BI-47755 fix: virtual_list先滚动在populate报错

src/base/grid/grid.js

@@ -208,7 +208,8 @@ BI.GridView = BI.inherit(BI.Widget, {
             BI.each(addSet, function (index, key) {
                 addedItems.push(renderedCells[key[2]]);
             });
-            this.container.addItems(addedItems);
+            // 与listview一样, 给上下文
+            this.container.addItems(addedItems, this);
             // 拦截父子级关系
             this.container._children = renderedWidgets;
             this.container.attr("items", renderedCells);

src/base/list/virtuallist.js

@@ -151,7 +151,7 @@ BI.VirtualList = BI.inherit(BI.Widget, {
 
     _clearChildren: function () {
         BI.each(this.container._children, function (i, cell) {
-            cell && cell.el._destroy();
+            cell && cell._destroy();
         });
         this.container._children = {};
         this.container.attr("items", []);
@@ -162,6 +162,9 @@ BI.VirtualList = BI.inherit(BI.Widget, {
         this._clearChildren();
         this.cache = {};
         this.options.scrollTop = 0;
+        // 依赖于cache的占位元素也要初始化
+        this.topBlank.setHeight(0);
+        this.bottomBlank.setHeight(0);
     },
 
     populate: function (items) {

src/core/utils/prefixIntervalTree.js

@@ -23,13 +23,15 @@
     BI.PrefixIntervalTree = function (xs) {
         this._size = xs.length;
         this._half = ceilLog2(this._size);
+        // _heap是一个_size两倍以上的堆
         this._heap = new Int32Array(2 * this._half);
 
         var i;
+        // 初始化 >= _size 的堆空间, 即叶子节点
         for (i = 0; i < this._size; ++i) {
             this._heap[this._half + i] = xs[i];
         }
-
+        // 初始化 < _size 的堆空间, 即非叶子节点，根节点包含整个区间
         for (i = this._half - 1; i > 0; --i) {
             this._heap[i] = this._heap[2 * i] + this._heap[2 * i + 1];
         }
@@ -37,6 +39,7 @@
 
     BI.PrefixIntervalTree.prototype = {
         constructor: BI.PrefixIntervalTree,
+        // 往_half之后的空间set值，需要更新其所有祖先节点的值
         set: function (index, value) {
             var node = this._half + index;
             this._heap[node] = value;