let shareInfo = {
 headerImg: 'tempfilepath',
 bgImg: '本地路徑的圖片',
 qrcode: 'tempfilepath'
}
wx.navigateTo({
 url: '/pages/createPoster/main?shareInfo=' + JSON.stringify(shareInfo)
})

mounted () {
 const options = this.$root.$mp.query
 this.shareInfo= JSON.parse(options.shareInfo)
}
// 如果是通過微信開發(fā)工具直接開發(fā)則在onLoad函數(shù)中獲取options
onLoad (options) {
 const shareInfo = JSON.parse(options.shareInfo)
}

wx.getSystemInfo({
 success (res) {
 // 通過像素比計(jì)算出畫布的實(shí)際大?。?30x490）是展示的出來的大小
 this.width = 330 * res.pixelRatio
 this.height = 490 * res.pixelRatio
 }
})
// 結(jié)構(gòu)樣式
<canvas class="canvas-poster" id="canvasPoster" :style="{width:width+'px;',height: height+'px'}" canvas-id="canvasPoster"></canvas>
<img :src="poster" class="poster-img" @click="previewImg" alt="">
<div type="button" @click="savePoster" class="save-btn">
 <img src="../img/0.3_btn_yellow_bg.png" alt="">
 <div class="btn-text">保存圖片</div>
</div>
.canvas-poster{
 background-color: #fafafa;
 zoom: 50%; // 將畫布縮小到50%（最好通過像素比進(jìn)行縮小，像素比是2的話就是50%，如果不全是以像素比為標(biāo)準(zhǔn)，在生成圖片的時(shí)候可能會出現(xiàn)四周黑邊）
 position: absolute;
 left: -10000px; // 將畫布隱藏在可視區(qū)域外
 background: #206949;
}

mounted () {
 var query = wx.createSelectorQuery()
 query.select('#canvasPoster').boundingClientRect((res) => {
 // 返回值包括畫布的實(shí)際寬高
 this.drawImage(res)
 }).exec()
}

methods: {
 drawImage (canvasAttrs) {
 let ctx = wx.createCanvasContext('canvasPoster', this)
 let canvasW = canvasAttrs.width // 畫布的真實(shí)寬度
 let canvasH = canvasAttrs.height //畫布的真實(shí)高度
 // 頭像和二維碼大小都需要在規(guī)定大小的基礎(chǔ)上放大像素比的比例后面都會 *this.systemInfo.pixelRatio
 let headerW = 48 * this.systemInfo.pixelRatio
 let headerX = (canvasW - headerW) / 2
 let headerY = 40 * this.systemInfo.pixelRatio
 let qrcodeW = 73 * this.systemInfo.pixelRatio
 let qrcodeX = 216 * this.systemInfo.pixelRatio
 let qrcodeY = 400 * this.systemInfo.pixelRatio
 // 填充背景
 ctx.drawImage(this.shareInfo.bgImg, 0, 0, canvasW, canvasH)
 ctx.save()
 // 控制頭像為圓形
 ctx.setStrokeStyle('rgba(0,0,0,.2)') //設(shè)置線條顏色，如果不設(shè)置默認(rèn)是黑色，頭像四周會出現(xiàn)黑邊框
 ctx.arc(headerX + headerW / 2, headerY + headerW / 2, headerW / 2, 0, 2 * Math.PI)
 ctx.stroke()
 //畫完之后執(zhí)行clip()方法，否則不會出現(xiàn)圓形效果
 ctx.clip()
 // 將頭像畫到畫布上
 ctx.drawImage(this.shareInfo.headerImg, headerX, headerY, headerW, headerW)
 ctx.restore()
 ctx.save()
 // 繪制二維碼
 ctx.drawImage(this.shareInfo.qrcode, qrcodeX, qrcodeY, qrcodeW, qrcodeW)
 ctx.save()
 ctx.draw()
 setTimeout(() => {
 //下面的13以及減26推測是因?yàn)樵趯憳邮降臅r(shí)候?qū)懥斯潭ǖ膠oom: 50%而沒有用像素比縮放導(dǎo)致的黑邊，所以在生成時(shí)進(jìn)行了適當(dāng)?shù)目s小生成，這個(gè)大家可以自行嘗試
 wx.canvasToTempFilePath({
 canvasId: 'canvasPoster',
 x: 13,
 y: 13,
 width: canvasW - 26,
 height: canvasH - 26,
 destWidth: canvasW - 26,
 destHeight: canvasH - 26,
 success: (res) => {
  this.poster = res.tempFilePath
 }
 })
 }, 200)
 },
 previewImg () {
 if (this.poster) {
 //預(yù)覽圖片，預(yù)覽后可長按保存或者分享給朋友
 wx.previewImage({
 urls: [this.poster]
 })
 }
 },
 savePoster () {
 if (this.poster) {
 wx.saveImageToPhotosAlbum({
 filePath: this.poster,
 success: (result) => {
  wx.showToast({
  title: '海報(bào)已保存，快去分享給好友吧。',
  icon: 'none'
  })
 }
 })
 }
 }
}