[sdf] Added functions to decompose `FT_Outline'.

* src/sdf/ftsdf.c (sdf_outline_decompose): Added a function which decompose
  a `FT_Outline' using `FT_Outline_Decompose' and adds the outline data to a
  `SDF_Shape' for easier handling later on.

src/sdf/ftsdf.c

@@ -602,4 +602,199 @@
     SDF_FREE( *shape );
   }
 
+  /**************************************************************************
+   *
+   * shape decomposition functions
+   *
+   */
+
+  /* This function is called when walking along a new contour */
+  /* so add a new contour to the shape's list.                */
+  static FT_Error
+  sdf_move_to( const FT_26D6_Vec* to,
+               void*              user )
+  {
+    SDF_Shape*    shape    = ( SDF_Shape* )user;
+    SDF_Contour*  contour  = NULL;
+
+    FT_Error      error    = FT_Err_Ok;
+    FT_Memory     memory   = shape->memory;
+
+
+    if ( !to || !user )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    FT_CALL( sdf_contour_new( memory, &contour ) );
+
+    contour->last_pos = *to;
+    contour->next = shape->contours;
+    shape->contours = contour;
+
+  Exit:
+    return error;
+  }
+
+  /* This function is called when there is a line in the  */
+  /* contour. The line is from the previous edge point to */
+  /* the parameter `to'.                                  */
+  static FT_Error
+  sdf_line_to( const FT_26D6_Vec*  to,
+               void*               user )
+  {
+    SDF_Shape*    shape    = ( SDF_Shape* )user;
+    SDF_Edge*     edge     = NULL;
+    SDF_Contour*  contour  = NULL;
+
+    FT_Error      error    = FT_Err_Ok;
+    FT_Memory     memory   = shape->memory;
+
+
+    if ( !to || !user )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    contour = shape->contours;
+
+    if ( contour->last_pos.x == to->x && 
+         contour->last_pos.y == to->y )
+      goto Exit;
+
+    FT_CALL( sdf_edge_new( memory, &edge ) );
+
+    edge->edge_type = SDF_EDGE_LINE;
+    edge->start_pos = contour->last_pos;
+    edge->end_pos   = *to;
+
+    edge->next = contour->edges;
+    contour->edges = edge;
+    contour->last_pos = *to;
+
+  Exit:
+    return error;
+  }
+
+  /* This function is called when there is a conic bezier  */
+  /* curve in the contour. The bezier is from the previous */
+  /* edge point to the parameter `to' with the control     */
+  /* point being `control_1'.                              */
+  static FT_Error
+  sdf_conic_to( const FT_26D6_Vec*  control_1,
+                const FT_26D6_Vec*  to,
+                void*               user )
+  {
+    SDF_Shape*    shape    = ( SDF_Shape* )user;
+    SDF_Edge*     edge     = NULL;
+    SDF_Contour*  contour  = NULL;
+
+    FT_Error      error    = FT_Err_Ok;
+    FT_Memory     memory   = shape->memory;
+
+
+    if ( !control_1 || !to || !user )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    contour = shape->contours;
+
+    FT_CALL( sdf_edge_new( memory, &edge ) );
+
+    edge->edge_type = SDF_EDGE_CONIC;
+    edge->start_pos = contour->last_pos;
+    edge->control_a = *control_1;
+    edge->end_pos   = *to;
+
+    edge->next = contour->edges;
+    contour->edges = edge;
+    contour->last_pos = *to;
+
+  Exit:
+    return error;
+  }
+
+  /* This function is called when there is a cubic bezier  */
+  /* curve in the contour. The bezier is from the previous */
+  /* edge point to the parameter `to' with one control     */
+  /* point being `control_1' and another `control_2'.      */
+  static FT_Error
+  sdf_cubic_to( const FT_26D6_Vec*  control_1,
+                const FT_26D6_Vec*  control_2,
+                const FT_26D6_Vec*  to,
+                void*               user )
+  {
+    SDF_Shape*    shape    = ( SDF_Shape* )user;
+    SDF_Edge*     edge     = NULL;
+    SDF_Contour*  contour  = NULL;
+
+    FT_Error      error    = FT_Err_Ok;
+    FT_Memory     memory   = shape->memory;
+
+
+    if ( !control_2 || !control_1 || !to || !user )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    contour = shape->contours;
+
+    FT_CALL( sdf_edge_new( memory, &edge ) );
+
+    edge->edge_type = SDF_EDGE_CUBIC;
+    edge->start_pos = contour->last_pos;
+    edge->control_a = *control_1;
+    edge->control_b = *control_2;
+    edge->end_pos   = *to;
+
+    edge->next = contour->edges;
+    contour->edges = edge;
+    contour->last_pos = *to;
+
+  Exit:
+    return error;
+  }
+
+  /* Construct the struct to hold all four outline */
+  /* decomposition functions.                      */
+  FT_DEFINE_OUTLINE_FUNCS(
+    sdf_decompose_funcs,
+
+    (FT_Outline_MoveTo_Func)  sdf_move_to,   /* move_to  */
+    (FT_Outline_LineTo_Func)  sdf_line_to,   /* line_to  */
+    (FT_Outline_ConicTo_Func) sdf_conic_to,  /* conic_to */
+    (FT_Outline_CubicTo_Func) sdf_cubic_to,  /* cubic_to */
+
+    0,                                       /* shift    */
+    0                                        /* delta    */
+  )
+
+  /* The function decomposes the outline and puts it */
+  /* into the `shape' struct.                        */
+  static FT_Error
+  sdf_outline_decompose( FT_Outline*  outline,
+                         SDF_Shape*   shape )
+  {
+    FT_Error  error = FT_Err_Ok;
+
+
+    if ( !outline || !shape )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    error = FT_Outline_Decompose( outline, 
+                                  &sdf_decompose_funcs,
+                                  (void*)shape );
+
+  Exit:
+    return error;
+  }
+
 /* END */