* blur.c: support for variable blur radius and Gaussian offset.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2617 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/filter/blur.c

@@ -28,6 +28,12 @@
 #include "pipi_internals.h"
 
 pipi_image_t *pipi_gaussian_blur(pipi_image_t *src, float radius)
+{
+    return pipi_gaussian_blur_ext(src, radius, radius, 0.0, 0.0);
+}
+
+pipi_image_t *pipi_gaussian_blur_ext(pipi_image_t *src, float rx, float ry,
+                                     float dx, float dy)
 {
     pipi_image_t *dst;
     pipi_pixels_t *srcp, *dstp;
@@ -46,23 +52,23 @@ pipi_image_t *pipi_gaussian_blur(pipi_image_t *src, float radius)
     dstp = pipi_getpixels(dst, PIPI_PIXELS_RGBA_F);
     dstdata = (float *)dstp->pixels;
 
-    kr = (int)(3. * radius + 0.99999);
+    buffer = malloc(w * h * 4 * sizeof(double));
+
+    kr = (int)(3. * rx + 0.99999);
     kw = 2 * kr + 1;
-    K = 1. / (sqrt(2. * M_PI) * radius);
-    L = -1. / (2. * radius * radius);
+    K = 1. / (sqrt(2. * M_PI) * rx);
+    L = -1. / (2. * rx * rx);
 
     kernel = malloc(kw * sizeof(double));
     for(i = -kr; i <= kr; i++)
-        kernel[i + kr] = exp(L * i * i) * K;
-
-    buffer = malloc(w * h * 4 * sizeof(double));
+        kernel[i + kr] = exp(L * ((double)i - dx) * ((double)i - dx)) * K;
 
     for(y = 0; y < h; y++)
     {
         for(x = 0; x < w; x++)
         {
             double R = 0., G = 0., B = 0., t = 0.;
-            int x2;
+            int x2, off = 4 * (y * w + x);
 
             for(i = -kr; i <= kr; i++)
             {
@@ -78,18 +84,29 @@ pipi_image_t *pipi_gaussian_blur(pipi_image_t *src, float radius)
                 t += f;
             }
 
-            buffer[(y * w + x) * 4] = R / t;
-            buffer[(y * w + x) * 4 + 1] = G / t;
-            buffer[(y * w + x) * 4 + 2] = B / t;
+            buffer[off] = R / t;
+            buffer[off + 1] = G / t;
+            buffer[off + 2] = B / t;
         }
     }
 
+    free(kernel);
+
+    kr = (int)(3. * ry + 0.99999);
+    kw = 2 * kr + 1;
+    K = 1. / (sqrt(2. * M_PI) * ry);
+    L = -1. / (2. * ry * ry);
+
+    kernel = malloc(kw * sizeof(double));
+    for(i = -kr; i <= kr; i++)
+        kernel[i + kr] = exp(L * ((double)i - dy) * ((double)i - dy)) * K;
+
     for(y = 0; y < h; y++)
     {
         for(x = 0; x < w; x++)
         {
             double R = 0., G = 0., B = 0., t = 0.;
-            int y2;
+            int y2, off = 4 * (y * w + x);
 
             for(i = -kr; i <= kr; i++)
             {
@@ -105,9 +122,9 @@ pipi_image_t *pipi_gaussian_blur(pipi_image_t *src, float radius)
                 t += f;
             }
 
-            dstdata[(y * w + x) * 4] = R / t;
-            dstdata[(y * w + x) * 4 + 1] = G / t;
-            dstdata[(y * w + x) * 4 + 2] = B / t;
+            dstdata[off] = R / t;
+            dstdata[off + 1] = G / t;
+            dstdata[off + 2] = B / t;
         }
     }
 

pipi/pipi.h

@@ -58,6 +58,8 @@ extern pipi_pixels_t *pipi_getpixels(pipi_image_t *, pipi_format_t);
 extern pipi_image_t *pipi_resize(pipi_image_t *, int, int);
 
 extern pipi_image_t *pipi_gaussian_blur(pipi_image_t *, float);
+extern pipi_image_t *pipi_gaussian_blur_ext(pipi_image_t *,
+                                            float, float, float, float);
 
 extern void pipi_dither_24to16(pipi_image_t *);