如果您想要紧凑数据而不是原始ImageData对象,请考虑使用canvas.toBlob()
而不是。context.getImageData()
例子:
const imageIn = document.querySelector('#image-in');
const imageOut = document.querySelector('#image-out');
const canvas = document.querySelector('#canvas');
const imageDataByteLen = document.querySelector('#imagedata-byte-length');
const bufferByteLen = document.querySelector('#arraybuffer-byte-length');
const mimeType = 'image/png';
imageIn.addEventListener('load', () => {
// Draw image to canvas.
canvas.width = imageIn.width;
canvas.height = imageIn.height;
const ctx = canvas.getContext('2d');
ctx.drawImage(imageIn, 0, 0);
// Convert canvas to ImageData.
const imageData = ctx.getImageData(0, 0, imageIn.width, imageIn.height);
imageDataByteLen.textContent = imageData.data.byteLength + ' bytes.';
// Convert canvas to Blob, then Blob to ArrayBuffer.
canvas.toBlob((blob) => {
const reader = new FileReader();
reader.addEventListener('loadend', () => {
const arrayBuffer = reader.result;
bufferByteLen.textContent = arrayBuffer.byteLength + ' bytes.';
// Dispay Blob content in an Image.
const blob = new Blob([arrayBuffer], {type: mimeType});
imageOut.src = URL.createObjectURL(blob);
});
reader.readAsArrayBuffer(blob);
}, mimeType);
});
<h1>Canvas ↔ ArrayBuffer</h1>
<h2>1. Source <code><img></code></h2>
<img id="image-in" src="https://ucarecdn.com/a0338bfa-9f88-4ce7-b53f-e6b61000df89/" crossorigin="">
<h2>2. Canvas</h2>
<canvas id="canvas"></canvas>
<h2>3. ImageData</h2>
<p id="imagedata-byte-length"></p>
<h2>4. ArrayBuffer</h2>
<p id="arraybuffer-byte-length"></p>
<h2>5. Final <code><img></code></h2>
<img id="image-out">
JSFiddle:https ://jsfiddle.net/donmccurdy/jugzk15b/
另请注意,图像必须托管在提供 CORS 标头的服务上,否则您会看到诸如“画布已被跨域数据污染”之类的错误。