Converting HTML to images allows you to transform HTML content into static images that can be easily shared on social media, embedded in emails, or used as thumbnails in search engine results. This conversion process ensures that your content is displayed consistently across different devices and browsers, improving the overall user experience. In this article, you will learn how to convert HTML to images in React using Spire.Doc for JavaScript.
Install Spire.Doc for JavaScript
To get started with converting Word documents to PDF in a React application, you can either download Spire.Doc for JavaScript from our website or install it via npm with the following command:
npm i spire.officeThe downloaded product package integrates Spire.Doc for JavaScript, Spire.XLS for JavaScript, Spire.PDF for JavaScript, and Spire.Presentation for JavaScript. To use the features of Spire.Doc for JavaScript, you need to copy the corresponding files (spire.doc.js, Spire.Doc.Wasm.zip, spire.common.js, Spire.Common.Wasm.zip, and the _framework folder) to the public folder of your project. To ensure proper text rendering, you can add relevant font files with a custom path. In the following example, the font is added to the path: public\static\font.
For more details, refer to the documentation: How to Integrate Spire.Doc for JavaScript in a React Project
Convert an HTML File to an Image in JavaScript
Spire.Doc for JavaScript allows you to load an HTML file and convert a specific page to an image stream using the Document.SaveImageToStreams() method. The image streams can then be further saved to a desired image format such as jpg, png, bmp, gif. The following are the main steps.
- Load the font file to ensure correct text rendering.
- Create a new document using the new wasmModule.Document() method.
- Load the HTML file using the Document.LoadFromFile() method.
- Convert a specific page to an image stream using the Document.SaveImageToStreams() method.
- Save the image stream to a specified image format.
- JavaScript
import React, { useState, useEffect } from 'react';
function App() {
const [wasmModule, setWasmModule] = useState(null);
// Load Spire.Doc
useEffect(() => {
(async () => {
try {
const publicUrl = process.env.PUBLIC_URL || '';
const spireModule = await import(/* webpackIgnore: true */ `${publicUrl}/spire.doc.js`);
const rawModule = spireModule.default || spireModule;
window.wasmModule = typeof rawModule === 'function'
? await rawModule({ locateFile: p => p.endsWith('.wasm') ? `${publicUrl}/${p}` : p })
: rawModule;
setWasmModule(window.wasmModule);
} catch (error) {
console.error('Failed to load spire.doc.js WASM module:', error);
}
})();
}, []);
// Function to convert an HTML file to an image
const HtmlToImage = async () => {
const wasmModule = window.wasmModule.spiredoc;
if (wasmModule) {
// Load the font files into the virtual file system (VFS)
await window.spire.FetchFileToVFS('CALIBRI.ttf', '/Library/Fonts/', `${process.env.PUBLIC_URL}/static/font/`);
// Specify the input file name
const inputFileName = 'sample.html';
// Fetch the input file and add it to the VFS
await window.spire.FetchFileToVFS(inputFileName, '', `${process.env.PUBLIC_URL}/static/data/`);
// Create an instance of the Document class
const doc = new wasmModule.Document();
// Load the HTML file
doc.LoadFromFile({ fileName: inputFileName, fileFormat: wasmModule.FileFormat.Html, validationType: wasmModule.XHTMLValidationType.None });
// Save the first page as an image stream
let image = doc.SaveImageToStreams({ pageIndex: 0, type: wasmModule.ImageType.Bitmap });
// Save the image stream as a PNG file
const outputFileName = 'HtmlToImage.png';
image.Save(outputFileName);
// Read the generated image from VFS
const modifiedFileArray = window.dotnetRuntime.Module.FS.readFile(outputFileName);
// Create a Blog object from the image file
const modifiedFile = new Blob([modifiedFileArray], { type: 'image/png' });
// Create a URL for the Blob
const url = URL.createObjectURL(modifiedFile);
// Create an anchor element to trigger the download
const a = document.createElement("a");
a.href = url;
a.download = outputFileName;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
URL.revokeObjectURL(url);
// Clean up resources
doc.Dispose();
}
};
return (
<div style={{ textAlign: 'center', height: '300px' }}>
<h1>Convert an HTML File to an Image Using JavaScript in React</h1>
<button onClick={HtmlToImage} disabled={!wasmModule}>
Convert
</button>
</div>
);
}
export default App;Run the code to launch the React app at localhost:3000. Once it's running, click on the "Convert" button to download the image converted from an HTML file:
Below is the converted image file:
Convert an HTML String to an Image in JavaScript
To convert HTML strings to images, you'll need to first add HTML strings to the paragraphs of a Word page through the Paragraph.AppendHTML() method, and then convert the page to an image. The following are the main steps.
- Load the font file to ensure correct text rendering.
- Specify the HTML string.
- Create a new document using the new wasmModule.Document() method.
- Add a new section using the Document.AddSection() method.
- Add a paragraph to the section using the Section.AddParagraph() method.
- Append the HTML string to the paragraph using the Paragraph.AppendHTML() method.
- Convert a specific page to an image stream using the Document.SaveImageToStreams() method.
- Save the image stream to a specified image format.
- JavaScript
import React, { useState, useEffect } from 'react';
function App() {
const [wasmModule, setWasmModule] = useState(null);
// Load Spire.Doc
useEffect(() => {
(async () => {
try {
const publicUrl = process.env.PUBLIC_URL || '';
const spireModule = await import(/* webpackIgnore: true */ `${publicUrl}/spire.doc.js`);
const rawModule = spireModule.default || spireModule;
window.wasmModule = typeof rawModule === 'function'
? await rawModule({ locateFile: p => p.endsWith('.wasm') ? `${publicUrl}/${p}` : p })
: rawModule;
setWasmModule(window.wasmModule);
} catch (error) {
console.error('Failed to load spire.doc.js WASM module:', error);
}
})();
}, []);
// Function to convert an HTML string to an image
const HtmlStringToImage = async () => {
const wasmModule = window.wasmModule.spiredoc;
if (wasmModule) {
// Load the font files into the virtual file system (VFS)
await window.spire.FetchFileToVFS('CALIBRI.ttf', '/Library/Fonts/', `${process.env.PUBLIC_URL}/static/font/`);
// Create an instance of the Document class
const doc = new wasmModule.Document();
// Specify the output file path
const outputFileName = 'HtmlStringToImage.png';
// Specify the HTML string
let HTML = "<html><head><title>HTML to Word Example</title><style>, body {font-family: 'Calibri';}, h1 {color: #FF5733; font-size: 24px; margin-bottom: 20px;}, p {color: #333333; font-size: 16px; margin-bottom: 10px;}";
HTML += "ul {list-style-type: disc; margin-left: 20px; margin-bottom: 15px;}, li {font-size: 14px; margin-bottom: 5px;}, table {border-collapse: collapse; width: 100%; margin-bottom: 20px;}";
HTML += "th, td {border: 1px solid #CCCCCC; padding: 8px; text-align: left;}, th {background-color: #F2F2F2; font-weight: bold;}, td {color: #0000FF;}</style></head>";
HTML += "<body><h1>This is a Heading</h1><p>This is a paragraph demonstrating the conversion of HTML to Word document.</p><p>Here's an example of an unordered list:</p><ul><li>Item 1</li><li>Item 2</li><li>Item 3</li></ul>";
HTML += "<p>Here's a table:</p><table><tr><th>Product</th><th>Quantity</th><th>Price</th></tr><tr><td>Jacket</td><td>30</td><td>$150</td></tr><tr><td>Sweater</td><td>25</td><td>$99</td></tr></table></body></html>";
// Add a section to the document
let section = doc.AddSection();
// Add a paragraph to the section
let paragraph = section.AddParagraph();
// Append the HTML string to the paragraph
paragraph.AppendHTML(HTML.toString('utf8', 0, HTML.length));
// Save the first page as an image stream
let image = doc.SaveImageToStreams({ pageIndex: 0, type: wasmModule.ImageType.Bitmap });
// Save the image stream as a PNG file
image.Save(outputFileName);
// Read the generated image from VFS
const modifiedFileArray = window.dotnetRuntime.Module.FS.readFile(outputFileName);
// Create a Blog object from the image file
const modifiedFile = new Blob([modifiedFileArray], { type: 'image/png' });
// Create a URL for the Blob
const url = URL.createObjectURL(modifiedFile);
// Create an anchor element to trigger the download
const a = document.createElement("a");
a.href = url;
a.download = outputFileName;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
URL.revokeObjectURL(url);
// Clean up resources
doc.Dispose();
}
};
return (
<div style={{ textAlign: 'center', height: '300px' }}>
<h1>Convert an HTML String to an Image Using JavaScript in React</h1>
<button onClick={HtmlStringToImage} disabled={!wasmModule}>
Convert
</button>
</div>
);
}
export default App;
Get a Free License
To fully experience the capabilities of Spire.Doc for JavaScript without any evaluation limitations, you can request a free 30-day trial license.
