
   Qxbm = intern ("xbm");
   staticpro (&Qxbm);
+  ADD_SUPPORTED_IMAGE_TYPE(Qxbm);
 
 #if defined (HAVE_XPM) || defined (MAC_OS)
   Qxpm = intern ("xpm");
   staticpro (&Qxpm);
+  ADD_SUPPORTED_IMAGE_TYPE(Qxpm);
 #endif
 
@@ -7941,4 +8043,5 @@
   Qjpeg = intern ("jpeg");
   staticpro (&Qjpeg);
+  ADD_SUPPORTED_IMAGE_TYPE(Qjpeg);
 #endif
 
@@ -7946,4 +8049,5 @@
   Qtiff = intern ("tiff");
   staticpro (&Qtiff);
+  ADD_SUPPORTED_IMAGE_TYPE(Qtiff);
 #endif
 
@@ -7951,4 +8055,5 @@
   Qgif = intern ("gif");
   staticpro (&Qgif);
+  ADD_SUPPORTED_IMAGE_TYPE(Qgif);
 #endif
 
@@ -7956,6 +8061,8 @@
   Qpng = intern ("png");
   staticpro (&Qpng);
+  ADD_SUPPORTED_IMAGE_TYPE(Qpng);
 #endif
 
+  defsubr (&Sinit_image_library);
   defsubr (&Sclear_image_cache);
   defsubr (&Simage_size);
@@ -7985,50 +8092,12 @@
 }
 
-
-#ifdef HAVE_NTGUI
-/* Image types that rely on external libraries are loaded dynamically
-   if the library is available.  */
-#define IF_LIB_AVAILABLE(init_lib_fn)  if (init_lib_fn())
-#else
-#define IF_LIB_AVAILABLE(init_func)    /* Load unconditionally */
-#endif /* HAVE_NTGUI */
-
 void
 init_image ()
 {
   image_types = NULL;
-  Vimage_types = Qnil;
-
-  define_image_type (&xbm_type);
-  define_image_type (&pbm_type);
-
-#if defined (HAVE_XPM) || defined (MAC_OS)
-  IF_LIB_AVAILABLE(init_xpm_functions)
-    define_image_type (&xpm_type);
-#endif
-
-#if defined (HAVE_JPEG) || defined (MAC_OS)
-  IF_LIB_AVAILABLE(init_jpeg_functions)
-    define_image_type (&jpeg_type);
-#endif
-
-#if defined (HAVE_TIFF) || defined (MAC_OS)
-  IF_LIB_AVAILABLE(init_tiff_functions)
-    define_image_type (&tiff_type);
-#endif
-
-#if defined (HAVE_GIF) || defined (MAC_OS)
-  IF_LIB_AVAILABLE(init_gif_functions)
-    define_image_type (&gif_type);
-#endif
+  image_type_cache = Qnil;
 
-#if defined (HAVE_PNG) || defined (MAC_OS)
-  IF_LIB_AVAILABLE(init_png_functions)
-    define_image_type (&png_type);
-#endif
-
-#ifdef HAVE_GHOSTSCRIPT
-  define_image_type (&gs_type);
-#endif
+  define_image_type (&xbm_type, TRUE);
+  define_image_type (&pbm_type, TRUE);
 
 #ifdef MAC_OS
--- lisp/image.el.orig  2004-06-07 13:13:55.000000000 +0200
+++ lisp/image.el       2004-06-08 02:06:53.000000000 +0200
@@ -49,4 +49,15 @@
 a non-nil value, TYPE is the image's type.")
 
+;;;###autoload
+(defvar image-library-alist nil
+  "Alist of image types vs external libraries needed to display them.
+
+Each element is a list (IMAGE-TYPE LIBRARY...), where the car is a symbol
+representing a supported image type, and the rest are strings giving
+alternate filenames for the corresponding external libraries to load.
+They are tried in the order they appear on the list; if none of them can
+be loaded, the running session of Emacs won't display the image type.
+No entries are needed for pbm and xbm images; they're always supported.")
+;;;###autoload (put 'image-library-alist 'risky-local-variable t)
 
 (defun image-jpeg-p (data)
@@ -112,6 +123,6 @@
   "Value is non-nil if image type TYPE is available.
 Image types are symbols like `xbm' or `jpeg'."
-  (and (boundp 'image-types) (not (null (memq type image-types)))))
-
+  (and (fboundp 'init-image-library)
+       (init-image-library type image-library-alist)))
 
 ;;;###autoload
--- lisp/term/w32-win.el.orig   2004-06-07 13:16:33.000000000 +0200
+++ lisp/term/w32-win.el        2004-06-08 02:06:58.000000000 +0200
@@ -1262,4 +1262,12 @@
            (error "Font not found")))))
 
+;;; Set default known names for image libraries
+(setq image-library-alist
+      '((xpm "libXpm-nox4.dll" "libxpm.dll")
+        (png "libpng13d.dll" "libpng13.dll" "libpng12d.dll" "libpng12.dll" 
"libpng.dll")
+        (jpeg "jpeg62.dll" "libjpeg.dll" "jpeg-62.dll" "jpeg.dll")
+        (tiff "libtiff3.dll" "libtiff.dll")
+        (gif "libungif.dll")))
+
 ;;; arch-tag: 69fb1701-28c2-4890-b351-3d1fe4b4f166
 ;;; w32-win.el ends here