From f63bb2a2af8c987feeb0511d92f73931a2968392 Mon Sep 17 00:00:00 2001
From: Michael Jumper <zhangmaike@users.sourceforge.net>
Date: Sun, 1 Apr 2012 18:20:18 -0700
Subject: [PATCH] Set scroll and click thresholds relative to screen pixel
 density (if readable) and size of gesture.

---
 src/main/resources/mouse.js |   21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/main/resources/mouse.js b/src/main/resources/mouse.js
index d1217d4..5475793 100644
--- a/src/main/resources/mouse.js
+++ b/src/main/resources/mouse.js
@@ -59,10 +59,10 @@ Guacamole.Mouse = function(element) {
     var guac_mouse = this;
 
     /**
-     * The number of pixels a touch must move for it to be considered a scroll
-     * wheel event.
+     * The distance a two-finger touch must move per scrollwheel event, relative
+     * to the distance between the two touches.
      */
-    this.scrollThreshold = 20;
+    this.scrollThreshold = 0.5;
 
     /**
      * The maximum number of milliseconds to wait for a touch to end for the
@@ -74,7 +74,7 @@ Guacamole.Mouse = function(element) {
      * The maximum number of pixels to allow a touch to move for the gesture to
      * be considered a click.
      */
-    this.clickMoveThreshold = 10;
+    this.clickMoveThreshold = 10 * (window.displayPixelRatio || 1);
 
     /**
      * The current mouse state. The properties of this state are updated when
@@ -166,6 +166,7 @@ Guacamole.Mouse = function(element) {
     var last_touch_y = 0;
     var last_touch_time = 0;
     var pixels_moved = 0;
+    var touch_distance = 0;
 
     var touch_buttons = {
         1: "left",
@@ -262,6 +263,12 @@ Guacamole.Mouse = function(element) {
 
         }
 
+        else if (e.touches.length == 2) {
+            var diff_x = e.touches[0].screenX - e.touches[1].screenX;
+            var diff_y = e.touches[0].screenY - e.touches[1].screenY;
+            touch_distance = Math.sqrt(diff_x*diff_x + diff_y*diff_y);
+        }
+
     }, false);
 
     element.addEventListener("touchmove", function(e) {
@@ -305,11 +312,11 @@ Guacamole.Mouse = function(element) {
 
         }
 
-        // Otherwise, interpret as scrollwheel
-        else {
+        // Interpret two-finger touch as scrollwheel
+        else if (touch_count == 2) {
 
             // If change in location passes threshold for scroll
-            if (Math.abs(delta_y) >= guac_mouse.scrollThreshold) {
+            if (Math.abs(delta_y) >= touch_distance * guac_mouse.scrollThreshold) {
 
                 // Decide button based on Y movement direction
                 var button;
-- 
1.7.10.4