Register ``pinch to zoom'' touch screen gestures

* doc/emacs/input.texi (Touchscreens): Address pinch gestures.

* doc/lispref/commands.texi (Touchscreen Events): Address touch
screen pinch events and the process by which they are produced.

* java/org/gnu/emacs/EmacsWindow.java (figureChange)
<ACTION_POINTER_DOWN>: Supply pointer index to getX and getY,
correcting a mistake where the first touch point's coordinate
was saved here in lieu of the pointer that was pressed's.

* lisp/touch-screen.el (touch-screen-current-tool): Revise doc
string.
(touch-screen-aux-tool): New variable.
(touch-screen-scroll-point-to-y, touch-screen-pinch): New
functions.
(global-map): Bind [touchscreen-pinch] to touch-screen-pinch.
(touch-screen-handle-point-update): Revise doc string; set new
tenth field of t-s-c-t to POINT relative to its window, without
regard to whether an event has been sent.
(touch-screen-distance, touch-screen-centrum): New functions.
(touch-screen-handle-aux-point-update): New function; generate
and send touchscreen-pinch if need be.
(touch-screen-handle-point-up): If an ancillary tool exists,
transfer the information there into touch-screen-current-tool
and clear t-s-a-t.
(touch-screen-handle-touch): Call t-s-a-p-u as is proper; set
t-s-a-t if a touchscreen-down event arrives and t-s-c-t is set.

* src/androidterm.c (handle_one_android_event): Properly save
the event's X and Y when a new touch point is registered.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/androidterm.c b/src/androidterm.c
index 1593cac36ba..cfb64cd69a0 100644
--- a/src/androidterm.c
+++ b/src/androidterm.c
@@ -1377,7 +1377,7 @@ handle_one_android_event (struct android_display_info *dpyinfo,
         {
           /* Simply update the tool position and send an update.  */
           touchpoint->x = event->touch.x;
-          touchpoint->y = event->touch.x;
+          touchpoint->y = event->touch.y;
           android_update_tools (any, &inev.ie);
           inev.ie.timestamp = event->touch.time;
 
@@ -1390,7 +1390,7 @@ handle_one_android_event (struct android_display_info *dpyinfo,
       touchpoint = xmalloc (sizeof *touchpoint);
       touchpoint->tool_id = event->touch.pointer_id;
       touchpoint->x = event->touch.x;
-      touchpoint->y = event->touch.x;
+      touchpoint->y = event->touch.y;
       touchpoint->next = FRAME_OUTPUT_DATA (any)->touch_points;
       touchpoint->tool_bar_p = false;
       FRAME_OUTPUT_DATA (any)->touch_points = touchpoint;