使用HTML5技术开发的超酷颜色选择器

可能大家见过很多使用jquery/js开发的颜色选择器，今天这里我们将使用HTML5技术来自己实现一个更棒的颜色选择器。希望大家喜欢！

HTML代码

<!-- preview element -->
<p class="preview"></p>
<!-- colorpicker element -->
<p class="colorpicker" style="display:none">
    <canvas id="picker" var="1" width="300" height="300"></canvas>
    <p class="controls">
        <p><label>R</label> <input type="text" id="rVal" /></p>
        <p><label>G</label> <input type="text" id="gVal" /></p>
        <p><label>B</label> <input type="text" id="bVal" /></p>
        <p><label>RGB</label> <input type="text" id="rgbVal" /></p>
        <p><label>HEX</label> <input type="text" id="hexVal" /></p>
    </p>
</p>

代码很简单，包含了2个部分，一个点击元素，一个用来展示颜色选择器的元素。

Javascript代码

$(function(){
    var bCanPreview = true; // can preview

    // create canvas and context objects
    var canvas = document.getElementById('picker');
    var ctx = canvas.getContext('2d');

    // drawing active image
    var image = new Image();
    image.onload = function () {
        ctx.drawImage(image, 0, 0, image.width, image.height); // draw the image on the canvas
    }

    // select desired colorwheel
    var imagesrc="images/colorwheel1.png";
    switch ($(canvas).attr('var')) {
        case '2':
            imagesrc="images/colorwheel2.png";
            break;
        case '3':
            imagesrc="images/colorwheel3.png";
            break;
        case '4':
            imagesrc="images/colorwheel4.png";
            break;
        case '5':
            imagesrc="images/colorwheel5.png";
            break;
    }
    image.src = imageSrc;

    $('#picker').mousemove(function(e) { // mouse move handler
        if (bCanPreview) {
            // get coordinates of current position
            var canvasOffset = $(canvas).offset();
            var canvasX = Math.floor(e.pageX - canvasOffset.left);
            var canvasY = Math.floor(e.pageY - canvasOffset.top);

            // get current pixel
            var imageData = ctx.getImageData(canvasX, canvasY, 1, 1);
            var pixel = imageData.data;

            // update preview color
            var pixelColor = "rgb("+pixel[0]+", "+pixel[1]+", "+pixel[2]+")";
            $('.preview').css('backgroundColor', pixelColor);

            // update controls
            $('#rVal').val(pixel[0]);
            $('#gVal').val(pixel[1]);
            $('#bVal').val(pixel[2]);
            $('#rgbVal').val(pixel[0]+','+pixel[1]+','+pixel[2]);

            var dColor = pixel[2] + 256 * pixel[1] + 65536 * pixel[0];
            $('#hexVal').val('#' + ('0000' + dColor.toString(16)).substr(-6));
        }
    });
    $('#picker').click(function(e) { // click event handler
        bCanPreview = !bCanPreview;
    });
    $('.preview').click(function(e) { // preview click
        $('.colorpicker').fadeToggle("slow", "linear");
        bCanPreview = true;
    });
});

大家可以看到，这是一个非常短的js代码，用来创建新的画布和对象，然后我们画出一个圆形的颜色板。你可以选择不同颜色底板。 这里使用一个参数来设定不同的选择。如下：

<canvas id="picker" var="1" width="300" height="300"></canvas>
<canvas id="picker" var="2" width="300" height="300"></canvas>
<canvas id="picker" var="3" width="300" height="300"></canvas>
<canvas id="picker" var="4" width="300" height="300"></canvas>
<canvas id="picker" var="5" width="300" height="300"></canvas>

下面我们添加事件：mousemove，click事件。这里使用jQuery来实现选择器的展现和隐藏。

$('.preview').click(function(e) { // preview click     
$('.colorpicker').fadeToggle("slow", "linear");     
bCanPreview = true; });

$('#picker').mousemove(function(e) { // mouse move handler
    if (bCanPreview) {
        // get coordinates of current position
        var canvasOffset = $(canvas).offset();
        var canvasX = Math.floor(e.pageX - canvasOffset.left);
        var canvasY = Math.floor(e.pageY - canvasOffset.top);

        // get current pixel
        var imageData = ctx.getImageData(canvasX, canvasY, 1, 1);
        var pixel = imageData.data;

        // update preview color
        var pixelColor = "rgb("+pixel[0]+", "+pixel[1]+", "+pixel[2]+")";
        $('.preview').css('backgroundColor', pixelColor);

        // update controls
        $('#rVal').val(pixel[0]);
        $('#gVal').val(pixel[1]);
        $('#bVal').val(pixel[2]);
        $('#rgbVal').val(pixel[0]+','+pixel[1]+','+pixel[2]);

        var dColor = pixel[2] + 256 * pixel[1] + 65536 * pixel[0];
        $('#hexVal').val('#' + ('0000' + dColor.toString(16)).substr(-6));
    }
});
$('#picker').click(function(e) { // click event handler
    bCanPreview = !bCanPreview;
});

CSS代码

不同颜色底板的CSS：

/* colorpicker styles */
.colorpicker {
    background-color: #222222;
    border-radius: 5px 5px 5px 5px;
    box-shadow: 2px 2px 2px #444444;
    color: #FFFFFF;
    font-size: 12px;
    position: absolute;
    width: 460px;
}
#picker {
    cursor: crosshair;
    float: left;