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Gaussian Blur filter for fabric.js
/**
* Gaussian blur filter for fabricjs
* Example:
* obj.filters.push(new fabric.Image.filters.GaussianBlur(6));
* obj.applyFilters(canvas.renderAll.bind(canvas));
*
* Adapted from <a href="http://www.quasimondo.com/BoxBlurForCanvas">http://www.quasimondo.com/BoxBlurForCanvas</a>
*/
(function() {
var fabric = window.fabric,
extend = fabric.util.object.extend;
var mul_table = [ 1,57,41,21,203,34,97,73,227,91,149,62,105,45,39,137,241,107,3,173,39,71,65,238,219,101,187,87,81,151,141,133,249,117,221,209,197,187,177,169,5,153,73,139,133,127,243,233,223,107,103,99,191,23,177,171,165,159,77,149,9,139,135,131,253,245,119,231,224,109,211,103,25,195,189,23,45,175,171,83,81,79,155,151,147,9,141,137,67,131,129,251,123,30,235,115,113,221,217,53,13,51,50,49,193,189,185,91,179,175,43,169,83,163,5,79,155,19,75,147,145,143,35,69,17,67,33,65,255,251,247,243,239,59,29,229,113,111,219,27,213,105,207,51,201,199,49,193,191,47,93,183,181,179,11,87,43,85,167,165,163,161,159,157,155,77,19,75,37,73,145,143,141,35,138,137,135,67,33,131,129,255,63,250,247,61,121,239,237,117,29,229,227,225,111,55,109,216,213,211,209,207,205,203,201,199,197,195,193,48,190,47,93,185,183,181,179,178,176,175,173,171,85,21,167,165,41,163,161,5,79,157,78,154,153,19,75,149,74,147,73,144,143,71,141,140,139,137,17,135,134,133,66,131,65,129,1];
var shg_table = [0,9,10,10,14,12,14,14,16,15,16,15,16,15,15,17,18,17,12,18,16,17,17,19,19,18,19,18,18,19,19,19,20,19,20,20,20,20,20,20,15,20,19,20,20,20,21,21,21,20,20,20,21,18,21,21,21,21,20,21,17,21,21,21,22,22,21,22,22,21,22,21,19,22,22,19,20,22,22,21,21,21,22,22,22,18,22,22,21,22,22,23,22,20,23,22,22,23,23,21,19,21,21,21,23,23,23,22,23,23,21,23,22,23,18,22,23,20,22,23,23,23,21,22,20,22,21,22,24,24,24,24,24,22,21,24,23,23,24,21,24,23,24,22,24,24,22,24,24,22,23,24,24,24,20,23,22,23,24,24,24,24,24,24,24,23,21,23,22,23,24,24,24,22,24,24,24,23,22,24,24,25,23,25,25,23,24,25,25,24,22,25,25,25,24,23,24,25,25,25,25,25,25,25,25,25,25,25,25,23,25,23,24,25,25,25,25,25,25,25,25,25,24,22,25,25,23,25,25,20,24,25,24,25,25,22,24,25,24,25,24,25,25,24,25,25,25,25,22,25,25,25,24,25,24,25,18];
fabric.Image.filters.GaussianBlur = fabric.util.createClass(fabric.Image.filters.BaseFilter,{
/**
* Filter type
*/
type: 'GaussianBlur',
/**
* Constructor
*/
initialize: function(radius) { //radius of the blur
this.radius = radius || 1;
if(this.radius > 180) {
this.radius = 180;
}
if(this.radius < 1) {
this.radius = 1;
}
},
/**
* Applies blur to canvas element
*/
applyTo: function(canvas) {
var radius = this.radius;
var width = canvas.width;
var height = canvas.height;
var context = canvas.getContext("2d");
var imageData;
imageData = context.getImageData( 0, 0, width, height );
var pixels = imageData.data;
var rsum,gsum,bsum,asum,x,y,i,p,p1,p2,yp,yi,yw,idx;
var wm = width - 1;
var hm = height - 1;
var wh = width * height;
var rad1 = radius + 1;
var r = [];
var g = [];
var b = [];
var mul_sum = mul_table[radius];
var shg_sum = shg_table[radius];
var vmin = [];
var vmax = [];
yw = yi = 0;
for ( y=0; y < height; y++ ){
rsum = pixels[yw] * rad1;
gsum = pixels[yw+1] * rad1;
bsum = pixels[yw+2] * rad1;
for( i = 1; i <= radius; i++ ){
p = yw + (((i > wm ? wm : i )) << 2 );
rsum += pixels[p++];
gsum += pixels[p++];
bsum += pixels[p++];
}
for ( x = 0; x < width; x++ ){
r[yi] = rsum;
g[yi] = gsum;
b[yi] = bsum;
if( y==0) {
vmin[x] = ( ( p = x + rad1) < wm ? p : wm ) << 2;
vmax[x] = ( ( p = x - radius) > 0 ? p << 2 : 0 );
}
p1 = yw + vmin[x];
p2 = yw + vmax[x];
rsum += pixels[p1++] - pixels[p2++];
gsum += pixels[p1++] - pixels[p2++];
bsum += pixels[p1++] - pixels[p2++];
yi++;
}
yw += ( width << 2 );
}
for ( x = 0; x < width; x++ ){
yp = x;
rsum = r[yp] * rad1;
gsum = g[yp] * rad1;
bsum = b[yp] * rad1;
for( i = 1; i <= radius; i++ ){
yp += ( i > hm ? 0 : width );
rsum += r[yp];
gsum += g[yp];
bsum += b[yp];
}
yi = x << 2;
for ( y = 0; y < height; y++){
pixels[yi] = (rsum * mul_sum) >>> shg_sum;
pixels[yi+1] = (gsum * mul_sum) >>> shg_sum;
pixels[yi+2] = (bsum * mul_sum) >>> shg_sum;
if( x == 0 ) {
vmin[y] = ( ( p = y + rad1) < hm ? p : hm ) * width;
vmax[y] = ( ( p = y - radius) > 0 ? p * width : 0 );
}
p1 = x + vmin[y];
p2 = x + vmax[y];
rsum += r[p1] - r[p2];
gsum += g[p1] - g[p2];
bsum += b[p1] - b[p2];
yi += width << 2;
}
}
context.putImageData( imageData, 0, 0 );
},
/**
* Returns object representation of an instance
*/
toObject: function() {
return extend(this.callSuper('toObject'), {
radius: this.radius
});
}
});
fabric.Image.filters.GaussianBlur.fromObject = function(object) {
return new fabric.Image.filters.GaussianBlur(object);
};
})()
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