纯JavaScript实现HTML5 Canvas六种特效滤镜

小试牛刀，实现了六款简单常见HTML5 Canvas特效滤镜，并且封装成一个纯

JavaScript可调用的API文件gloomyfishfilter.js。支持的特效滤镜分别为：

1. 反色

2. 灰色调

3. 模糊

4. 浮雕

5. 雕刻

6. 镜像

滤镜原理解释：

1. 反色：获取一个像素点RGB值r, g, b则新的RGB值为(255-r, 255-g, 255-b)

2. 灰色调：获取一个像素点RGB值r, g, b则新的RGB值为

newr = (r * 0.272) + (g * 0.534) + (b * 0.131);

newg = (r * 0.349) + (g * 0.686) + (b * 0.168);

newb = (r * 0.393) + (g * 0.769) + (b * 0.189);

3. 模糊：基于一个5*5的卷积核

4. 浮雕与雕刻：

基于当前像素的前一个像素RGB值与它的后一个像素的RGB值之差再加上128

5. 镜像：模拟了物体在镜子中与之对应的效果。

杂项准备

1. 如何获取Canvas 2d context对象

var canvas = document.getElementById("target");

canvas.width = source.clientWidth;

canvas.height = source.clientHeight;

if(!canvas.getContext) {

console.log("Canvas not supported. Please install a HTML5compatible browser.");

return;

}

// get 2D context of canvas and draw image

tempContext = canvas.getContext("2d");

2. 如何绘制一个DOM img对象到Canvas对象中

var source = document.getElementById("source");

tempContext.drawImage(source, 0, 0, canvas.width,canvas.height);

3. 如何从Canvas对象中获取像素数据

var canvas = document.getElementById("target");

varlen = canvas.width * canvas.height * 4;

var canvasData = tempContext.getImageData(0, 0, canvas.width, canvas.height);

var binaryData = canvasData.data;

4. 如何对DOM对象实现鼠标Click事件绑定

function bindButtonEvent(element, type, handler)

{

if(element.addEventListener){

element.addEventListener(type, handler,false);

}else {

element.attachEvent('on'+type, handler);// for IE6,7,8

}

5. 如何调用实现的gfilter API完成滤镜功能

<scriptsrc="gloomyfishfilter.js"></script> //导入API文件

gfilter.colorInvertProcess(binaryData, len); //调用 API

6. 浏览器支持：IE, FF, Chrome上测试通过，其中IE上支持通过以下标签实现：

效果演示：

应用程序源代码：

CSS部分：

[css]
#svgContainer {
    width:800px;
    height:600px;
    background-color:#EEEEEE;
}

#sourceDiv { float: left; border: 2px solid blue}
#targetDiv { float: right;border: 2px solid red}

#svgContainer {
width:800px;
height:600px;
background-color:#EEEEEE;
}

#sourceDiv { float: left; border: 2px solid blue}
#targetDiv { float: right;border: 2px solid red} filter1.html中HTML源代码：

[html]
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="X-UA-Compatible" content="chrome=IE8">
<meta http-equiv="Content-type" content="text/html;charset=UTF-8">
<title>Canvas Filter Demo</title>
<link href="default.css" rel="stylesheet" />
<script src="gloomyfishfilter.js"></scrip>
</head>
<body>
    <h1>HTML Canvas Image Process - By Gloomy Fish</h1>
    <div id="svgContainer">
        <div id="sourceDiv">
            <img id="source" src="../test.png" />
        </div>
        <div id="targetDiv">
            <canvas id="target"></canvas>
        </div>
    </div>
    <div id="btn-group">
        <button type="button" id="invert-button">反色</button>
        <button type="button" id="adjust-button">灰色调</button>
        <button type="button" id="blur-button">模糊</button>
        <button type="button" id="relief-button">浮雕</button>
        <button type="button" id="diaoke-button">雕刻</button>
        <button type="button" id="mirror-button">镜像</button>
    </div>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="X-UA-Compatible" content="chrome=IE8">
<meta http-equiv="Content-type" content="text/html;charset=UTF-8">
<title>Canvas Filter Demo</title>
<link href="default.css" rel="stylesheet" />
<script src="gloomyfishfilter.js"></scrip>
</head>
<body>
<h1>HTML Canvas Image Process - By Gloomy Fish</h1>
<div id="svgContainer">
  <div id="sourceDiv">
   <img id="source" src="../test.png" />
  </div>
  <div id="targetDiv">
   <canvas id="target"></canvas>
  </div>
</div>
<div id="btn-group">
  <button type="button" id="invert-button">反色</button>
  <button type="button" id="adjust-button">灰色调</button>
  <button type="button" id="blur-button">模糊</button&g

补充：web前端 , HTML 5 ,