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  • 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:

    <meta http-equiv="X-UA-Compatible"content="chrome=IE8"> 

    效果演示:

    应用程序源代码:

    CSS部分:

    #svgContainer {
    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:
    <!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>
    filter1.html中JavaScript源代码:

    var tempContext = null; // global variable 2d context
    window.onload = function() {
    var source = document.getElementById("source");
    var canvas = document.getElementById("target");
    canvas.width = source.clientWidth;
    canvas.height = source.clientHeight;

    if (!canvas.getContext) {
    console.log("Canvas not supported. Please install a HTML5 compatible browser.");
    return;
    }

    // get 2D context of canvas and draw image
    tempContext = canvas.getContext("2d");
    tempContext.drawImage(source, 0, 0, canvas.width, canvas.height);

    // initialization actions
    var inButton = document.getElementById("invert-button");
    var adButton = document.getElementById("adjust-button");
    var blurButton = document.getElementById("blur-button");
    var reButton = document.getElementById("relief-button");
    var dkButton = document.getElementById("diaoke-button");
    var mirrorButton = document.getElementById("mirror-button");

    // bind mouse click event
    bindButtonEvent(inButton, "click", invertColor);
    bindButtonEvent(adButton, "click", adjustColor);
    bindButtonEvent(blurButton, "click", blurImage);
    bindButtonEvent(reButton, "click", fudiaoImage);
    bindButtonEvent(dkButton, "click", kediaoImage);
    bindButtonEvent(mirrorButton, "click", mirrorImage);
    }

    function bindButtonEvent(element, type, handler)
    {
    if(element.addEventListener) {
    element.addEventListener(type, handler, false);
    } else {
    element.attachEvent('on'+type, handler); // for IE6,7,8
    }
    }

    function invertColor() {
    var canvas = document.getElementById("target");
    var len = canvas.width * canvas.height * 4;
    var canvasData = tempContext.getImageData(0, 0, canvas.width, canvas.height);
    var binaryData = canvasData.data;

    // Processing all the pixels
    gfilter.colorInvertProcess(binaryData, len);

    // Copying back canvas data to canvas
    tempContext.putImageData(canvasData, 0, 0);
    }

    function adjustColor() {
    var canvas = document.getElementById("target");
    var len = canvas.width * canvas.height * 4;
    var canvasData = tempContext.getImageData(0, 0, canvas.width, canvas.height);
    var binaryData = canvasData.data;

    // Processing all the pixels
    gfilter.colorAdjustProcess(binaryData, len);

    // Copying back canvas data to canvas
    tempContext.putImageData(canvasData, 0, 0);
    }

    function blurImage()
    {
    var canvas = document.getElementById("target");
    var len = canvas.width * canvas.height * 4;
    var canvasData = tempContext.getImageData(0, 0, canvas.width, canvas.height);

    // Processing all the pixels
    gfilter.blurProcess(tempContext, canvasData);

    // Copying back canvas data to canvas
    tempContext.putImageData(canvasData, 0, 0);
    }

    function fudiaoImage()
    {
    var canvas = document.getElementById("target");
    var len = canvas.width * canvas.height * 4;
    var canvasData = tempContext.getImageData(0, 0, canvas.width, canvas.height);

    // Processing all the pixels
    gfilter.reliefProcess(tempContext, canvasData);

    // Copying back canvas data to canvas
    tempContext.putImageData(canvasData, 0, 0);
    }

    function kediaoImage()
    {
    var canvas = document.getElementById("target");
    var len = canvas.width * canvas.height * 4;
    var canvasData = tempContext.getImageData(0, 0, canvas.width, canvas.height);

    // Processing all the pixels
    gfilter.diaokeProcess(tempContext, canvasData);

    // Copying back canvas data to canvas
    tempContext.putImageData(canvasData, 0, 0);
    }

    function mirrorImage()
    {
    var canvas = document.getElementById("target");
    var len = canvas.width * canvas.height * 4;
    var canvasData = tempContext.getImageData(0, 0, canvas.width, canvas.height);

    // Processing all the pixels
    gfilter.mirrorProcess(tempContext, canvasData);

    // Copying back canvas data to canvas
    tempContext.putImageData(canvasData, 0, 0);
    }
    滤镜源代码(gloomyfishfilter.js):
    var gfilter = {
    type: "canvas",
    name: "filters",
    author: "zhigang",
    getInfo: function () {
    return this.author + ' ' + this.type + ' ' + this.name;
    },

    /**
    * invert color value of pixel, new pixel = RGB(255-r, 255-g, 255 - b)
    *
    * @param binaryData - canvas's imagedata.data
    * @param l - length of data (width * height of image data)
    */
    colorInvertProcess: function(binaryData, l) {
    for (var i = 0; i < l; i += 4) {
    var r = binaryData[i];
    var g = binaryData[i + 1];
    var b = binaryData[i + 2];

    binaryData[i] = 255-r;
    binaryData[i + 1] = 255-g;
    binaryData[i + 2] = 255-b;
    }
    },

    /**
    * adjust color values and make it more darker and gray...
    *
    * @param binaryData
    * @param l
    */
    colorAdjustProcess: function(binaryData, l) {
    for (var i = 0; i < l; i += 4) {
    var r = binaryData[i];
    var g = binaryData[i + 1];
    var b = binaryData[i + 2];

    binaryData[i] = (r * 0.272) + (g * 0.534) + (b * 0.131);
    binaryData[i + 1] = (r * 0.349) + (g * 0.686) + (b * 0.168);
    binaryData[i + 2] = (r * 0.393) + (g * 0.769) + (b * 0.189);
    }
    },

    /**
    * deep clone image data of canvas
    *
    * @param context
    * @param src
    * @returns
    */
    copyImageData: function(context, src)
    {
    var dst = context.createImageData(src.width, src.height);
    dst.data.set(src.data);
    return dst;
    },

    /**
    * convolution - keneral size 5*5 - blur effect filter(模糊效果)
    *
    * @param context
    * @param canvasData
    */
    blurProcess: function(context, canvasData) {
    console.log("Canvas Filter - blur process");
    var tempCanvasData = this.copyImageData(context, canvasData);
    var sumred = 0.0, sumgreen = 0.0, sumblue = 0.0;
    for ( var x = 0; x < tempCanvasData.width; x++) {
    for ( var y = 0; y < tempCanvasData.height; y++) {

    // Index of the pixel in the array
    var idx = (x + y * tempCanvasData.width) * 4;
    for(var subCol=-2; subCol<=2; subCol++) {
    var colOff = subCol + x;
    if(colOff <0 || colOff >= tempCanvasData.width) {
    colOff = 0;
    }
    for(var subRow=-2; subRow<=2; subRow++) {
    var rowOff = subRow + y;
    if(rowOff < 0 || rowOff >= tempCanvasData.height) {
    rowOff = 0;
    }
    var idx2 = (colOff + rowOff * tempCanvasData.width) * 4;
    var r = tempCanvasData.data[idx2 + 0];
    var g = tempCanvasData.data[idx2 + 1];
    var b = tempCanvasData.data[idx2 + 2];
    sumred += r;
    sumgreen += g;
    sumblue += b;
    }
    }

    // calculate new RGB value
    var nr = (sumred / 25.0);
    var ng = (sumgreen / 25.0);
    var nb = (sumblue / 25.0);

    // clear previous for next pixel point
    sumred = 0.0;
    sumgreen = 0.0;
    sumblue = 0.0;

    // assign new pixel value
    canvasData.data[idx + 0] = nr; // Red channel
    canvasData.data[idx + 1] = ng; // Green channel
    canvasData.data[idx + 2] = nb; // Blue channel
    canvasData.data[idx + 3] = 255; // Alpha channel
    }
    }
    },

    /**
    * after pixel value - before pixel value + 128
    * 浮雕效果
    */
    reliefProcess: function(context, canvasData) {
    console.log("Canvas Filter - relief process");
    var tempCanvasData = this.copyImageData(context, canvasData);
    for ( var x = 1; x < tempCanvasData.width-1; x++)
    {
    for ( var y = 1; y < tempCanvasData.height-1; y++)
    {

    // Index of the pixel in the array
    var idx = (x + y * tempCanvasData.width) * 4;
    var bidx = ((x-1) + y * tempCanvasData.width) * 4;
    var aidx = ((x+1) + y * tempCanvasData.width) * 4;

    // calculate new RGB value
    var nr = tempCanvasData.data[aidx + 0] - tempCanvasData.data[bidx + 0] + 128;
    var ng = tempCanvasData.data[aidx + 1] - tempCanvasData.data[bidx + 1] + 128;
    var nb = tempCanvasData.data[aidx + 2] - tempCanvasData.data[bidx + 2] + 128;
    nr = (nr < 0) ? 0 : ((nr >255) ? 255 : nr);
    ng = (ng < 0) ? 0 : ((ng >255) ? 255 : ng);
    nb = (nb < 0) ? 0 : ((nb >255) ? 255 : nb);

    // assign new pixel value
    canvasData.data[idx + 0] = nr; // Red channel
    canvasData.data[idx + 1] = ng; // Green channel
    canvasData.data[idx + 2] = nb; // Blue channel
    canvasData.data[idx + 3] = 255; // Alpha channel
    }
    }
    },

    /**
    * before pixel value - after pixel value + 128
    * 雕刻效果
    *
    * @param canvasData
    */
    diaokeProcess: function(context, canvasData) {
    console.log("Canvas Filter - process");
    var tempCanvasData = this.copyImageData(context, canvasData);
    for ( var x = 1; x < tempCanvasData.width-1; x++)
    {
    for ( var y = 1; y < tempCanvasData.height-1; y++)
    {

    // Index of the pixel in the array
    var idx = (x + y * tempCanvasData.width) * 4;
    var bidx = ((x-1) + y * tempCanvasData.width) * 4;
    var aidx = ((x+1) + y * tempCanvasData.width) * 4;

    // calculate new RGB value
    var nr = tempCanvasData.data[bidx + 0] - tempCanvasData.data[aidx + 0] + 128;
    var ng = tempCanvasData.data[bidx + 1] - tempCanvasData.data[aidx + 1] + 128;
    var nb = tempCanvasData.data[bidx + 2] - tempCanvasData.data[aidx + 2] + 128;
    nr = (nr < 0) ? 0 : ((nr >255) ? 255 : nr);
    ng = (ng < 0) ? 0 : ((ng >255) ? 255 : ng);
    nb = (nb < 0) ? 0 : ((nb >255) ? 255 : nb);

    // assign new pixel value
    canvasData.data[idx + 0] = nr; // Red channel
    canvasData.data[idx + 1] = ng; // Green channel
    canvasData.data[idx + 2] = nb; // Blue channel
    canvasData.data[idx + 3] = 255; // Alpha channel
    }
    }
    },

    /**
    * mirror reflect
    *
    * @param context
    * @param canvasData
    */
    mirrorProcess : function(context, canvasData) {
    console.log("Canvas Filter - process");
    var tempCanvasData = this.copyImageData(context, canvasData);
    for ( var x = 0; x < tempCanvasData.width; x++) // column
    {
    for ( var y = 0; y < tempCanvasData.height; y++) // row
    {

    // Index of the pixel in the array
    var idx = (x + y * tempCanvasData.width) * 4;
    var midx = (((tempCanvasData.width -1) - x) + y * tempCanvasData.width) * 4;

    // assign new pixel value
    canvasData.data[midx + 0] = tempCanvasData.data[idx + 0]; // Red channel
    canvasData.data[midx + 1] = tempCanvasData.data[idx + 1]; ; // Green channel
    canvasData.data[midx + 2] = tempCanvasData.data[idx + 2]; ; // Blue channel
    canvasData.data[midx + 3] = 255; // Alpha channel
    }
    }
    },

    ---------------------
    作者:gloomyfish
    来源:CSDN
    原文:https://blog.csdn.net/jia20003/article/details/9195915
    版权声明:本文为博主原创文章,转载请附上博文链接!

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  • 原文地址:https://www.cnblogs.com/ckAng/p/9811332.html
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