2 * Pixastic Lib - Edge detection 2 - 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]
6 * Contribution by Oliver Hunt (http://nerget.com/, http://nerget.com/canvas/edgeDetection.js). Thanks Oliver!
10 Pixastic.Actions.edges2 = {
11 process : function(params) {
13 if (Pixastic.Client.hasCanvasImageData()) {
14 var data = Pixastic.prepareData(params);
15 var dataCopy = Pixastic.prepareData(params, true)
17 var rect = params.options.rect;
22 var pixel = w4 + 4; // Start at (1,1)
25 for (var y = 1; y < hm1; ++y) {
26 // Prepare initial cached values for current row
27 var centerRow = pixel - 4;
28 var priorRow = centerRow - w4;
29 var nextRow = centerRow + w4;
31 var r1 = - dataCopy[priorRow] - dataCopy[centerRow] - dataCopy[nextRow];
32 var g1 = - dataCopy[++priorRow] - dataCopy[++centerRow] - dataCopy[++nextRow];
33 var b1 = - dataCopy[++priorRow] - dataCopy[++centerRow] - dataCopy[++nextRow];
35 var rp = dataCopy[priorRow += 2];
36 var gp = dataCopy[++priorRow];
37 var bp = dataCopy[++priorRow];
39 var rc = dataCopy[centerRow += 2];
40 var gc = dataCopy[++centerRow];
41 var bc = dataCopy[++centerRow];
43 var rn = dataCopy[nextRow += 2];
44 var gn = dataCopy[++nextRow];
45 var bn = dataCopy[++nextRow];
47 var r2 = - rp - rc - rn;
48 var g2 = - gp - gc - gn;
49 var b2 = - bp - bc - bn;
51 // Main convolution loop
52 for (var x = 1; x < wm1; ++x) {
53 centerRow = pixel + 4;
54 priorRow = centerRow - w4;
55 nextRow = centerRow + w4;
57 var r = 127 + r1 - rp - (rc * -8) - rn;
58 var g = 127 + g1 - gp - (gc * -8) - gn;
59 var b = 127 + b1 - bp - (bc * -8) - bn;
65 rp = dataCopy[ priorRow];
66 gp = dataCopy[++priorRow];
67 bp = dataCopy[++priorRow];
69 rc = dataCopy[ centerRow];
70 gc = dataCopy[++centerRow];
71 bc = dataCopy[++centerRow];
73 rn = dataCopy[ nextRow];
74 gn = dataCopy[++nextRow];
75 bn = dataCopy[++nextRow];
77 r += (r2 = - rp - rc - rn);
78 g += (g2 = - gp - gc - gn);
79 b += (b2 = - bp - bc - bn);
91 //data[++pixel] = 255; // alpha
100 checkSupport : function() {
101 return Pixastic.Client.hasCanvasImageData();