异步函数

SpreadJS 提供了 AsyncFunction 函数来计算异步数据; 该函数用在不能立刻获取计算结果的时候使用, 比如数据或者计算方法在服务器端的时候。

新建一个类型并且从 GC.Spread.CalcEngine.Functions.AsyncFunction 派生。 当结果不能立即计算完成时可以使用 defaultValue 来暂时代替计算结果。 使用 evaluateAsync 方法来进行计算, 并且在异步计算完毕后使用 context.setAsyncResult 方法来讲计算结果通知 SpreadJS。 AsyncFunctionEvaluateMode 代表了异步函数的计算模式, 总共有如下3种计算模式: 0 表示函数在单元格需要计算是进行重算. 例如: B1='MyAsync1(A1) + MyAsync2(A2)', 当 A1 的值改变时, B1中的公式就会重新计算, 因此 'MyAsync1(A1)' 和 'MyAsync2(A2)' 都会进行重算。 1 表示函数只需要计算一次。 2 表示‘FRESH’函数中的公式会随着时间的间隔去进行计算。 SpreadJS 提供了 refresh 方法。 第一个参数可以使任意公式。 计算模式应该是GC.Spread.CalcEngine.Functions.AsyncFunctionEvaluateMode枚举类型中的一个。 interval只有在计算模式是2的时候才会起作用。 一般来说,REFRESH 函数是最外层的函数。 当我们把异步函数放在 REFRESH 函数中时, 异步函数将会使用 REFRESH 的参数, 而自己的那些参数将不再起作用。 使用 addCustomFunction 方法来添加并定义异步函数,然后这个自定义函数就能够在 setFormula 方法中使用或者直接通过键盘输入了。
window.onload = function () { var spread = new GC.Spread.Sheets.Workbook(document.getElementById("ss"), {sheetCount: 2}); initSpread(spread); }; function initSpread(spread) { var asyncSum = function () { }; asyncSum.prototype = new GC.Spread.CalcEngine.Functions.AsyncFunction("ASUM", 1, 255); asyncSum.prototype.defaultValue = function () { return "Loading..."; }; asyncSum.prototype.evaluateAsync = function (context) { // use setTimeout to simulate server side evaluation // in read world it maybe an ajax post to server for evaluation var args = arguments; setTimeout(function () { var result = 0; for (var i = 1; i < args.length; i++) { result += args[i]; } result *= 2; context.setAsyncResult(result); }, 2000); }; var GetNumberFromServer = function () { }; GetNumberFromServer.prototype = new GC.Spread.CalcEngine.Functions.AsyncFunction("GETNUMBERFROMSERVER", 1, 2); GetNumberFromServer.prototype.evaluate = function (context, arg1, arg2) { setTimeout(function () { var value = Math.random() + 1; context.setAsyncResult(value); }, 500); }; GC.Spread.CalcEngine.Functions.defineGlobalCustomFunction("GETNUMBERFROMSERVER", new GetNumberFromServer()); var GetTimeFromServer = function () { }; GetTimeFromServer.prototype = new GC.Spread.CalcEngine.Functions.AsyncFunction("GETTIMEFROMSERVER"); GetTimeFromServer.prototype.evaluate = function (context) { setTimeout(function () { var date = new Date(); context.setAsyncResult(date); }, 500); }; GetTimeFromServer.prototype.evaluateMode = function () { return 2; }; GetTimeFromServer.prototype.interval = function () { return 1000; }; GC.Spread.CalcEngine.Functions.defineGlobalCustomFunction("GETTIMEFROMSERVER", new GetTimeFromServer()); var sheet = spread.sheets[0]; sheet.suspendPaint(); sheet.options.allowCellOverflow = true; sheet.setArray(0, 0, [[5, 15]]); sheet.addCustomFunction(new asyncSum()); sheet.setFormula(1, 1, "ASUM(A1,B1)"); sheet.getCell(1, 1).foreColor("green"); sheet.setValue(4, 0, "Edit the formula of B2 or referenced cell' value to see how async function works."); sheet.setValue(8, 0, 'ChangeValue'); sheet.setValue(8, 1, 'Formula'); sheet.setValue(8, 2, 'Result'); sheet.setValue(8, 3, 'Comments'); sheet.setValue(9, 3, 'On A10 changed'); sheet.setValue(10, 3, 'On A10 changed'); sheet.setValue(11, 3, 'Evaluate once'); sheet.setValue(12, 3, 'Every 2 seconds'); sheet.setValue(9, 0, 1); sheet.setValue(9, 1, '=GetNumberFromServer(A10)'); sheet.setValue(10, 1, '=Refresh(GetNumberFromServer(A10), 0)'); sheet.setValue(11, 1, '=Refresh(GetNumberFromServer(A10), 1)'); sheet.setValue(12, 1, '=Refresh(GetNumberFromServer(A10), 2, 2000)'); sheet.setFormula(9, 2, '=GetNumberFromServer(A10)'); sheet.setFormula(10, 2, '=Refresh(GetNumberFromServer(A10), 0)'); sheet.setFormula(11, 2, '=Refresh(GetNumberFromServer(A10), 1)'); sheet.setFormula(12, 2, '=Refresh(GetNumberFromServer(A10), 2, 2000)'); sheet.setColumnWidth(0, 100); sheet.setColumnWidth(1, 300); sheet.setColumnWidth(2, 200); sheet.setColumnWidth(3, 200); sheet.setValue(15, 1, "=Refresh(now(), 2, 1000)"); sheet.setValue(15, 3, "Every 1 seconds"); sheet.setFormula(15, 2, "=Refresh(now(), 2, 1000)"); sheet.setValue(18, 1, "=GetTimeFromServer()"); sheet.setValue(18, 3, "Every 1 seconds"); sheet.setFormula(18, 2, "=GetTimeFromServer()"); sheet.getCell(18, 2).hAlign(GC.Spread.Sheets.HorizontalAlign.right); sheet.resumePaint(); }
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