昨天写了一个canvas滤镜的取反色效果，今天加一点效果，主要思路都是一样的，改变getImageData.data[]的值，并返回
代码如下：
<!DOCTYPE html>
<html>
<head>
<meta charset=“UTF-8”>
<title>Canvas Filter Demo</title>
<style type=”text/css”>
#wrap {
width: 600px;
height: 600px;
background-color: #EEEEEE;
}
#sourceDiv {
float: left;
border: 2px solid blue;
}
#canvasDiv {
float: right;
border: 2px solid red;
}
</style>
</head>
<body>
<!–最大的wrap–>
<div id=”wrap”>
<div id=”sourceDiv”><!–图片–>
<img id=”img” src=”img/bg6.jpg” />
</div>
<!–画布–>
<div id=”canvasDiv”>
<canvas id=“canvas”></canvas>
</div>
</div>
<!–按钮组–>
<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>
<script type=”text/javascript”>
window.onload = function() {
var img = document.getElementById(“img”);
var canvas = document.getElementById(“canvas”);
canvas.width = img.clientWidth;
canvas.height = img.clientHeight;
// get 2D context of canvas and draw image
pen = canvas.getContext(“2d”);
pen.drawImage(img, 0, 0, canvas.width, canvas.height);//把图片放在画布上
//获取到所有的按钮
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”);
// 给按钮添加事件
bindButtonEvent(inButton, “click”, invertColor);
bindButtonEvent(adButton, “click”, adjustColor);
bindButtonEvent(blurButton, “click”, blurImage);
bindButtonEvent(reButton, “click”, fudiaoImage);
bindButtonEvent(dkButton, “click”, kediaoImage);
bindButtonEvent(mirrorButton, “click”, mirrorImage);
}
//考虑到浏览器兼容
function bindButtonEvent(element, type, handler) {
if(element.addEventListener) {
element.addEventListener(type, handler, false);
} else {
element.attachEvent(‘on’ + type, handler); // for IE6,7,8
}
}
//通用代码 得到画布上的图片像素数据 返回ImageData对象
function getUseData(canvas){ //形参为画布
//getImageData() 复制画布上指定矩形的像素数据 然后通过putImageData()将图像数据放回画布：
//返回ImageData对象，该对象拷贝了画布指定矩形的像素数据
//对于 ImageData 对象中的每个像素，都存在着四方面的信息,即 RGBA 值 eg:red=ImageData.data[0];
return pen.getImageData(0, 0, canvas.width, canvas.height);
}
function getUseLen(canvas){ //形参为画布
return canvas.width * canvas.height * 4;//图片的数据长度的像素值 图片是由像素组成的
}
//反色
function invertColor() {
var len = getUseLen(canvas);
var canvasData =getUseData(canvas);
//color/alpha 信息以数组形式存在，并存储于 ImageData 对象的 data 属性中
var binaryData = canvasData.data;//存图片的像素值
// 处理所有的像素
gfilter.colorInvertProcess(binaryData, len);
// 将图像数据放回画布
pen.putImageData(canvasData, 0, 0);
}
//灰色调
function adjustColor() {
var canvasData = getUseData(canvas);
var len=getUseLen(canvas);
var binaryData = canvasData.data;
gfilter.colorAdjustProcess(binaryData, len);
pen.putImageData(canvasData, 0, 0);
}
//模糊
function blurImage() {
var canvasData = getUseData(canvas);
var len=getUseLen(canvas);
gfilter.blurProcess(pen, canvasData);
pen.putImageData(canvasData, 0, 0);
}
//浮雕
function fudiaoImage() {
var canvasData = getUseData(canvas);
var len=getUseLen(canvas);
gfilter.reliefProcess(pen, canvasData);
pen.putImageData(canvasData, 0, 0);
}
//雕刻
function kediaoImage() {
var canvasData = getUseData(canvas);
var len=getUseLen(canvas);
gfilter.diaokeProcess(pen, canvasData);
pen.putImageData(canvasData, 0, 0);
}
//镜像
function mirrorImage() {
var canvasData = getUseData(canvas);
var len=getUseLen(canvas);
gfilter.mirrorProcess(pen, canvasData);
pen.putImageData(canvasData, 0, 0);
}
var gfilter = {
type: “canvas”,
name: “filters”,
author: “zhigang”,
getInfo: function() {
return this.author + ‘ ‘ + this.type + ‘ ‘ + this.name;
},
//取反色new pixel = RGB(255-r, 255-g, 255 – b)
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;
}
},
/*灰色调*/
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);
}
},
copyImageData: function(context, src) {
var dst = context.createImageData(src.width, src.height);
dst.data.set(src.data);
return dst;
},
/*图像模糊*/
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
}
}
},
/** * 浮雕效果 after pixel value – before pixel value + 128 */
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
}
}
},
/** 雕刻效果 before pixel value – after pixel value + 128 */
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
}
}
},
//镜像
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
}
}
},
};
</script>
</html>
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原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/13859.html