html2canvas保存图片压缩图片

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async $html2canvas(el, options = {}) {
	const {
		type
	} = options;
	const canvas = await html2canvas(el, {
		useCORS: true
	});
	try {
		if(type && type === "dataURL") {
			return canvas.toDataURL("image/png");
		} else {
			console.warn("warn");
			return canvas;
		}
	} catch(err) {
		console.log("err");
		console.log(err);
	}
	return canvas;
},

async print() {
	const el = document.getElementById("invite");
	var width = el.offsetWidth * 0.8;
	var height = el.offsetHeight * 0.8;
	const options = {
		type: "dataURL",
		useCORS: true,
		logging: true,
		taintTest: false,
		allowTaint: false,
		width: el.offsetWidth * 0.8,
		height: el.offsetHeight * 0.8
	};
	var output = await this.$html2canvas(el, options);
	this.ImgToBase64(output, width, height);
},

ImgToBase64(base64, width, height) {   //压缩图片
	var that = this;
	var img = new Image();
	img.src = base64;
	img.onload = function() {
		var rate = 0.8;   //压缩图片
		img.width = width * rate;
		img.height = height * rate;
		//生成canvas
		var canvas = document.createElement("canvas");
		var ctx = canvas.getContext("2d");
		canvas.width = img.width;
		canvas.height = img.height;
		ctx.drawImage(img, 0, 0, img.width, img.height);
		var base64 = canvas.toDataURL('image/jpeg', 0.95);
		that.output = base64;
		that.$nextTick(() => {
			setTimeout(() => {
				that.$emit("savaImg", that.output);
			}, 0)
		})
		console.log('that.output')
		console.log(that.output)
	}
}