純JavaScript實(shí)現(xiàn)HTML5 Canvas 6種特效濾鏡

者：前端Q

轉(zhuǎn)發(fā)鏈接：https://mp.weixin.qq.com/s/ewFfXptccFs5KvjUINLGbQ

前端

小試牛刀，實(shí)現(xiàn)了六款簡(jiǎn)單常見(jiàn)HTML5 Canvas特效濾鏡，并且封裝成一個(gè)純JavaScript可調(diào)用的API文件gloomyfishfilter.js。支持的特效濾鏡分別為：

1.反色

2.灰色調(diào)

3.模糊

4.浮雕

5.雕刻

6.合理

濾鏡原理解釋：

2.灰色調(diào)：獲取一個(gè)預(yù)期點(diǎn)RGB值r，g，b則新的RGB值

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：基于一個(gè)5 * 5的卷積核

4.浮雕與雕刻：

根據(jù)當(dāng)前預(yù)期的前一個(gè)預(yù)期RGB值與它的后一個(gè)重新的RGB值之差再加上128

5.總體：模擬了物體在鏡子中與之對(duì)應(yīng)的效果。

雜項(xiàng)準(zhǔn)備

1、如何獲取Canvas 2d context對(duì)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、如何添加一個(gè)DOM img對(duì)象到Canvas對(duì)象中

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

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

3、如何從Canvas對(duì)象中獲取預(yù)定數(shù)據(jù)

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;

4、如何對(duì)DOM對(duì)象實(shí)現(xiàn)鼠標(biāo)ClickEvent綁定

function bindButtonEvent(element, type, handler) 
{  

if(element.addEventListener){ 

      element.addEventListener(type, handler,**false**); 

   }else{ 

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

   } 

}

5、如何調(diào)用實(shí)現(xiàn)的gfilter API完成濾鏡功能

<scriptsrc=*"gloomyfishfilter.js"*></script> //導(dǎo)入API文件

gfilter.colorInvertProcess(binaryData, len); //調(diào)用 API

6、瀏覽器支持：IE，F(xiàn)F，Chrome上測(cè)試通過(guò)，其中IE上支持通過(guò)以下標(biāo)簽實(shí)現(xiàn)：

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

效果演示：

應(yīng)用程序源代碼：

CSS部分：

#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源代碼：

<!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">灰色調(diào)</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">鏡像</button>
  </div>
</body>
</html>

filter1.html中JavaScript源代碼：

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);
    }

濾鏡源代碼（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    
            }
    }
  },
};

總結(jié)

感謝閱讀，如果你覺(jué)得我今天分享的內(nèi)容，不錯(cuò)，請(qǐng)點(diǎn)一個(gè)贊，謝謝！！

家好，今天給大家介紹一款，canvas實(shí)現(xiàn)的炫酷文字特效html頁(yè)面源碼（圖1）。送給大家哦，獲取方式在本文末尾。

圖1

動(dòng)畫(huà)預(yù)覽如下（圖2）

圖2

代碼完整，需要的朋友可以下載學(xué)習(xí)（圖3）

圖3

本源碼編碼：10155，需要的朋友，點(diǎn)擊下面的鏈接后，搜索10155，即可獲取。

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