Prefer 'frame-parameter' where it is expected to be a bit faster

[gnu-emacs] / lisp / scroll-bar.el

diff --git a/lisp/scroll-bar.el b/lisp/scroll-bar.el
index 588ac3b0f8acd7a3076f07e4482d880156ac159a..e5fe31675da3c199c037a80e614f4ae8b1de7214 100644 (file)
--- a/lisp/scroll-bar.el
+++ b/lisp/scroll-bar.el
@@ -1,6 +1,6 @@
 ;;; scroll-bar.el --- window system-independent scroll bar support
 
-;; Copyright (C) 1993-1995, 1999-2014 Free Software Foundation, Inc.
+;; Copyright (C) 1993-1995, 1999-2016 Free Software Foundation, Inc.
 
 ;; Maintainer: emacs-devel@gnu.org
 ;; Keywords: hardware
@@ -79,7 +79,7 @@ SIDE must be the symbol `left' or `right'."
      (htype lines)
      ((frame-parameter nil 'horizontal-scroll-bars)
       ;; nil means it's a non-toolkit scroll bar (which is currently
-      ;; impossible), and its width in columns is 14 pixels rounded up.
+      ;; impossible), and its height in lines is 14 pixels rounded up.
       (ceiling (or (frame-parameter nil 'scroll-bar-height) 14)
                (frame-char-width)))
      (0))))
@@ -144,6 +144,12 @@ created in the future."
                            (if v (or previous-scroll-bar-mode
                                      default-frame-scroll-bars))))))
 
+(defun horizontal-scroll-bars-available-p ()
+  "Return non-nil when horizontal scroll bars are available on this system."
+  (and (display-graphic-p)
+       (boundp 'x-toolkit-scroll-bars)
+       x-toolkit-scroll-bars))
+
 (define-minor-mode horizontal-scroll-bar-mode
   "Toggle horizontal scroll bars on all frames (Horizontal Scroll Bar mode).
 With a prefix argument ARG, enable Horizontal Scroll Bar mode if
@@ -155,32 +161,48 @@ created in the future."
   :init-value nil
   :global t
   :group 'frames
-  (dolist (frame (frame-list))
-    (set-frame-parameter
-     frame 'horizontal-scroll-bars horizontal-scroll-bar-mode))
-  ;; Handle `default-frame-alist' entry.
-  (setq default-frame-alist
-       (cons (cons 'horizontal-scroll-bars horizontal-scroll-bar-mode)
-             (assq-delete-all 'horizontal-scroll-bars
-                              default-frame-alist))))
+  (if (and horizontal-scroll-bar-mode
+          (not (horizontal-scroll-bars-available-p)))
+      (progn
+       (setq horizontal-scroll-bar-mode nil)
+       (message "Horizontal scroll bars are not implemented on this system"))
+    (dolist (frame (frame-list))
+      (set-frame-parameter
+       frame 'horizontal-scroll-bars horizontal-scroll-bar-mode))
+    ;; Handle `default-frame-alist' entry.
+    (setq default-frame-alist
+         (cons (cons 'horizontal-scroll-bars horizontal-scroll-bar-mode)
+               (assq-delete-all 'horizontal-scroll-bars
+                                default-frame-alist)))))
 
 (defun toggle-scroll-bar (arg)
   "Toggle whether or not the selected frame has vertical scroll bars.
-With arg, turn vertical scroll bars on if and only if arg is positive.
+With ARG, turn vertical scroll bars on if and only if ARG is positive.
 The variable `scroll-bar-mode' controls which side the scroll bars are on
 when they are turned on; if it is nil, they go on the left."
   (interactive "P")
   (if (null arg)
       (setq arg
-           (if (cdr (assq 'vertical-scroll-bars
-                          (frame-parameters (selected-frame))))
-               -1 1))
+           (if (frame-parameter nil 'vertical-scroll-bars) -1 1))
     (setq arg (prefix-numeric-value arg)))
   (modify-frame-parameters
    (selected-frame)
    (list (cons 'vertical-scroll-bars
               (if (> arg 0)
                   (or scroll-bar-mode default-frame-scroll-bars))))))
+
+(defun toggle-horizontal-scroll-bar (arg)
+  "Toggle whether or not the selected frame has horizontal scroll bars.
+With ARG, turn vertical scroll bars on if and only if ARG is positive."
+  (interactive "P")
+  (if (null arg)
+      (setq arg
+           (if (frame-parameter nil 'horizontal-scroll-bars) -1 1))
+    (setq arg (prefix-numeric-value arg)))
+  (modify-frame-parameters
+   (selected-frame)
+   (list (cons 'horizontal-scroll-bars
+              (when (> arg 0) 'bottom)))))
 \f
 ;;;; Buffer navigation using the scroll bar.