canvas保存图片为空白？
[图片][图片] 代码部分
happyNow() {
console.log(1)
// 获取并设置画布的信息
const canvasQuery = wx.createSelectorQuery()
canvasQuery.select('#MyCanvas')
.fields({
node: true,
size: true,
rect: true
})
.exec(this.CanvasInit.bind(this))
},
CanvasInit(res) {
console.log(res)
const width = res[0].width
const height = res[0].height
const canvas = res[0].node
const ctx = canvas.getContext('2d')
const dpr = wx.getSystemInfoSync().pixelRatio
canvas.width = width * dpr
canvas.height = height * dpr
ctx.scale(dpr, dpr)
//画布背景颜色
ctx.fillStyle = '#fff'
ctx.fillRect(0, 0, width, height)
// 绘制图片
const img = canvas.createImage()
img.src = ImgPath
img.onload = () => ctx.drawImage(img, 0, 0, this.widthImg, this.heightImg)
// 绘制文字部分
console.log(this.widthImg)
ctx.fillStyle = "#000000"
ctx.font = "normal 18px Arial"
ctx.fillText(this.time, 18, this.heightImg + 20)
ctx.fillText(this.wea, 150, this.heightImg + 20)
this.canvasText(ctx)
wx.canvasToTempFilePath({
canvas: canvas,
x:0,
y:0,
width:width,
height:height,
destWidth:width,
destHeight:height,
success:res=>{
console.log(res.tempFilePath)//http://tmp/3ifoGRo7kGKW1cc162bcbe1b93b416a623f78e0d96d9.png 这个图片无法打开
this.saveTempFilePath = res.tempFilePath
},
fail:err=>{
console.log(err)
}
})
},
canvasText(ctx) {
let num = parseInt(this.userText.length / 14)
console.log(num)
let aa = this.userText.length % 14
ctx.font = "normal 16px Arial"
ctx.fillText(this.userText.substr(14 * num + aa, aa), 0, this.heightImg + 38)
for (let a = 0; a <= num; a++) {
ctx.font = "normal 16px Arial"
ctx.fillText(this.userText.substr(a * 14, 14), 0, this.heightImg + 40 + a * 16)
}
},
saveCnavs(){
wx.saveImageToPhotosAlbum({
filePath: this.saveTempFilePath,
success:res=>{
wx.showModal({
title:"图片保存成功！"
})
}
})
}
绘制出来的都没有问题，在保存到相册中也没有任何错误，就是保存的图片全都是空白的，这是什么错误
