1 files changed, 79 insertions, 0 deletions
diff --git a/convolve.js b/convolve.js
new file mode 100644
index 0000000..2e59c6c
--- /dev/null
+++ b/convolve.js
@@ -0,0 +1,79 @@
+Kernel = function (w, h, a) {
+	this.w = w
+	this.h = h
+	this.a = a
+}
+Kernel.prototype.normalize = function(){
+	var n = 0;
+	for (var i = 0; i < this.a.length; i++)
+		n += this.a[i];
+	for (var i = 0; i < this.a.length; i++)
+		this.a[i] /= n;
+	return this
+}
+ConvolveOp = function (kernel, edge_zero_fill, idk) {
+	var k = kernel.a
+	var klen = k.length
+	var kw = kernel.w
+	var kh = kernel.h
+	var kx = -((kw / 2)|0)
+	var ky = -((kh / 2)|0)
+	this.filter = function(srcImageData, destImageData){
+		// assume these are both identically sized canvas objects..
+		var src = srcImageData.data
+		var dest = destImageData.data
+		var w = srcImageData.width
+		var h = srcImageData.height
+		var ix, iy, it, jx, jy, jt
+		var r, g, b, a
+
+		for (var i = 0, len = w*h; i < len; i++) {
+			ix = i%w
+			iy = (i/w)|0
+			it = i * 4
+			r = g = b = a = 0
+			for (var j = 0; j < klen; j++) {
+				jx = ix +  j%kw + kx
+				jy = iy + ((j/kh)|0) + ky
+				jt = 4 * (jx + jy*w)
+				if (0 > jx || jx > w || 0 > jy || jy > h) {
+					if (edge_zero_fill) {
+						continue
+					}
+					jt = it
+				}
+				r += src[jt]   * k[j]
+				g += src[jt+1] * k[j]
+				b += src[jt+2] * k[j]
+				a += src[jt+3] * k[j]
+			}
+			dest[it]   = r
+			dest[it+1] = g
+			dest[it+2] = b
+			dest[it+3] = a
+		}
+		return destImageData
+	}
+	this.convolveCanvas = function(image){
+		var target = document.createElement("canvas")
+		var w = target.width = image.width
+		var h = target.height = image.height
+		var imagectx = image.getContext('2d')
+		var targetctx = target.getContext('2d')
+
+		targetctx.drawImage(image, 0, 0);
+
+		// get source pixels
+		var src = imagectx.getImageData(0,0,w,h)
+		var dest = targetctx.getImageData(0,0,w,h)
+
+		// convolve the cloned image
+		dest = this.filter(src, dest);
+
+		targetctx.putImageData(dest, 0,0)
+
+		return target
+	}
+}
+ConvolveOp.prototype.EDGE_NO_OP = 0
+ConvolveOp.prototype.EDGE_ZERO_FILL = 1