HTML5 canvas颜色选择器

2024-09-05 12:18:53

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HTML5 Canvas实现的网页颜色选择器功能，首先用Canvas画一幅图，然后添加鼠标事件 “鼠标移动”，“鼠标点击”。在鼠标移动的时候，显示当前划过的颜色预览，在鼠标点击的时候，选中当前颜色，显示颜色的细节。为确保效果正常运行，请在IE9、火狐或Chrome下运行代码。

<!DOCTYPE html><html lang="en" ><head><meta charset="utf-8" /><title>HTML5 canvas颜色选择器</title><style>*{margin:0; padding:0;}body{background-color:#bababa; color:#fff; font:14px/1.3 Arial,sans-serif;}footer{background-color:#212121; bottom:0; box-shadow: 0 -1px 2px #111111; display:block; height:70px; left:0; position:fixed; width:100%; z-index:100;}footer h2{font-size:22px; font-weight:normal; left:50%; margin-left:-400px; padding:22px 0; position:absolute; width:540px;}footer a.stuts,a.stuts:visited{border:none; text-decoration:none; color:#fcfcfc; font-size:14px; left:50%; line-height:31px; margin:23px 0 0 110px; position:absolute; top:0;}footer .stuts span{font-size:22px; font-weight:bold; margin-left:5px;}.container{color:#000; margin:20px auto; position:relative; width:730px;}.column1{float:left; width:500px;}.column2{float:left; padding-left:20px; width:170px;}#panel{border:1px #000 solid; box-shadow:4px 6px 6px #444444; cursor:crosshair;}.column2 > div{margin-bottom:10px;}#swImage{border:1px #000 solid; box-shadow:2px 3px 3px #444444; cursor:pointer; height:25px; line-height:25px; border-radius:3px; -moz-border-radius:3px; -webkit-border-radius:3px;}#swImage:hover{margin-left:2px;}#preview{border:1px #000 solid; box-shadow:2px 3px 3px #444444; height:80px; width:80px; border-radius:3px; -moz-border-radius:3px; -webkit-border-radius:3px;}.column2 input[type=text]{float:right; width:110px;}</style><script type="text/javascript" src="/ajaxjs/jquery-1.6.2.min.js"></script><script type="text/javascript">var canvas;var ctx;var images = [     '/jscss/demoimg/wall1.jpg',    '/jscss/demoimg/wall2.jpg',    '/jscss/demoimg/wall3.jpg',    '/jscss/demoimg/wall4.jpg',    '/jscss/demoimg/wall5.jpg',    '/jscss/demoimg/wall6.jpg',    '/jscss/demoimg/wall7.jpg',    '/jscss/demoimg/wall8.jpg',    '/jscss/demoimg/wall9.jpg',    '/jscss/demoimg/wall10.jpg'];var iActiveImage = 0;$(function(){    var image = new Image();    image.onload = function () {        ctx.drawImage(image, 0, 0, image.width, image.height); // draw the image on the canvas    }    image.src = images[iActiveImage];    canvas = document.getElementById('panel');    ctx = canvas.getContext('2d');    $('#panel').mousemove(function(e) { // mouse move handler        var canvasOffset = $(canvas).offset();        var canvasX = Math.floor(e.pageX - canvasOffset.left);        var canvasY = Math.floor(e.pageY - canvasOffset.top);        var imageData = ctx.getImageData(canvasX, canvasY, 1, 1);        var pixel = imageData.data;        var pixelColor = "rgba("+pixel[0]+", "+pixel[1]+", "+pixel[2]+", "+pixel[3]+")";        $('#preview').css('backgroundColor', pixelColor);    });    $('#panel').click(function(e) { // mouse click handler        var canvasOffset = $(canvas).offset();        var canvasX = Math.floor(e.pageX - canvasOffset.left);        var canvasY = Math.floor(e.pageY - canvasOffset.top);        var imageData = ctx.getImageData(canvasX, canvasY, 1, 1);        var pixel = imageData.data;        $('#rVal').val(pixel[0]);        $('#gVal').val(pixel[1]);        $('#bVal').val(pixel[2]);        $('#rgbVal').val(pixel[0]+','+pixel[1]+','+pixel[2]);        $('#rgbaVal').val(pixel[0]+','+pixel[1]+','+pixel[2]+','+pixel[3]);        var dColor = pixel[2] + 256 * pixel[1] + 65536 * pixel[0];        $('#hexVal').val( '#' + dColor.toString(16) );    });     $('#swImage').click(function(e) { // switching images        iActiveImage++;        if (iActiveImage >= 10) iActiveImage = 0;        image.src = images[iActiveImage];    });});</script>    </head>    <body>        <div class="container">            <div class="column1">                <canvas id="panel" width="500" height="333"></canvas>            </div>            <div class="column2">                <div><input type="button" value="Next image" id="swImage" /></div>                <div>Preview:</div>                <div id="preview"></div>                <div>Color:</div>                <div>R: <input type="text" id="rVal" /></div>                <div>G: <input type="text" id="gVal" /></div>                <div>B: <input type="text" id="bVal" /></div>                <div>RGB: <input type="text" id="rgbVal" /></div>                <div>RGBA: <input type="text" id="rgbaVal" /></div>                <div>HEX: <input type="text" id="hexVal" /></div>                <hr />            </div>            <div style="clear:both;"></div>        </div>        <footer>            <h2>HTML5 canvas - Image color picker</h2>            Back to original tutorial on <span>Script Tutorials</span>        </footer>    </body></html>

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