通过 JavaScript 及 C++ 将图表转换为图片
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渲染图表
Aspose.Cells API支持将Excel图表转换成图片格式，无需额外工具或应用程序。为了支持渲染，Chart类提供了toImage(string)方法及多种重载以满足不同应用需求。
将图表渲染为图像
Chart.toImage(string) 方法具有多种重载，以支持简单和高级渲染。如果应用需求是在默认尺寸中渲染图表，建议使用如下 Chart.toImage(string) 方法：
<!DOCTYPE html>
<html>
<head>
<title>Aspose.Cells Example</title>
</head>
<body>
<h1>Aspose.Cells Chart to Image Example</h1>
<input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
<button id="runExample">Run Example</button>
<br/><br/>
<a id="downloadLinkEMF" style="display: none; margin-right: 10px;">Download EMF Image</a>
<a id="downloadLinkBMP" style="display: none;">Download BMP Image</a>
<div id="result"></div>
</body>
<script src="aspose.cells.js.min.js"></script>
<script type="text/javascript">
const { Workbook, SaveFormat, ChartType, ImageType } = AsposeCells;
AsposeCells.onReady({
license: "/lic/aspose.cells.enc",
fontPath: "/fonts/",
fontList: [
"arial.ttf",
"NotoSansSC-Regular.ttf"
]
}).then(() => {
console.log("Aspose.Cells initialized");
});
document.getElementById('runExample').addEventListener('click', async () => {
// This example does not require an input file; an empty workbook is created as in the original JavaScript example.
// Instantiating a Workbook object
const workbook = new Workbook();
// Adding a new worksheet to the Workbook
const sheetIndex = workbook.worksheets.add();
// Obtaining the reference of the newly added worksheet by passing its index to WorksheetCollection
const worksheet = workbook.worksheets.get(sheetIndex);
// Adding sample values to cells
worksheet.cells.get("A1").value = 50;
worksheet.cells.get("A2").value = 100;
worksheet.cells.get("A3").value = 150;
worksheet.cells.get("B1").value = 4;
worksheet.cells.get("B2").value = 20;
worksheet.cells.get("B3").value = 50;
// Adding a chart to the worksheet
const chartIndex = worksheet.charts.add(ChartType.Column, 5, 0, 15, 5);
// Accessing the instance of the newly added chart
const chart = worksheet.charts.get(chartIndex);
// Adding Series Collection (chart data source) to the chart ranging from "A1" cell to "B3"
chart.nSeries.add("A1:B3", true);
// Converting chart to image (EMF)
const emfData = chart.toImage(ImageType.Emf);
const emfBlob = new Blob([emfData], { type: "image/emf" });
const downloadLinkEMF = document.getElementById('downloadLinkEMF');
downloadLinkEMF.href = URL.createObjectURL(emfBlob);
downloadLinkEMF.download = 'chartEMF_out.emf';
downloadLinkEMF.style.display = 'inline-block';
downloadLinkEMF.textContent = 'Download EMF Image';
// Converting chart to Bitmap (BMP)
const bmpData = chart.toImage(ImageType.Bmp);
const bmpBlob = new Blob([bmpData], { type: "image/bmp" });
const downloadLinkBMP = document.getElementById('downloadLinkBMP');
downloadLinkBMP.href = URL.createObjectURL(bmpBlob);
downloadLinkBMP.download = 'chartBMP_out.bmp';
downloadLinkBMP.style.display = 'inline-block';
downloadLinkBMP.textContent = 'Download BMP Image';
document.getElementById('result').innerHTML = '<p style="color: green;">Chart images created. Click the download links to save them.</p>';
});
</script>
</html>
也可以使用高级设置将图表渲染为图片。Aspose.Cells API提供了Chart.toImage(string)方法的重载版本，接受ImageOrPrintOptions实例，同时允许设置分辨率、平滑模式、图片格式等参数。
<!DOCTYPE html>
<html>
<head>
<title>Aspose.Cells Example</title>
</head>
<body>
<h1>Create Chart and Export as PNG</h1>
<input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
<button id="runExample">Run Example</button>
<a id="downloadLink" style="display: none;">Download Result</a>
<div id="result"></div>
</body>
<script src="aspose.cells.js.min.js"></script>
<script type="text/javascript">
const { Workbook, SaveFormat, ChartType, ImageOrPrintOptions, ImageFormat } = AsposeCells;
AsposeCells.onReady({
license: "/lic/aspose.cells.enc",
fontPath: "/fonts/",
fontList: [
"arial.ttf",
"NotoSansSC-Regular.ttf"
]
}).then(() => {
console.log("Aspose.Cells initialized");
});
document.getElementById('runExample').addEventListener('click', async () => {
// Creating a new Workbook object
const workbook = new Workbook();
// Adding a new worksheet to the Workbook
const sheetIndex = workbook.worksheets.add();
// Obtaining the reference of the newly added worksheet by passing its index to WorksheetCollection
const worksheet = workbook.worksheets.get(sheetIndex);
// Adding sample values to cells
worksheet.cells.get("A1").value = 50;
worksheet.cells.get("A2").value = 100;
worksheet.cells.get("A3").value = 150;
worksheet.cells.get("B1").value = 4;
worksheet.cells.get("B2").value = 20;
worksheet.cells.get("B3").value = 50;
// Adding a chart to the worksheet
const chartIndex = worksheet.charts.add(ChartType.Column, 5, 0, 15, 5);
// Accessing the instance of the newly added chart
const chart = worksheet.charts.get(chartIndex);
// Adding Series Collection (chart data source) to the chart ranging from "A1" cell to "B3"
chart.nSeries.add("A1:B3", true);
// Create an instance of ImageOrPrintOptions and set a few properties
const options = new ImageOrPrintOptions();
options.verticalResolution = 300;
options.horizontalResolution = 300;
options.imageFormat = ImageFormat.Png;
// Convert chart to image with additional settings
const imageData = chart.toImage(options);
const blob = new Blob([imageData], { type: 'image/png' });
const downloadLink = document.getElementById('downloadLink');
downloadLink.href = URL.createObjectURL(blob);
downloadLink.download = 'chartPNG_out.png';
downloadLink.style.display = 'block';
downloadLink.textContent = 'Download Chart PNG';
document.getElementById('result').innerHTML = '<p style="color: green;">Chart exported successfully! Click the download link to get the image.</p>';
});
</script>
</html>
支持的图表类型的渲染
目前有一些不支持渲染的图表类型。这些图表类型在下表的Supported列中包含N。
| 图表类型 | 图表子类型 | 支持 |
|---|---|---|
| Column | Column | Y |
| ColumnStacked | Y | |
| Column100PercentStacked | Y | |
| Column3DClustered | Y | |
| Column3DStacked | Y | |
| Column3D100PercentStacked | Y | |
| Column3D | Y | |
| Bar | Bar | Y |
| BarStacked | Y | |
| Bar100PercentStacked | Y | |
| Bar3DClustered | Y | |
| Bar3DStacked | Y | |
| Bar3D100PercentStacked | Y | |
| Line | Line | Y |
| LineStacked | Y | |
| Line100PercentStacked | Y | |
| LineWithDataMarkers | Y | |
| LineStackedWithDataMarkers | Y | |
| Line100PercentStackedWithDataMarkers | Y | |
| Line3D | Y | |
| Pie | Pie | Y |
| Pie3D | Y | |
| PiePie | Y | |
| PieExploded | Y | |
| Pie3DExploded | Y | |
| PieBar | Y | |
| Scatter | Scatter | Y |
| ScatterConnectedByCurvesWithDataMarker | Y | |
| ScatterConnectedByCurvesWithoutDataMarker | Y | |
| ScatterConnectedByLinesWithDataMarker | Y | |
| ScatterConnectedByLinesWithoutDataMarker | Y | |
| Area | Area | Y |
| AreaStacked | Y | |
| Area100PercentStacked | Y | |
| Area3D | Y | |
| Area3DStacked | Y | |
| Area3D100PercentStacked | Y | |
| Doughnut | Doughnut | Y |
| DoughnutExploded | Y | |
| Radar | Radar | Y |
| RadarWithDataMarkers | Y | |
| RadarFilled | Y | |
| Surface | Surface3D | N |
| SurfaceWireframe3D | N | |
| SurfaceContour | N | |
| SurfaceContourWireframe | N | |
| Bubble | Bubble | Y |
| Bubble3D | N | |
| Stock | StockHighLowClose | Y |
| StockOpenHighLowClose | Y | |
| StockVolumeHighLowClose | Y | |
| StockVolumeOpenHighLowClose | Y | |
| Cylinder | Cylinder | Y |
| CylinderStacked | Y | |
| Cylinder100PercentStacked | Y | |
| CylindricalBar | Y | |
| CylindricalBarStacked | Y | |
| CylindricalBar100PercentStacked | Y | |
| CylindricalColumn3D | Y | |
| Cone | Cone | Y |
| ConeStacked | Y | |
| Cone100PercentStacked | Y | |
| ConicalBar | Y | |
| ConicalBarStacked | Y | |
| ConicalBar100PercentStacked | Y | |
| ConicalColumn3D | Y | |
| Pyramid | Pyramid | Y |
| PyramidStacked | Y | |
| Pyramid100PercentStacked | Y | |
| PyramidBar | Y | |
| PyramidBarStacked | Y | |
| PyramidBar100PercentStacked | Y | |
| PyramidColumn3D | Y | |
| BoxWhisker | BoxWhisker | Y |
| Funnel | Funnel | Y |
| ParetoLine | ParetoLine | Y |
| Sunburst | Sunburst | Y |
| Treemap | Treemap | Y |
| Waterfall | Waterfall | Y |
| Histogram | Histogram | Y |
| Map | Map | N |
如果尝试将不受支持的图表类型渲染为图像或PDF，则可能会得到大小为0的图像或空白PDF。