guy
3 years ago
5 changed files with 186 additions and 8 deletions
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/** |
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* 同时用于virtualGroup和virtualList特性的虚拟列表 |
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* |
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* Created by GUY on 2017/5/22. |
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* @class BI.VirtualList |
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* @extends BI.Widget |
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*/ |
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BI.VirtualGroupList = BI.inherit(BI.Widget, { |
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props: function () { |
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return { |
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baseCls: "bi-virtual-group-list", |
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overscanHeight: 100, |
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blockSize: 10, |
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scrollTop: 0, |
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rowHeight: "auto", |
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items: [] |
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}; |
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}, |
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init: function () { |
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var self = this; |
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this.renderedIndex = -1; |
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}, |
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render: function () { |
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var self = this, o = this.options; |
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return { |
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type: "bi.vertical", |
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items: [{ |
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type: "bi.layout", |
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ref: function () { |
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self.topBlank = this; |
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} |
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}, { |
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type: "bi.virtual_group", |
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height: o.rowHeight * o.items.length, |
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ref: function () { |
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self.container = this; |
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}, |
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layouts: [{ |
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type: "bi.vertical", |
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scrolly: false |
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}] |
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}, { |
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type: "bi.layout", |
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ref: function () { |
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self.bottomBlank = this; |
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} |
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}], |
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element: this |
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}; |
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}, |
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// mounted之后绑定事件
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mounted: function () { |
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var self = this, o = this.options; |
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this._populate(); |
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this.element.scroll(function (e) { |
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o.scrollTop = self.element.scrollTop(); |
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self._calculateBlocksToRender(); |
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}); |
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BI.ResizeDetector.addResizeListener(this, function () { |
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self._calculateBlocksToRender(); |
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}); |
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}, |
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_isAutoHeight: function () { |
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return this.options.rowHeight === "auto"; |
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}, |
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_renderMoreIf: function () { |
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var self = this, o = this.options; |
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var height = this.element.height(); |
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var minContentHeight = o.scrollTop + height + o.overscanHeight; |
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var index = (this.renderedIndex + 1) * o.blockSize, cnt = this.renderedIndex + 1; |
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var lastHeight; |
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var getElementHeight = function () { |
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return self.container.element.height() + self.topBlank.element.height() + self.bottomBlank.element.height(); |
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}; |
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while ((lastHeight = getElementHeight()) < minContentHeight && index < o.items.length) { |
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var items = o.items.slice(index, index + o.blockSize); |
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this.container.addItems(items, this); |
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var addedHeight = getElementHeight() - lastHeight; |
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this.tree.set(cnt, addedHeight); |
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this.renderedIndex = cnt; |
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cnt++; |
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index += o.blockSize; |
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} |
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}, |
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_calculateBlocksToRender: function () { |
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var o = this.options; |
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this._isAutoHeight() && this._renderMoreIf(); |
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var height = this.element.height(); |
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var minContentHeightFrom = o.scrollTop - o.overscanHeight; |
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var minContentHeightTo = o.scrollTop + height + o.overscanHeight; |
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var start = this.tree.greatestLowerBound(minContentHeightFrom); |
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var end = this.tree.leastUpperBound(minContentHeightTo); |
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var items = []; |
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var topHeight = this.tree.sumTo(Math.max(-1, start - 1)); |
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this.topBlank.setHeight(topHeight); |
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if (this._isAutoHeight()) { |
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for (var i = (start < 0 ? 0 : start); i <= end && i <= this.renderedIndex; i++) { |
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var index = i * o.blockSize; |
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for (var j = index; j < index + o.blockSize && j < o.items.length; j++) { |
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items.push(o.items[j]); |
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} |
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} |
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this.bottomBlank.setHeight(this.tree.sumTo(this.renderedIndex) - this.tree.sumTo(Math.min(end, this.renderedIndex))); |
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this.container.element.height(this.container.element.height()); |
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this.container.populate(items); |
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this.container.element.height("auto"); |
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} else { |
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for (var i = (start < 0 ? 0 : start); i <= end; i++) { |
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var index = i * o.blockSize; |
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for (var j = index; j < index + o.blockSize && j < o.items.length; j++) { |
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items.push(o.items[j]); |
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} |
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} |
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this.container.element.height(o.rowHeight * o.items.length - topHeight); |
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this.container.populate(items); |
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} |
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}, |
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_populate: function (items) { |
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var o = this.options; |
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if (items && this.options.items !== items) { |
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this.options.items = items; |
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} |
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this.tree = BI.PrefixIntervalTree.uniform(Math.ceil(o.items.length / o.blockSize), this._isAutoHeight() ? 0 : o.rowHeight * o.blockSize); |
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this._calculateBlocksToRender(); |
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try { |
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this.element.scrollTop(o.scrollTop); |
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} catch (e) { |
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} |
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}, |
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restore: function () { |
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this.renderedIndex = -1; |
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this.options.scrollTop = 0; |
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// 依赖于cache的占位元素也要初始化
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this.topBlank.setHeight(0); |
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this.bottomBlank.setHeight(0); |
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}, |
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populate: function (items) { |
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if (items && this.options.items !== items) { |
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this.restore(); |
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} |
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this._populate(items); |
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} |
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}); |
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BI.shortcut("bi.virtual_group_list", BI.VirtualGroupList); |
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