Canvas 转为图片
我们可以使用 Canvas2image 库将 canvas 转换为图片。
本地下载：http://static.runoob.com/assets/canvas2image/canvas2image.js。
Github 地址：https://github.com/hongru/canvas2image
使用方式如下：
Canvas2Image.saveAsImage(canvasObj, width, height, type) Canvas2Image.saveAsPNG(canvasObj, width, height) Canvas2Image.saveAsJPEG(canvasObj, width, height) Canvas2Image.saveAsGIF(canvasObj, width, height) Canvas2Image.saveAsBMP(canvasObj, width, height) Canvas2Image.convertToImage(canvasObj, width, height, type) Canvas2Image.convertToPNG(canvasObj, width, height) Canvas2Image.convertToJPEG(canvasObj, width, height) Canvas2Image.convertToGIF(canvasObj, width, height) Canvas2Image.convertToBMP(canvasObj, width, height)
测试实例：
var canvas, ctx, bMouseIsDown = false, iLastX, iLastY,
$save, $imgs,
$convert, $imgW, $imgH,
$sel;
function init () {
canvas = document.getElementById('cvs');
ctx = canvas.getContext('2d');
$save = document.getElementById('save');
$convert = document.getElementById('convert');
$sel = document.getElementById('sel');
$imgs = document.getElementById('imgs');
$imgW = document.getElementById('imgW');
$imgH = document.getElementById('imgH');
bind();
draw();
}
function bind () {
canvas.onmousedown = function(e) {
bMouseIsDown = true;
iLastX = e.clientX - canvas.offsetLeft + (window.pageXOffset||document.body.scrollLeft||document.documentElement.scrollLeft);
iLastY = e.clientY - canvas.offsetTop + (window.pageYOffset||document.body.scrollTop||document.documentElement.scrollTop);
}
canvas.onmouseup = function() {
bMouseIsDown = false;
iLastX = -1;
iLastY = -1;
}
canvas.onmousemove = function(e) {
if (bMouseIsDown) {
var iX = e.clientX - canvas.offsetLeft + (window.pageXOffset||document.body.scrollLeft||document.documentElement.scrollLeft);
var iY = e.clientY - canvas.offsetTop + (window.pageYOffset||document.body.scrollTop||document.documentElement.scrollTop);
ctx.moveTo(iLastX, iLastY);
ctx.lineTo(iX, iY);
ctx.stroke();
iLastX = iX;
iLastY = iY;
}
};
$save.onclick = function (e) {
var type = $sel.value,
w = $imgW.value,
h = $imgH.value;
Canvas2Image.saveAsImage(canvas, w, h, type);
}
$convert.onclick = function (e) {
var type = $sel.value,
w = $imgW.value,
h = $imgH.value;
$imgs.appendChild(Canvas2Image.convertToImage(canvas, w, h, type))
}
}
function draw () {
ctx.fillStyle = '#ffffff';
ctx.fillRect(0, 0, 600, 400);
ctx.fillStyle = 'red';
ctx.fillRect(100, 100, 50, 50);
}
