From 7ee897ead54b501015aba1fbd900cf73eb300ce7 Mon Sep 17 00:00:00 2001
From: "Jasper St. Pierre" <jstpierre@mecheye.net>
Date: Tue, 31 Jul 2012 10:58:58 -0300
Subject: [PATCH] layout: Don't show the tray if the user is just skirting the
 barrier

If the user is just pushing their mouse along the barrier's edge, rather
than pushing down onto the barrier, we shouldn't show the tray. Do this
by keeping track of the distance traveled perpendicular to the barrier,
and releasing the accumulated pressure if we pass a threshold.
---
 js/ui/layout.js | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/js/ui/layout.js b/js/ui/layout.js
index 35b9e1afc..83f47ba39 100644
--- a/js/ui/layout.js
+++ b/js/ui/layout.js
@@ -20,6 +20,10 @@ const KEYBOARD_ANIMATION_TIME = 0.5;
 const PLYMOUTH_TRANSITION_TIME = 1;
 
 const MESSAGE_TRAY_PRESSURE_THRESHOLD = 200;
+// The maximium amount that the user is allowed to travel
+// perpendicular to the barrier before we release the accumulated
+// pressure.
+const MESSAGE_TRAY_MAX_SKIRT = 100;
 
 const MonitorConstraint = new Lang.Class({
     Name: 'MonitorConstraint',
@@ -299,7 +303,9 @@ const LayoutManager = new Lang.Class({
                                                    y1: monitor.y + monitor.height, y2: monitor.y + monitor.height,
                                                    directions: Meta.BarrierDirection.NEGATIVE_Y });
 
-            this._trayPressure = new PressureBarrier(this._trayBarrier, MESSAGE_TRAY_PRESSURE_THRESHOLD);
+            this._trayPressure = new PressureBarrier(this._trayBarrier,
+                                                     MESSAGE_TRAY_PRESSURE_THRESHOLD,
+                                                     MESSAGE_TRAY_MAX_SKIRT);
             this._trayPressure.connect('trigger', function() {
                 Main.messageTray.openTray();
             });
@@ -1160,10 +1166,11 @@ Signals.addSignalMethods(Chrome.prototype);
 const PressureBarrier = new Lang.Class({
     Name: 'TrayPressure',
 
-    _init: function(barrier, threshold) {
+    _init: function(barrier, pressureThreshold, perpThreshold) {
         this._barrier = barrier;
-        this._threshold = threshold;
-        this._getVelocity = this._makeGetVelocity(barrier);
+        this._pressureThreshold = pressureThreshold;
+        this._perpThreshold = perpThreshold;
+        this._getVelocityAndPerp = this._makeGetVelocityAndPerp(barrier);
 
         this._reset(0);
 
@@ -1178,16 +1185,17 @@ const PressureBarrier = new Lang.Class({
     _reset: function(eventId) {
         this._currentEventId = eventId;
         this._currentPressure = 0;
+        this._perpAccumulator = 0;
     },
 
-    _makeGetVelocity: function(barrier) {
+    _makeGetVelocityAndPerp: function(barrier) {
         if (barrier.y1 === barrier.y2) {
             return function(event) {
-                return Math.abs(event.dy);
+                return [Math.abs(event.dy), event.dx];
             };
         } else {
             return function(event) {
-                return Math.abs(event.dx);
+                return [Math.abs(event.dx), event.dy];
             };
         }
     },
@@ -1200,10 +1208,19 @@ const PressureBarrier = new Lang.Class({
             this._reset(event.event_id);
         }
 
-        let velocity = this._getVelocity(event);
+        let [velocity, perp] = this._getVelocityAndPerp(event);
+        this._perpAccumulator += perp;
+
+        // If the user travels too far in the direction perpendicular
+        // to the barrier, start over from scratch -- the user is simply
+        // trying to skirt along the barrier.
+        if (Math.abs(this._perpAccumulator) >= this._perpThreshold) {
+            this._reset(0);
+            return;
+        }
 
         this._currentPressure += velocity;
-        if (this._currentPressure >= this._threshold) {
+        if (this._currentPressure >= this._pressureThreshold) {
             this.emit('trigger');
             this._reset(0);
         }