Vue自适应滚动条触底更新

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<template>
	<div id="box">
		<scrollbar @bottom="bottom" @top="top" :changeTop.sync="changeTop">
			<div id="container">
				<p>Vue自定义滚动条</p>
				<p v-for="n in 30">自定义滚动条{{n}}</p>
				<div v-for="(str,index) in data">add data-{{str}}-{{index}}</div>
			</div>
		</scrollbar>
		<div id="loadingbox" v-show="isloading">loading...</div>
	</div>
</template>

<script>
	import scrollbar from './4'
	export default {
		components: {
			scrollbar
		},
		data() {
			return {
				data: [],
				isloading: false,
				changeTop: 0,
			}
		},
		methods: {
			top() {
				console.log('top');
			},
			bottom() {
				console.log('bottom')
				this.isloading = true;
				var newdata = [
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
					'我是新加的数据',
				];
				setTimeout(() => {
					this.data = this.data.concat(newdata);
					this.isloading = false;
				}, 1000);
			}
		},
	}
</script>

<style>
	* {
		padding: 0px;
		margin: 0px;
	}
	
	#box {
		margin: 0 auto;
		text-align: center;
		width: 500px;
		height: 500px;
		border: 1px solid red;
		border-radius: 3px;
		position: relative;
	}
	
	#container {
		width: 100%;
	}
	
	#loadingbox {
		width: 100%;
		background: rgba(255, 255, 255, .8);
		position: absolute;
		left: 0;
		bottom: 0;
		text-align: center;
		font-weight: bold;
	}
</style>
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<template>
	<div ref="box" class="scrollbar_box" @wheel="scroll" @mouseenter="mouseenter($event)" @mouseleave="mouseleave($event)">
		<div ref="container" class="scrollbar_container" :style="{ transform : `translate(0px, ${top*-1}px)` }">
			<slot></slot>
		</div>
		<div ref="scrollbarPath" class="scrollbar_path" v-show="isVerticalBtn" :class="{on: verticalCur}">
			<div ref="verticalBtn" class="scrollbar_verticalBtn" :style="{ height: `${barHeight}%`, top : `${barTop}%` }" 
				 @mousedown="startmoveV" >
			</div>
		</div>
	</div>
</template>

<script>
	export default {
		data() {
			return {
				top: 0, //box偏移量px
				barHeight: 0, //竖直滚动条高度
				barTop: 0, //竖直滚动条上下偏移量%
				isVerticalBtn: false, //竖直滚动条是否显示
                verticalCur:false,
                
				isStartmoveV: false, //点击拖拽垂直标志位
                
				point: { //相对拖快左上角的x,y坐标
					x: 0,
					y: 0,
				},
				boxPoint: { // 4个角容器的坐标
					minX: 0,
					maxX: 0,
					minY: 0,
					maxY: 0,
				},
				isrun: false, //是否在运行 优化 因为 频繁 触发 resize 函数，导致页面很卡的 问题 节流函数
				throttleTime: 400, //节流函数定时器时间
			}
		},
		props: {
			speed: {
				type: Number,
				default: 30
			},

			changeTop: { //上下偏移量 px
				type: Number,
				default: 0
			},

			timeOut: { //延时调用changeWinSize
				type: Number,
				default: 0
			},
		},
		watch: {
			changeTop() {  // 当外面传这个发送变化时就让到这个位置
				this.setbarTop();
			}
		},
		computed: {},
		methods: {
			mouseenter(){
				this.verticalCur=true;
			},
			mouseleave(){
				setTimeout(()=>{
					this.verticalCur=false;
				},1000)
			},
			// 初始化
			getPropData() {
				this.setbarTop();
			},
			setbarTop() {
				if(this.top == this.changeTop) return false;
				let size = this.getSize();
				let topEnd = size.containerHeight - size.boxHeight;
				if(this.changeTop < 0) {
					this.top = 0;
				} else if(this.changeTop >= topEnd) {
					this.top = topEnd;
				} else {
					this.top = this.changeTop;
				}
				this.barTop = ((this.top * 100) / size.containerHeight) * 1;
			},

			// 滚动
			scroll(e) {
				if(this.isVerticalBtn) {
					e.preventDefault();
					e.stopPropagation();
				} else {
					return false;
				}
				let speed = this.speed;
				let shifted = e.shiftKey
				let scrollY = e.deltaY > 0 ? speed * 1 : speed * -1;

				if(shifted && e.deltaX == 0) scrollX = e.deltaY > 0 ? speed : speed * -1;
				let nextY = this.top * 1 + scrollY;

				// 如果没有垂直的滚动条就滚动横向的
				if(this.isVerticalBtn) {
					this.setVerticalScroll(nextY)
				}
			},
			// 垂直btn点击后的事件
			startmoveV(e) {
				this.verticalCur=true;
				e.preventDefault(); //阻止默认事件，取消文字选中
				let _point = this.windowToBox(e.clientX, e.clientY, this.$refs.verticalBtn); //得出来的是相对这垂直btn的点位置
				this.isStartmoveV = true;
				this.point.x = _point.x;
				this.point.y = _point.y;
				document.addEventListener('mousemove', this.fnMousemoveV, false);
				document.addEventListener('mouseup', this.fnMouseup, false);
			},

			// 垂直移动监听
			fnMousemoveV(e) {
				this.verticalCur=true;
				e.preventDefault();
				if(this.isStartmoveV) {
					this.setVerticalClick(e.clientY - this.point.y);
				}
			},

			// 鼠标抬起监听
			fnMouseup(e) {
				e.preventDefault();
				this.isStartmoveV = false;
				this.clearMousemove();
			},
			// 清除监听
			clearMousemove() {
				document.removeEventListener('mousemove', this.fnMousemoveV, false);
				document.removeEventListener('mouseup', this.fnMouseup, false);
			},
			// 包围盒的信息坐标轴
			windowToBox(x, y, el) {
				let _bbox = el.getBoundingClientRect();
				return {
					x: x - _bbox.left,
					y: y - _bbox.top
				}
			},

			getSize() { // 返回盒子尺寸
				let _container = this.$refs.container;
				let _box = this.$refs.box;
				let size = {

					containerHeight: _container.scrollHeight, //滚动内容的高度宽度
					containerWidth: _container.scrollWidth,

					boxHeight: _box.clientHeight, //最外面盒子的高度宽度
					boxWidth: _box.clientWidth,
				}
				return size;
			},
			// 点击拖拽设置
			setVerticalClick(val) {
				let size = this.getSize();
				let barTop = ((val - this.boxPoint.minY) / this.$refs.box.clientHeight) * 100;  //换算成百分比
				if(barTop <= 0) {
					barTop = 0;
					if(this.barTop == barTop) {
						return false;
					}
					this.$emit('top');
				}
				if(barTop + this.barHeight >= 100) {
					barTop = 100 - this.barHeight;
					if(this.barTop == barTop) {
						return false;
					}
					this.$emit('bottom');
				}
				this.barTop = barTop; // 这里是百分比的需要转换
				this.top = ((barTop / 100) * size.containerHeight).toFixed(2) * 1; //换算百分百
				this.$emit('update:changeTop', this.top);
			},

			setVerticalScroll(val) { //val是偏移量 滚动的 
				let size = this.getSize();
				let topEnd = size.containerHeight - size.boxHeight;
				if(val >= topEnd) {
					val = topEnd;
					if(this.top == val) { // 已经到底部就不用继续执行了
						return false;
					}
					this.$emit('bottom');
				};
				if(val <= 0) {
					val = 0;
					if(this.top == val) { // 已经到顶部就不用继续执行了
						return false;
					}
					this.$emit('top');
				}
				this.top = val;
				this.$emit('update:changeTop', this.top);

				this.barTop = (val / size.containerHeight) * 100; // 导航条的top的计算 
			},
			changeWinSize() {   //最重要的一个方法，触底计算，滑块的top不变，只改变高度
				let size = this.getSize();
				let boxPoint = this.$refs.box.getBoundingClientRect(); // container的极坐标
				// 保存box窗口坐标
				this.boxPoint.minX = boxPoint.left;
				this.boxPoint.maxX = boxPoint.right;
				this.boxPoint.minY = boxPoint.top;
				this.boxPoint.maxY = boxPoint.bottom;
				// 计算拖拽条的宽高
				this.barHeight = (size.boxHeight / size.containerHeight) * 100;  //100是百分比，box的高度是100%,比例计算

				// 是否显示拖拽条
				this.isVerticalBtn = (this.barHeight >= 100 && !!this.barHeight) ? false : true;
				if(!this.isVerticalBtn) {
					this.top = 0;
					this.barTop = 0;
				}
			}
		},
		mounted() {
			this.$nextTick(() => {
				this.getPropData();
				this.changeWinSize();
			});
		},
		updated() { //由于数据更改导致的虚拟 DOM 重新渲染和打补丁，在这之后会调用该钩子
			this.$nextTick(() => {
				if(this.timeOut != 0) { //防止某些动画影响如el-collapse-transition
					setTimeout(() => {
						this.changeWinSize();
					}, this.timeOut);
				} else {
					this.changeWinSize();
				}
			});
		}
	}
</script>

<style scoped lang="less">
	.scrollbar_box {
		overflow: hidden;
		position: relative;
		height: 100%;
		width: 100%;
		transform: translateZ(0);
		backface-visibility: hidden;
		perspective: 1000;
		transform: translate3d(0, 0, 0);
		.scrollbar_container {
			overflow: visible;
			width: 100%;
			height: 100%;
		}
		.scrollbar_path {
			position: absolute;
			top: 0px;
			right: 0px;
			width: 6px;
			height: 100%;
			background-color: white;
			opacity: 0;
		    transition: opacity 500ms;
		    &.on{
		    	opacity: 1;
		    }
			.scrollbar_verticalBtn {
				position: absolute;
				top: 0px;
				right: 0px;
				width: 6px;
				border-radius: 3px;
				background-color: #51555e;
				cursor: pointer;
				z-index: 50;
				&:hover {
					background-color: green;z-index: 51;
				}
			}
		}
	}
</style>