[gnome-shell/wip/gestures: 9/10] Add AppSwitchAction Clutter.GestureAction

[Carlos Garnacho <carlosg src gnome org>]

commit f659b66a9db44504c67d93947ea249eaec520e90
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Jun 27 22:44:30 2014 +0200

    Add AppSwitchAction Clutter.GestureAction
    
    This action implements 3-finger hold + 4th finger tap to switch
    the focused application.

 js/js-resources.gresource.xml |    1 +
 js/ui/appSwitchAction.js      |   64 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 0 deletions(-)
---
diff --git a/js/js-resources.gresource.xml b/js/js-resources.gresource.xml
index 3fed6a4..319a9de 100644
--- a/js/js-resources.gresource.xml
+++ b/js/js-resources.gresource.xml
@@ -32,6 +32,7 @@
     <file>ui/animation.js</file>
     <file>ui/appDisplay.js</file>
     <file>ui/appFavorites.js</file>
+    <file>ui/appSwitchAction.js</file>
     <file>ui/backgroundMenu.js</file>
     <file>ui/background.js</file>
     <file>ui/boxpointer.js</file>
diff --git a/js/ui/appSwitchAction.js b/js/ui/appSwitchAction.js
new file mode 100644
index 0000000..018f174
--- /dev/null
+++ b/js/ui/appSwitchAction.js
@@ -0,0 +1,64 @@
+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+
+const Lang = imports.lang;
+const Signals = imports.signals;
+const Clutter = imports.gi.Clutter;
+
+//in milliseconds
+let LONG_PRESS_TIMEOUT = 250;
+
+let MOTION_THRESHOLD = 30;
+
+const AppSwitchAction = new Lang.Class({
+    Name: 'AppSwitchAction',
+    Extends: Clutter.GestureAction,
+
+    _init : function() {
+       this.parent();
+       this.set_n_touch_points (3);
+       global.display.connect('grab-op-begin', Lang.bind(this, this.cancel));
+       global.display.connect('grab-op-end', Lang.bind(this, this.cancel));
+    },
+
+    vfunc_gesture_prepare : function(action, actor) {
+       return this.get_n_current_points() <= 4;
+    },
+
+    vfunc_gesture_begin : function(action, actor) {
+       let nPoints = this.get_n_current_points();
+       let event = this.get_last_event (nPoints - 1);
+
+       if (nPoints == 3)
+           this._longPressStartTime = event.get_time();
+       else if (nPoints == 4) {
+           // Check whether the 4th finger press happens after a 3-finger long press,
+           // this only needs to be checked on the first 4th finger press
+           if (this._longPressStartTime != null &&
+               event.get_time() < this._longPressStartTime + LONG_PRESS_TIMEOUT)
+               this.cancel();
+           else {
+               this._longPressStartTime = null;
+               this.emit('activated');
+           }
+       }
+
+       return this.get_n_current_points() <= 4;
+    },
+
+    vfunc_gesture_progress : function(action, actor) {
+       if (this.get_n_current_points() == 3) {
+           for (let i = 0; i < this.get_n_current_points(); i++) {
+               [startX, startY] = this.get_press_coords(i);
+               [x, y] = this.get_motion_coords(i);
+
+               if (Math.abs(x - startX) > MOTION_THRESHOLD ||
+                   Math.abs(y - startY) > MOTION_THRESHOLD)
+                   return false;
+           }
+
+       }
+
+       return true;
+    }
+});
+Signals.addSignalMethods(AppSwitchAction.prototype);