使用 JavaScript 通过 C++ 使用 ImageOrPrint 选项将工作表转换为图片
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本文旨在详细介绍如何将工作表转换为图像文件，并应用不同的图像和打印选项，如分辨率、TIFF压缩、图像格式和页面质量。
将工作表保存为图像-不同方法
有时候，您可能需要将工作表呈现为图形表示。您可能需要将工作表图像嵌入到应用程序或网页中。您可能需要将图像插入到Word文档、PDF文件、PowerPoint演示文稿中，或者在某些其他情景中使用。简单来说，您希望将工作表呈现为图像，以便在别处使用。Aspose.Cells支持将Excel文件中的工作表转换为图像。此外，Aspose.Cells支持设置不同选项，如图像格式、分辨率（垂直和水平）、图像质量以及其他图像和打印选项。
你可以尝试使用Office自动化，但Office自动化有其自身的缺点。存在若干原因和问题，比如安全、稳定性、可扩展性和速度、价格以及功能等。简而言之，原因很多，其中最主要的是微软自己强烈建议不要在软件方案中使用Office自动化。
本文介绍了如何在Visual Studio .NET中创建控制台应用程序，使用Aspose.Cells API以及几行简单的代码执行工作表转换为图像的转换，并使用不同的图像和打印选项。
SheetRender类代表一张工作表，用于渲染工作表的图片，具有一个重载的toImage(number)方法，可以直接将工作表转换为指定属性或选项的图片文件。它可以返回一个对象，你可以将图片保存到磁盘/流中。支持多种图片格式，例如BMP、PNG、GIF、JPEG、TIFF、EMF等。
使用Aspose.Cells将工作表转换为图像，使用图像或打印选项。
在Microsoft Excel中创建一个模板工作簿
我在MS Excel中创建了一个新的工作簿，并在第一个工作表中添加了一些数据。现在，我将把模板文件的工作表“Sheet1”转换为图像文件“SheetImage.tiff”，并将应用不同的图像选项，如水平和垂直分辨率、TiffCompression等。
下载并安装Aspose.Cells
首先，你需要下载 通过 C++ 使用的 Aspose.Cells for JavaScript。安装到你的开发电脑上。所有 Aspose 组件，安装后都以评估模式运行。评估模式没有时间限制，只会在生成的文档中添加水印。
创建一个项目
启动你的首选开发环境（例如，Visual Studio）。创建一个新的控制台应用程序。
添加引用
这个项目将使用 Aspose.Cells。因此，你必须在你的项目中添加对 Aspose.Cells 组件的引用。例如，添加对 ….\Program Files\Aspose\Aspose.Cells for JavaScript 通过 C++\Bin\Aspose.Cells.node 的引用。
将工作表转换为图像文件
<!DOCTYPE html>
<html>
<head>
<title>Aspose.Cells Example</title>
</head>
<body>
<h1>Worksheet to Image Example</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, ImageOrPrintOptions, SheetRender, ImageType, TiffCompression, PrintingPageType, Utils } = 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 () => {
const fileInput = document.getElementById('fileInput');
const resultDiv = document.getElementById('result');
if (!fileInput.files.length) {
resultDiv.innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
return;
}
const file = fileInput.files[0];
const arrayBuffer = await file.arrayBuffer();
// Instantiating a Workbook object from the uploaded file
const workbook = new Workbook(new Uint8Array(arrayBuffer));
// Get the first worksheet
const sheet = workbook.worksheets.get(0);
// Apply different Image and Print options
const options = new ImageOrPrintOptions();
// Set Horizontal Resolution
options.horizontalResolution = 300;
// Set Vertical Resolution
options.verticalResolution = 300;
// Set TiffCompression
options.tiffCompression = TiffCompression.CompressionLZW;
// Set Image Format
options.imageType = ImageType.Tiff;
// Set printing page type
options.printingPage = PrintingPageType.Default;
// Render the sheet with respect to specified image/print options
const sr = new SheetRender(sheet, options);
// Render/save the image for the sheet (pageIndex is zero-based)
const pageIndex = 3;
const imageData = sr.toImage(pageIndex);
const blob = new Blob([imageData], { type: 'image/tiff' });
const downloadLink = document.getElementById('downloadLink');
downloadLink.href = URL.createObjectURL(blob);
downloadLink.download = `outputWorksheetToAnImage_${pageIndex + 1}.tiff`;
downloadLink.style.display = 'block';
downloadLink.textContent = 'Download TIFF Image';
resultDiv.innerHTML = '<p style="color: green;">Image rendered successfully! Click the download link to get the image.</p>';
});
</script>
</html>
转换选项
可以保存特定页面到图像。下面的代码将工作簿中的第一个和第二个工作表转换为JPG图像。
<!DOCTYPE html>
<html>
<head>
<title>Aspose.Cells Example - Specific Pages To Images</title>
</head>
<body>
<h1>Specific Pages To Images Example</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, ImageOrPrintOptions, SheetRender, ImageType, Utils } = 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 () => {
const fileInput = document.getElementById('fileInput');
if (!fileInput.files.length) {
document.getElementById('result').innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
return;
}
const file = fileInput.files[0];
const arrayBuffer = await file.arrayBuffer();
// Instantiating a Workbook object by opening the Excel file through the file stream
const workbook = new Workbook(new Uint8Array(arrayBuffer));
// Get the first worksheet.
const sheet = workbook.worksheets.get(0);
// Define ImageOrPrintOptions
const imgOptions = new ImageOrPrintOptions();
// Specify the image format
imgOptions.imageType = ImageType.Jpeg;
// Render the sheet with respect to specified image/print options
const sr = new SheetRender(sheet, imgOptions);
// Specify page index to be rendered
const idxPage = 3;
// Render the third image for the sheet
const bitmap = sr.toImage(idxPage);
// Save the image file as a downloadable blob
const blob = new Blob([bitmap], { type: 'image/jpeg' });
const downloadLink = document.getElementById('downloadLink');
downloadLink.href = URL.createObjectURL(blob);
downloadLink.download = `outputSpecificPagesToImage_${idxPage + 1}.jpg`;
downloadLink.style.display = 'block';
downloadLink.textContent = 'Download Image File';
document.getElementById('result').innerHTML = '<p style="color: green;">Image rendered successfully! Click the download link to get the image file.</p>';
});
</script>
</html>
使用 WorkbookRender 进行图片转换
TIFF图像可以包含多个帧。你可以将整个工作簿保存为具有多个帧或页面的单一TIFF图像：
<!DOCTYPE html>
<html>
<head>
<title>Use WorkbookRender for Image Conversion Example</title>
</head>
<body>
<h1>Use WorkbookRender for Image Conversion Example</h1>
<input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
<button id="runExample">Run Example</button>
<a id="downloadLink" style="display: none;"></a>
<div id="result"></div>
</body>
<script src="aspose.cells.js.min.js"></script>
<script type="text/javascript">
const { Workbook, ImageOrPrintOptions, ImageType, WorkbookRender, Utils } = 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 () => {
const fileInput = document.getElementById('fileInput');
if (!fileInput.files.length) {
document.getElementById('result').innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
return;
}
const file = fileInput.files[0];
const arrayBuffer = await file.arrayBuffer();
// Instantiating a Workbook object from uploaded file
const workbook = new Workbook(new Uint8Array(arrayBuffer));
// Prepare image/print options
const opts = new ImageOrPrintOptions();
opts.imageType = AsposeCells.ImageType.Tiff;
// Create WorkbookRender and convert to image
const workbookRender = new WorkbookRender(workbook, opts);
// toImage may return a single Uint8Array or an array of Uint8Array pages
const imageResult = await workbookRender.toImage();
let imageData = imageResult;
if (Array.isArray(imageResult) && imageResult.length > 0) {
imageData = imageResult[0];
}
// Ensure imageData is a Uint8Array or ArrayBuffer
let blob;
if (imageData instanceof Uint8Array || imageData instanceof ArrayBuffer) {
blob = new Blob([imageData], { type: 'image/tiff' });
} else {
// Fallback: try to stringify/convert if possible
blob = new Blob([imageData], { type: 'application/octet-stream' });
}
const downloadLink = document.getElementById('downloadLink');
downloadLink.href = URL.createObjectURL(blob);
downloadLink.download = 'outputUseWorkbookRenderForImageConversion.tiff';
downloadLink.style.display = 'block';
downloadLink.textContent = 'Download Converted TIFF Image';
document.getElementById('result').innerHTML = '<p style="color: green;">Image conversion completed! Click the download link to get the TIFF file.</p>';
});
</script>
</html>