[uniapp] uniapp draws the QR code picture and text on the canvas and downloads it:

---

1. Use the uQRCode plugin: https://ext.dcloud.net.cn/plugin?id=1287

2. Use cases:

<template>
	<view class="container">
		<view class="qrcode">
			<uqrcode ref="uqrcode" canvas-id="qrcode" :value="qrcodeText" :options="options"></uqrcode>
		</view>

		<!-- 下载的二维码+文字图片，下载之前和下载完不可见（样式设置了z-index:-999;） -->
		<view v-if="showImg">
			<canvas class="canvas" canvas-id="myCanvasId"></canvas>
		</view>

		<view class="button-group">
			<button type="primary" size="small" @click="saveQrcodeBtn">下载二维码</button>
			<button type="primary" size="small" @click="shareQrcodeBtn">分享</button>
		</view>
	</view>
</template>


<script>
	export default {
    
    
		data() {
    
    
			return {
    
    
				options: {
    
     // 二维码log
					foregroundImageSrc: require("../../static/favicon.png"),
					foregroundImageWidth: 50,
					foregroundImageHeight: 50,
				},
				qrcodeText: 'https://yun.kldhq.com/carplanenter/index.html#/?jgid=1', // 要生成的二维码内容
				showImg: true,
			}
		},
		onLoad() {
    
    

		},
		methods: {
    
    
			//下载二维码按钮
			saveQrcodeBtn() {
    
    
				let that = this;
				that.$refs.uqrcode.toTempFilePath({
    
    
					success: res => {
    
    
						that.saveQrcode(res.tempFilePath)
					}
				})
			},
			saveQrcode(src) {
    
    
				let that = this;
				that.showImg = true
				uni.showLoading({
    
     title: '加载中~' });
				let ctx = uni.createCanvasContext("myCanvasId", this);
				// 画布填充背景色，默认白色
				ctx.setFillStyle("#fff");
				// 设置画布尺寸
				ctx.fillRect(0, 0, 400, 600);
				// 绘制图片
				ctx.drawImage(src, 20, 20, 360, 300);
				// 画笔颜色
				ctx.setFillStyle("#000000");
				// 字体大小
				ctx.setFontSize(14);
				ctx.setTextAlign("left");

				//绘制二维码上方文字
				// ctx.fillText("*" + that.personName.substring(1, that.personName.length), 150, 40);
				// ctx.fillText("电子健康卡静态码", 150, 70);

				//绘制二维码下方文字
				// ctx.fillText("*" + that.personName.substring(1, that.personName.length), 20, 370);
				ctx.fillText("电子健康卡静态码", 20, 350);
				// ctx.fillText(that.i18n.index.zandianID + ":" + that.stationId, 20, 370);
				// ctx.fillText(that.i18n.index.jigouID + ":" + that.deptId, 250, 370);

				// 把以上内容画到 canvas 中
				ctx.draw(true, (ret) => {
    
    
					uni.canvasToTempFilePath({
    
     // 保存canvas为图片
						canvasId: "myCanvasId",
						quality: 1,
						complete: function(response) {
    
    
							// #ifndef H5
							uni.saveImageToPhotosAlbum({
    
     //图片保存至相册
								filePath: response.tempFilePath,
								success: (res) => {
    
    
									uni.showToast({
    
     icon: "success", title: "保存成功" + res });
								},
								fail: (error) => {
    
    
									uni.showToast({
    
     icon: "success", title: "保存失败" + error });
								},
								complete: () => {
    
    
									that.showImg = false
									uni.hideLoading();
								}
							});
							// #endif
							// #ifdef H5
							/* 可以在电脑浏览器下载，移动端iOS不行，安卓微信浏览器不行，安卓外部浏览器可以 */
							const aEle = document.createElement('a');
							aEle.download = '二维码'; // 设置下载的文件名，默认是'二维码'
							aEle.href = response.tempFilePath;
							document.body.appendChild(aEle);
							aEle.click();
							aEle.remove(); // 下载之后把创建的元素删除
							that.showImg = false
							uni.hideLoading();
							// #endif
						},
					});
				});
			},
			//分享
			shareQrcodeBtn() {
    
    

			},
		}
	}
</script>

<style lang="scss" scoped>
	.container {
    
    
		width: 100%;
		height: 100%;
		position:reactive;

		.qrcode {
    
    
			display: flex;
			justify-content: center;
		}

		.canvas {
    
    
			width: 400px;
			height: 600px;
			position:absolute;
			z-index:-999;
		}

		.button-group {
    
    
			position: fixed;
			bottom: 0;
			width: 100%;
			display: flex;
			align-items: center;
			justify-content: space-between;

			button {
    
    
				flex: 1;
				border-radius: 0 !important;
			}
		}
	}
</style>

3. Effect: