[dia] [substitute] improve Convert to Path

[Hans Breuer <hans src gnome org>]

commit 3ec25448ae14f38c59b2ec504d45f02836b74ab9
Author: Hans Breuer <hans breuer org>
Date:   Fri Apr 25 12:00:29 2014 +0200

    [substitute] improve Convert to Path
    
    'Convert to Path' based on the DiaPathRenderer was not producing the
    desired effect for some standard objects. Filled objects were not
    necessarily filled anymore after conversion. Even simple objects were
    producing a group of objects rather than a single path object. Now:
     - start a new path when switching from fill to stroke color use
     - optimize for duplicated path coming from Dia's current split to fill
       and stroke in two steps (with the same path data)
     - be more tolerant regarding path extending so that rounded rectangles
       lead to a single path object
    Also included a test/demo file convert-to-path.dia.

 lib/diapathrenderer.c       |   56 +++++++++++++++++++++++++++++++++++++++++-
 samples/convert-to-path.dia |  Bin 0 -> 3954 bytes
 2 files changed, 54 insertions(+), 2 deletions(-)
---
diff --git a/lib/diapathrenderer.c b/lib/diapathrenderer.c
index 96ea988..b7ec40b 100644
--- a/lib/diapathrenderer.c
+++ b/lib/diapathrenderer.c
@@ -27,6 +27,11 @@
 
 #include "attributes.h" /* attributes_get_foreground() */
 
+typedef enum {
+  PATH_STROKE = (1<<0),
+  PATH_FILL   = (1<<1)
+} PathLastOp;
+
 /*!
  * \brief Renderer which turns everything into a path (or a list thereof)
  *
@@ -44,6 +49,8 @@ struct _DiaPathRenderer
 
   Color stroke;
   Color fill;
+
+  PathLastOp last_op;
 };
 
 struct _DiaPathRendererClass
@@ -94,7 +101,7 @@ dia_path_renderer_finalize (GObject *object)
  * @param self   explicit this pointer
  * @param stroke line color or NULL
  * @param fill   fill color or NULL
- * \private \memeberof _DiaPathRenderer
+ * \private \memberof _DiaPathRenderer
  */
 static GArray *
 _get_current_path (DiaPathRenderer *self,
@@ -113,6 +120,11 @@ _get_current_path (DiaPathRenderer *self,
     memcpy (&self->fill, fill, sizeof(*fill));
     new_path = TRUE;
   }
+  /* also create a new path if the last op was a fill and we now stroke */
+  if (   stroke && self->last_op == PATH_FILL 
+      || fill && self->last_op == PATH_STROKE)
+    new_path = TRUE;
+  self->last_op = stroke ? PATH_STROKE : PATH_FILL;
 
   if (!self->pathes || new_path) {
     if (!self->pathes)
@@ -123,6 +135,40 @@ _get_current_path (DiaPathRenderer *self,
   return path;
 }
 /*!
+ * \brief Optimize away potential duplicated path
+ * Dia's object rendering often consists of identical consecutive fill and stroke
+ * operations. This function check if two identical pathes are at the end of our
+ * list and just removes the second one.
+ * \private \memberof _DiaPathRenderer
+ */
+static void
+_remove_duplicated_path (DiaPathRenderer *self)
+{
+  if (self->pathes && self->pathes->len >= 2) {
+    GArray *p1 = g_ptr_array_index (self->pathes, self->pathes->len - 2);
+    GArray *p2 = g_ptr_array_index (self->pathes, self->pathes->len - 1);
+    if (p1->len == p2->len) {
+      gboolean same = TRUE;
+      guint i;
+      for (i = 0; i < p1->len; ++i) {
+       const BezPoint *bp1 = &g_array_index (p1, BezPoint, i);
+       const BezPoint *bp2 = &g_array_index (p2, BezPoint, i);
+
+       same &= (bp1->type == bp2->type);
+       same &= (memcmp (&bp1->p1, &bp2->p1, sizeof(Point)) == 0);
+       if (bp1->type == BEZ_CURVE_TO) {
+         same &= (memcmp (&bp1->p2, &bp2->p2, sizeof(Point)) == 0);
+         same &= (memcmp (&bp1->p3, &bp2->p3, sizeof(Point)) == 0);
+       }
+      }
+      if (same) {
+       g_array_free (p2, TRUE);
+       g_ptr_array_set_size (self->pathes, self->pathes->len - 1);
+      }
+    }
+  }
+}
+/*!
  * \brief Starting a new rendering run
  * Could be used to clean the path leftovers from a previous run.
  * Typical export renderers flush here.
@@ -188,7 +234,7 @@ _path_append (GArray *points, const Point *pt)
   const BezPoint *prev = (points->len > 0) ? &g_array_index (points, BezPoint, points->len - 1) : NULL;
   const Point *last = prev ? (prev->type == BEZ_CURVE_TO ? &prev->p3 : &prev->p1) : NULL;
 
-  if (!last || last->x != pt->x || last->y != pt->y) {
+  if (!last || distance_point_point(last, pt) > 0.001) {
     BezPoint bp;
     bp.type = BEZ_MOVE_TO;
     bp.p1 = *pt;
@@ -282,6 +328,7 @@ draw_polyline(DiaRenderer *self,
              Color *line_colour)
 {
   _polyline (self, points, num_points, line_colour, NULL);
+  _remove_duplicated_path (DIA_PATH_RENDERER (self));
 }
 static void
 draw_polygon(DiaRenderer *self, 
@@ -294,6 +341,7 @@ draw_polygon(DiaRenderer *self,
   /* FIXME: can't be that simple ;) */
   _polyline (self, points, num_points, line_colour, NULL);
   _path_lineto (path, &points[0]);
+  _remove_duplicated_path (renderer);
 }
 static void
 fill_polygon(DiaRenderer *self, 
@@ -336,6 +384,7 @@ draw_rect (DiaRenderer *self,
           Color *color)
 {
   _rect (self, ul_corner, lr_corner, color, NULL);
+  _remove_duplicated_path (DIA_PATH_RENDERER (self));
 }
 static void
 fill_rect (DiaRenderer *self, 
@@ -423,6 +472,7 @@ draw_arc (DiaRenderer *self,
          Color *color)
 {
   _arc (self, center, width, height, angle1, angle2, color, NULL);
+  _remove_duplicated_path (DIA_PATH_RENDERER (self));
 }
 static void
 fill_arc (DiaRenderer *self, 
@@ -508,6 +558,7 @@ draw_ellipse (DiaRenderer *self,
              Color *color)
 {
   _ellipse (self, center, width, height, color, NULL);
+  _remove_duplicated_path (DIA_PATH_RENDERER (self));
 }
 static void
 fill_ellipse (DiaRenderer *self, 
@@ -545,6 +596,7 @@ draw_bezier (DiaRenderer *self,
             Color *color)
 {
   _bezier(self, points, numpoints, color, NULL);
+  _remove_duplicated_path (DIA_PATH_RENDERER (self));
 }
 static void
 fill_bezier(DiaRenderer *self, 
diff --git a/samples/convert-to-path.dia b/samples/convert-to-path.dia
new file mode 100644
index 0000000..6ff7264
Binary files /dev/null and b/samples/convert-to-path.dia differ