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利用vue組件實現(xiàn)圖片的拖拽和縮放功能

更新時間：2022年01月18日 15:39:51 作者：封號斗羅-逆天而行

這篇文章主要給大家介紹了關(guān)于利用vue組件實現(xiàn)圖片的拖拽和縮放功能的相關(guān)資料,文中通過實例代碼介紹的非常詳細(xì)，對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值,需要的朋友可以參考下

前言

vue實現(xiàn)一個組件其實很簡單但是要寫出一個好的可復(fù)用的組件那就需要多學(xué)習(xí)和鉆研一下，一個好的組件必須有其必不可少的有優(yōu)點：一是能提高應(yīng)用開發(fā)效率、測試性、復(fù)用性等；二是組件應(yīng)該是高內(nèi)聚、低耦合的；三是組件應(yīng)遵循單向數(shù)據(jù)流的原則。

在實現(xiàn)我的圖片的拖拽組件我們的搞清其原理，在這里我使用的是mousedown,mousemove和mouseup來實現(xiàn)拖拽。

如圖所示：

方法如下：

1.新建ElementDrag.vue文件內(nèi)容如下：

<template>
    <div class="drag-outer" 
    ref="dragWrap"
    @mousemove="dragMousemove">
        <div class="drag-inner"
        ref="dragElement" 
        @mousedown="dragMousedown"
        @mouseup.stop="isMousedown = false">
            <slot></slot>
        </div>
    </div>
</template>

2. 定義moveStart用于記錄拖拽元素初始位置。定義isMousedown變量來判斷鼠標(biāo)是否按下，如果isMousedown === true鼠標(biāo)移動就改變darg-inner位置。

<script>
export default {
    name: 'ElementDrag',
    data() {
        return {
            isMousedown: false, //鼠標(biāo)是否按下
            moveStart: {x: 0, y: 0}, //拖拽元素初始位置
            translate: {x: 0, y: 0}, //計算拖拽元素在下下x,y方向各移動了多少
            scale: 1, //拖拽元素縮放值
        }
    },
    methods: {
        dragMousedown() {
            this.moveStart.x = event.clientX
            this.moveStart.y = event.clientY
            this.isMousedown = true 
        },
        dragMousemove() {
            if(this.isMousedown) {
                this.translate.x += (event.clientX - this.moveStart.x) / this.scale
                this.translate.y += (event.clientY - this.moveStart.y) / this.scale
                this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
                this.moveStart.x = event.clientX
                this.moveStart.y = event.clientY
            }
        }
    }
}
</script>

3.樣式部分我們設(shè)置外層drag-outer用flex布局讓里面元素快速居中, user-drag: none;禁用圖片等元素的可拖拽屬性。

<style lang="scss" scoped>
.drag-outer {
    width: 100%;
    height: 100%;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    .drag-inner {
        transform-origin: center center;
        display: flex;
        justify-content: center;
        align-items: center;
        cursor: move;
        user-select: none;
        >* {
            -webkit-user-drag: none;
            user-drag: none;
        }
    }
}
</style>

4.添加鼠標(biāo)滾輪事件縮放drag-inner元素, e.wheelDelta為正表示放大，為負(fù)縮小，值越大表示滾動越快。通過scale控制拖拽元素縮放。同過對組件傳值scaleZoom來控制其縮放最大最小程度值。

...
methods: {
    props: {
        type: Object,
        default(){ 
            return {
                min: 0.5,
                max: 5   
            }
        }
    },
    ...
    handleScroll(e) {
        let speed = e.wheelDelta/120
        if(e.wheelDelta > 0 && this.scale < this.scaleZoom.max) {
            this.scale+=0.04*speed
            this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
        }else if(e.wheelDelta < 0 && this.scale > this.scaleZoom.min){
            this.scale+=0.04*speed
            this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
        }
    }
},
mounted() {
    window.addEventListener('mousewheel',this.handleScroll,false) 
}

5.以上代碼已經(jīng)實現(xiàn)了功能我們預(yù)期的功能，但是為了更好的體驗，需要進(jìn)一步優(yōu)化組件。添加isHover來控制鼠標(biāo)是否移動到了drag-outer以外，如果isHover為false這時鼠標(biāo)滾輪滾動不會縮放元素，并且將isMousedown設(shè)置為false。再使用插槽slot預(yù)覽位置。

<template>
    <div class="drag-outer" 
    ref="dragWrap"
    @mouseenter="isHover = true" 
    @mouseleave="isHover = isMousedown = false"
    @mousemove="dragMousemove">
        <div class="drag-inner"
        ref="dragElement" 
        @mousedown="dragMousedown"
        @mouseup.stop="isMousedown = false">
            <slot></slot>
        </div>
    </div>
</template>
....
data() {
    return {
        ...,
        isHover: false,
    }
},
methods: {
    ...
    handleScroll(e) {
        if(this.isHover) {
            let speed = e.wheelDelta/120
            if(e.wheelDelta > 0 && this.scale < this.scaleZoom.max) {
                this.scale+=0.04*speed
                this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
            }else if(e.wheelDelta < 0 && this.scale > this.scaleZoom.min){
                this.scale+=0.04*speed
                this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
            }
        }
    }
}

貼上組件的最終代碼：

<template>
    <div class="drag-outer" 
    ref="dragWrap"
    :style="outerOptions"
    @mouseenter="isHover = true" 
    @mouseleave="isHover = isMousedown = false"
    @mousemove="dragMousemove">
        <div class="drag-inner"
        ref="dragElement" 
        :style="innerOptions"
        @mousedown="dragMousedown"
        @mouseup.stop="isMousedown = false">
            <slot></slot>
        </div>
    </div>
</template>

<script>
export default {
    name: 'ElementDrag',
    props: {
        outerOptions: {
            type: Object,
            default () {
                return {
                    background: 'rgba(0,0,0,0.9)'
                }
            }
        },
        innerOptions: {
            type: Object,
            default () {
                return {
                    background: 'rgba(0,0,0,0.1)',
                }
            }
        },
        scaleZoom: {
            type: Object,
            default () {
                return {
                    max: 5, 
                    min: 0.2
                }
            }
        }
    },
    data() {
        return {
            isMousedown: false,
            isHover: false,
            moveStart: {},
            translate: {x: 0, y: 0},
            scale: 1
        }
    },
    methods: {
        handleScroll(e) {
            if(this.isHover) {
                let speed = e.wheelDelta/120
                if(e.wheelDelta > 0 && this.scale < this.scaleZoom.max) {
                    this.scale+=0.04*speed
                    this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
                }else if(e.wheelDelta < 0 && this.scale > this.scaleZoom.min){
                    this.scale+=0.04*speed
                    this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
                }
            }
        },
        dragMousedown() {
            this.moveStart.x = event.clientX
            this.moveStart.y = event.clientY
            this.isMousedown = true 
        },
        dragMousemove() {
            if(this.isMousedown) {
                this.translate.x += (event.clientX - this.moveStart.x) / this.scale
                this.translate.y += (event.clientY - this.moveStart.y) / this.scale
                this.$refs.dragElement.style.transform = `scale(${this.scale}) translate(${this.translate.x}px, ${this.translate.y}px)`
                this.moveStart.x = event.clientX
                this.moveStart.y = event.clientY
            }
        }
    },
    mounted() {
        window.addEventListener('mousewheel',this.handleScroll,false) 
    }
}
</script>

<style lang="scss" scoped>
.drag-outer {
    width: 100%;
    height: 100%;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    .drag-inner {
        transform-origin: center center;
        display: flex;
        justify-content: center;
        align-items: center;
        cursor: move;
        user-select: none;
        >* {
            -webkit-user-drag: none;
            user-drag: none;
        }
    }
}
</style>

在home.vue文件使用：點擊體驗

<template>
  <div class="home">
    <ElementDrag>
        <img src="https://img0.baidu.com/it/u=937276518,3474029246&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=750">
    </ElementDrag>
  </div>
</template>

<script>
import ElementDrag from '@/components/ElementDrag'
export default {
  name: 'Home',
  components: {
    ElementDrag
  }
}
</script>

<style scoped>
.home {
  width: 100vw;
  height: 100vh;
} 
</style>