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6174/canvas-blur-image.js

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canvas image blur
Raw
canvas-blur-image.js
/**
* Light layer on top of a canvas element to represent an image displayed
* within. Pass in a canvas element and an Image object and you'll see the
* image within the canvas element. Use the provided methods (e.g. blur) to
* manipulate it.
*
* @constructor
* @param {HTMLElement} element HTML canvas element.
* @param {Image} image Image object.
*/
var CanvasImage = function(element, image) {
this.image = image;
this.element = element;
this.element.width = this.image.width;
this.element.height = this.image.height;
this.context = this.element.getContext("2d");
this.context.drawImage(this.image, 0, 0);
};
CanvasImage.prototype = {
/**
* Runs a blur filter over the image.
*
* @param {int} strength Strength of the blur.
*/
blur: function (strength) {
this.context.globalAlpha = 0.5; // Higher alpha made it more smooth
// Add blur layers by strength to x and y
// 2 made it a bit faster without noticeable quality loss
for (var y = -strength; y <= strength; y += 2) {
for (var x = -strength; x <= strength; x += 2) {
// Apply layers
this.context.drawImage(this.element, x, y);
// Add an extra layer, prevents it from rendering lines
// on top of the images (does makes it slower though)
if (x>=0 && y>=0) {
this.context.drawImage(this.element, -(x-1), -(y-1));
}
}
}
this.context.globalAlpha = 1.0;
}
};
/**
* Initialise an image on the page and blur it.
*/
window.onload = function() {
var url = '../sunset.jpg',
image,
canvasImage;
image = new Image();
image.onload = function () {
canvasImage = new CanvasImage(document.getElementById('blur_1'), this);
try{console.time('blur_1');}catch(err){}
canvasImage.blur(1);
try{console.timeEnd('blur_1');}catch(err){}
canvasImage = new CanvasImage(document.getElementById('blur_2'), this);
try{console.time('blur_2');}catch(err){}
canvasImage.blur(2);
try{console.timeEnd('blur_2');}catch(err){}
canvasImage = new CanvasImage(document.getElementById('blur_3'), this);
try{console.time('blur_3');}catch(err){}
canvasImage.blur(3);
try{console.timeEnd('blur_3');}catch(err){}
canvasImage = new CanvasImage(document.getElementById('blur_4'), this);
try{console.time('blur_4');}catch(err){}
canvasImage.blur(4);
try{console.timeEnd('blur_4');}catch(err){}
};
image.src = url;
};
Raw
demo.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!-- saved from url=(0014)about:internet -->
<html class="yui3-js-enabled" xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head>
<title>StackBlur - A fast, almost Gaussian blur for Canvas by Mario Klingemann, Quasimondo</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<style type="text/css" media="screen">
body { text-align:center; background-color: #ffffff; }
.slider {
position: relative;
text-align: center;
cursor: move;
padding: 0;
margin: 0;
height: 21px;
width: 21px;
}
.slider div { }
#slider-contentbox {
position: absolute;
top: 400px;
left: 20px;
height: 1px;
width: 181px;
padding: 10px;
background-color: #CDCDCD;
}
#slider-valuebox {
position: relative;
height: 1px;
background-color: #666;
}
#slider-thumb {
background-color: #202020;
top:-10px;
left:-10px;
color: #000;
}
</style>
<script src="StackBlurDemo_files/yui-min.js"></script>
<script src="StackBlurDemo_files/yui.js" type="text/javascript"></script>
<script src="StackBlur.js" language="javascript"></script>
<script type="text/javascript">
/* <![CDATA[ */
(function() {
var s = document.createElement('script'), t = document.getElementsByTagName('script')[0];
s.type = 'text/javascript';
s.async = true;
s.src = 'http://api.flattr.com/js/0.5.0/load.js?mode=auto';
t.parentNode.insertBefore(s, t);
})();
/* ]]> */
</script>
<script src="StackBlurDemo_files/loader-min.js" type="text/javascript" id="yui_3_1_0_1_12868170921042"></script><script src="StackBlurDemo_files/combo.js" type="text/javascript" id="yui_3_1_0_1_12868170921043"></script></head>
<body>
<div id="imageHolder" style="position:absolute;left:20px; top:20px;text-align:center;font-size:10px;">
<img id="srcimg" src="StackBlurDemo_files/lonerider2.jpg"><br>
</div>
<div id="canvasHolder" style="position:absolute;left:20px; top:20px;text-align:center;font-size:10px;">
<canvas height="375" width="500" style="width: 500px; height: 375px;" id="canvas">
</canvas></div>
<div id="slider-contentbox">
<div id="slider-valuebox">
<div style="left: -5px; top: -10px;" id="slider-thumb" class="slider yui3-dd-draggable"> </div>
</div>
</div>
<div id="centerlog" style="position:absolute; left: 230px; top:403px;font-size:12px;">Radius: 0</div>
<div style="position:absolute; left: 450px; top:400px;">
<script type="text/javascript">
var blurRadius = 0;
YUI({
//Last Gallery Build of this module
gallery: 'gallery-2010.02.19-03'
}).use('dd-constrain', 'node', 'gallery-center', 'gallery-simpleslider', function( Y ) {
var thumb = Y.one('#slider-thumb'),
slider = new Y.apm.SimpleSlider({
node: '#slider-contentbox'
}).render();
slider.on('valueChange', function(e) {
blurRadius = e.newVal[0];
Y.one('#centerlog').set('innerHTML', "Radius: " + e.newVal[0]);
stackBlurImage( 'srcimg', 'canvas', blurRadius, false );
});
})
</script></div>
<div style="position:absolute; left: 20px; top:430px;font-size:12px;text-align:left;">This is a demo for a Javascript / Canvas based implementation of my <a href="http://incubator.quasimondo.com/processing/fast_blur_deluxe.php">StackBlur algorithm</a>.<br/><br/>
Usage: stackBlurImage( sourceImageID, targetCanvasID, radius, blurAlphaChannel );<br/>
or: stackBlurCanvasRGBA( targetCanvasID, top_x, top_y, width, height, radius );<br/>
or: stackBlurCanvasRGB( targetCanvasID, top_x, top_y, width, height, radius );<br/><br />
Download source: <a href="StackBlur.js"/>StackBlur v0.5</a>
<a class="FlattrButton" style="display:none;"
href="http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html"></a> <br/><br/><br/>
Thank you to <a href="http://shaver.off.net/diary/">Mike Shaver</a> for fixing my first slider implementation.<br/>
Thanks to Michael Deal for noticing and fixing the ARGB/RGBA mixup and the pre-multiplied alpha bug.<br/><br />
For some slightly faster box blurs which do not look as good though check out my <a href="http://www.quasimondo.com/BoxBlurForCanvas/FastBlurDemo.html">Superfast Blur</a>, <a href="http://www.quasimondo.com/BoxBlurForCanvas/FastBlur2Demo.html">StackBox Blur</a> and <a href="http://www.quasimondo.com/IntegralImageForCanvas/IntegralImageBlurDemo.html">Integral Image Blur</a>.<br/><br />
For a speed comparison of all 4 blur algorithms check <a href="http://jsperf.com/superfastblur-vs-stackboxblur-vs-stackblur/2">this jsPerf test</a>.
</div>
</body>
</html>
Raw
stackBlur.js
/*
StackBlur - a fast almost Gaussian Blur For Canvas
Version: 0.5
Author: Mario Klingemann
Contact: mario@quasimondo.com
Website: http://www.quasimondo.com/StackBlurForCanvas
Twitter: @quasimondo
In case you find this class useful - especially in commercial projects -
I am not totally unhappy for a small donation to my PayPal account
mario@quasimondo.de
Or support me on flattr:
https://flattr.com/thing/72791/StackBlur-a-fast-almost-Gaussian-Blur-Effect-for-CanvasJavascript
Copyright (c) 2010 Mario Klingemann
Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
*/
var mul_table = [
512,512,456,512,328,456,335,512,405,328,271,456,388,335,292,512,
454,405,364,328,298,271,496,456,420,388,360,335,312,292,273,512,
482,454,428,405,383,364,345,328,312,298,284,271,259,496,475,456,
437,420,404,388,374,360,347,335,323,312,302,292,282,273,265,512,
497,482,468,454,441,428,417,405,394,383,373,364,354,345,337,328,
320,312,305,298,291,284,278,271,265,259,507,496,485,475,465,456,
446,437,428,420,412,404,396,388,381,374,367,360,354,347,341,335,
329,323,318,312,307,302,297,292,287,282,278,273,269,265,261,512,
505,497,489,482,475,468,461,454,447,441,435,428,422,417,411,405,
399,394,389,383,378,373,368,364,359,354,350,345,341,337,332,328,
324,320,316,312,309,305,301,298,294,291,287,284,281,278,274,271,
268,265,262,259,257,507,501,496,491,485,480,475,470,465,460,456,
451,446,442,437,433,428,424,420,416,412,408,404,400,396,392,388,
385,381,377,374,370,367,363,360,357,354,350,347,344,341,338,335,
332,329,326,323,320,318,315,312,310,307,304,302,299,297,294,292,
289,287,285,282,280,278,275,273,271,269,267,265,263,261,259];
var shg_table = [
9, 11, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17,
17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19,
19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20,
20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24 ];
function stackBlurImage( imageID, canvasID, radius, blurAlphaChannel )
{
var img = document.getElementById( imageID );
var w = img.naturalWidth;
var h = img.naturalHeight;
var canvas = document.getElementById( canvasID );
canvas.style.width = w + "px";
canvas.style.height = h + "px";
canvas.width = w;
canvas.height = h;
var context = canvas.getContext("2d");
context.clearRect( 0, 0, w, h );
context.drawImage( img, 0, 0 );
if ( isNaN(radius) || radius < 1 ) return;
if ( blurAlphaChannel )
stackBlurCanvasRGBA( canvasID, 0, 0, w, h, radius );
else
stackBlurCanvasRGB( canvasID, 0, 0, w, h, radius );
}
function stackBlurCanvasRGBA( id, top_x, top_y, width, height, radius )
{
if ( isNaN(radius) || radius < 1 ) return;
radius |= 0;
var canvas = document.getElementById( id );
var context = canvas.getContext("2d");
var imageData;
try {
try {
imageData = context.getImageData( top_x, top_y, width, height );
} catch(e) {
// NOTE: this part is supposedly only needed if you want to work with local files
// so it might be okay to remove the whole try/catch block and just use
// imageData = context.getImageData( top_x, top_y, width, height );
try {
netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");
imageData = context.getImageData( top_x, top_y, width, height );
} catch(e) {
alert("Cannot access local image");
throw new Error("unable to access local image data: " + e);
return;
}
}
} catch(e) {
alert("Cannot access image");
throw new Error("unable to access image data: " + e);
}
var pixels = imageData.data;
var x, y, i, p, yp, yi, yw, r_sum, g_sum, b_sum, a_sum,
r_out_sum, g_out_sum, b_out_sum, a_out_sum,
r_in_sum, g_in_sum, b_in_sum, a_in_sum,
pr, pg, pb, pa, rbs;
var div = radius + radius + 1;
var w4 = width << 2;
var widthMinus1 = width - 1;
var heightMinus1 = height - 1;
var radiusPlus1 = radius + 1;
var sumFactor = radiusPlus1 * ( radiusPlus1 + 1 ) / 2;
var stackStart = new BlurStack();
var stack = stackStart;
for ( i = 1; i < div; i++ )
{
stack = stack.next = new BlurStack();
if ( i == radiusPlus1 ) var stackEnd = stack;
}
stack.next = stackStart;
var stackIn = null;
var stackOut = null;
yw = yi = 0;
var mul_sum = mul_table[radius];
var shg_sum = shg_table[radius];
for ( y = 0; y < height; y++ )
{
r_in_sum = g_in_sum = b_in_sum = a_in_sum = r_sum = g_sum = b_sum = a_sum = 0;
r_out_sum = radiusPlus1 * ( pr = pixels[yi] );
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1] );
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2] );
a_out_sum = radiusPlus1 * ( pa = pixels[yi+3] );
r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;
a_sum += sumFactor * pa;
stack = stackStart;
for( i = 0; i < radiusPlus1; i++ )
{
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack.a = pa;
stack = stack.next;
}
for( i = 1; i < radiusPlus1; i++ )
{
p = yi + (( widthMinus1 < i ? widthMinus1 : i ) << 2 );
r_sum += ( stack.r = ( pr = pixels[p])) * ( rbs = radiusPlus1 - i );
g_sum += ( stack.g = ( pg = pixels[p+1])) * rbs;
b_sum += ( stack.b = ( pb = pixels[p+2])) * rbs;
a_sum += ( stack.a = ( pa = pixels[p+3])) * rbs;
r_in_sum += pr;
g_in_sum += pg;
b_in_sum += pb;
a_in_sum += pa;
stack = stack.next;
}
stackIn = stackStart;
stackOut = stackEnd;
for ( x = 0; x < width; x++ )
{
pixels[yi+3] = pa = (a_sum * mul_sum) >> shg_sum;
if ( pa != 0 )
{
pa = 255 / pa;
pixels[yi] = ((r_sum * mul_sum) >> shg_sum) * pa;
pixels[yi+1] = ((g_sum * mul_sum) >> shg_sum) * pa;
pixels[yi+2] = ((b_sum * mul_sum) >> shg_sum) * pa;
} else {
pixels[yi] = pixels[yi+1] = pixels[yi+2] = 0;
}
r_sum -= r_out_sum;
g_sum -= g_out_sum;
b_sum -= b_out_sum;
a_sum -= a_out_sum;
r_out_sum -= stackIn.r;
g_out_sum -= stackIn.g;
b_out_sum -= stackIn.b;
a_out_sum -= stackIn.a;
p = ( yw + ( ( p = x + radius + 1 ) < widthMinus1 ? p : widthMinus1 ) ) << 2;
r_in_sum += ( stackIn.r = pixels[p]);
g_in_sum += ( stackIn.g = pixels[p+1]);
b_in_sum += ( stackIn.b = pixels[p+2]);
a_in_sum += ( stackIn.a = pixels[p+3]);
r_sum += r_in_sum;
g_sum += g_in_sum;
b_sum += b_in_sum;
a_sum += a_in_sum;
stackIn = stackIn.next;
r_out_sum += ( pr = stackOut.r );
g_out_sum += ( pg = stackOut.g );
b_out_sum += ( pb = stackOut.b );
a_out_sum += ( pa = stackOut.a );
r_in_sum -= pr;
g_in_sum -= pg;
b_in_sum -= pb;
a_in_sum -= pa;
stackOut = stackOut.next;
yi += 4;
}
yw += width;
}
for ( x = 0; x < width; x++ )
{
g_in_sum = b_in_sum = a_in_sum = r_in_sum = g_sum = b_sum = a_sum = r_sum = 0;
yi = x << 2;
r_out_sum = radiusPlus1 * ( pr = pixels[yi]);
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1]);
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2]);
a_out_sum = radiusPlus1 * ( pa = pixels[yi+3]);
r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;
a_sum += sumFactor * pa;
stack = stackStart;
for( i = 0; i < radiusPlus1; i++ )
{
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack.a = pa;
stack = stack.next;
}
yp = width;
for( i = 1; i <= radius; i++ )
{
yi = ( yp + x ) << 2;
r_sum += ( stack.r = ( pr = pixels[yi])) * ( rbs = radiusPlus1 - i );
g_sum += ( stack.g = ( pg = pixels[yi+1])) * rbs;
b_sum += ( stack.b = ( pb = pixels[yi+2])) * rbs;
a_sum += ( stack.a = ( pa = pixels[yi+3])) * rbs;
r_in_sum += pr;
g_in_sum += pg;
b_in_sum += pb;
a_in_sum += pa;
stack = stack.next;
if( i < heightMinus1 )
{
yp += width;
}
}
yi = x;
stackIn = stackStart;
stackOut = stackEnd;
for ( y = 0; y < height; y++ )
{
p = yi << 2;
pixels[p+3] = pa = (a_sum * mul_sum) >> shg_sum;
if ( pa > 0 )
{
pa = 255 / pa;
pixels[p] = ((r_sum * mul_sum) >> shg_sum ) * pa;
pixels[p+1] = ((g_sum * mul_sum) >> shg_sum ) * pa;
pixels[p+2] = ((b_sum * mul_sum) >> shg_sum ) * pa;
} else {
pixels[p] = pixels[p+1] = pixels[p+2] = 0;
}
r_sum -= r_out_sum;
g_sum -= g_out_sum;
b_sum -= b_out_sum;
a_sum -= a_out_sum;
r_out_sum -= stackIn.r;
g_out_sum -= stackIn.g;
b_out_sum -= stackIn.b;
a_out_sum -= stackIn.a;
p = ( x + (( ( p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1 ) * width )) << 2;
r_sum += ( r_in_sum += ( stackIn.r = pixels[p]));
g_sum += ( g_in_sum += ( stackIn.g = pixels[p+1]));
b_sum += ( b_in_sum += ( stackIn.b = pixels[p+2]));
a_sum += ( a_in_sum += ( stackIn.a = pixels[p+3]));
stackIn = stackIn.next;
r_out_sum += ( pr = stackOut.r );
g_out_sum += ( pg = stackOut.g );
b_out_sum += ( pb = stackOut.b );
a_out_sum += ( pa = stackOut.a );
r_in_sum -= pr;
g_in_sum -= pg;
b_in_sum -= pb;
a_in_sum -= pa;
stackOut = stackOut.next;
yi += width;
}
}
context.putImageData( imageData, top_x, top_y );
}
function stackBlurCanvasRGB( id, top_x, top_y, width, height, radius )
{
if ( isNaN(radius) || radius < 1 ) return;
radius |= 0;
var canvas = document.getElementById( id );
var context = canvas.getContext("2d");
var imageData;
try {
try {
imageData = context.getImageData( top_x, top_y, width, height );
} catch(e) {
// NOTE: this part is supposedly only needed if you want to work with local files
// so it might be okay to remove the whole try/catch block and just use
// imageData = context.getImageData( top_x, top_y, width, height );
try {
netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");
imageData = context.getImageData( top_x, top_y, width, height );
} catch(e) {
alert("Cannot access local image");
throw new Error("unable to access local image data: " + e);
return;
}
}
} catch(e) {
alert("Cannot access image");
throw new Error("unable to access image data: " + e);
}
var pixels = imageData.data;
var x, y, i, p, yp, yi, yw, r_sum, g_sum, b_sum,
r_out_sum, g_out_sum, b_out_sum,
r_in_sum, g_in_sum, b_in_sum,
pr, pg, pb, rbs;
var div = radius + radius + 1;
var w4 = width << 2;
var widthMinus1 = width - 1;
var heightMinus1 = height - 1;
var radiusPlus1 = radius + 1;
var sumFactor = radiusPlus1 * ( radiusPlus1 + 1 ) / 2;
var stackStart = new BlurStack();
var stack = stackStart;
for ( i = 1; i < div; i++ )
{
stack = stack.next = new BlurStack();
if ( i == radiusPlus1 ) var stackEnd = stack;
}
stack.next = stackStart;
var stackIn = null;
var stackOut = null;
yw = yi = 0;
var mul_sum = mul_table[radius];
var shg_sum = shg_table[radius];
for ( y = 0; y < height; y++ )
{
r_in_sum = g_in_sum = b_in_sum = r_sum = g_sum = b_sum = 0;
r_out_sum = radiusPlus1 * ( pr = pixels[yi] );
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1] );
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2] );
r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;
stack = stackStart;
for( i = 0; i < radiusPlus1; i++ )
{
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack = stack.next;
}
for( i = 1; i < radiusPlus1; i++ )
{
p = yi + (( widthMinus1 < i ? widthMinus1 : i ) << 2 );
r_sum += ( stack.r = ( pr = pixels[p])) * ( rbs = radiusPlus1 - i );
g_sum += ( stack.g = ( pg = pixels[p+1])) * rbs;
b_sum += ( stack.b = ( pb = pixels[p+2])) * rbs;
r_in_sum += pr;
g_in_sum += pg;
b_in_sum += pb;
stack = stack.next;
}
stackIn = stackStart;
stackOut = stackEnd;
for ( x = 0; x < width; x++ )
{
pixels[yi] = (r_sum * mul_sum) >> shg_sum;
pixels[yi+1] = (g_sum * mul_sum) >> shg_sum;
pixels[yi+2] = (b_sum * mul_sum) >> shg_sum;
r_sum -= r_out_sum;
g_sum -= g_out_sum;
b_sum -= b_out_sum;
r_out_sum -= stackIn.r;
g_out_sum -= stackIn.g;
b_out_sum -= stackIn.b;
p = ( yw + ( ( p = x + radius + 1 ) < widthMinus1 ? p : widthMinus1 ) ) << 2;
r_in_sum += ( stackIn.r = pixels[p]);
g_in_sum += ( stackIn.g = pixels[p+1]);
b_in_sum += ( stackIn.b = pixels[p+2]);
r_sum += r_in_sum;
g_sum += g_in_sum;
b_sum += b_in_sum;
stackIn = stackIn.next;
r_out_sum += ( pr = stackOut.r );
g_out_sum += ( pg = stackOut.g );
b_out_sum += ( pb = stackOut.b );
r_in_sum -= pr;
g_in_sum -= pg;
b_in_sum -= pb;
stackOut = stackOut.next;
yi += 4;
}
yw += width;
}
for ( x = 0; x < width; x++ )
{
g_in_sum = b_in_sum = r_in_sum = g_sum = b_sum = r_sum = 0;
yi = x << 2;
r_out_sum = radiusPlus1 * ( pr = pixels[yi]);
g_out_sum = radiusPlus1 * ( pg = pixels[yi+1]);
b_out_sum = radiusPlus1 * ( pb = pixels[yi+2]);
r_sum += sumFactor * pr;
g_sum += sumFactor * pg;
b_sum += sumFactor * pb;
stack = stackStart;
for( i = 0; i < radiusPlus1; i++ )
{
stack.r = pr;
stack.g = pg;
stack.b = pb;
stack = stack.next;
}
yp = width;
for( i = 1; i <= radius; i++ )
{
yi = ( yp + x ) << 2;
r_sum += ( stack.r = ( pr = pixels[yi])) * ( rbs = radiusPlus1 - i );
g_sum += ( stack.g = ( pg = pixels[yi+1])) * rbs;
b_sum += ( stack.b = ( pb = pixels[yi+2])) * rbs;
r_in_sum += pr;
g_in_sum += pg;
b_in_sum += pb;
stack = stack.next;
if( i < heightMinus1 )
{
yp += width;
}
}
yi = x;
stackIn = stackStart;
stackOut = stackEnd;
for ( y = 0; y < height; y++ )
{
p = yi << 2;
pixels[p] = (r_sum * mul_sum) >> shg_sum;
pixels[p+1] = (g_sum * mul_sum) >> shg_sum;
pixels[p+2] = (b_sum * mul_sum) >> shg_sum;
r_sum -= r_out_sum;
g_sum -= g_out_sum;
b_sum -= b_out_sum;
r_out_sum -= stackIn.r;
g_out_sum -= stackIn.g;
b_out_sum -= stackIn.b;
p = ( x + (( ( p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1 ) * width )) << 2;
r_sum += ( r_in_sum += ( stackIn.r = pixels[p]));
g_sum += ( g_in_sum += ( stackIn.g = pixels[p+1]));
b_sum += ( b_in_sum += ( stackIn.b = pixels[p+2]));
stackIn = stackIn.next;
r_out_sum += ( pr = stackOut.r );
g_out_sum += ( pg = stackOut.g );
b_out_sum += ( pb = stackOut.b );
r_in_sum -= pr;
g_in_sum -= pg;
b_in_sum -= pb;
stackOut = stackOut.next;
yi += width;
}
}
context.putImageData( imageData, top_x, top_y );
}
function BlurStack()
{
this.r = 0;
this.g = 0;
this.b = 0;
this.a = 0;
this.next = null;
}
@code913
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code913 commented Sep 12, 2020

i didn't get this

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