使用大屏展示的时候有很多种场景，众多场景都是为了实现大屏自适应。
大屏，顾名思义，就是放在一个固定的屏幕上看的，即使你不做自适应，放在一个固定的屏幕上看也没啥问题，但是很多做大屏的是为了在PC端看，PC端屏幕又是参差不齐的，所以需要做自适应。

方案一：
使用transform的大小缩放来实现，我们先写一个缩放容器AutoScalContainer.vue，代码如下：

<template>
    <div 
        class="auto-scal-container"
        ref="AutoScalContainerRef">
        <div 
            ref="DomRef" 
            class="auto-scal-container-inner">
            <slot></slot>
        </div>
    </div>
</template>

<script>
/** 
 * 自动缩放容器
 * 使用transform进行缩放
 *  */
import { 
    defineComponent,ref,getCurrentInstance,reactive,toRef, 
    computed,onMounted,onActivated,watch,
    onBeforeUnmount,
} from "vue";

export default defineComponent({
    props:{
        width:{
            type:Number,
            default:1920,
        },
        height:{
            type:Number,
            default:1080,
        },
        /** 内部容器的宽高比例 */
        ratio:{
            type:Number,
            default:1920 / 1080,
        },
        /** 
         * fit，原理同img的object-fit
         * contain : 被替换的内容将被缩放，以在填充元素的内容框时保持其宽高比。
         * cover : 被替换的内容在保持其宽高比的同时填充元素的整个内容框。如果对象的宽高比与内容框不相匹配，该对象将被剪裁以适应内容框。
         *  */
        fit:{
            type:String,
            default:'contain',
        },
    },
    emits:['onResizeScreen'],
    setup(props,{emit}){
        const DomRef = ref(null);  //组件实例
        const AutoScalContainerRef = ref(null);  //组件实例
        const dataContainer = reactive({
            height:toRef(props,'height'),
            width:toRef(props,'width'),
            ratio:toRef(props,'ratio'),
            fit:toRef(props,'fit'),
        });
        /** 是否是文档上 */
        function isActive(){
            if(!DomRef.value) return false;
            return DomRef.value.getRootNode() === document;
        }
        /** 自动缩放 */
        function autoResizeScreen(){
            if(!AutoScalContainerRef.value) return;
            if(!DomRef.value) return;
            if(!isActive) return;
            let rect = AutoScalContainerRef.value.getBoundingClientRect();
            let clientWidth = rect.width;
            let clientHeight = rect.height;
            var width = dataContainer.width;
            var height = dataContainer.height;
            let left = 0;
            let top = 0;
            let scale = 0;
            /** 使用外部传入的比例或者传入的宽高计算比例 */
            let ratio = dataContainer.ratio || (width / height);
            // 获取比例  可视化区域的宽高比与 屏幕的宽高比  来进行对应屏幕的缩放
            if(dataContainer.fit == 'contain'){
                if ((clientWidth / clientHeight) > ratio) {
                    scale = clientHeight / height;
                    top = 0;
                    left = (clientWidth - width * scale) / 2;
                } else {
                    scale = clientWidth / width;
                    left = 0;
                    top = (clientHeight - height * scale) / 2;
                }
            }
            if(dataContainer.fit == 'cover'){
                if ((clientWidth / clientHeight) > ratio) {
                    scale = clientWidth / width;
                } else {
                    scale = clientHeight / height;
                }
            }
            // 防止组件销毁后还执行设置状态s
            Object.assign(DomRef.value.style, {
                transform: `scale(${scale})`,
                left: `${left}px`,
                top: `${top}px`,
            });
            /** 向外部通知已经计算缩放 */
            emit('onResizeScreen');
        }
        /** 防抖 */
        let timer_1;
        function fnContainer(){
            clearTimeout(timer_1);
            // timer_1 = setTimeout(()=>{
                autoResizeScreen();
            // },16);
        }
        let timer = setInterval(()=>{
            fnContainer();
        },300);
        onMounted(() => {
            autoResizeScreen();
        });
        window.addEventListener('resize', fnContainer);
        onBeforeUnmount(() => {
            window.removeEventListener('resize', fnContainer);
            window.clearInterval(timer);
        });
        return {
            dataContainer,
            DomRef,
            AutoScalContainerRef,
        };
    },
});
</script>

<style lang="scss" scoped>
.auto-scal-container {
    width: 100%;
    height: 100%;
    position: relative;
    overflow: auto;
    /** 隐藏滚动条 */
    -ms-overflow-style: none;
    scrollbar-width: none;
    &::-webkit-scrollbar {
        display: none;
    }
    >.auto-scal-container-inner {
        overflow: hidden;
        transform-origin: left top;
        z-index: 999;
        width: max-content;
        height: max-content;
        position: absolute;
        top: 0;
        left: 0;
    }
}
</style>

使用方式

<script>
/** 
 * 大屏主页面
 * 采用缩放的形式进行适配，搭配rem的话很方便实用
 *  */
import { defineComponent,ref,getCurrentInstance,reactive,toRef, computed,onMounted,onActivated,watch } from "vue";
import AutoScalContainer from "@/components/AutoScalContainer.vue";
import ViewHead from "./components/ViewHead.vue";
import img_1 from "./assets/bg.png";
import img_2 from "./assets/1-1-bg.png";
import Box_1 from "./components/Box_1.vue";
import Box_2 from "./components/Box_2.vue";
import Box_3 from "./components/Box_3.vue";
import Box_4 from "./components/Box_4.vue";
import Box_5 from "./components/Box_5.vue";
import Box_6 from "./components/Box_6.vue";
import { useRoute } from "vue-router";

export default defineComponent({
    name:'BigScreenView',
    components: {
        AutoScalContainer,
        ViewHead,
        Box_1,
        Box_2,
        Box_3,
        Box_4,
        Box_5,
        Box_6,
    },
    setup(){
        let route = useRoute();
        const dataContainer = reactive({
            loading:false,
            img:{
                img_1,
                img_2,
            },
            fit:'contain',
        }); 
        watch(route,()=>{
            let queryParams = route.query || {};
            let fitMap = {
                'cover':'cover',
                'contain':'contain',
            };
            dataContainer.fit = fitMap[queryParams.fit] || 'contain';
        },{
            immediate:true,
        });
        return {
            dataContainer,
        };
    },
});
</script>

<template>
    <div class="big-screen-view">
        <AutoScalContainer
            :height="1080"
            :width="1920"
            :fit="dataContainer.fit">
            <div 
                class="big-screen-view-container"
                :style="{
                    '--bg-img-1':`url(${dataContainer.img.img_1})`,
                    '--bg-img-2':`url(${dataContainer.img.img_2})`,
                }" >
                <div class="head">
                    <ViewHead
                        title="数据可视化大屏展示"></ViewHead>
                </div>
                <div class="content">
                    <div class="top">
                        <Box_1></Box_1> 
                    </div>
                    <div class="content">
                        <div class="left">
                            <div class="box">
                                <Box_2></Box_2> 
                            </div>
                            <div class="box">
                                <Box_3></Box_3> 
                            </div>
                        </div>
                        <div class="right">
                            <div class="box">
                                <Box_4></Box_4> 
                            </div>
                            <div class="box">
                                <Box_5></Box_5> 
                            </div>
                        </div>
                    </div>
                </div>
                <div class="centre-box">
                    <div class="v-height"></div>
                    <div class="container">
                        <Box_6></Box_6> 
                    </div>
                </div>
            </div>
        </AutoScalContainer>
    </div>
</template>

<style lang="scss" scoped>
.big-screen-view{
    width: 100vw;
    height: 100vh;
    overflow: hidden;
    background-color: #031045c7;
    .big-screen-view-container{
        width: 1920px;
        height: 1080px;
        background-color: rgb(169, 169, 169);
        display: flex;
        flex-direction: column;
        background-image: var(--bg-img-1);
        background-repeat: no-repeat;
        background-size: 100% 100%;
        background-position: center;
        position: relative;
        >.head{
            height: 91px;
            position: relative;
            z-index: 2;
        }
        >.content{
            display: flex;
            flex-direction: column;
            flex: 1 1 0;
            width: 100%;
            height: 0;
            position: relative;
            z-index: 2;
            pointer-events: none;
            >.top{
                width: 100%;
                height: 199px;
                pointer-events: initial;
            }
            >.content{
                display: flex;
                flex-direction: row;
                justify-content: space-between;
                flex: 1 1 0;
                width: 100%;
                height: 0;
                padding: 0 15px 15px 15px;
                box-sizing: border-box;
                >.left,>.right{
                    display: flex;
                    flex-direction: column;
                    >.box{
                        width: 100%;
                        flex: 1 1 0;
                        height: 0;
                        background-image: var(--bg-img-2);
                        background-repeat: no-repeat;
                        background-size: 100% 100%;
                        background-position: center;
                        margin: 0 0 15px 0;
                        pointer-events: initial;
                        &:last-child{
                            margin: 0;
                        }
                    }
                }
                >.left{
                    height: 100%;
                    width: 550px;
                }
                >.right{
                    height: 100%;
                    width: 550px;
                }
            }
        }
        >.centre-box{
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            z-index: 1;
            display: flex;
            flex-direction: column;
            >.v-height{
                width: 100%;
                height: 270px;
            }
            >.container{
                flex: 1 1 0;
                height: 0;
                width: 100%;
            }
        }
    }
}
</style>

好了，一个用transfor缩放的例子就完成了，使用rem的例子以后为大家讲解
源码
DEMO