/** 
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 * 使用bindingx方案实现slider 
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 * 只能使用于nvue下 
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 */ 
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// 引入bindingx,此库类似于微信小程序wxs,目的是让js运行在视图层,减少视图层和逻辑层的通信折损 
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const BindingX = uni.requireNativePlugin('bindingx') 
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// nvue操作dom的库,用于获取dom的尺寸信息 
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const dom = uni.requireNativePlugin('dom') 
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// nvue中用于操作元素动画的库,类似于uni.animation,只不过uni.animation不能用于nvue 
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const animation = uni.requireNativePlugin('animation') 
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export default { 
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    data() { 
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        return { 
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            // 位移的偏移量 
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            x: 0, 
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            // 是否正在触摸过程中,用于标记动画类是否添加或移除 
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            touching: false, 
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            changeFromInside: false 
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        } 
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    }, 
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    watch: { 
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        // 监听vlaue的变化,此变化可能是由于内部修改v-model的值,或者外部 
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        // 从服务端获取一个值后,赋值给slider的v-model而导致的 
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        value(n) { 
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            if (!this.changeFromInside) { 
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                this.initX() 
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            } else { 
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                this.changeFromInside = false 
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            } 
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        } 
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    }, 
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    mounted() { 
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        this.init() 
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    }, 
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    methods: { 
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        init() { 
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            // 更新滑块尺寸信息 
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            this.getSliderRect().then((size) => { 
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                this.sliderRect = size 
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                this.initX() 
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            }) 
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        }, 
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        // 获取节点信息 
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        // 获取slider尺寸 
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        getSliderRect() { 
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            // 获取滑块条的尺寸信息 
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            // 通过nvue的dom模块,查询节点信息 
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            return new Promise((resolve) => { 
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                this.$nextTick(() => { 
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                    dom.getComponentRect(this.$refs.slider, (res) => { 
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                        resolve(res.size) 
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                    }) 
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                }) 
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            }) 
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        }, 
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        // 初始化按钮位置 
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        initButtonStyle({ 
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            barStyle, 
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            buttonWrapperStyle 
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        }) { 
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            this.barStyle = barStyle 
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            this.buttonWrapperStyle = buttonWrapperStyle 
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        }, 
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        emitEvent(event, value) { 
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            this.$emit(event, value || this.value) 
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        }, 
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        // 滑动开始 
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        async onTouchStart(e) { 
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            // if (this.disabled) return 
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            // // 阻止页面滚动,可以保证在滑动过程中,不让页面可以上下滚动,造成不好的体验 
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            // e.stopPropagation && e.stopPropagation() 
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            // e.preventDefault && e.preventDefault() 
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            // // 更新滑块的尺寸信息 
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            // this.sliderRect = await this.getSliderRect() 
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            // // 标记滑动过程中触摸点的信息 
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            // this.touchStart(e) 
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            // this.startValue = this.format(this.value) 
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            // this.dragStatus = 'start' 
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            // 标记滑动过程中触摸点的信息 
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            // this.touchStart(e) 
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        }, 
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        // 开始滑动 
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        onTouchMove(e) { 
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            // if (this.disabled) return; 
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            // if (this.dragStatus === 'start') { 
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            //     this.$emit('drag-start') 
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            // } 
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            // // 标记当前滑动过程中的触点信息,此方法在touch mixin中 
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            // this.touchMove(e) 
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            // this.dragStatus = 'draging' 
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            // const { 
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            //     width: sliderWidth 
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            // } = this.sliderRect 
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            // const diff = (this.deltaX / sliderWidth) * this.getRange() 
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            // this.newValue = this.startValue + diff 
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            // this.updateValue(this.newValue, false, true) 
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            // 获取元素ref 
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            // const button = this.$refs['nvue-button'].ref 
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            // const gap = this.$refs['nvue-gap'].ref 
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            //          animation.transition(gap, { 
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            //     styles: { 
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            //                  width: `${this.startX + this.deltaX}px` 
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            //     } 
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            // }) 
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            // // console.log(this.startX + this.deltaX); 
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            // animation.transition(button, { 
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            //     styles: { 
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            //         transform: `translateX(${this.startX + this.deltaX}px)` 
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            //     } 
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            // }) 
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            // this.barStyle = { 
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            //     width: `${this.startX + this.deltaX}px` 
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            // } 
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            const { 
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                x 
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            } = this.getTouchPoint(e) 
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            this.buttonWrapperStyle = { 
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                transform: `translateX(${x}px)` 
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            } 
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            // this.buttonWrapperStyle = { 
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            //     transform: `translateX(${this.format(this.startX + this.deltaX)}px)` 
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            // } 
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        }, 
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        // onTouchEnd() { 
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        //     if (this.disabled) return; 
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        //     if (this.dragStatus === 'draging') { 
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        //         this.updateValue(this.newValue, true) 
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        //         this.$emit('drag-end'); 
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        //     } 
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        // }, 
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        updateValue(value, end, drag) { 
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            value = this.format(value) 
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            const { 
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                width: sliderWidth 
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            } = this.sliderRect 
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            const width = `${((value - this.min) * sliderWidth) / this.getRange()}` 
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            this.value = value 
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            this.barStyle = { 
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                width: `${width}px` 
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            } 
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            // console.log('width', width); 
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            if (drag) { 
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                this.$emit('drag', { 
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                    value 
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                }) 
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            } 
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            if (end) { 
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                this.$emit('change', value) 
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            } 
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            if ((drag || end)) { 
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                this.changeFromInside = true 
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                this.$emit('update', value) 
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            } 
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        }, 
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        // 从value的变化,倒推得出x的值该为多少 
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        initX() { 
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            const { 
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                left, 
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                width 
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            } = this.sliderRect 
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            // 得出x的初始偏移值,之所以需要这么做,是因为在bindingX中,触摸滑动时,只能的值本次移动的偏移值 
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            // 而无法的值准确的前后移动的两个点的坐标值,weex纯粹为阿里巴巴的KPI(部门业绩考核)产物,也就这样了 
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            this.x = this.value / 100 * width 
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            // 设置移动的值 
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            const barStyle = { 
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                width: `${this.x}px` 
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            } 
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            // 按钮的初始值 
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            const buttonWrapperStyle = { 
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                transform: `translateX(${this.x - this.blockHeight / 2}px)` 
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            } 
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            this.initButtonStyle({ 
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                barStyle, 
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                buttonWrapperStyle 
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            }) 
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        }, 
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        // 移动点占总长度的百分比,此处需要先除以step,是为了保证step大于1时,比如10,那么在滑动11,12px这样的 
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        // 距离时,实际上滑块是不会滑动的,到了16,17px,经过四舍五入后,就变成了20px,进行了下一个跳变 
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        format(value) { 
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            return Math.round(uni.$u.range(this.min, this.max, value) / this.step) * this.step 
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        }, 
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        getRange() { 
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            const { 
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                max, 
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                min 
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            } = this 
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            return max - min 
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        } 
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    } 
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} 
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