amend(collectionRepeat): do not allow computed height/width to be 0

js/angular/directive/collectionRepeat.js

@@ -4,7 +4,7 @@
  * @restrict A
  * @name collectionRepeat
  * @module ionic
- * @codepen mFygh
+ * @codepen 7ec1ec58f2489ab8f359fa1a0fe89c15
  * @description
  * `collection-repeat` allows an app to show huge lists of items much more performantly than
  * `ng-repeat`.
@@ -30,7 +30,7 @@
  *   if possible, lower the number of unique images. Check out [this codepen]().
  *
  * @usage
- * #### Basic Item List (codepen)
+ * #### Basic Item List ([codepen](http://codepen.io/ionic/pen/0c2c35a34a8b18ad4d793fef0b081693))
  * ```html
  * <ion-content>
  *   <ion-item collection-repeat="item in items">
@@ -39,7 +39,7 @@
  * </ion-content>
  * ```
  *
- * #### Grid of Images (codepen)
+ * #### Grid of Images ([codepen])
  * ```html
  * <ion-content>
  *   <img collection-repeat="photo in photos"
@@ -208,12 +208,22 @@ function CollectionRepeatDirective($ionicCollectionManager, $parse, $window, $$r
 
       if (heightData.computed) {
         heightData.value = computedStyleDimensions.height;
+        if (!heightData.value) {
+          throw new Error('collection-repeat tried to compute the height of elements "' +
+            listExpression + '", but was unable to. Please provide the "item-height" attribute. ' +
+            'http://ionicframework.com/docs/api/directive/collectionRepeat/');
+        }
       } else if (!heightData.dynamic && heightData.getValue) {
         // If it's a constant with a getter (eg percent), we just refresh .value after resize
         heightData.value = heightData.getValue();
       }
       if (widthData.computed) {
         widthData.value = computedStyleDimensions.width;
+        if (!widthData.value) {
+          throw new Error('collection-repeat tried to compute the width of elements in "' +
+            listExpression + '", but was unable to. Please provide the "item-width" attribute. ' +
+            'http://ionicframework.com/docs/api/directive/collectionRepeat/');
+        }
       } else if (!widthData.dynamic && widthData.getValue) {
         // If it's a constant with a getter (eg percent), we just refresh .value after resize
         widthData.value = widthData.getValue();
@@ -518,10 +528,13 @@ function RepeatManagerFactory($rootScope, $window, $$rAF) {
       // one frame, causing visible jank.
       // DON'T call any other functions inside this loop unless it's vital.
       for (i = renderStartIndex; i <= renderEndIndex; i++) {
-        // If the item at this index is already shown, skip
-        if (i >= data.length || itemsShownMap[i] && !forceRerender) continue;
+        // We only go forward with render if the index is in data, the item isn't already shown,
+        // or forceRerender is on.
+        if (i >= data.length || (itemsShownMap[i] && !forceRerender)) continue;
 
-        item = itemsShownMap[i] || (itemsShownMap[i] = getNextItem());
+        item = itemsShownMap[i] || (itemsShownMap[i] = itemsLeaving.length ? itemsLeaving.pop() :
+                                    itemsPool.length ? itemsPool.shift() :
+                                    new RepeatItem())
         itemsEntering.push(item);
         item.isShown = true;
 
@@ -606,13 +619,13 @@ function RepeatManagerFactory($rootScope, $window, $$rAF) {
 
       $$rAF(function process() {
         if( (len = itemsEntering.length) ) {
-          var count = Math.floor(len / 1.5) || 1;
           var rootScopePhase = $rootScope.$$phase;
+          var count = Math.floor(len / 1.25) || 1;
           while (count && itemsEntering.length) {
             item = itemsEntering.pop();
             if (item.isShown) {
               count--;
-              if (!$rootScope.$$phase) item.scope.$digest();
+              if (!rootScopePhase) item.scope.$digest();
             }
           }
           $$rAF(process);