fix(loading): make showDelay option work correctly

The 'showDelay' configuration option of $ionicLoading exists but
does not lead to any delay whatsoever.

This change implements that functionality.

Closes #562

js/views/loadingView.js

@@ -1,10 +1,10 @@
 (function(ionic) {
 'use strict';
   /**
-   * An ActionSheet is the slide up menu popularized on iOS.
+   * Loading
    *
-   * You see it all over iOS apps, where it offers a set of options 
-   * triggered after an action.
+   * The Loading is an overlay that can be used to indicate
+   * activity while blocking user interaction.
    */
   ionic.views.Loading = ionic.views.View.inherit({
     initialize: function(opts) {
@@ -14,6 +14,8 @@
 
       this.maxWidth = opts.maxWidth || 200;
 
+      this.showDelay = opts.showDelay || 0;
+
       this._loadingBox = this.el.querySelector('.loading');
     },
     show: function() {
@@ -29,13 +31,19 @@
         lb.style.marginLeft = (-lb.offsetWidth) / 2 + 'px';
         lb.style.marginTop = (-lb.offsetHeight) / 2 + 'px';
 
-        _this.el.classList.add('active');
+        // Wait 'showDelay' ms before showing the loading screen
+        this._showDelayTimeout = window.setTimeout(function() {
+          _this.el.classList.add('active');
+        }, _this.showDelay);
       }
     },
     hide: function() {
       // Force a reflow so the animation will actually run
       this.el.offsetWidth;
 
+      // Prevent unnecessary 'show' after 'hide' has already been called
+      window.clearTimeout(this._showDelayTimeout);
+
       this.el.classList.remove('active');
     }
   });