js canvas九宫格切图 JavaScript canvas实现九宫格切图效果

时间:2021-09-01 前端起步人气:0

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首先页面展示

直接上代码

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body {
            text-align: center;
        }
        
        canvas {
            border: 1px solid;
        }
        
        .newcanvas {
            width: 316px;
            height: 316px;
            margin: auto;
        }
        
        .newpohoto,
        .download {
            width: 300px;
            height: 40px;
            line-height: 40px;
            margin: auto;
            background-color: cornflowerblue;
            border-radius: 5px;
            cursor: pointer;
            margin: 10px auto;
            color: white;
        }
    </style>
</head>

<body>
    <h3>使用canvas实现九宫格切图的效果</h3>
    <div class="mycanvas">
        <canvas width="300" height="300" id="mycnavas"></canvas>
    </div>
    <div class="newpohoto">
        开始切图
    </div>
    <div class="newcanvas">
        <canvas width="100" height="100" id="img1"></canvas>
        <canvas width="100" height="100" id="img2"></canvas>
        <canvas width="100" height="100" id="img3"></canvas>
        <canvas width="100" height="100" id="img4"></canvas>
        <canvas width="100" height="100" id="img5"></canvas>
        <canvas width="100" height="100" id="img6"></canvas>
        <canvas width="100" height="100" id="img7"></canvas>
        <canvas width="100" height="100" id="img8"></canvas>
        <canvas width="100" height="100" id="img9"></canvas>
    </div>
    <div class="download">
        下载图片
    </div>
    <script>
         var canvas = document.getElementById("mycnavas");      //现将图片放上去
        var cxt = mycnavas.getContext("2d");
        var img = new Image();
        img.src = "../img/img10.jpg";
        window.onload = function() {
            cxt.drawImage(img, 0, 0, 400, 300);             //画好图片的位置
        } 
        var arr = [];        //将切的图片存到数组里面
        document.getElementsByClassName("newpohoto")[0].onclick = function() {
            var q = 1;
            for (var i = 0; i < 3; i++) {     
                for (var j = 0; j < 3; j++) {
                    var data = cxt.getImageData(j * 100, i * 100, 400, 100);      //类似于“复制”功能
                    var img = document.getElementById("img" + q)
                    var newcxt = img.getContext("2d");
                    newcxt.putImageData(data, 0, 0);    //类似“粘贴”功能
                  arr.push(console.log(img.toDataURL(q + ".png")))     //toDataURL()方法的两个参数：DataURL(type, encoderOptions) type指定转换为base64编码后图片的格式，如：image/png、image/jpeg、image/webp等等，默认为image/png格式；                                     
                    q++;
                    console.log(arr)
                }
            }

        }
         //下载切的图片
        var arr = [];
        document.getElementsByClassName('download')[0].onclick = function() {
            for (var i = 0; i < 9; i++) {
                var a = document.createElement('a');
                a.download = 'img' + (i + 1);
                a.href = arr[i];
                document.body.appendChild(a);
                a.click();
            }
        }
    </script>

</body>

</html>

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