[Emacs-diffs] master db9af10: For SVG, 8192 is the new 256

[Paul Eggert]

branch: master
commit db9af103944959be640a53fcf0f0b696f25d553f
Author: Paul Eggert <address@hidden>
Commit: Paul Eggert <address@hidden>

    For SVG, 8192 is the new 256
    
    Prefer librsvg for display of splash.svg
    When both librsvg and Imagemagick are available, Emacs should
    prefer librsvg to render SVG images.  However, Emacs was using
    Imagemagick to render its own splash.svg file because
    image-type-from-file-header returned nil for that file.
    * lisp/image.el (image-type-from-buffer)
    (image-type-from-file-header): Look at the first 8192 bytes of
    the image, not just the first 256.  For Emacs’s own splash.svg
    file, image-type-header-regexps needs to look at 939 bytes.
    8192 bytes is a reasonable number nowadays given typical file
    system design.
    * test/lisp/image-tests.el (image-tests--emacs-images-directory):
    New contant.
    (image-type-from-file-header-test): New test.
---
 lisp/image.el            |  4 ++--
 test/lisp/image-tests.el | 11 +++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/lisp/image.el b/lisp/image.el
index ba87d7f..db11302 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -315,7 +315,7 @@ be determined."
                                        (buffer-substring
                                         (point-min)
                                         (min (point-max)
-                                             (+ (point-min) 256))))))
+                                             (+ (point-min) 8192))))))
                     (setq image-type (cdr image-type))))
            (setq type image-type
                  types nil)
@@ -339,7 +339,7 @@ be determined."
        (file-readable-p file)
        (with-temp-buffer
         (set-buffer-multibyte nil)
-        (insert-file-contents-literally file nil 0 256)
+        (insert-file-contents-literally file nil 0 8192)
         (image-type-from-buffer))))
 
 
diff --git a/test/lisp/image-tests.el b/test/lisp/image-tests.el
index 89b926e..621646e 100644
--- a/test/lisp/image-tests.el
+++ b/test/lisp/image-tests.el
@@ -22,6 +22,10 @@
 (require 'ert)
 (require 'image)
 
+(defconst image-tests--emacs-images-directory
+  (expand-file-name "../etc/images" (getenv "EMACS_TEST_DIRECTORY"))
+  "Directory containing Emacs images.")
+
 (ert-deftest image--set-property ()
   "Test `image--set-property' behavior."
   (let ((image (list 'image)))
@@ -42,4 +46,11 @@
     (setf (image-property image :width) nil)
     (should (equal image '(image)))))
 
+(ert-deftest image-type-from-file-header-test ()
+  "Test image-type-from-file-header."
+  (should (eq 'svg
+             (image-type-from-file-header
+              (expand-file-name "splash.svg"
+                                image-tests--emacs-images-directory)))))
+
 ;;; image-tests.el ends here