[bsdf] Added function to copy the SDF data into the output bitmap.

* src/sdf/ftbsdf.c (finalize_sdf): The function uses the final data present in the 
  distance map and copies is to the output bitmap. It also converts our data into the
  desired format.

src/sdf/ftbsdf.c

@@ -931,4 +931,101 @@
     return error;
   }
 
+  /**************************************************************************
+   *
+   * @Function:
+   *   finalize_sdf
+   *
+   * @Description:
+   *   This function copy the SDF data from `worker->distance_map' to the
+   *   `target' bitmap. It aslo transforms the data to our output format,
+   *    i.e. 6.10 fixed point format at the moment.
+   *
+   * @Input:
+   *   worker ::
+   *     Conaints source distance map and parameters/properties which contains
+   *     SDF data.
+   *
+   * @Return:
+   *   target ::
+   *     Target bitmap to which the SDF data is copied to.
+   *
+   *   FT_Error ::
+   *     FreeType error, 0 means success.
+   *
+   */
+  static FT_Error
+  finalize_sdf( BSDF_Worker*      worker,
+                const FT_Bitmap*  target )
+  {
+    FT_Error   error = FT_Err_Ok;
+    FT_Int     w, r;
+    FT_Int     i, j;
+    FT_6D10*   t_buffer;
+    FT_16D16   spread;
+
+    if ( !worker || !target )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    w = target->width;
+    r = target->rows;
+    t_buffer = (FT_6D10*)target->buffer;
+
+    if ( w != worker->width ||
+         r != worker->rows )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;      
+    }
+
+  #if USE_SQUARED_DISTANCES
+    spread = FT_INT_16D16( worker->params.spread *
+                           worker->params.spread );
+  #else
+    spread = FT_INT_16D16( worker->params.spread );
+  #endif
+
+    for ( j = 0; j < r; j++ )
+    {
+      for ( i = 0; i < w; i++ )
+      {
+        FT_Int    index;
+        FT_16D16  dist;
+        FT_6D10   final_dist;
+        FT_Char   sign;
+
+
+        index = j * w + i;
+        dist = worker->distance_map[index].dist;
+
+        if ( dist < 0 || dist > spread )
+          dist = spread;
+
+  #if USE_SQUARED_DISTANCES
+          dist = square_root( dist );
+  #endif
+
+        /* convert from 16.16 to 6.10 */
+        dist /= 64;
+        final_dist = (FT_6D10)(dist & 0x0000FFFF);
+
+        /* We assume that if the pixel is inside a contour */
+        /* then it's coverage value must be > 127.         */
+        sign = worker->distance_map[index].alpha < 127 ? -1 : 1;
+
+        /* flip the sign according to the property */
+        if ( worker->params.flip_sign )
+          sign = -sign;
+
+        t_buffer[index] = final_dist * sign;
+      }
+    }
+
+  Exit:
+    return error;
+  }
+
 /* END */