harris: Fix convolution clamping

1 files changed, 9 insertions, 8 deletions

diff --git a/harris.c b/harris.c
index 502e976..1099f61 100644
--- a/harris.c
+++ b/harris.c
@@ -50,8 +50,8 @@ grey_scale(GdkPixbuf *image)
 int *
 conv(GdkPixbuf *pixbuf, gint *operator, gint block_size)
 {
-	gint Y, i, j, x, y, width, height, nch, stride;
-	guchar *p, *row, *v;
+	gint Y, i, j, ci, cj, x, y, width, height, nch, stride;
+	guchar *p, *row, v;
 	int *out;
 	
 	pixbuf_get(pixbuf, &row, &width, &height, &nch, &stride);
@@ -62,12 +62,13 @@ conv(GdkPixbuf *pixbuf, gint *operator, gint block_size)
 	for (y = 0; y < height; ++y, row += stride) {
 		for (x = 0, p = row; x < width; ++x, p += nch) {
 			Y = 0;
-			for (i = 0; i < block_size; ++i) {
-				for (j = 0; j < block_size; ++j) {
-					/* TODO: fix clamping */
-					v = p + (CLAMP((j-block_size/2), 0, width-1)  * stride +
-						 CLAMP((i-block_size/2), 0, height-1) * nch);
-					Y += v[0] * operator[j*block_size + i];
+			for (j = 0; j < block_size; ++j) {
+				cj = CLAMP(j - block_size/2, -y, height-1-y);
+				for (i = 0; i < block_size; ++i) {
+					ci = CLAMP(i - block_size/2, -x, width-1-x);
+
+					v = p[cj * stride + ci * nch + 0];
+					Y += v * operator[j*block_size + i];
 				}
 			}
 			out[y * width + x] = Y/4;