<template>
	<view>
	</view>
</template>
 
<script>
let promiseIndex = 0
let promiseArray = []
let imageArray = []
let imageIndex = 0
export default {
  name: 'kt-view2canvas',
  data() {
    return {
 
    }
  },
  props: {
    canvasWidth: {
      type: Number,
      default: 1080
    },
    canvasHeight: {
      type: Number,
      default: 2500
    }
  },
  methods: {
 
    //rpx转换为px的工具函数
    rpxtopx(rpx) {
      let deviceWidth = wx.getSystemInfoSync().windowWidth //获取设备屏幕宽度
      let px = (deviceWidth / 750) * Number(rpx)
      return Math.floor(px)
    },
 
    drawCanvas(arrayInfo) {
      promiseIndex = 0
      promiseArray = []
      imageArray = []
      imageIndex = 0
      uni.showLoading({
        title: '保存中...'
      })
      // 0.创建canvas及ctx,并获取屏幕的dpr
      const canvas = wx.createOffscreenCanvas({
        type: '2d',
        width: this.canvasWidth,
        height: this.canvasHeight
      })
      const ctx = canvas.getContext('2d')
 
      const dpr = uni.getWindowInfo().pixelRatio
 
      // 1.根据数组数量创建promise数组
      for (let i = 0; i < arrayInfo.length; i++) {
        promiseArray.push(promiseIndex)
        promiseIndex++
      }
 
      // 2.根据数组给promise数组赋值
      let that = this
      for (let i = 0; i < arrayInfo.length; i++) {
        promiseArray[i] = new Promise(function(resolve, reject) {
          if (arrayInfo[i].type == 'text') {
            resolve()
          } else if (arrayInfo[i].type == 'view') {
            resolve()
          } else if (arrayInfo[i].type == 'image2') {
            let img = canvas.createImage()
            img.src = arrayInfo[i].src
            img.onload = function() {
              imageArray.push(img)
              resolve()
            }
            img.src = arrayInfo[i].src + `?${new Date().getTime()}`
          }else if (arrayInfo[i].type == 'image1') {
            let img = canvas.createImage()
            img.src = arrayInfo[i].src
            img.onload = function() {
              imageArray.push(img)
              resolve()
            }
            img.src = arrayInfo[i].src + `?${new Date().getTime()}`
          }
        })
      }
 
      // 3.异步全部加载完成后，绘制图片
      let p = Promise.all(promiseArray)
      p.then(function() {
        //根据数组顺序绘制图片
        for (let i = 0; i < arrayInfo.length; i++) {
          if (arrayInfo[i].type == 'text') {
            ctx.fillStyle = arrayInfo[i].color
            ctx.font = that.rpxtopx(arrayInfo[i].size) * dpr + 'px sans-serif'
            ctx.textBaseline = 'top'
            ctx.fillText(arrayInfo[i].word, arrayInfo[i].posX * dpr, (arrayInfo[i].posY + that
              .rpxtopx(20)) * dpr)
          } else if (arrayInfo[i].type == 'view') {
            ctx.fillStyle = arrayInfo[i].bgColor
            ctx.fillRect(arrayInfo[i].posX * dpr, arrayInfo[i].posY * dpr, arrayInfo[i].width *
								dpr, arrayInfo[i].height * dpr)
          } else if (arrayInfo[i].type == 'image2') {
            ctx.drawImage(imageArray[imageIndex], arrayInfo[i].posX * dpr, arrayInfo[i].posY * dpr,
              arrayInfo[i].width * dpr, arrayInfo[i].height * dpr)
            imageIndex++
          } else if (arrayInfo[i].type == 'image1') {
            console.log(arrayInfo[i].swidth*dpr+','+arrayInfo[i].sheight*dpr+','+arrayInfo[i].width*dpr+','+arrayInfo[i].height*dpr+','+arrayInfo[i].posX+','+arrayInfo[i].posY)
            ctx.drawImage(imageArray[imageIndex],
              0,0,arrayInfo[i].width * dpr,arrayInfo[i].height * dpr, 
              arrayInfo[i].posX * dpr, arrayInfo[i].posY * dpr,arrayInfo[i].swidth * dpr, arrayInfo[i].sheight * dpr)
            imageIndex++
          }
        }
        const fileData = canvas.toDataURL()
        const fs = uni.getFileSystemManager()
        const path = `${wx.env.USER_DATA_PATH}/` + new Date().getTime() + 'hello.png'
        //数据归零
        promiseIndex = 0
        promiseArray = []
        imageArray = []
        imageIndex = 0
        fs.writeFile({
          filePath: path,
          data: fileData.replace(/^data:image\/\w+;base64,/, ''),
          encoding: 'base64',
          success(res) {
            uni.showShareImageMenu({
              path: path,
              success: res => {
                console.log(res)
              }
            })
          },
          fail(res) {
            console.error(res)
          },
          complete() {
            uni.hideLoading()
          }
        })
      })
    }
  }
}
</script>
 
<style>
 
</style>