[微信小程序]fail canvas is empty [fail canvas is empty]+ 查看更多
- 当前 Bug 的表现（可附上截图）
选择图片后显示canvasToTempFilePath: fail canvas is empty
- 预期表现
返回success信息
- 复现路径
？
- 提供一个最简复现 Demo
wx.chooseImage({
//2019.3.2 压缩上传
//count: 1,
sizeType: ['original', 'compressed'],
success: function (res) {
var _that = this;
var path = res.tempFilePaths[0];
that.data.scardimg = res.tempFilePaths;
console.log("the old path:")
console.log(res.tempFilePaths[0])
//-----返回选定照片的本地文件路径列表，获取照片信息-----------
wx.getImageInfo({
src: res.tempFilePaths[0],
success: function (res) {
//---------利用canvas压缩图片--------------
console.log("getinfo")
console.log(res)
var ratio = 2;
var canvasWidth = res.width //图片原始长宽
var canvasHeight = res.height
while (canvasWidth > 400 || canvasHeight > 400){// 保证宽高在400以内
canvasWidth = Math.trunc(res.width / ratio)
canvasHeight = Math.trunc(res.height / ratio)
ratio++;
}
that.setData({
cWidth: canvasWidth,
cHeight: canvasHeight
})
console.log(canvasHeight)
console.log(canvasWidth)
console.log(res.path)
//----------绘制图形并取出图片路径--------------
var ctx = wx.createCanvasContext('firstCanvas');
ctx.drawImage(res.path, 0, 0, canvasWidth, canvasHeight);
//ctx.draw();
//将生成好的图片保存到本地，需要延迟一会，绘制期间耗时
wx.showToast({
title: '图片压缩中...',
icon: 'loading',
duration: 500
});
ctx.draw(false,
setTimeout(function(){
wx.canvasToTempFilePath({
canvasId: 'firstCanvas',
destWidth: canvasWidth,
destHeight: canvasHeight,
success: function (res) {
var tempFilePath = res.tempFilePath;
console.log("success canvas");
that.setData({
scardimg:res.tempFilePaths,
img_arr: that.data.scardimg.concat(res.tempFilePaths),
show_addimg: 0
});
wx.hideToast()
},
fail: function (res) {
console.log(res);
}
})
}, 500));
}
})//info
}//success
})
}