update library menu

dashboard-ui/components/scrollthreshold.js

@@ -0,0 +1,72 @@
+define(['events'], function (events) {
+
+    function thresholdMonitor(elem, horizontal, lowerTolerance, upperTolerance) {
+
+        var defaultTolerance = horizontal ? (screen.availWidth / 2) : (screen.availHeight / 2);
+        lowerTolerance = lowerTolerance || defaultTolerance;
+        upperTolerance = upperTolerance || defaultTolerance;
+
+        var self = this;
+        var upperTriggered = false;
+        var lowerTriggered = false;
+
+        var scrollSize;
+
+        function getScrollSize() {
+
+            if (!scrollSize) {
+                scrollSize = horizontal ? (elem.scrollWidth - elem.clientWidth) : (elem.scrollHeight - elem.clientHeight);
+            }
+            return scrollSize;
+        }
+
+        function onScroll(e) {
+
+            if (lowerTriggered && upperTriggered) {
+                return;
+            }
+
+            var position = horizontal ? elem.scrollLeft : elem.scrollTop;
+
+            // Detect upper threshold
+            if (!upperTriggered && position < upperTolerance) {
+                upperTriggered = true;
+                events.trigger(self, 'upper-threshold');
+            }
+            // Detect lower threshold
+            if (!lowerTriggered && position >= (getScrollSize() - lowerTolerance)) {
+                lowerTriggered = false;
+                events.trigger(self, 'lower-threshold');
+            }
+        }
+
+        self.reset = function () {
+            self.resetSize();
+            upperTriggered = false;
+            lowerTriggered = false;
+        };
+
+        self.resetSize = function () {
+            scrollSize = null;
+        };
+
+        self.enabled = function (enabled) {
+
+            self.reset();
+
+            if (enabled) {
+                elem.addEventListener('scroll', onScroll, true);
+            } else {
+                elem.removeEventListener('scroll', onScroll, true);
+            }
+        };
+
+        self.enabled(true);
+
+        self.destroy = function () {
+            self.enabled(false);
+        };
+    }
+
+    return thresholdMonitor;
+});