纯JavaScript实现HTML5 Canvas六种特效滤镜示例
2018-10-12 13:57
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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
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
2.如何绘制一个DOM img对象到Canvas对象中
3.如何从Canvas对象中获取像素数据
4.如何对DOM对象实现鼠标Click事件绑定
5.如何调用实现的gfilter API完成滤镜功能
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：
filter1.html中HTML源代码：
filter1.html中JavaScript源代码：
滤镜源代码(gloomyfishfilter.js)：
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
}
}
},
};
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