// 图片压缩
            compressImage(src) {
                let that = this
                uni.getImageInfo({
                    src,
                    success(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.cWidth = canvasWidth
                        that.cHeight = canvasHeight
                        var ctx = uni.createCanvasContext('canvas')

                        ctx.drawImage(res.path, 0, 0, canvasWidth, canvasHeight)

                        ctx.draw(false, setTimeout(() => {
                            uni.canvasToTempFilePath({
                                canvasId: 'canvas',
                                destWidth: canvasWidth,
                                destHeight: canvasHeight,
                                fileType: 'jpg',
                                quality: 0.4,
                                success: function(res1) {
                                    uni.getFileInfo({
                                        filePath: res1.tempFilePath,
                                        success(ress) {
                                            console.log(ress)
                                        }
                                    })

                                },
                                fail: function(res) {
                                    console.log(res.errMsg)
                                }
                            })
                        }, 100)) //留一定的时间绘制canvas
                    },
                    fail(err) {
                        console.log(err.errMsg)
                    }
                })
            },