如何在HTML中允许跨域使用图像和画布？
- 王林转载
- 2023-08-30 16:25:06698浏览
为了允许跨域使用图像和画布，服务器必须在其HTTP响应中包含适当的CORS（跨域资源共享）头。这些头可以设置为允许特定的来源或方法，或者允许任何来源访问资源。
HTML Canvas
An HTML5 Canvas is a rectangular area on a web page that is controlled by JavaScript code. Anything can be drawn on the canvas, including images, shapes, text, and animations. The canvas is a great tool for creating games, graphics, and web applications.
方法
允许跨域使用图像和画布的方法是将以下内容添加到标头中−
Access-Control-Allow-Origin − *
的中文翻译为：访问控制允许来源 − *
这将允许所有的图像和画布元素在跨源时使用。
Example
的中文翻译为：示例
下面是一个完整的工作示例，演示如何允许跨域使用图像和画布。要运行它，只需在Web浏览器中打开HTML文件。
<!DOCTYPE html>
<html>
<head>
<script>
function allowCrossOrigin(img, url) {
if (url.indexOf('https://') !== 0 && url.indexOf('http://') !== 0) {
// only allow cross-origin requests for images that are hosted on a secure
// (HTTPS/HTTP) server
return;
}
// create a new Image object and set its src property to the url of the image
// that we want to load
var image = new Image();
image.src = url;
// when the image has loaded, set the src property of the img element to the
// url of the image
image.onload = function() {
img.src = url;
};
}
</script>
</head>
<body>
<!-- define an img element and set its src property to a local image -->
<img id='local-image' src='https://cdn.pixabay.com/photo/2012/08/27/14/19/mountains-55067__340.png' style="max-width:90%" style="max-width:90%" alt="如何在HTML中允许跨域使用图像和画布？" >
<!-- define another img element and try to set its src property to
an image that is hosted on a different domain -->
<img id='remote-image' style="max-width:90%" style="max-width:90%" alt="如何在HTML中允许跨域使用图像和画布？" >
<script>
// get a reference to the img element with id="remote-image"
var remoteImage = document.getElementById('remote-image');
// set the src property of the img element to the url of the image that we want
// to load
remoteImage.src = 'https://i.natgeofe.com/n/2a832501-483e-422f-985c-0e93757b7d84/6_square.jpg';
// call the allowCrossOrigin function, passing in the img element and the url
// of the image that we want to load
allowCrossOrigin(remoteImage, 'https://i.natgeofe.com/n/2a832501-483e-422f-985c-0e93757b7d84/6_square.jpg');
</script>
</body>
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