摘抄代码：
<html>
<meta http-equiv="X-UA-Compatible" content="chrome=1">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<head>
<script>
window.onload = function () {
draw();
var saveButton = document.getElementById("saveImageBtn");
bindButtonEvent(saveButton, "click", saveImageInfo);
var dlButton = document.getElementById("downloadImageBtn");
bindButtonEvent(dlButton, "click", saveAsLocalImage);
};
function draw() {
var canvas = document.getElementById("thecanvas");
var ctx = canvas.getContext("2d");
ctx.fillStyle = "rgba(125, 46, 138, 0.5)";
ctx.fillRect(25, 25, 100, 100);
ctx.fillStyle = "rgba( 0, 146, 38, 0.5)";
ctx.fillRect(58, 74, 125, 100);
ctx.fillStyle = "rgba( 0, 0, 0, 1)"; // black color
ctx.fillText("Gloomyfish - Demo", 50, 50);
}
function bindButtonEvent(element, type, handler) {
if (element.addEventListener) {
element.addEventListener(type, handler, false);
} else {
element.attachEvent('on' + type, handler);
}
}
function saveImageInfo() {
var mycanvas = document.getElementById("thecanvas");
var image = mycanvas.toDataURL("image/png");
var w = window.open('about:blank', 'image from canvas');
w.document.write("<img src='" + image + "' alt='from canvas'/>");
}
function saveAsLocalImage() {
var myCanvas = document.getElementById("thecanvas");
// here is the most important part because if you dont replace you will get a DOM 18 exception.
// var image = myCanvas.toDataURL("image/png").replace("image/png", "image/octet-stream;Content-Disposition: attachment;filename=foobar.png");
var image = myCanvas.toDataURL("image/png").replace("image/png", "image/octet-stream");
window.location.href = image; // it will save locally
}
</script>
</head>
<body bgcolor="#E6E6FA">
<div>
<canvas width=200 height=200 id="thecanvas"></canvas>
<button id="saveImageBtn">Save Image</button>
<button id="downloadImageBtn">Download Image</button>
</div>
</body>
</html>
备注： 保存图片 -- PC端和移动端正常浏览器可用（微信不可用）
下载图片 -- 仅PC可用