这里有新鲜出炉的 Javascript 教程,程序狗速度看过来!
Javascript 是一种由 Netscape 的 LiveScript 发展而来的原型化继承的基于对象的动态类型的区分大小写的客户端脚本语言,主要目的是为了解决服务器端语言,比如 Perl,遗留的速度问题,为客户提供更流畅的浏览效果。
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。
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,程序源代码如下,感兴趣的朋友可以参考下哈
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
- }
- }
- },
- };
来源: http://www.phperz.com/article/17/0429/279920.html