nerffei opened a new issue #10223: Echartjs 对TypedArray的支持问题 URL: https://github.com/apache/incubator-echarts/issues/10223 ### Version 4.2.1 ### Steps to reproduce 我需要用echarts渲染一些折线图，但是我的数据源是TypedArray,我的配置大概如下面 ```javascript { xAxis: { type: 'value' }, yAxis: { type: 'value' }, dataset: { dimensions:[ { name: 'x', type: 'float'}, { name: 'y', type: 'float'} ], source: [ x, y ], }, series: { type: 'line', sampling: 'max', encode: { 'y': 'y', 'x': 'x' }, seriesLayoutBy: 'row' } } ``` 其中**dataset.source**中的**x**,**y**是**float64Array** ### What is expected? 正确的显示折线图 ### What is actually happening? 页面空白没有显示任何信息 --- 但是如果我用 ```javascript Array.from(x) Array.from(y) ``` 即把typedarray转化成array之后, 图表能正常显示 我尝试去定位这个问题. 我在 **lib/data/helper/sourceHelper.js**中的函数**detectSourceFormat**中发现了些问题, 这个函数的功能好像是决定source类型 ```javascript function detectSourceFormat(datasetModel) { var data = datasetModel.option.source; // 这个data来自于配置中的source .... for (var i = 0, len = data.length; i < len; i ) { var item = data[i]; if (item == null) { continue; // 问题出现在这边判断上, 如果是source是[typedarray, typedarray], 无法识别为typedarray } else if (isArray(item)) { sourceFormat = SOURCE_FORMAT_ARRAY_ROWS; break; } else if (isObject(item)) { sourceFormat = SOURCE_FORMAT_OBJECT_ROWS; break; } } } ``` 后面我加上了判断 ```javascript .... var item = data[i]; // 有问题 if (item == null) { continue; } else if(isTypedArray(item)) { // 判断了是不是类型数组 sourceFormat = SOURCE_FORMAT_TYPED_ARRAY break; } else if (isArray(item)) { sourceFormat = SOURCE_FORMAT_ARRAY_ROWS; break; } else if (isObject(item)) { sourceFormat = SOURCE_FORMAT_OBJECT_ROWS; break; } ... ``` 修改完成之后，图表依旧无法显示.之后，我在**lib/data/List.js**下发现 **listProto.initData**中的 ``` this._initDataFromProvider(0, data.count()) ``` 这行好像有问题，**data.count()**的返回值是1, 这个错误的返回值导致后面计算storage时候出现了问题,在**listProto._initDataFromProvider** ```javascript prepareChunks(storage, dimInfo, chunkSize, originalChunkCount, end); // 这里storage是[NaN] ``` 我在**lib/data/helper/dataProvider.js**中找到了typedArray **count**方法的实现 ```javascript 'typedArray': { persistent: false, pure: true, count: function () { // 我的dataset.source是输入两个类型数组, 这里永远返回1 return this._data ? this._data.length / this._dimSize : 0; }, getItem: function (idx, out) { idx = idx - this._offset; out = out || []; var offset = this._dimSize * idx; for (var i = 0; i < this._dimSize; i ) { out[i] = this._data[offset i]; } return out; }, appendData: function (newData) { this._data = newData; }, // Clean self if data is already used. clean: function () { // PENDING this._offset = this.count(); this._data = null; } } ``` 我很想继续追踪解决这个问题，但是我不是很清楚这个cout跟**prepareChunks**具体是做什么的，水平有限，特来求助 <!-- This issue is generated by echarts-issue-helper. DO NOT REMOVE -->
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