Allow negative x, y in padding

src/ufo-anka-padding-task.c

@@ -39,7 +39,8 @@ struct _UfoAnkaPaddingTaskPrivate {
     cl_sampler sampler;
 
     /* properties */
-    guint width, height, x, y;
+    guint width, height;
+    gint x, y;
     cl_addressing_mode addressing_mode;
 };
 
@@ -228,10 +229,10 @@ ufo_anka_padding_task_set_property (GObject *object,
             priv->height = g_value_get_uint (value);
             break;
         case PROP_X:
-            priv->x = g_value_get_uint (value);
+            priv->x = g_value_get_int (value);
             break;
         case PROP_Y:
-            priv->y = g_value_get_uint (value);
+            priv->y = g_value_get_int (value);
             break;
         case PROP_ADDRESSING_MODE:
             if (!g_strcmp0 (g_value_get_string (value), "none")) {
@@ -276,10 +277,10 @@ ufo_anka_padding_task_get_property (GObject *object,
             g_value_set_uint (value, priv->height);
             break;
         case PROP_X:
-            g_value_set_uint (value, priv->x);
+            g_value_set_int (value, priv->x);
             break;
         case PROP_Y:
-            g_value_set_uint (value, priv->y);
+            g_value_set_int (value, priv->y);
             break;
         case PROP_ADDRESSING_MODE:
             switch (priv->addressing_mode) {
@@ -362,17 +363,17 @@ ufo_anka_padding_task_class_init (UfoAnkaPaddingTaskClass *klass)
                            G_PARAM_READWRITE);
 
     properties[PROP_X] =
-        g_param_spec_uint ("x",
+        g_param_spec_int ("x",
                            "X start index",
                            "X index for input's 0th column",
-                           0, +8192, 0,
+                           -8192, +8192, 0,
                            G_PARAM_READWRITE);
 
     properties[PROP_Y] =
-        g_param_spec_uint ("y",
+        g_param_spec_int ("y",
                            "Y start index",
                            "Y index for input's 0th row",
-                           0, +8192, 0,
+                           -8192, +8192, 0,
                            G_PARAM_READWRITE);
 
     properties[PROP_ADDRESSING_MODE] =