13.resize妙用（书上看到的）

上效果图

准备一张类似比例的图

DOM

<div class="shape-9 box">
    <div>
        <img src="img/bg-2.jpg" alt="before"/>
    </div>
        <img src="img/bg-2.jpg" alt="after"/>
</div>

css

.box{
    height: 300px;
     534px;
    margin: 20px auto;
    border: 1px solid rgba(0,0,0,.16);
    border-radius: 4px;
    overflow: hidden;
}

　　　　　　　.shape-9{
                position: relative;
            }
            .shape-9>div{
                position: absolute;
                top: 0;left: 0;bottom: 0;
                width: 10%;
                max-width: 100%;
                overflow: hidden;
                resize: horizontal;
            }
            .shape-9>div>img{
                
                filter: blur(4px);
            }
            .shape-9>div::before{
                content: '';
                position: absolute;
                bottom: 0;right: 0;
                width: 12px;height: 12px;
                padding: 5px;
                background: linear-gradient(-45deg,white 50%,transparent 0);
                background-clip: content-box;
                cursor: ew-resize;
                z-index: 1;
            }
            .shape-9 img{
                display: block;
                user-select:none;
            }