[Emacs-diffs] trunk r113410: Fix bug #14838 with slow scrolling with certain fonts.

[Eli Zaretskii]

------------------------------------------------------------
revno: 113410
revision-id: address@hidden
parent: address@hidden
fixes bug: http://debbugs.gnu.org/14838
committer: Eli Zaretskii <address@hidden>
branch nick: trunk
timestamp: Sat 2013-07-13 10:26:43 +0300
message:
  Fix bug #14838 with slow scrolling with certain fonts.
  
   lisp/simple.el (default-font-height): Don't call font-info if the
   frame's default font didn't change since the frame was created.
modified:
  lisp/ChangeLog                 changelog-20091113204419-o5vbwnq5f7feedwu-1432
  lisp/simple.el                 simple.el-20091113204419-o5vbwnq5f7feedwu-403

=== modified file 'lisp/ChangeLog'
--- a/lisp/ChangeLog    2013-07-13 04:44:19 +0000
+++ b/lisp/ChangeLog    2013-07-13 07:26:43 +0000
@@ -1,3 +1,9 @@
+2013-07-13  Eli Zaretskii  <address@hidden>
+
+       * simple.el (default-font-height): Don't call font-info if the
+       frame's default font didn't change since the frame was created.
+       (Bug#14838)
+
 2013-07-13  Leo Liu  <address@hidden>
 
        * ido.el (ido-read-file-name): Guard against non-symbol value.

=== modified file 'lisp/simple.el'
--- a/lisp/simple.el    2013-07-12 08:35:42 +0000
+++ b/lisp/simple.el    2013-07-13 07:26:43 +0000
@@ -4739,10 +4739,15 @@
 
 (defun default-font-height ()
   "Return the height in pixels of the current buffer's default face font."
-  (cond
-   ((display-multi-font-p)
-    (aref (font-info (face-font 'default)) 3))
-   (t (frame-char-height))))
+  (let ((default-font (face-font 'default)))
+    (cond
+     ((and (display-multi-font-p)
+          ;; Avoid calling font-info if the frame's default font was
+          ;; not changed since the frame was created.  That's because
+          ;; font-info is expensive for some fonts, see bug #14838.
+          (not (string= (frame-parameter nil 'font) default-font)))
+      (aref (font-info default-font) 3))
+     (t (frame-char-height)))))
 
 (defun default-line-height ()
   "Return the pixel height of current buffer's default-face text line.