2 * Pixastic Lib - Edge detection filter - v0.1.0
3 * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
4 * MIT License [http://www.opensource.org/licenses/mit-license.php]
7 Pixastic.Actions.edges = {
8 process : function(params) {
10 var mono = !!(params.options.mono);
14 //if (typeof params.options.strength != "undefined")
15 // strength = parseFloat(params.options.strength)||0;
17 var invert = !!(params.options.invert);
19 if (Pixastic.Client.hasCanvasImageData()) {
20 var data = Pixastic.prepareData(params);
21 var dataCopy = Pixastic.prepareData(params, true)
32 var rect = params.options.rect;
39 var offsetY = (y-1)*w4;
41 var nextY = (y == h) ? y - 1 : y;
42 var prevY = (y == 1) ? 0 : y-2;
44 var offsetYPrev = prevY*w*4;
45 var offsetYNext = nextY*w*4;
49 var offset = offsetY + (x*4-4);
51 var offsetPrev = offsetYPrev + ((x == 1) ? 0 : x-2) * 4;
52 var offsetNext = offsetYNext + ((x == w) ? x-1 : x) * 4;
54 var r = ((dataCopy[offsetPrev-4]
55 + dataCopy[offsetPrev]
56 + dataCopy[offsetPrev+4]
59 + dataCopy[offsetNext-4]
60 + dataCopy[offsetNext]
61 + dataCopy[offsetNext+4]) * c
66 var g = ((dataCopy[offsetPrev-3]
67 + dataCopy[offsetPrev+1]
68 + dataCopy[offsetPrev+5]
71 + dataCopy[offsetNext-3]
72 + dataCopy[offsetNext+1]
73 + dataCopy[offsetNext+5]) * c
77 var b = ((dataCopy[offsetPrev-2]
78 + dataCopy[offsetPrev+2]
79 + dataCopy[offsetPrev+6]
82 + dataCopy[offsetNext-2]
83 + dataCopy[offsetNext+2]
84 + dataCopy[offsetNext+6]) * c
89 var brightness = (r*0.3 + g*0.59 + b*0.11)||0;
90 if (invert) brightness = 255 - brightness;
91 if (brightness < 0 ) brightness = 0;
92 if (brightness > 255 ) brightness = 255;
93 r = g = b = brightness;
103 if (r > 255 ) r = 255;
104 if (g > 255 ) g = 255;
105 if (b > 255 ) b = 255;
118 checkSupport : function() {
119 return Pixastic.Client.hasCanvasImageData();