adding fast blur function

[dosdemo] / src / gfxutil.c

diff --git a/src/gfxutil.c b/src/gfxutil.c
index 0257f79..811915e 100644 (file)
--- a/src/gfxutil.c
+++ b/src/gfxutil.c
@@ -142,3 +142,47 @@ void draw_line(int x0, int y0, int x1, int y1, unsigned short color)
                }
        }
 }
+
+
+/* TODO bound blur rad to image size to avoid inner loop conditionals */
+/* TODO make version with pow2 (rad*2+1) to avoid div with count everywhere */
+void blur_grey_horiz(uint16_t *dest, uint16_t *src, int xsz, int ysz, int rad)
+{
+       int i, j;
+
+       for(i=0; i<ysz; i++) {
+               int sum = src[0] * (rad + 1);
+               int count = rad * 2 + 1;
+               uint16_t lastpix = src[xsz - 1];
+
+               /* add up the contributions for the -1 pixel */
+               for(j=0; j<rad; j++) {
+                       sum += src[j];
+               }
+
+               /* first part adding src[rad] and subtracting src[0] */
+               for(j=0; j<rad; j++) {
+                       sum += src[rad] - src[0];
+                       ++src;
+                       *dest++ = sum / count;
+               }
+
+               /* middle part adding src[rad] and subtracting src[-(rad+1)] */
+               for(j=0; j<xsz - rad; j++) {
+                       sum += src[rad] - src[-(rad + 1)];
+                       ++src;
+                       *dest++ = sum / count;
+               }
+
+               /* last part adding lastpix and subtracting src[-(rad+1)] */
+               for(j=0; j<rad; j++) {
+                       sum += lastpix - src[-(rad + 1)];
+                       ++src;
+                       *dest++ = sum / count;
+               }
+       }
+}
+
+void blur_grey_vert(uint16_t *dest, uint16_t *src, int xsz, int ysz, int radius)
+{
+}