Fix bug #7716 with PNG image support libraries on Windows.

 src/image.c <Qlibpng_version>: New variable.
 (syms_of_image): Intern and staticpro it.  Set its value to the
 version of PNG library we were compiled with.
 (my_png_error, png_load): Avoid GCC warnings about direct access
 to png_ptr->jmpbuf.
 lisp/term/w32-win.el (image-library-alist): Set up correctly for
 libpng versions both before and after 1.4.0.
 admin/nt/README.W32: Update the information about PNG support libraries.
 nt/INSTALL: Update the information about PNG support libraries.

2 files changed, 24 insertions, 11 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index dad4c68cffa..c38f6a87b14 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2010-12-31  Eli Zaretskii  <eliz@gnu.org>
+
+        * term/w32-win.el (image-library-alist): Set up correctly for
+        libpng versions both before and after 1.4.0.  (Bug#7716)
+
 2010-12-25  Eli Zaretskii  <eliz@gnu.org>
 
         * time.el (display-time-mode): Mention display-time-interval in
diff --git a/lisp/term/w32-win.el b/lisp/term/w32-win.el
index 1779d1025e0..7bded5b8758 100644
--- a/lisp/term/w32-win.el
+++ b/lisp/term/w32-win.el
@@ -200,17 +200,25 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
 
 ;;; Set default known names for image libraries
 (setq image-library-alist
-      '((xpm "libxpm.dll" "xpm4.dll" "libXpm-nox4.dll")
-        (png "libpng12d.dll" "libpng12.dll" "libpng.dll"
-         ;; these are libpng 1.2.8 from GTK+
-         "libpng13d.dll" "libpng13.dll")
-        (jpeg "jpeg62.dll" "libjpeg.dll" "jpeg-62.dll" "jpeg.dll")
-        (tiff "libtiff3.dll" "libtiff.dll")
-        (gif "giflib4.dll" "libungif4.dll" "libungif.dll")
-        (svg "librsvg-2-2.dll")
-        (gdk-pixbuf "libgdk_pixbuf-2.0-0.dll")
-        (glib "libglib-2.0-0.dll")
-        (gobject "libgobject-2.0-0.dll")))
+      (list
+       '(xpm "libxpm.dll" "xpm4.dll" "libXpm-nox4.dll")
+       ;; Versions of libpng 1.4.x and later are incompatible with
+       ;; earlier versions.  Set up the list of libraries according to
+       ;; the version we were compiled against.  (If we were compiled
+       ;; without PNG support, libpng-version's value is -1.)
+       (if (>= libpng-version 10400)
+           ;; libpng14-14.dll is libpng 1.4.3 from GTK+
+           '(png "libpng14-14.dll" "libpng14.dll")
+         '(png "libpng12d.dll" "libpng12.dll" "libpng3.dll" "libpng.dll"
+               ;; these are libpng 1.2.8 from GTK+
+               "libpng13d.dll" "libpng13.dll"))
+        '(jpeg "jpeg62.dll" "libjpeg.dll" "jpeg-62.dll" "jpeg.dll")
+        '(tiff "libtiff3.dll" "libtiff.dll")
+        '(gif "giflib4.dll" "libungif4.dll" "libungif.dll")
+        '(svg "librsvg-2-2.dll")
+        '(gdk-pixbuf "libgdk_pixbuf-2.0-0.dll")
+        '(glib "libglib-2.0-0.dll")
+        '(gobject "libgobject-2.0-0.dll")))
 
 ;;; multi-tty support
 (defvar w32-initialized nil