canvas.toTempFilePath({

                x: 0,

                y: 0,

                width: canvas.width,

                height: canvas.height,

                destWidth: canvas.width,

                destHeight: canvas.height,

                success (res) {

                    console.log(res);

                    //不能用 ："saveFile:fail tempFilePath file not exist"

                    const fs = wx.getFileSystemManager();

                    fs.saveFile({

                        tempFilePath: res.tempFilePath, // 传入一个本地临时文件路径

                        success(res) {

                          console.log(res.savedFilePath) // res.savedFilePath 为一个本地缓存文件路径

                        },

                        fail(res){

                            console.log(res);

                        }

                    })

                }

            })

toTempFilePath的res:

{errMsg: "canvasToTempFilePath:ok", tempFilePath: "ffd3e413-c811-4efc-a9a3-9d078ce358fa"}

saveFile的fail打印的res:

{errMsg: "saveFile:fail tempFilePath file not exist"}

saveFile保存临时截图失败，但是可以使用saveImageToPhotosAlbum保存到相册。

不知道为何，求解啊~

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