js实现图片切割功能

本文实例为大家分享了js实现图片切割的具体代码，供大家参考，具体内容如下

代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .cube{
            height: 0;
            width: 0;
            position: absolute;
            left: 0;
            top:0;

            box-sizing: border-box;
            background-color: lightseagreen;
            opacity: .3;
            z-index: 99;pointer-events: none;
        }
        #big{
            border: 1px solid black;
            height: 500px;
            width: 500px;
            position: relative;
            background-image: url("img/pixel.png");
            line-height: 500px;
            overflow: hidden;
            vertical-align: middle;
            text-align: center;
            float: left;
        }
        #big>img{line-height: 500px; vertical-align: middle;
            max-height: 100%;
            max-width: 100%;
            pointer-events: none;
        }
        .cv{
            position: relative;
            float: left; border: 2px solid lightseagreen;
        }
    </style>
    <script>
        let count=0;let c,b,d,p1,p2,cv,cx,img,p;
        window.onload=function (){
            c=document.querySelectorAll(".cube");
            b=document.getElementById("big");
            cv=document.getElementById("c");
            cx=cv.getContext('2d');
            img=new Image();
            d=b.querySelector("img");
            img.src=d.src;
            img.onload=function(){
                cx.drawImage(img, 0,0,500,500,0,0,500,500);
               p=img.width/b.querySelector("img").width;
               console.log(img);
            }
             p1={
                 x:0,
                 y:0
             };
            p2={
                x:0,
                y:0
            };
            b.addEventListener("click",function (e){
                count++;
                if(count===1){
                    p1.x=e .offsetX;
                    p1.y=e.offsetY;
                    p2.x=e .offsetX;
                    p2.y=e.offsetY;
                    f2();
                    f4();
                }
                if(count===2){
                    p2.x=e.offsetX;
                    p2.y=e.offsetY;
                    myDraw();
                 }
            });
            function f1(){
                c[0].style.height=p2.y+"px";
                c[1].style.height=p2.y+"px";
                c[2].style.height=p2.y+"px";
                c[3].style.top=p2.y+"px";
                c[4].style.top=p2.y+"px";
                c[3].style.height=(p1.y-p2.y)+"px";
                c[4].style.height=(p1.y-p2.y)+"px";
                c[5].style.top=p1.y+"px";
                c[6].style.top=p1.y+"px";
                c[5].style.height=(b.offsetHeight-p1.y)+"px";
                c[6].style.height=b.offsetHeight-p1.y+"px";
                c[7].style.top=p1.y+"px";
                c[7].style.height=(b.offsetHeight-p1.y)+"px";
            }
            function f2(){
                c[0].style.height=p1.y+"px";
                c[1].style.height=p1.y+"px";
                c[2].style.height=p1.y+"px";
                c[3].style.top=p1.y+"px";
                c[4].style.top=p1.y+"px";
                c[3].style.height=(p2.y-p1.y)+"px";
                c[4].style.height=(p2.y-p1.y)+"px";
                c[5].style.top=p2.y+"px";
                c[6].style.top=p2.y+"px";
                c[5].style.height=(b.offsetHeight-p2.y)+"px";
                c[6].style.height=b.offsetHeight-p2.y+"px";
                c[7].style.top=p2.y+"px";
                c[7].style.height=(b.offsetHeight-p2.y)+"px";
            }
            function f3(){
                c[0].style.width=p2.x+"px";
                c[1].style.left=p2.x+"px";
                c[1].style.width=(p1.x-p2.x)+"px";
                c[2].style.left=p1.x+"px";
                c[2].style.width=(b.offsetWidth-p1.x)+"px";
                c[3].style.width=p2.x+"px";
                c[4].style.left=p1.x+"px";
                c[4].style.width=(b.offsetWidth-p2.x)+"px";
                c[5].style.width=p2.x+"px";
                c[6].style.left=p2.x+"px";
                c[6].style.width=(p1.x-p2.x)+"px";
                c[7].style.left=p1.x+"px";
                c[7].style.width=(b.offsetWidth-p1.x)+"px";
            }
            function f4(){
                c[0].style.width=p1.x+"px";
                c[1].style.left=p1.x+"px";
                c[1].style.width=(p2.x-p1.x)+"px";
                c[2].style.left=p2.x+"px";
                c[2].style.width=(b.offsetWidth-p2.x)+"px";
                c[3].style.width=p1.x+"px";
                c[4].style.left=p2.x+"px";
                c[4].style.width=(b.offsetWidth-p2.x)+"px";
                c[5].style.width=p1.x+"px";
                c[6].style.left=p1.x+"px";
                c[6].style.width=(p2.x-p1.x)+"px";
                c[7].style.left=p2.x+"px";
                c[7].style.width=(b.offsetWidth-p2.x)+"px";
            }
            b.addEventListener("mousemove",function (e){
                if(count===1){
                    p2.x=e.offsetX;
                    p2.y=e.offsetY;
                     if(p2.y<p1.y){
                        f1();
                     }else{
                         f2();
                     }

                    if(p2.x<p1.x){
                        f3();
                    }else{
                        f4();
                     }

                 }
            })

        }
        function myDraw(){
            cx.clearRect(0,0,500,500);
            let w=p1.x-p2.x;
            if(w<0){
                w=-w;
            }
            w*=p;
            let h=p1.y-p2.y;
            if(h<0){
                h=-h;
            }
            h*=p;
            if(p1.x<p2.x){
                p1.x=(p1.x-b.querySelector("img").offsetLeft)*p;
            }else{
                p1.x=(p2.x-b.querySelector("img").offsetLeft)*p;
            }
            if(p1.y<p2.y){
                p1.y=(p1.y-b.querySelector("img").offsetTop)*p;
            }else{
                p1.y=(p2.y-b.querySelector("img").offsetTop)*p;
            }
            cx.drawImage(img,
                p1.x,p1.y,
                w,h,0,0,500,500);
            p1.x=0;
            p1.y=0;
            p2.x=0;
            p2.y=0;
        }
    </script>

</head>
<body >

<div
id="big">
    <!--    8个div覆盖-->
    <div class="cube"></div>
    <div class="cube"></div>
    <div class="cube"></div>
    <div class="cube"></div>
    <div class="cube"></div>
    <div class="cube"></div>
    <div class="cube"></div>
    <div class="cube"></div>
    <img src="img/katy2.jpg" alt=""/>
</div>
<div class="cv">
    <canvas id="c" height="500" width="500">

    </canvas>
</div>
</body>
</html>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。