menduner-uniapp/pagesA/student/certificateDetailCanvas.vue

<!-- 分享招聘会 -->
<template>
  <view style="position: relative;">
    <view v-if="shareUrl" class="d-flex align-center flex-column justify-center" style="height: 100vh;">
      <image v-if="!!shareUrl" :style="imgStyle" @click="handlePreviewSharePoster" :src="shareUrl" :show-menu-by-longpress="true"></image>
      <view class="color-999 ss-m-t-20 font-size-14 ss-m-b-50">点击图片预览，长按图片保存</view>
    </view>
		<canvas canvas-id="posterCanvas" class="shareCanvas" :style="`width: ${canvasWidth}px; height: ${canvasHeight}px;`"></canvas>
  </view>
</template>

<script setup>
import { ref, computed } from 'vue'
import { onLoad } from '@dcloudio/uni-app'
import { timesTampChange } from '@/utils/date'
import { formatName } from '@/utils/getText'

const canvasWidth = 500
const canvasHeight = 700

const shareUrl = ref('')
const windowWidth = ref(0)

const itemData = ref(null)
onLoad(async (options) => {
  if (options.itemData) {
    itemData.value = JSON.parse(options.itemData)
    createPoster()
  }
  const windowInfo = wx.getWindowInfo()
  windowWidth.value = windowInfo.windowWidth
})

const imgStyle = computed(() => {
  if (windowWidth.value <= 320) return `width: 259px; height: ${Math.round((canvasHeight*259)/canvasWidth)}px;`
  if (windowWidth.value > 320 && windowWidth.value <= 375) return `width: 313px; height: ${Math.round((canvasHeight*313)/canvasWidth)}px;`
  if (windowWidth.value > 375) return `width: 328px; height: ${Math.round((canvasHeight*328)/canvasWidth)}px;`
})

// 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)
      }
    })
  })
}

const createPoster = async () => {
  uni.showLoading({ title: '生成中...', mask: true })
  var ctx = uni.createCanvasContext('posterCanvas')
  //清空画布
  ctx.clearRect(0, 0, canvasWidth, canvasHeight)

  //背景图片
  const { path: bgUrl } = await getImageTempRatio('https://minio.citupro.com/dev/static/bgc.jpg')
  ctx.drawImage(bgUrl, 0, 0, canvasWidth, canvasHeight) // 路径、x、y、宽、高
  
  const info = { ...itemData.value }
  // 绘制文字内容
  ctx.setFontSize(16)
  if (info?.student?.schoolName) ctx.fillText(info.student.schoolName, 50, 130)
  if (info?.student?.majorName) ctx.fillText(info.student.majorName, 50, 160)
  if (info?.person?.name) ctx.fillText(info.person.name, 50, 190)
  if (info?.startTime) ctx.fillText(timesTampChange(info.startTime, 'Y-M-D'), 50, 250)
  if (info?.endTime) ctx.fillText(timesTampChange(info?.endTime, 'Y-M-D'), 50, 310)
  if (info?.enterprise?.anotherName || info?.enterprise?.name) ctx.fillText(formatName(info.enterprise?.anotherName || info.enterprise.name), 50, 400)
  if (info?.evaluate) ctx.fillText(info.evaluate, 20, 460)
  if (info?.createTime) ctx.fillText(timesTampChange(info?.createTime, 'Y-M-D'), 200, 520)

  ctx.font = 'bold';
  ctx.fillText('兹有', 20, 100)
  ctx.fillText('同学于', 20, 220)
  ctx.fillText('至', 20, 280)
  ctx.fillText('在', 20, 340)
  ctx.fillText('实习。', 20, 430)
  ctx.fillText('特此证明。', 20, 490)

  ctx.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)
      }
    })
  })
}
</script>

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