Add Gaussian 5x5 blur

2 files changed, 54 insertions, 4 deletions

diff --git a/downscaling.c b/downscaling.c
index 9a0723b..d0dd3b9 100644
--- a/downscaling.c
+++ b/downscaling.c
@@ -235,10 +235,60 @@ typedef struct
     set_filter_func_t set_filter;
 } filter_t;
 
+static pixman_fixed_16_16_t *
+create_gaussian_kernel (int r, int *n_params)
+{
+    pixman_fixed_16_16_t *params;
+    double sigma = r / 2.0;
+    int i, j;
+
+    *n_params = 2 * r + 1;
+    *n_params *= *n_params;
+    *n_params += 2;
+    
+    params = g_malloc (*n_params * sizeof (pixman_fixed_16_16_t));
+
+    for (i = -r; i <= r; i++)
+    {
+	for (j = -r; j <= r; j++)
+	{
+	    int idx = (i + r) * (2 * r + 1) + j + r + 2;
+
+	    double v = (1 / (2 * G_PI * sigma * sigma)) * exp (-(j * j + i * i) / (2 * sigma * sigma));
+
+	    g_assert (idx < n_params);
+
+	    params[idx] = _cairo_fixed_16_16_from_double (v);
+	    
+#if 0
+	    g_print ("%f ", v);
+#endif
+	}
+
+#if 0
+	g_print ("\n");
+#endif
+    }
+
+    return params;
+}
+
 static void
-set_lanczos (pixman_image_t *image, int w, int h)
+set_gaussian (pixman_image_t *image, int w, int h)
 {
+    int n_params;
+
+#define RAD 5
+
+    pixman_fixed_16_16_t *params =
+	create_gaussian_kernel (RAD, &n_params);
+
+    params[0] = (RAD * 2 + 1) << 16;
+    params[1] = (RAD * 2 + 1) << 16;
     
+    pixman_image_set_filter (image, PIXMAN_FILTER_CONVOLUTION, params, n_params);
+
+    g_free (params);
 }
 
 static void
@@ -257,7 +307,7 @@ static const filter_t filters[] =
 {
     { "nearest", set_nearest },
     { "bilinear", set_bilinear },
-    { "lanczos", set_bilinear /* FIXME */ },
+    { "gaussian", set_gaussian /* FIXME */ },
     { NULL },
 };
 
diff --git a/downscaling.ui b/downscaling.ui
index f0a3e2b..397d6a1 100644
--- a/downscaling.ui
+++ b/downscaling.ui
@@ -79,10 +79,10 @@ const char *uidef =
 "              </packing>" \
 "            </child>" \
 "            <child>" \
-"              <object class=\"GtkRadioButton\" id=\"lanczos\">" \
+"              <object class=\"GtkRadioButton\" id=\"gaussian\">" \
 "                <property name=\"visible\">True</property>" \
 "                <property name=\"can_focus\">True</property>" \
-"                <property name=\"label\" translatable=\"yes\">Lanczos</property>" \
+"                <property name=\"label\" translatable=\"yes\">Gaussian 11 x 11</property>" \
 "                <property name=\"active\">True</property>" \
 "                <property name=\"draw_indicator\">True</property>" \
 "                <property name=\"group\">nearest</property>" \