menduner-uniapp/pagesB/sharePoster/index.vue

<template>
  <view style="position: relative;">
    <view v-if="shareUrl" class="d-flex align-center flex-column">
      <image v-if="!!shareUrl" class="imgBox" @click="handlePreviewSharePoster" :src="shareUrl" :show-menu-by-longpress="true"></image>
      <view class="color-999 ss-m-t-20 font-size-14">点击图片预览，长按图片保存</view>
    </view>
		<canvas canvas-id="posterCanvas" class="shareCanvas" style="width: 330px; height: 600px;"></canvas>
  </view>
</template>

<script setup>
import { ref, computed } from 'vue'
import { userStore } from '@/store/user'

const useUserStore = userStore()
const baseInfo = computed(() => useUserStore?.baseInfo)
const shareUrl = ref('')

// 图片预览
const handlePreviewSharePoster = () => {
	uni.previewImage({
		current: 0,
		longPressActions: {
			itemList: ['发送给朋友', '保存图片', '收藏']
		},
		urls: [shareUrl.value]
	})
}

const getImageTempRatio = (url) => {
  return new Promise((req, rej)=>{
    wx.getImageInfo({
      src:url,
      success:(res) =>{
        req(res)
      }
    })
  })
}

// 个人头像
const drawAvatar = (ctx, imagePath, x, y, radius) => {
  ctx.save() // 保存当前绘图上下文
  // 绘制圆形裁剪路径
  ctx.beginPath();
  ctx.arc(x + radius, y + radius, radius, 0, 2 * Math.PI)
  ctx.clip();
  // 绘制图片
  ctx.drawImage(imagePath, x, y, 2 * radius, 2 * radius) // 注意这里的宽高是直径的2倍
  ctx.restore() // 恢复之前保存的绘图上下文
}

const createPoster = async () => {
  uni.showLoading({ title: '生成中...', mask: true })
  var context = uni.createCanvasContext('posterCanvas')

  //清空画布
  context.clearRect(0, 0, 330, 600)

  //背景图片
  const { path: bgUrl } = await getImageTempRatio('https://minio.menduner.com/dev/a3cfa7975c5905441175abaa738cfca0bd794dbb6249318328c8cfff69ca91fe.jpg')
  context.drawImage(bgUrl, 0, 0, 330, 600) // 路径、x、y、宽、高
  
  // 头像
  const { path } = await getImageTempRatio(baseInfo.value.avatar)
  drawAvatar(context, path, 121.5, 74, 43.5) // canvas、图片路径、x、y、半径

  //分享二维码
  const { path: qrCode } = await getImageTempRatio('https://minio.citupro.com/dev/menduner/miniProgram.jpg')
  context.drawImage(qrCode, 108, 310, 110, 110)

  context.draw(false, () =>{
    wx.canvasToTempFilePath({ 
      canvasId: 'posterCanvas',
      success:(res)=>{
        shareUrl.value = res.tempFilePath
        console.log('canvas-success', shareUrl.value)
		    uni.hideLoading({})
      },
      fail:(err)=>{
        uni.hideLoading({})
        console.log('canvas-fail', err)
      }
    })
  })
}
createPoster()
</script>

<style scoped lang="scss">
.shareCanvas {
	position: fixed;
	top: -99999upx;
	left: -99999upx;
	z-index: -99999;
}
.imgBox {
  width: 330px;
  height: 600px;
}
</style>