纯JavaScript实现HTML5 Canvas六种特效滤镜
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 {
- 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:
- <!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
- }
- }
- },
- };