Add support for pinch gestures to the XI2 build

* doc/lispref/commands.texi (Misc Events): Document new event
type `pinch'.
* etc/NEWS: Announce new event `pinch'.
* etc/PROBLEMS: Document problems with mismatched libXi
versions.
* lisp/face-remap.el (text-scale--pinch-start-scale): New
variable.
(text-scale-pinch): New command.
* src/keyboard.c (make_lispy_event): Handle PINCH_EVENTs.
(syms_of_keyboard): New symbol `pinch'.
* src/termhooks.h (enum event_kind): New enum `PINCH_EVENT'.
* src/xfns.c (setup_xi_event_mask): Add pinch events to event
mask if available.
* src/xterm.c (handle_one_xevent): Handle pinch events.

1 files changed, 24 insertions, 0 deletions

diff --git a/lisp/face-remap.el b/lisp/face-remap.el
index 50302b9682c..8507f7e8e36 100644
--- a/lisp/face-remap.el
+++ b/lisp/face-remap.el
@@ -390,6 +390,30 @@ a top-level keymap, `text-scale-increase' or
                (lambda () (interactive) (text-scale-adjust (abs inc))))))
          map))))) ;; )
 
+(defvar-local text-scale--pinch-start-scale 0
+  "The text scale at the start of a pinch sequence.")
+
+;;;###autoload (define-key global-map [pinch] 'text-scale-pinch)
+;;;###autoload
+(defun text-scale-pinch (event)
+  "Adjust the height of the default face by the scale in EVENT."
+  (interactive "e")
+  (let ((window (posn-window (nth 1 event)))
+        (scale (nth 4 event))
+        (dx (nth 2 event))
+        (dy (nth 3 event))
+        (angle (nth 5 event)))
+    (with-selected-window window
+      (when (and (zerop dx)
+                 (zerop dy)
+                 (zerop angle)
+                 (equal scale 1.0))
+        (setq text-scale--pinch-start-scale
+              (if text-scale-mode text-scale-mode-amount 0)))
+      (text-scale-set
+       (+ text-scale--pinch-start-scale
+          (round (log scale text-scale-mode-step)))))))
+
 
 ;; ----------------------------------------------------------------
 ;; buffer-face-mode