1 files changed, 62 insertions, 0 deletions
diff --git a/public/assets/javascripts/rectangles/util/wheel.js b/public/assets/javascripts/rectangles/util/wheel.js
new file mode 100644
index 0000000..6836772
--- /dev/null
+++ b/public/assets/javascripts/rectangles/util/wheel.js
@@ -0,0 +1,62 @@
+/*
+	usage:
+	
+		base.wheel = new wheel({
+			el: document.querySelector("#map"),
+			update: function(e, val, delta){
+				// do something with val
+			},
+		})
+
+*/
+
+function wheel (opt) {
+	opt = defaults(opt, {
+		el: document,
+		fn: function(e, val, delta){},
+		propagate: false,
+		locked: false,
+		reversible: true,
+		ratio: 0.02,
+		val: 0,
+	})
+
+	opt.el.addEventListener('mousewheel', onMouseWheel, false);
+	opt.el.addEventListener('DOMMouseScroll', onMouseWheel, false);
+
+	function onMouseWheel (e) {
+		if (opt.locked) {
+			return
+		}
+		if (! opt.propagate) {
+			e.stopPropagation()
+			e.preventDefault()
+		}
+		
+		var delta = 0;
+		
+		// WebKit
+		if ( event.wheelDeltaY ) {
+			delta -= event.wheelDeltaY * opt.ratio
+		}
+		// Opera / Explorer 9
+		else if ( event.wheelDelta ) {
+			delta -= event.wheelDelta * opt.ratio
+		}
+		// Firefox
+		else if ( event.detail ) {
+			delta += event.detail * 2
+		}
+		if (! opt.reversible && delta < 0) return;
+		
+		opt.val = clamp(opt.val + delta, opt.min, opt.max)
+		
+		opt.update(e, opt.val, delta)
+	}
+
+	opt.lock = function(){ opt.locked = true }
+	opt.unlock = function(){ opt.locked = false }
+
+	return opt
+}
+