1 背景

需要设计一个纵向滚动菜单，要求丝滑点，默认显示选中菜单

2 思路

• 给定一个容器，样式包含overflow:hidden，默认高宽足够显示一个菜单（以下用图标代替菜单），鼠标悬浮时增大容器高度，显示更多图标
• 设置两个div用于触发上下滚动（本意直接用每页第一和最后图标进行触发，但是这样会导致鼠标悬停时直接滚动，体验不好）
• 鼠标点击时将点击图标滚动到当前页的第一个图标，鼠标没有点击，移出后菜单还原

3 实现

<template><div class="container" @mouseleave="handleMouseLeave"><divclass="action up"v-if="scrollTop !== -1 * (totalHeight - pageHeight)"@mouseover="handleMouseOver('up')"></div><ul :style="{ transform: `translateY(${scrollTop}px)` }"><liv-for="(item, index) in imgs":key="index":style="{ padding: itemPadding + 'px' }"><img:src="item"alt="":style="{ width: iconSize[0] + 'px', height: iconSize[1] + 'px' }"@click="handleClick(index)"/></li></ul><divclass="action dowm"v-if="scrollTop !== 0"@mouseover="handleMouseOver('down')"></div></div>
</template><script setup lang="ts">
import { ref, computed } from "vue";const props = defineProps({iconSize: {type: Array,default: () => [60, 60],},pageSize: {type: Number,default: 6,},itemPadding: {type: Number,default: 20,},
});
const list = ["vue.svg","back.svg","behance.svg","down.svg","hands.svg","hdd.svg","next.svg", //"one.svg","snow.svg","three.svg","up.svg","upload.svg","vip.svg", //"dvi.svg","bone.svg","bird.svg","ipad.svg","duck.svg","deer.svg", //"fish.svg","clap.svg","eagle.svg",
];
const imgs = ref(list.map((item) => new URL(`./assets/${item}`, import.meta.url).href)
);const scrollTop = ref(0);
const baseIndex = ref(0);const actionHeight = computed(() => {return props.itemPadding+ "px";
});const itemHeight = computed(() => {return props.iconSize[1] + 2 * props.itemPadding;
});
const containerBaseSize = computed(() => {return itemHeight.value + "px";
});
const containerHeight = computed(() => {return itemHeight.value * props.pageSize + "px";
});
const pageHeight = computed(() => {return props.pageSize * itemHeight.value;
});
const totalHeight = computed(() => {return imgs.value.length * itemHeight.value;
});const handleMouseOver = async (direction: string) => {if (direction === "up") {if (scrollTop.value + (totalHeight.value - pageHeight.value) >pageHeight.value) {scrollTop.value += -1 * pageHeight.value;} else {scrollTop.value = -1 * (totalHeight.value - pageHeight.value);}} else {if (scrollTop.value + pageHeight.value >= 0) {scrollTop.value = 0;} else {scrollTop.value += pageHeight.value;}}
};const handleClick = (index: number) => {scrollTop.value = -1 * index * itemHeight.value;baseIndex.value = index;
};
const handleMouseLeave = () => {handleClick(baseIndex.value);
};
</script><style scoped lang="scss">
.container {overflow: hidden;transition: all 0.5s;position: relative;width: v-bind(containerBaseSize);height: v-bind(containerBaseSize);&:hover {height: v-bind(containerHeight);}.action {cursor: pointer;position: absolute;width: 100%;height: v-bind(actionHeight);z-index: 10;&.up {top: 0;}&.dowm {bottom: 0;}}ul {box-sizing: content-box;margin: 0;padding: 0;height: 100%;transition: all ease-in-out 1s;list-style: none;li {line-height: 0;position: relative;img {cursor: pointer;transition: all 0.5s;&:hover {scale: 1.3;}}}}
}
</style>