华为安卓机将画布转图片成黑块，iOS正常

this.ctx.draw(true, (() => {

setTimeout(function () {

wx.canvasToTempFilePath({

canvasId: that.canvasName,

destWidth: 160,

destHeight: 320,

fileType: ‘jpg’,

quality: 0.1,

success: function (res) {

if (that.callBack) {

that.callBack(res.tempFilePath);

}

}

}, that);

}, 1000);

})());