传入了canvas实例也不行，报错为this.canvasToTempFilePath is not a function



export() {
            this.canvasToTempFilePath({
                canvas:canvas,
                destWidth: this.data.width * (wx.getSystemInfoSync().pixelRatio / 2),
                destHeight: this.data.height * (wx.getSystemInfoSync().pixelRatio / 2),
                success: (res) => {
                    resolve(res.tempFilePath);
                },
                fail: (e) => {
                    reject(e);
                },
            });