applied a patch from Simon.

--Sven

ChangeLog

@@ -1,3 +1,16 @@
+Wed Sep 15 12:43:39 MEST 1999 Simon Budig <Simon.Budig@unix-ag.org>
+
+	* app/tools.c
+	* app/pixmaps2.h
+	* app/path_tool.c
+	* app/path_toolP.h
+
+	Own pixmap for the Path Tool. It is now possible to connect
+	open ends of curves. Simply activate one end and shift click
+	on the other. Control-Click deletes points.
+
+	Still no bezier/painting functions...
+
 1999-09-14  Tor Lillqvist  <tml@iki.fi>
 
 	* app/brush_select.c: Include config.h, guard inclusion of

app/path_tool.c

@@ -29,6 +29,8 @@
  * segments between two anchors.
  */
 
+#undef PATH_TOOL_DEBUG
+
 #include <math.h>
 /* #include "appenv.h"
  */
@@ -38,7 +40,9 @@
 #include "path_tool.h"
 #include "path_toolP.h"
 
+#ifdef PATH_TOOL_DEBUG
 #include <stdio.h>
+#endif PATH_TOOL_DEBUG
 
 #include "libgimp/gimpintl.h"
 
@@ -68,15 +72,18 @@ static gdouble path_locate_point            (Path *, PathCurve **, PathSegment *
 /* Tools to manipulate paths, curves, segments */
 
 static PathCurve   * path_add_curve       (Path *, gint, gint);
-static inline PathSegment * path_append_segment  (Path *, PathCurve *, SegmentType, gint, gint);
+static PathSegment * path_append_segment  (Path *, PathCurve *, SegmentType, gint, gint);
 static PathSegment * path_prepend_segment (Path *, PathCurve *, SegmentType, gint, gint);
 static PathSegment * path_split_segment   (PathSegment *, gdouble);
+static void          path_join_curves     (PathSegment *, PathSegment *);
+static void          path_flip_curve      (PathCurve *);
 static void          path_free_path       (Path *);
 static void          path_free_curve      (PathCurve *);
 static void          path_free_segment    (PathSegment *);
+static void          path_delete_segment  (PathSegment *);
 static void          path_print           (Path *);
 static void          path_offset_active   (Path *, gdouble, gdouble);
-static void          path_clear_active    (Path *, PathCurve *, PathSegment *);
+static void          path_set_flags       (PathTool *, Path *, PathCurve *, PathSegment *, guint32, guint32);
 
 /* High level image-manipulation functions */
 
@@ -116,8 +123,9 @@ static ToolOptions *path_options = NULL;
  */
 
 /*
- * These functions are for applying a function over a complete path/curve/segment
+ * These functions are for applying a function over a complete
- * they can pass information to each other with a arbitrary data structure
+ * path/curve/segment. They can pass information to each other
+ * with a arbitrary data structure
  *
  * The idea behind the three different functions is:
  *  if pathfunc != NULL
@@ -176,7 +184,9 @@ path_traverse_curve (Path *path, PathCurve *curve, CurveTraverseFunc curvefunc,
 static void
 path_traverse_segment (Path *path, PathCurve *curve, PathSegment *segment, SegmentTraverseFunc function, gpointer data)
 {
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_traverse_segment\n");
+#endif PATH_TOOL_DEBUG
 
    /* Something like:
     * for i = 1 to subsamples {
@@ -190,34 +200,48 @@ path_traverse_segment (Path *path, PathCurve *curve, PathSegment *segment, Segme
  * Helper functions for manipulating the data-structures:
  */
 
-static PathCurve   * path_add_curve       (Path * cur_path, gint x, gint y)
+static PathCurve *path_add_curve (Path * cur_path, gint x, gint y)
 {
    PathCurve * tmp = cur_path->curves;
-   PathCurve * new_curve;
+   PathCurve * new_curve = NULL;
 
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_add_curve\n");
+#endif PATH_TOOL_DEBUG
    
-   new_curve = g_new (PathCurve, 1);
+   if (cur_path) {
+      new_curve = g_new (PathCurve, 1);
    
-   new_curve->next = tmp;
+      new_curve->parent = cur_path;
-   new_curve->prev = NULL;
+      new_curve->next = tmp;
-   new_curve->cur_segment = NULL;
+      new_curve->prev = NULL;
-   new_curve->segments = NULL;
+      new_curve->cur_segment = NULL;
+      new_curve->segments = NULL;
 
-   if (tmp) tmp->prev = new_curve;
+      if (tmp) tmp->prev = new_curve;
    
-   cur_path->curves = cur_path->cur_curve = new_curve;
+      cur_path->curves = cur_path->cur_curve = new_curve;
    
-   new_curve->segments = path_append_segment (cur_path, new_curve, SEGMENT_LINE, x, y);
+      new_curve->segments = path_prepend_segment (cur_path, new_curve, SEGMENT_LINE, x, y);
+   }
+#ifdef PATH_TOOL_DEBUG
+   else
+      fprintf (stderr, "Fatal Error: path_add_curve called without valid path\n");
+#endif PATH_TOOL_DEBUG
+
    return new_curve;
 }
    
    
-static inline PathSegment * path_append_segment  (Path * cur_path, PathCurve * cur_curve, SegmentType type, gint x, gint y)
+static PathSegment * path_append_segment  (Path * cur_path, PathCurve * cur_curve, SegmentType type, gint x, gint y)
 {
    PathSegment * tmp = cur_curve->segments;
    PathSegment * new_segment = NULL;
    
+#ifdef PATH_TOOL_DEBUG
+      fprintf(stderr, "path_append_segment\n");
+#endif PATH_TOOL_DEBUG
+
    if (cur_curve) {
       tmp = cur_curve->segments;
       while (tmp && tmp->next && tmp->next != cur_curve->segments) {
@@ -230,32 +254,239 @@ static inline PathSegment * path_append_segment  (Path * cur_path, PathCurve * c
          new_segment->type = type;
          new_segment->x = x;
          new_segment->y = y;
-         new_segment->flags = SEGMENT_ACTIVE;
+         new_segment->flags = 0;
+         new_segment->parent = cur_curve;
          new_segment->next = NULL;
          new_segment->prev = tmp;
          new_segment->data = NULL;
          
          if (tmp) 
-         {
             tmp->next = new_segment;
-         }
 
          cur_curve->cur_segment = new_segment;
       }
+#ifdef PATH_TOOL_DEBUG
       else
          fprintf(stderr, "Fatal Error: path_append_segment called with a closed curve\n");
+#endif PATH_TOOL_DEBUG
    }
+#ifdef PATH_TOOL_DEBUG
    else
       fprintf(stderr, "Fatal Error: path_append_segment called without valid curve\n");
+#endif PATH_TOOL_DEBUG
    
    return new_segment;
 }
 
 
-/* static PathSegment * path_prepend_segment (Path *, PathCurve *, gint, gint);
+static PathSegment * path_prepend_segment  (Path * cur_path, PathCurve * cur_curve, SegmentType type, gint x, gint y)
- * static PathSegment * path_split_segment   (PathSegment *, gdouble);
+{
+   PathSegment * tmp = cur_curve->segments;
+   PathSegment * new_segment = NULL;
+   
+#ifdef PATH_TOOL_DEBUG
+      fprintf(stderr, "path_prepend_segment\n");
+#endif PATH_TOOL_DEBUG
+
+   if (cur_curve) {
+      tmp = cur_curve->segments;
+   
+      if (tmp == NULL || tmp->prev == NULL) {
+         new_segment = g_new (PathSegment, 1);
+         
+         new_segment->type = type;
+         new_segment->x = x;
+         new_segment->y = y;
+         new_segment->flags = 0;
+         new_segment->parent = cur_curve;
+         new_segment->next = tmp;
+         new_segment->prev = NULL;
+         new_segment->data = NULL;
+         
+         if (tmp) 
+            tmp->prev = new_segment;
+
+         cur_curve->segments = new_segment;
+         cur_curve->cur_segment = new_segment;
+      }
+#ifdef PATH_TOOL_DEBUG
+      else
+         fprintf(stderr, "Fatal Error: path_prepend_segment called with a closed curve\n");
+#endif PATH_TOOL_DEBUG
+   }
+#ifdef PATH_TOOL_DEBUG
+   else
+      fprintf(stderr, "Fatal Error: path_prepend_segment called without valid curve\n");
+#endif PATH_TOOL_DEBUG
+   
+   return new_segment;
+}
+
+/* static PathSegment * path_split_segment   (PathSegment *, gdouble);
  */
 
+/*
+ * Join two arbitrary endpoints and free the parent from the second
+ * segment, if it differs from the first parents.
+ */
+
+static void
+path_join_curves (PathSegment *segment1, PathSegment *segment2) {
+   PathCurve *curve1, *curve2;
+   PathSegment *tmp;
+
+   if ((segment1->next && segment1->prev) || (segment2->next && segment2->prev)) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf(stderr, "Fatal Error: path_join_curves called with a closed segment\n");
+#endif PATH_TOOL_DEBUG
+      return;
+   }
+   if (segment1->parent == segment2->parent) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Joining beginning and end of the same curve...\n");
+#endif PATH_TOOL_DEBUG
+      if (segment2->next == NULL) {
+	 segment2->next = segment1;
+	 segment1->prev = segment2;
+      } else {
+	 segment2->prev = segment1;
+	 segment1->next = segment2;
+      }
+      return;
+   }
+
+   if (segment1->next == NULL && segment2->next == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Flipping second curve (next, next)...\n");
+#endif PATH_TOOL_DEBUG
+      path_flip_curve (segment2->parent);
+      /* segment2 = segment2->parent->segments;
+       */
+   }
+      
+   if (segment1->prev == NULL && segment2->prev == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Flipping second curve (prev, prev)...\n");
+#endif PATH_TOOL_DEBUG
+      path_flip_curve (segment2->parent);
+      /* segment2 = segment2->parent->segments;
+       * while (segment2->next)
+       * segment2 = segment2->next;
+       */
+   }
+      
+   if (segment1->next == NULL && segment2->prev == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Appending second to first curve...\n");
+#endif PATH_TOOL_DEBUG
+      curve1 = segment1->parent;
+      curve2 = segment2->parent;
+      
+      segment1->next = segment2;
+      segment2->prev = segment1;
+      
+      curve2->segments = NULL;
+      
+      if (curve2->prev)
+	 curve2->prev->next = curve2->next;
+      if (curve2->next)
+	 curve2->next->prev = curve2->prev;
+      
+      if (curve2->parent->curves == curve2)
+	 curve2->parent->curves = curve2->next;
+      
+      path_free_curve (curve2);
+      
+      tmp = segment2;
+      
+      while (tmp) {
+	 tmp->parent = curve1;
+	 tmp = tmp->next;
+      }
+      return;
+   }
+
+   if (segment1->prev == NULL && segment2->next == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Prepending second to first curve...\n");
+#endif PATH_TOOL_DEBUG
+      curve1 = segment1->parent;
+      curve2 = segment2->parent;
+      
+      segment1->prev = segment2;
+      segment2->next = segment1;
+      
+      curve2->segments = NULL;
+      if (curve2->prev)
+	 curve2->prev->next = curve2->next;
+      if (curve2->next)
+	 curve2->next->prev = curve2->prev;
+      if (curve2->parent->curves == curve2)
+	 curve2->parent->curves = curve2->next;
+      path_free_curve (curve2);
+      
+      tmp = segment2;
+      
+      while (tmp) {
+	 tmp->parent = curve1;
+	 curve1->segments = tmp;
+	 tmp = tmp->prev;
+      }
+      return;
+   }
+
+#ifdef PATH_TOOL_DEBUG
+   fprintf (stderr, "Cant join these curves yet...\n");
+   return;
+#endif PATH_TOOL_DEBUG
+
+}
+
+/*
+ * This function reverses the order of the anchors. This is
+ * necessary for some joining operations.
+ */
+static void
+path_flip_curve (PathCurve *curve)
+{
+   gpointer *end_data;
+   SegmentType end_type;
+
+   PathSegment *tmp, *tmp2;
+   
+   if (!curve && !curve->segments) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "path_flip_curve: No curve o no segments to flip!\n");
+#endif PATH_TOOL_DEBUG
+      return;
+   }
+   
+   tmp = curve->segments;
+
+   while (tmp->next)
+      tmp = tmp->next;
+   
+   end_data = tmp->data;
+   end_type = tmp->type;
+
+   tmp->parent->segments = tmp;
+   
+   while (tmp) {
+      tmp2 = tmp->next;
+      tmp->next = tmp->prev;
+      tmp->prev = tmp2;
+      if (tmp->next) {
+	 tmp->type = tmp->next->type;
+	 tmp->data = tmp->next->data;
+      } else {
+	 tmp->type = end_type;
+	 tmp->data = end_data;
+      }
+      tmp = tmp->next;
+   }
+}
+
+
 static void
 path_free_path (Path * path)
 {
@@ -283,13 +514,17 @@ path_free_curve (PathCurve *curve)
    if (curve)
    {
       tmp2 = curve->segments;
-      g_free(curve);
+
+      /* break closed curves */
+      if (tmp2 && tmp2->prev)
+	 tmp2->prev->next = NULL;
 
       while ((tmp1 = tmp2) != NULL)
       {
          tmp2 = tmp1->next;
 	 path_free_segment (tmp1);
       } 
+      g_free(curve);
    }
 }
 
@@ -298,12 +533,62 @@ path_free_segment (PathSegment *segment)
 {
    if (segment)
    {
+      /* Clear the active flag to keep path_tool->single_active_segment consistent */
+      path_set_flags (segment->parent->parent->path_tool, segment->parent->parent,
+	              segment->parent, segment, 0, SEGMENT_ACTIVE);
       if (segment->data)
          g_free(segment->data);
       g_free (segment);
    }
 }
 
+static void
+path_delete_curve (PathCurve *curve)
+{
+   if (curve)
+   {
+      if (curve->next)
+	 curve->next->prev = curve->prev;
+      if (curve->prev)
+	 curve->prev->next = curve->next;
+      
+      if (curve == curve->parent->curves) {
+	 curve->parent->curves = curve->next;
+      }
+      
+      path_free_curve (curve);
+   }
+}
+
+static void
+path_delete_segment (PathSegment *segment)
+{
+   if (segment)
+   {
+      if (segment->next)
+	 segment->next->prev = segment->prev;
+      if (segment->prev)
+	 segment->prev->next = segment->next;
+      
+      /* If the remaining curve is closed and has a
+       * single point only, open it.
+       */
+      if (segment->next == segment->prev && segment->next)
+	 segment->next->next = segment->next->prev = NULL;
+
+      if (segment == segment->parent->segments)
+	 segment->parent->segments = segment->next;
+
+      if (segment->parent->segments == NULL)
+   	 path_delete_curve (segment->parent);
+      
+      path_free_segment (segment);
+
+      /*
+       * here we have to update the surrounding segments
+       */
+   }
+}
 
 
 /*
@@ -336,7 +621,9 @@ path_tool_button_press (Tool           *tool,
    gint grab_pointer=0;
    gint x, y, halfwidth, dummy;
 
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_button_press\n");
+#endif PATH_TOOL_DEBUG
 
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
@@ -344,7 +631,9 @@ path_tool_button_press (Tool           *tool,
   
    /* Transform window-coordinates to canvas-coordinates */
    gdisplay_untransform_coords (gdisp, bevent->x, bevent->y, &x, &y, TRUE, 0);
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "Clickcoordinates %d, %d\n",x,y);
+#endif PATH_TOOL_DEBUG
    path_tool->click_x = x;
    path_tool->click_y = y;
    path_tool->click_modifier = bevent->state;
@@ -395,20 +684,42 @@ path_tool_button_press_anchor (Tool *tool,
                                GdkEventButton *bevent,
                                GDisplay *gdisp)
 {
+   static guint32 last_click_time=0;
+   gboolean doubleclick=FALSE;
    PathTool *path_tool = tool->private;
    
    Path * cur_path = path_tool->cur_path;
+   PathSegment *p_sas;
    gint grab_pointer;
    
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_tool_button_press_anchor:\n");
+#endif PATH_TOOL_DEBUG
    
    grab_pointer = 1;
 
    if (!cur_path) {
+#ifdef PATH_TOOL_DEBUG
       fprintf (stderr, "Fatal error: No current Path\n");
+#endif PATH_TOOL_DEBUG
       return 0;
    }
    
+   /* 
+    * We have to determine, if this was a doubleclick for ourself, because
+    * disp_callback.c ignores the GDK_[23]BUTTON_EVENT's and adding them to
+    * the switch statement confuses some tools.
+    */
+   if (bevent->time - last_click_time < 250) {
+      doubleclick=TRUE;
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Doppelclick!\n");
+#endif PATH_TOOL_DEBUG
+   } else
+      doubleclick=FALSE;
+   last_click_time = bevent->time;
+
+
    draw_core_pause (path_tool->core, tool);
   
    /* The user pressed on an anchor:
@@ -416,15 +727,75 @@ path_tool_button_press_anchor (Tool *tool,
     *  + SHIFT toggles the activity of an anchor.
     *  if this anchor is at the end of an open curve and the other
     *  end is active, close the curve.
+    *  
+    *  Doubleclick (de)activates the whole curve (not Path!).
     */
 
-   if (path_tool->click_modifier & GDK_SHIFT_MASK)
+   p_sas = path_tool->single_active_segment;
-      path_tool->click_segment->flags ^= SEGMENT_ACTIVE;
+
-   else {
+#ifdef PATH_TOOL_DEBUG
-      if (!(path_tool->click_segment->flags & SEGMENT_ACTIVE))
+   fprintf (stderr, "p_sas: %p\n", p_sas);
-	 path_clear_active (cur_path, NULL, NULL);
+#endif PATH_TOOL_DEBUG
-      path_tool->click_segment->flags |= SEGMENT_ACTIVE;
+
+   if (path_tool->click_modifier & GDK_SHIFT_MASK) {
+      if (path_tool->active_count == 1 && p_sas && p_sas != path_tool->click_segment &&
+          (p_sas->next == NULL || p_sas->prev == NULL) &&
+	  (path_tool->click_segment->next == NULL || path_tool->click_segment->prev == NULL)) {
+	 /*
+	  * if this is the end of an open curve and the single active segment was another
+	  * open end, connect those ends.
+	  */
+	 path_join_curves (path_tool->click_segment, p_sas);
+	 path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+	                 NULL, 0, SEGMENT_ACTIVE);
+      }
+
+      if (doubleclick)
+	 /*
+	  * Doubleclick set the whole curve to the same state, depending on the
+	  * state of the clicked anchor.
+	  */
+	 if (path_tool->click_segment->flags & SEGMENT_ACTIVE)
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+		            NULL, SEGMENT_ACTIVE, 0);
+	 else
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+     		            NULL, 0, SEGMENT_ACTIVE);
+      else
+	 /*
+	  * Toggle the state of the clicked anchor.
+	  */
+	 if (path_tool->click_segment->flags & SEGMENT_ACTIVE)
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+	 	            path_tool->click_segment, 0, SEGMENT_ACTIVE);
+	 else
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+		            path_tool->click_segment, SEGMENT_ACTIVE, 0);
    }
+   /*
+    * Delete anchors, when CONTROL is pressed
+    */
+   else if (path_tool->click_modifier & GDK_CONTROL_MASK)
+   {
+      if (path_tool->click_segment->flags & SEGMENT_ACTIVE)
+      {
+	 if (path_tool->click_segment->prev)
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+   		            path_tool->click_segment->prev, SEGMENT_ACTIVE, 0);
+     	 else if (path_tool->click_segment->next)
+   	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+		            path_tool->click_segment->next, SEGMENT_ACTIVE, 0);
+      }
+
+      path_delete_segment (path_tool->click_segment);
+      path_tool->click_segment = NULL;
+   }
+   else if (!(path_tool->click_segment->flags & SEGMENT_ACTIVE))
+   {
+      path_set_flags (path_tool, cur_path, NULL, NULL, 0, SEGMENT_ACTIVE);
+      path_set_flags (path_tool, cur_path, path_tool->click_curve, path_tool->click_segment, SEGMENT_ACTIVE, 0);
+   }
+   
 
    /* Action goes here */
 
@@ -445,35 +816,47 @@ path_tool_button_press_canvas (Tool *tool,
    PathSegment * cur_segment;
    gint grab_pointer;
    
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_tool_button_press_canvas:\n");
+#endif PATH_TOOL_DEBUG
    
    grab_pointer = 1;
    
    if (!cur_path) {
+#ifdef PATH_TOOL_DEBUG
       fprintf (stderr, "Fatal error: No current Path\n");
+#endif PATH_TOOL_DEBUG
       return 0;
    }
    
    draw_core_pause (path_tool->core, tool);
-  
+   
-   path_clear_active (cur_path, NULL, NULL);
+   if (path_tool->active_count == 1 && path_tool->single_active_segment != NULL
+       && (path_tool->single_active_segment->prev == NULL || path_tool->single_active_segment->next == NULL)) {
+      cur_segment = path_tool->single_active_segment;
+      cur_curve = cur_segment->parent;
 
-   if (!(cur_curve = cur_path->cur_curve)) {
+      path_set_flags (path_tool, cur_path, NULL, NULL, 0, SEGMENT_ACTIVE);
+
+      if (cur_segment->next == NULL)
+	 cur_curve->cur_segment = path_append_segment(cur_path, cur_curve, SEGMENT_LINE, path_tool->click_x, path_tool->click_y);
+      else
+	 cur_curve->cur_segment = path_prepend_segment(cur_path, cur_curve, SEGMENT_LINE, path_tool->click_x, path_tool->click_y);
+      if (cur_curve->cur_segment) {
+	 path_set_flags (path_tool, cur_path, cur_curve, cur_curve->cur_segment, SEGMENT_ACTIVE, 0);
+      }
+   } else {
+      path_set_flags (path_tool, cur_path, NULL, NULL, 0, SEGMENT_ACTIVE);
       cur_path->cur_curve = path_add_curve(cur_path, path_tool->click_x, path_tool->click_y);
-      draw_core_resume(path_tool->core, tool);
+      path_set_flags (path_tool, cur_path, cur_path->cur_curve, cur_path->cur_curve->segments, SEGMENT_ACTIVE, 0);
-      return 0;
+
    }
    
-   cur_curve->cur_segment = path_append_segment(cur_path, cur_curve, SEGMENT_LINE, path_tool->click_x, path_tool->click_y);
-
    draw_core_resume(path_tool->core, tool);
 
    return 0;
 }
 
-	       
-
-
 static void
 path_tool_button_release (Tool           *tool,
 			  GdkEventButton *bevent,
@@ -482,13 +865,14 @@ path_tool_button_release (Tool           *tool,
    GDisplay * gdisp;
    PathTool * path_tool;
  
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_button_release\n");
+#endif PATH_TOOL_DEBUG
  
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
    
    path_tool->state &= ~PATH_TOOL_DRAG;
-   path_tool->state = 0;
 
    gdk_pointer_ungrab (bevent->time);
    gdk_flush ();
@@ -507,6 +891,8 @@ path_tool_motion (Tool           *tool,
    GDisplay * gdisp;
    PathTool * path_tool;
 
+   if (gtk_events_pending()) return;
+   
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
 
@@ -526,39 +912,68 @@ path_tool_motion_anchor (Tool           *tool,
 		         GDisplay       *gdisp)
 {
    PathTool * path_tool;
-   gdouble dx, dy;
+   gdouble dx, dy, d;
    gint x,y;
-   static gint lastx = 0;
+   static gint dxsum = 0;
-   static gint lasty = 0;
+   static gint dysum = 0;
-   
-   if (gtk_events_pending()) return; /* Is this OK? I want to ignore just the motion-events... */
    
    path_tool = (PathTool *) tool->private;
    
+   /*
+    * Dont do anything, if the user clicked with pressed CONTROL-Key,
+    * because he deleted an anchor.
+    */
+   if (path_tool->click_modifier & GDK_CONTROL_MASK)
+      return;
+   
    if (!(path_tool->state & PATH_TOOL_DRAG))
    {
       path_tool->state |= PATH_TOOL_DRAG;
-      lastx = path_tool->click_x;
+      dxsum = 0;
-      lasty = path_tool->click_y;
+      dysum = 0;
    }
 
    gdisplay_untransform_coords (gdisp, mevent->x, mevent->y, &x, &y, TRUE, 0);
    
-   dx = x - lastx;
+   dx = x - path_tool->click_x - dxsum;
-   dy = y - lasty;
+   dy = y - path_tool->click_y - dysum;
    
+   /* restrict to horizontal/vertical lines, if modifiers are pressed
+    * I'm not sure, if this is intuitive for the user. Esp. When moving
+    * an endpoint of an curve I'd expect, that the *line* is
+    * horiz/vertical - not the delta to the point, where the point was
+    * originally...
+    */
+   if (mevent->state & GDK_MOD1_MASK)
+   {
+      if (mevent->state & GDK_CONTROL_MASK)
+      {
+	 d  = (fabs(dx) + fabs(dy)) / 2;  
+	 d  = (fabs(x - path_tool->click_x) + fabs(y - path_tool->click_y)) / 2;  
+	 
+	 dx = ((x < path_tool->click_x) ? -d : d ) - dxsum;
+	 dy = ((y < path_tool->click_y) ? -d : d ) - dysum;
+      }
+      else
+	 dx = - dxsum;
+   }
+   else if (mevent->state & GDK_CONTROL_MASK)
+      dy = - dysum;
+   
+
    path_tool->draw |= PATH_TOOL_REDRAW_ACTIVE;
    
    draw_core_pause(path_tool->core, tool);
 
    path_offset_active (path_tool->cur_path, dx, dy);
 
+   dxsum += dx;
+   dysum += dy;
+
    draw_core_resume (path_tool->core, tool);
    
    path_tool->draw &= ~PATH_TOOL_REDRAW_ACTIVE;
 
-   lastx = x;
-   lasty = y;
 }
    
 
@@ -571,8 +986,10 @@ path_tool_cursor_update (Tool           *tool,
    GDisplay *gdisp;
    gint     x, y, halfwidth, dummy, cursor_location;
   
+#ifdef PATH_TOOL_DEBUG
    /* fprintf (stderr, "path_tool_cursor_update\n");
     */
+#endif PATH_TOOL_DEBUG
 
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
@@ -609,7 +1026,9 @@ path_tool_control (Tool       *tool,
    GDisplay * gdisp;
    PathTool * path_tool;
 
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_control\n");
+#endif PATH_TOOL_DEBUG
 
    gdisp = (GDisplay *) tool->gdisp_ptr;
    path_tool = (PathTool *) tool->private;
@@ -655,6 +1074,10 @@ tools_new_path_tool (void)
    private->click_y         = 0;
    private->click_halfwidth = 0;
    private->click_modifier  = 0;
+
+   private->active_count    = 0;
+   private->single_active_segment = NULL;
+
    private->state           = 0;
    private->draw            = PATH_TOOL_REDRAW_ALL;
    private->core            = draw_core_new (path_tool_draw);
@@ -674,6 +1097,7 @@ tools_new_path_tool (void)
    private->cur_path->cur_curve = NULL;
    private->cur_path->name      = g_string_new("Path 0");
    private->cur_path->state     = 0;
+   private->cur_path->path_tool = private;
    
    return tool;
 }
@@ -701,7 +1125,7 @@ tools_free_path_tool (Tool *tool)
 
 
 /**************************************************************
- * Set of tools to determine, if the click was on an anchor
+ * Set of function to determine, if the click was on an anchor
  */
 
 typedef struct {
@@ -767,7 +1191,7 @@ path_tool_on_anchors (Tool *tool, gint x, gint y, gint halfwidth, Path **ret_pat
 
 
 /**************************************************************
- * Set of tools to offset all active anchors
+ * Set of function to offset all active anchors
  */
 
 typedef struct {
@@ -802,34 +1226,70 @@ path_offset_active (Path *path, gdouble dx, gdouble dy)
 
 
 /**************************************************************
- * Set of tools to set the state of all anchors to inactive
+ * Set of function to set the state of all anchors to inactive
  */
 
+typedef struct {
+   guint32 bits_set;
+   guint32 bits_clear;
+   PathTool *path_tool;
+} Path_set_flags_type;
+
 /* This is a CurveTraverseFunc */
 static void
-path_clear_active_helper (Path *path, PathCurve *curve, PathSegment *segment, gpointer ptr)
+path_set_flags_helper (Path *path, PathCurve *curve, PathSegment *segment, gpointer ptr)
 {
-   gint distance;
+   Path_set_flags_type *tmp = (Path_set_flags_type *) ptr;
+   guint32 oldflags;
+   
+   if (segment) {
+      oldflags = segment->flags;
+      segment->flags &= ~(tmp->bits_clear);
+      segment->flags |= tmp->bits_set;
 
-   if (segment)
+      /* 
-      segment->flags &= ~SEGMENT_ACTIVE;
+       * Some black magic: We try to remember, which is the single active segment.
+       * We count, how many segments are active (in path_tool->active_count) and
+       * XOR path_tool->single_active_segment every time we select or deselect
+       * an anchor. So if exactly one anchor is active, path_tool->single_active_segment
+       * points to it.
+       */
+
+      /* If SEGMENT_ACTIVE state has changed change the PathTool data accordingly.*/
+      if (((segment->flags ^ oldflags) & SEGMENT_ACTIVE) && tmp && tmp->path_tool) {
+	 if (segment->flags & SEGMENT_ACTIVE)
+	    tmp->path_tool->active_count++;
+	 else
+	    tmp->path_tool->active_count--;
+
+	 /* Does this work on all (16|32|64)-bit Machines? */
+
+	 GPOINTER_TO_UINT(tmp->path_tool->single_active_segment) ^= GPOINTER_TO_UINT(segment);
+      }
+   }
 }
 
 static void
-path_clear_active (Path *path, PathCurve *curve, PathSegment *segment)
+path_set_flags (PathTool *path_tool, Path *path, PathCurve *curve, PathSegment *segment, guint32 bits_set, guint32 bits_clear)
 {
-   fprintf (stderr, "path_clear_active\n");
+   Path_set_flags_type *tmp = g_new (Path_set_flags_type, 1);
+   tmp->bits_set=bits_set;
+   tmp->bits_clear=bits_clear;
+   tmp->path_tool = path_tool;
+
    if (segment)
-      path_clear_active_helper (path, curve, segment, NULL);
+      path_set_flags_helper (path, curve, segment, tmp);
    else if (curve)
-      path_traverse_curve (path, curve, path_clear_active_helper, NULL, NULL);
+      path_traverse_curve (path, curve, path_set_flags_helper, NULL, tmp);
    else if (path)
-      path_traverse_path (path, NULL, path_clear_active_helper, NULL, NULL);
+      path_traverse_path (path, NULL, path_set_flags_helper, NULL, tmp);
+
+   g_free (tmp);
 }
 
 
 /**************************************************************
- * Set of tools to draw the segments to the window
+ * Set of functions to draw the segments to the window
  */
 
 /* This is a CurveTraverseFunc */
@@ -840,10 +1300,13 @@ path_tool_draw_helper (Path *path, PathCurve *curve, PathSegment * segment, gpoi
    GDisplay * gdisp;
    PathTool * path_tool;
    DrawCore * core;
-   gint x1, y1, x2, y2, draw;
+   gint x1, y1, x2, y2;
+   gboolean draw = TRUE;
    
    if (!tool) {
+#ifdef PATH_TOOL_DEBUG
       fprintf (stderr, "Fatal Error: path_tool_draw_segment called without valid tool *\n");
+#endif PATH_TOOL_DEBUG
       return;
    }
    
@@ -852,15 +1315,8 @@ path_tool_draw_helper (Path *path, PathCurve *curve, PathSegment * segment, gpoi
    path_tool = (PathTool *) tool->private;
    core = path_tool->core;
    
-   draw = 1;
-   
    if (path_tool->draw & PATH_TOOL_REDRAW_ACTIVE)
-   {
+      draw = (segment->flags & SEGMENT_ACTIVE || (segment->next && segment->next->flags & SEGMENT_ACTIVE));
-      if (segment->flags & SEGMENT_ACTIVE || (segment->next && segment->next->flags & SEGMENT_ACTIVE))
-	 draw=1;
-      else
-	 draw=0;
-   }
 
    if (segment && draw) 
    {
@@ -880,8 +1336,10 @@ path_tool_draw_helper (Path *path, PathCurve *curve, PathSegment * segment, gpoi
          gdk_draw_line (core->win, core->gc, x1, y1, x2, y2);
       }
    }
+#ifdef PATH_TOOL_DEBUG
    else if (!segment)
       fprintf(stderr, "path_tool_draw_segment: no segment to draw\n");
+#endif PATH_TOOL_DEBUG
 }
 
 static void
@@ -892,11 +1350,14 @@ path_tool_draw (Tool *tool)
    PathTool * path_tool;
    PathCurve * cur_curve;
   
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_draw\n");
+#endif PATH_TOOL_DEBUG
    
    gdisp = tool->gdisp_ptr;
    path_tool = tool->private;
    cur_path = path_tool->cur_path;
    
    path_traverse_path (cur_path, NULL, path_tool_draw_helper, NULL, tool);
+   
 }

app/path_toolP.h

@@ -40,45 +40,46 @@ typedef enum { SEGMENT_LINE, SEGMENT_BEZIER } SegmentType;
 
 
 typedef struct _path_segment PathSegment;
+typedef struct _path_curve PathCurve;
+typedef struct _path Path;
+
+typedef struct _path_tool PathTool;
 
 struct _path_segment
 {
    SegmentType type;          /* What type of segment */
    gdouble x, y;              /* location of starting-point in image space  */
+   gpointer data;             /* Additional data, dependant of segment-type */
    
    guint32 flags;             /* Various Flags: Is the Segment active? */
 
+   PathCurve *parent;         /* the parent Curve */
    PathSegment *next;         /* Next Segment or NULL */
    PathSegment *prev;         /* Previous Segment or NULL */
 
-   gpointer data;             /* Additional data, dependant of segment-type */
 };
 
 
-typedef struct _path_curve PathCurve;
-
 struct _path_curve
 {
    PathSegment * segments;    /* The segments of the curve */
    PathSegment * cur_segment; /* the current segment */
+   Path * parent;             /* the parent Path */
    PathCurve * next;          /* Next Curve or NULL */
    PathCurve * prev;          /* Previous Curve or NULL */
 };
 
 
-typedef struct _path Path;
-
 struct _path
 {
    PathCurve * curves;        /* the curves */
    PathCurve * cur_curve;     /* the current curve */
    GString * name;            /* the name of the path */
    guint32 state;             /* is the path locked? */
+   PathTool * path_tool;      /* The parent Path Tool */
 };
 
 
-typedef struct _path_tool PathTool;
-
 struct _path_tool
 {
    gint click_pos;            /* where did the user click?         */
@@ -90,6 +91,14 @@ struct _path_tool
    PathCurve *click_curve;    /* was the click?                    */
    PathSegment *click_segment;
 
+   gint active_count;         /* How many segments are active?     */
+   /*
+    * WARNING: single_active_segment may contain non NULL Values
+    * which point to the nirvana. But they are important!
+    * The pointer is garantueed to be valid, when active_count==1
+    */
+   PathSegment *single_active_segment;  /* The only active segment */
+
    gint state;                /* state of tool                     */
    gint draw;                 /* all or part                       */
    DrawCore *core;            /* Core drawing object               */

app/pixmaps2.h

@@ -1004,3 +1004,34 @@ static char *xinput_airbrush_bits [] =
   "......................"
 };               
 
+/*  GIMP icon image format -- S. Kimball, P. Mattis  */
+/*  Image name: path_tool  */
+
+
+#define path_tool_width 22
+#define path_tool_height 22
+static char *path_tool_bits [] = 
+{
+  "......................",
+  "......aaa.............",
+  "......ahae............",
+  "......aaae............",
+  ".......ee..aaae.......",
+  "......a..aae..aae.....",
+  "......e.a.......ae....",
+  ".....a.a.........aa...",
+  "......a.........aaaa..",
+  "....aa..........aaaae.",
+  ".....a..a........aaee.",
+  "...aa....aa.......ee..",
+  "..aae....aaaa.........",
+  ".ahha.....aaaa........",
+  ".ahhae....aaa.........",
+  "..aaee.....a.a........",
+  "..aee.........a.......",
+  "..a...................",
+  "..a...................",
+  "..a...................",
+  "..a...................",
+  "......................"
+};

app/tools.c

@@ -520,7 +520,7 @@ ToolInfo tool_info[] =
     26,
     N_("/Tools/Path"),
     "",
-    (char **) measure_bits,
+    (char **) path_tool_bits,
     N_("Manipulate paths"),
     "ContextHelp/path",
     PATH_TOOL,

app/tools/path_tool.c

@@ -29,6 +29,8 @@
  * segments between two anchors.
  */
 
+#undef PATH_TOOL_DEBUG
+
 #include <math.h>
 /* #include "appenv.h"
  */
@@ -38,7 +40,9 @@
 #include "path_tool.h"
 #include "path_toolP.h"
 
+#ifdef PATH_TOOL_DEBUG
 #include <stdio.h>
+#endif PATH_TOOL_DEBUG
 
 #include "libgimp/gimpintl.h"
 
@@ -68,15 +72,18 @@ static gdouble path_locate_point            (Path *, PathCurve **, PathSegment *
 /* Tools to manipulate paths, curves, segments */
 
 static PathCurve   * path_add_curve       (Path *, gint, gint);
-static inline PathSegment * path_append_segment  (Path *, PathCurve *, SegmentType, gint, gint);
+static PathSegment * path_append_segment  (Path *, PathCurve *, SegmentType, gint, gint);
 static PathSegment * path_prepend_segment (Path *, PathCurve *, SegmentType, gint, gint);
 static PathSegment * path_split_segment   (PathSegment *, gdouble);
+static void          path_join_curves     (PathSegment *, PathSegment *);
+static void          path_flip_curve      (PathCurve *);
 static void          path_free_path       (Path *);
 static void          path_free_curve      (PathCurve *);
 static void          path_free_segment    (PathSegment *);
+static void          path_delete_segment  (PathSegment *);
 static void          path_print           (Path *);
 static void          path_offset_active   (Path *, gdouble, gdouble);
-static void          path_clear_active    (Path *, PathCurve *, PathSegment *);
+static void          path_set_flags       (PathTool *, Path *, PathCurve *, PathSegment *, guint32, guint32);
 
 /* High level image-manipulation functions */
 
@@ -116,8 +123,9 @@ static ToolOptions *path_options = NULL;
  */
 
 /*
- * These functions are for applying a function over a complete path/curve/segment
+ * These functions are for applying a function over a complete
- * they can pass information to each other with a arbitrary data structure
+ * path/curve/segment. They can pass information to each other
+ * with a arbitrary data structure
  *
  * The idea behind the three different functions is:
  *  if pathfunc != NULL
@@ -176,7 +184,9 @@ path_traverse_curve (Path *path, PathCurve *curve, CurveTraverseFunc curvefunc,
 static void
 path_traverse_segment (Path *path, PathCurve *curve, PathSegment *segment, SegmentTraverseFunc function, gpointer data)
 {
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_traverse_segment\n");
+#endif PATH_TOOL_DEBUG
 
    /* Something like:
     * for i = 1 to subsamples {
@@ -190,34 +200,48 @@ path_traverse_segment (Path *path, PathCurve *curve, PathSegment *segment, Segme
  * Helper functions for manipulating the data-structures:
  */
 
-static PathCurve   * path_add_curve       (Path * cur_path, gint x, gint y)
+static PathCurve *path_add_curve (Path * cur_path, gint x, gint y)
 {
    PathCurve * tmp = cur_path->curves;
-   PathCurve * new_curve;
+   PathCurve * new_curve = NULL;
 
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_add_curve\n");
+#endif PATH_TOOL_DEBUG
    
-   new_curve = g_new (PathCurve, 1);
+   if (cur_path) {
+      new_curve = g_new (PathCurve, 1);
    
-   new_curve->next = tmp;
+      new_curve->parent = cur_path;
-   new_curve->prev = NULL;
+      new_curve->next = tmp;
-   new_curve->cur_segment = NULL;
+      new_curve->prev = NULL;
-   new_curve->segments = NULL;
+      new_curve->cur_segment = NULL;
+      new_curve->segments = NULL;
 
-   if (tmp) tmp->prev = new_curve;
+      if (tmp) tmp->prev = new_curve;
    
-   cur_path->curves = cur_path->cur_curve = new_curve;
+      cur_path->curves = cur_path->cur_curve = new_curve;
    
-   new_curve->segments = path_append_segment (cur_path, new_curve, SEGMENT_LINE, x, y);
+      new_curve->segments = path_prepend_segment (cur_path, new_curve, SEGMENT_LINE, x, y);
+   }
+#ifdef PATH_TOOL_DEBUG
+   else
+      fprintf (stderr, "Fatal Error: path_add_curve called without valid path\n");
+#endif PATH_TOOL_DEBUG
+
    return new_curve;
 }
    
    
-static inline PathSegment * path_append_segment  (Path * cur_path, PathCurve * cur_curve, SegmentType type, gint x, gint y)
+static PathSegment * path_append_segment  (Path * cur_path, PathCurve * cur_curve, SegmentType type, gint x, gint y)
 {
    PathSegment * tmp = cur_curve->segments;
    PathSegment * new_segment = NULL;
    
+#ifdef PATH_TOOL_DEBUG
+      fprintf(stderr, "path_append_segment\n");
+#endif PATH_TOOL_DEBUG
+
    if (cur_curve) {
       tmp = cur_curve->segments;
       while (tmp && tmp->next && tmp->next != cur_curve->segments) {
@@ -230,32 +254,239 @@ static inline PathSegment * path_append_segment  (Path * cur_path, PathCurve * c
          new_segment->type = type;
          new_segment->x = x;
          new_segment->y = y;
-         new_segment->flags = SEGMENT_ACTIVE;
+         new_segment->flags = 0;
+         new_segment->parent = cur_curve;
          new_segment->next = NULL;
          new_segment->prev = tmp;
          new_segment->data = NULL;
          
          if (tmp) 
-         {
             tmp->next = new_segment;
-         }
 
          cur_curve->cur_segment = new_segment;
       }
+#ifdef PATH_TOOL_DEBUG
       else
          fprintf(stderr, "Fatal Error: path_append_segment called with a closed curve\n");
+#endif PATH_TOOL_DEBUG
    }
+#ifdef PATH_TOOL_DEBUG
    else
       fprintf(stderr, "Fatal Error: path_append_segment called without valid curve\n");
+#endif PATH_TOOL_DEBUG
    
    return new_segment;
 }
 
 
-/* static PathSegment * path_prepend_segment (Path *, PathCurve *, gint, gint);
+static PathSegment * path_prepend_segment  (Path * cur_path, PathCurve * cur_curve, SegmentType type, gint x, gint y)
- * static PathSegment * path_split_segment   (PathSegment *, gdouble);
+{
+   PathSegment * tmp = cur_curve->segments;
+   PathSegment * new_segment = NULL;
+   
+#ifdef PATH_TOOL_DEBUG
+      fprintf(stderr, "path_prepend_segment\n");
+#endif PATH_TOOL_DEBUG
+
+   if (cur_curve) {
+      tmp = cur_curve->segments;
+   
+      if (tmp == NULL || tmp->prev == NULL) {
+         new_segment = g_new (PathSegment, 1);
+         
+         new_segment->type = type;
+         new_segment->x = x;
+         new_segment->y = y;
+         new_segment->flags = 0;
+         new_segment->parent = cur_curve;
+         new_segment->next = tmp;
+         new_segment->prev = NULL;
+         new_segment->data = NULL;
+         
+         if (tmp) 
+            tmp->prev = new_segment;
+
+         cur_curve->segments = new_segment;
+         cur_curve->cur_segment = new_segment;
+      }
+#ifdef PATH_TOOL_DEBUG
+      else
+         fprintf(stderr, "Fatal Error: path_prepend_segment called with a closed curve\n");
+#endif PATH_TOOL_DEBUG
+   }
+#ifdef PATH_TOOL_DEBUG
+   else
+      fprintf(stderr, "Fatal Error: path_prepend_segment called without valid curve\n");
+#endif PATH_TOOL_DEBUG
+   
+   return new_segment;
+}
+
+/* static PathSegment * path_split_segment   (PathSegment *, gdouble);
  */
 
+/*
+ * Join two arbitrary endpoints and free the parent from the second
+ * segment, if it differs from the first parents.
+ */
+
+static void
+path_join_curves (PathSegment *segment1, PathSegment *segment2) {
+   PathCurve *curve1, *curve2;
+   PathSegment *tmp;
+
+   if ((segment1->next && segment1->prev) || (segment2->next && segment2->prev)) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf(stderr, "Fatal Error: path_join_curves called with a closed segment\n");
+#endif PATH_TOOL_DEBUG
+      return;
+   }
+   if (segment1->parent == segment2->parent) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Joining beginning and end of the same curve...\n");
+#endif PATH_TOOL_DEBUG
+      if (segment2->next == NULL) {
+	 segment2->next = segment1;
+	 segment1->prev = segment2;
+      } else {
+	 segment2->prev = segment1;
+	 segment1->next = segment2;
+      }
+      return;
+   }
+
+   if (segment1->next == NULL && segment2->next == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Flipping second curve (next, next)...\n");
+#endif PATH_TOOL_DEBUG
+      path_flip_curve (segment2->parent);
+      /* segment2 = segment2->parent->segments;
+       */
+   }
+      
+   if (segment1->prev == NULL && segment2->prev == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Flipping second curve (prev, prev)...\n");
+#endif PATH_TOOL_DEBUG
+      path_flip_curve (segment2->parent);
+      /* segment2 = segment2->parent->segments;
+       * while (segment2->next)
+       * segment2 = segment2->next;
+       */
+   }
+      
+   if (segment1->next == NULL && segment2->prev == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Appending second to first curve...\n");
+#endif PATH_TOOL_DEBUG
+      curve1 = segment1->parent;
+      curve2 = segment2->parent;
+      
+      segment1->next = segment2;
+      segment2->prev = segment1;
+      
+      curve2->segments = NULL;
+      
+      if (curve2->prev)
+	 curve2->prev->next = curve2->next;
+      if (curve2->next)
+	 curve2->next->prev = curve2->prev;
+      
+      if (curve2->parent->curves == curve2)
+	 curve2->parent->curves = curve2->next;
+      
+      path_free_curve (curve2);
+      
+      tmp = segment2;
+      
+      while (tmp) {
+	 tmp->parent = curve1;
+	 tmp = tmp->next;
+      }
+      return;
+   }
+
+   if (segment1->prev == NULL && segment2->next == NULL) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Prepending second to first curve...\n");
+#endif PATH_TOOL_DEBUG
+      curve1 = segment1->parent;
+      curve2 = segment2->parent;
+      
+      segment1->prev = segment2;
+      segment2->next = segment1;
+      
+      curve2->segments = NULL;
+      if (curve2->prev)
+	 curve2->prev->next = curve2->next;
+      if (curve2->next)
+	 curve2->next->prev = curve2->prev;
+      if (curve2->parent->curves == curve2)
+	 curve2->parent->curves = curve2->next;
+      path_free_curve (curve2);
+      
+      tmp = segment2;
+      
+      while (tmp) {
+	 tmp->parent = curve1;
+	 curve1->segments = tmp;
+	 tmp = tmp->prev;
+      }
+      return;
+   }
+
+#ifdef PATH_TOOL_DEBUG
+   fprintf (stderr, "Cant join these curves yet...\n");
+   return;
+#endif PATH_TOOL_DEBUG
+
+}
+
+/*
+ * This function reverses the order of the anchors. This is
+ * necessary for some joining operations.
+ */
+static void
+path_flip_curve (PathCurve *curve)
+{
+   gpointer *end_data;
+   SegmentType end_type;
+
+   PathSegment *tmp, *tmp2;
+   
+   if (!curve && !curve->segments) {
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "path_flip_curve: No curve o no segments to flip!\n");
+#endif PATH_TOOL_DEBUG
+      return;
+   }
+   
+   tmp = curve->segments;
+
+   while (tmp->next)
+      tmp = tmp->next;
+   
+   end_data = tmp->data;
+   end_type = tmp->type;
+
+   tmp->parent->segments = tmp;
+   
+   while (tmp) {
+      tmp2 = tmp->next;
+      tmp->next = tmp->prev;
+      tmp->prev = tmp2;
+      if (tmp->next) {
+	 tmp->type = tmp->next->type;
+	 tmp->data = tmp->next->data;
+      } else {
+	 tmp->type = end_type;
+	 tmp->data = end_data;
+      }
+      tmp = tmp->next;
+   }
+}
+
+
 static void
 path_free_path (Path * path)
 {
@@ -283,13 +514,17 @@ path_free_curve (PathCurve *curve)
    if (curve)
    {
       tmp2 = curve->segments;
-      g_free(curve);
+
+      /* break closed curves */
+      if (tmp2 && tmp2->prev)
+	 tmp2->prev->next = NULL;
 
       while ((tmp1 = tmp2) != NULL)
       {
          tmp2 = tmp1->next;
 	 path_free_segment (tmp1);
       } 
+      g_free(curve);
    }
 }
 
@@ -298,12 +533,62 @@ path_free_segment (PathSegment *segment)
 {
    if (segment)
    {
+      /* Clear the active flag to keep path_tool->single_active_segment consistent */
+      path_set_flags (segment->parent->parent->path_tool, segment->parent->parent,
+	              segment->parent, segment, 0, SEGMENT_ACTIVE);
       if (segment->data)
          g_free(segment->data);
       g_free (segment);
    }
 }
 
+static void
+path_delete_curve (PathCurve *curve)
+{
+   if (curve)
+   {
+      if (curve->next)
+	 curve->next->prev = curve->prev;
+      if (curve->prev)
+	 curve->prev->next = curve->next;
+      
+      if (curve == curve->parent->curves) {
+	 curve->parent->curves = curve->next;
+      }
+      
+      path_free_curve (curve);
+   }
+}
+
+static void
+path_delete_segment (PathSegment *segment)
+{
+   if (segment)
+   {
+      if (segment->next)
+	 segment->next->prev = segment->prev;
+      if (segment->prev)
+	 segment->prev->next = segment->next;
+      
+      /* If the remaining curve is closed and has a
+       * single point only, open it.
+       */
+      if (segment->next == segment->prev && segment->next)
+	 segment->next->next = segment->next->prev = NULL;
+
+      if (segment == segment->parent->segments)
+	 segment->parent->segments = segment->next;
+
+      if (segment->parent->segments == NULL)
+   	 path_delete_curve (segment->parent);
+      
+      path_free_segment (segment);
+
+      /*
+       * here we have to update the surrounding segments
+       */
+   }
+}
 
 
 /*
@@ -336,7 +621,9 @@ path_tool_button_press (Tool           *tool,
    gint grab_pointer=0;
    gint x, y, halfwidth, dummy;
 
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_button_press\n");
+#endif PATH_TOOL_DEBUG
 
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
@@ -344,7 +631,9 @@ path_tool_button_press (Tool           *tool,
   
    /* Transform window-coordinates to canvas-coordinates */
    gdisplay_untransform_coords (gdisp, bevent->x, bevent->y, &x, &y, TRUE, 0);
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "Clickcoordinates %d, %d\n",x,y);
+#endif PATH_TOOL_DEBUG
    path_tool->click_x = x;
    path_tool->click_y = y;
    path_tool->click_modifier = bevent->state;
@@ -395,20 +684,42 @@ path_tool_button_press_anchor (Tool *tool,
                                GdkEventButton *bevent,
                                GDisplay *gdisp)
 {
+   static guint32 last_click_time=0;
+   gboolean doubleclick=FALSE;
    PathTool *path_tool = tool->private;
    
    Path * cur_path = path_tool->cur_path;
+   PathSegment *p_sas;
    gint grab_pointer;
    
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_tool_button_press_anchor:\n");
+#endif PATH_TOOL_DEBUG
    
    grab_pointer = 1;
 
    if (!cur_path) {
+#ifdef PATH_TOOL_DEBUG
       fprintf (stderr, "Fatal error: No current Path\n");
+#endif PATH_TOOL_DEBUG
       return 0;
    }
    
+   /* 
+    * We have to determine, if this was a doubleclick for ourself, because
+    * disp_callback.c ignores the GDK_[23]BUTTON_EVENT's and adding them to
+    * the switch statement confuses some tools.
+    */
+   if (bevent->time - last_click_time < 250) {
+      doubleclick=TRUE;
+#ifdef PATH_TOOL_DEBUG
+      fprintf (stderr, "Doppelclick!\n");
+#endif PATH_TOOL_DEBUG
+   } else
+      doubleclick=FALSE;
+   last_click_time = bevent->time;
+
+
    draw_core_pause (path_tool->core, tool);
   
    /* The user pressed on an anchor:
@@ -416,15 +727,75 @@ path_tool_button_press_anchor (Tool *tool,
     *  + SHIFT toggles the activity of an anchor.
     *  if this anchor is at the end of an open curve and the other
     *  end is active, close the curve.
+    *  
+    *  Doubleclick (de)activates the whole curve (not Path!).
     */
 
-   if (path_tool->click_modifier & GDK_SHIFT_MASK)
+   p_sas = path_tool->single_active_segment;
-      path_tool->click_segment->flags ^= SEGMENT_ACTIVE;
+
-   else {
+#ifdef PATH_TOOL_DEBUG
-      if (!(path_tool->click_segment->flags & SEGMENT_ACTIVE))
+   fprintf (stderr, "p_sas: %p\n", p_sas);
-	 path_clear_active (cur_path, NULL, NULL);
+#endif PATH_TOOL_DEBUG
-      path_tool->click_segment->flags |= SEGMENT_ACTIVE;
+
+   if (path_tool->click_modifier & GDK_SHIFT_MASK) {
+      if (path_tool->active_count == 1 && p_sas && p_sas != path_tool->click_segment &&
+          (p_sas->next == NULL || p_sas->prev == NULL) &&
+	  (path_tool->click_segment->next == NULL || path_tool->click_segment->prev == NULL)) {
+	 /*
+	  * if this is the end of an open curve and the single active segment was another
+	  * open end, connect those ends.
+	  */
+	 path_join_curves (path_tool->click_segment, p_sas);
+	 path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+	                 NULL, 0, SEGMENT_ACTIVE);
+      }
+
+      if (doubleclick)
+	 /*
+	  * Doubleclick set the whole curve to the same state, depending on the
+	  * state of the clicked anchor.
+	  */
+	 if (path_tool->click_segment->flags & SEGMENT_ACTIVE)
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+		            NULL, SEGMENT_ACTIVE, 0);
+	 else
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+     		            NULL, 0, SEGMENT_ACTIVE);
+      else
+	 /*
+	  * Toggle the state of the clicked anchor.
+	  */
+	 if (path_tool->click_segment->flags & SEGMENT_ACTIVE)
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+	 	            path_tool->click_segment, 0, SEGMENT_ACTIVE);
+	 else
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+		            path_tool->click_segment, SEGMENT_ACTIVE, 0);
    }
+   /*
+    * Delete anchors, when CONTROL is pressed
+    */
+   else if (path_tool->click_modifier & GDK_CONTROL_MASK)
+   {
+      if (path_tool->click_segment->flags & SEGMENT_ACTIVE)
+      {
+	 if (path_tool->click_segment->prev)
+	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+   		            path_tool->click_segment->prev, SEGMENT_ACTIVE, 0);
+     	 else if (path_tool->click_segment->next)
+   	    path_set_flags (path_tool, path_tool->click_path, path_tool->click_curve,
+		            path_tool->click_segment->next, SEGMENT_ACTIVE, 0);
+      }
+
+      path_delete_segment (path_tool->click_segment);
+      path_tool->click_segment = NULL;
+   }
+   else if (!(path_tool->click_segment->flags & SEGMENT_ACTIVE))
+   {
+      path_set_flags (path_tool, cur_path, NULL, NULL, 0, SEGMENT_ACTIVE);
+      path_set_flags (path_tool, cur_path, path_tool->click_curve, path_tool->click_segment, SEGMENT_ACTIVE, 0);
+   }
+   
 
    /* Action goes here */
 
@@ -445,35 +816,47 @@ path_tool_button_press_canvas (Tool *tool,
    PathSegment * cur_segment;
    gint grab_pointer;
    
+#ifdef PATH_TOOL_DEBUG
    fprintf(stderr, "path_tool_button_press_canvas:\n");
+#endif PATH_TOOL_DEBUG
    
    grab_pointer = 1;
    
    if (!cur_path) {
+#ifdef PATH_TOOL_DEBUG
       fprintf (stderr, "Fatal error: No current Path\n");
+#endif PATH_TOOL_DEBUG
       return 0;
    }
    
    draw_core_pause (path_tool->core, tool);
-  
+   
-   path_clear_active (cur_path, NULL, NULL);
+   if (path_tool->active_count == 1 && path_tool->single_active_segment != NULL
+       && (path_tool->single_active_segment->prev == NULL || path_tool->single_active_segment->next == NULL)) {
+      cur_segment = path_tool->single_active_segment;
+      cur_curve = cur_segment->parent;
 
-   if (!(cur_curve = cur_path->cur_curve)) {
+      path_set_flags (path_tool, cur_path, NULL, NULL, 0, SEGMENT_ACTIVE);
+
+      if (cur_segment->next == NULL)
+	 cur_curve->cur_segment = path_append_segment(cur_path, cur_curve, SEGMENT_LINE, path_tool->click_x, path_tool->click_y);
+      else
+	 cur_curve->cur_segment = path_prepend_segment(cur_path, cur_curve, SEGMENT_LINE, path_tool->click_x, path_tool->click_y);
+      if (cur_curve->cur_segment) {
+	 path_set_flags (path_tool, cur_path, cur_curve, cur_curve->cur_segment, SEGMENT_ACTIVE, 0);
+      }
+   } else {
+      path_set_flags (path_tool, cur_path, NULL, NULL, 0, SEGMENT_ACTIVE);
       cur_path->cur_curve = path_add_curve(cur_path, path_tool->click_x, path_tool->click_y);
-      draw_core_resume(path_tool->core, tool);
+      path_set_flags (path_tool, cur_path, cur_path->cur_curve, cur_path->cur_curve->segments, SEGMENT_ACTIVE, 0);
-      return 0;
+
    }
    
-   cur_curve->cur_segment = path_append_segment(cur_path, cur_curve, SEGMENT_LINE, path_tool->click_x, path_tool->click_y);
-
    draw_core_resume(path_tool->core, tool);
 
    return 0;
 }
 
-	       
-
-
 static void
 path_tool_button_release (Tool           *tool,
 			  GdkEventButton *bevent,
@@ -482,13 +865,14 @@ path_tool_button_release (Tool           *tool,
    GDisplay * gdisp;
    PathTool * path_tool;
  
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_button_release\n");
+#endif PATH_TOOL_DEBUG
  
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
    
    path_tool->state &= ~PATH_TOOL_DRAG;
-   path_tool->state = 0;
 
    gdk_pointer_ungrab (bevent->time);
    gdk_flush ();
@@ -507,6 +891,8 @@ path_tool_motion (Tool           *tool,
    GDisplay * gdisp;
    PathTool * path_tool;
 
+   if (gtk_events_pending()) return;
+   
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
 
@@ -526,39 +912,68 @@ path_tool_motion_anchor (Tool           *tool,
 		         GDisplay       *gdisp)
 {
    PathTool * path_tool;
-   gdouble dx, dy;
+   gdouble dx, dy, d;
    gint x,y;
-   static gint lastx = 0;
+   static gint dxsum = 0;
-   static gint lasty = 0;
+   static gint dysum = 0;
-   
-   if (gtk_events_pending()) return; /* Is this OK? I want to ignore just the motion-events... */
    
    path_tool = (PathTool *) tool->private;
    
+   /*
+    * Dont do anything, if the user clicked with pressed CONTROL-Key,
+    * because he deleted an anchor.
+    */
+   if (path_tool->click_modifier & GDK_CONTROL_MASK)
+      return;
+   
    if (!(path_tool->state & PATH_TOOL_DRAG))
    {
       path_tool->state |= PATH_TOOL_DRAG;
-      lastx = path_tool->click_x;
+      dxsum = 0;
-      lasty = path_tool->click_y;
+      dysum = 0;
    }
 
    gdisplay_untransform_coords (gdisp, mevent->x, mevent->y, &x, &y, TRUE, 0);
    
-   dx = x - lastx;
+   dx = x - path_tool->click_x - dxsum;
-   dy = y - lasty;
+   dy = y - path_tool->click_y - dysum;
    
+   /* restrict to horizontal/vertical lines, if modifiers are pressed
+    * I'm not sure, if this is intuitive for the user. Esp. When moving
+    * an endpoint of an curve I'd expect, that the *line* is
+    * horiz/vertical - not the delta to the point, where the point was
+    * originally...
+    */
+   if (mevent->state & GDK_MOD1_MASK)
+   {
+      if (mevent->state & GDK_CONTROL_MASK)
+      {
+	 d  = (fabs(dx) + fabs(dy)) / 2;  
+	 d  = (fabs(x - path_tool->click_x) + fabs(y - path_tool->click_y)) / 2;  
+	 
+	 dx = ((x < path_tool->click_x) ? -d : d ) - dxsum;
+	 dy = ((y < path_tool->click_y) ? -d : d ) - dysum;
+      }
+      else
+	 dx = - dxsum;
+   }
+   else if (mevent->state & GDK_CONTROL_MASK)
+      dy = - dysum;
+   
+
    path_tool->draw |= PATH_TOOL_REDRAW_ACTIVE;
    
    draw_core_pause(path_tool->core, tool);
 
    path_offset_active (path_tool->cur_path, dx, dy);
 
+   dxsum += dx;
+   dysum += dy;
+
    draw_core_resume (path_tool->core, tool);
    
    path_tool->draw &= ~PATH_TOOL_REDRAW_ACTIVE;
 
-   lastx = x;
-   lasty = y;
 }
    
 
@@ -571,8 +986,10 @@ path_tool_cursor_update (Tool           *tool,
    GDisplay *gdisp;
    gint     x, y, halfwidth, dummy, cursor_location;
   
+#ifdef PATH_TOOL_DEBUG
    /* fprintf (stderr, "path_tool_cursor_update\n");
     */
+#endif PATH_TOOL_DEBUG
 
    gdisp = (GDisplay *) gdisp_ptr;
    path_tool = (PathTool *) tool->private;
@@ -609,7 +1026,9 @@ path_tool_control (Tool       *tool,
    GDisplay * gdisp;
    PathTool * path_tool;
 
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_control\n");
+#endif PATH_TOOL_DEBUG
 
    gdisp = (GDisplay *) tool->gdisp_ptr;
    path_tool = (PathTool *) tool->private;
@@ -655,6 +1074,10 @@ tools_new_path_tool (void)
    private->click_y         = 0;
    private->click_halfwidth = 0;
    private->click_modifier  = 0;
+
+   private->active_count    = 0;
+   private->single_active_segment = NULL;
+
    private->state           = 0;
    private->draw            = PATH_TOOL_REDRAW_ALL;
    private->core            = draw_core_new (path_tool_draw);
@@ -674,6 +1097,7 @@ tools_new_path_tool (void)
    private->cur_path->cur_curve = NULL;
    private->cur_path->name      = g_string_new("Path 0");
    private->cur_path->state     = 0;
+   private->cur_path->path_tool = private;
    
    return tool;
 }
@@ -701,7 +1125,7 @@ tools_free_path_tool (Tool *tool)
 
 
 /**************************************************************
- * Set of tools to determine, if the click was on an anchor
+ * Set of function to determine, if the click was on an anchor
  */
 
 typedef struct {
@@ -767,7 +1191,7 @@ path_tool_on_anchors (Tool *tool, gint x, gint y, gint halfwidth, Path **ret_pat
 
 
 /**************************************************************
- * Set of tools to offset all active anchors
+ * Set of function to offset all active anchors
  */
 
 typedef struct {
@@ -802,34 +1226,70 @@ path_offset_active (Path *path, gdouble dx, gdouble dy)
 
 
 /**************************************************************
- * Set of tools to set the state of all anchors to inactive
+ * Set of function to set the state of all anchors to inactive
  */
 
+typedef struct {
+   guint32 bits_set;
+   guint32 bits_clear;
+   PathTool *path_tool;
+} Path_set_flags_type;
+
 /* This is a CurveTraverseFunc */
 static void
-path_clear_active_helper (Path *path, PathCurve *curve, PathSegment *segment, gpointer ptr)
+path_set_flags_helper (Path *path, PathCurve *curve, PathSegment *segment, gpointer ptr)
 {
-   gint distance;
+   Path_set_flags_type *tmp = (Path_set_flags_type *) ptr;
+   guint32 oldflags;
+   
+   if (segment) {
+      oldflags = segment->flags;
+      segment->flags &= ~(tmp->bits_clear);
+      segment->flags |= tmp->bits_set;
 
-   if (segment)
+      /* 
-      segment->flags &= ~SEGMENT_ACTIVE;
+       * Some black magic: We try to remember, which is the single active segment.
+       * We count, how many segments are active (in path_tool->active_count) and
+       * XOR path_tool->single_active_segment every time we select or deselect
+       * an anchor. So if exactly one anchor is active, path_tool->single_active_segment
+       * points to it.
+       */
+
+      /* If SEGMENT_ACTIVE state has changed change the PathTool data accordingly.*/
+      if (((segment->flags ^ oldflags) & SEGMENT_ACTIVE) && tmp && tmp->path_tool) {
+	 if (segment->flags & SEGMENT_ACTIVE)
+	    tmp->path_tool->active_count++;
+	 else
+	    tmp->path_tool->active_count--;
+
+	 /* Does this work on all (16|32|64)-bit Machines? */
+
+	 GPOINTER_TO_UINT(tmp->path_tool->single_active_segment) ^= GPOINTER_TO_UINT(segment);
+      }
+   }
 }
 
 static void
-path_clear_active (Path *path, PathCurve *curve, PathSegment *segment)
+path_set_flags (PathTool *path_tool, Path *path, PathCurve *curve, PathSegment *segment, guint32 bits_set, guint32 bits_clear)
 {
-   fprintf (stderr, "path_clear_active\n");
+   Path_set_flags_type *tmp = g_new (Path_set_flags_type, 1);
+   tmp->bits_set=bits_set;
+   tmp->bits_clear=bits_clear;
+   tmp->path_tool = path_tool;
+
    if (segment)
-      path_clear_active_helper (path, curve, segment, NULL);
+      path_set_flags_helper (path, curve, segment, tmp);
    else if (curve)
-      path_traverse_curve (path, curve, path_clear_active_helper, NULL, NULL);
+      path_traverse_curve (path, curve, path_set_flags_helper, NULL, tmp);
    else if (path)
-      path_traverse_path (path, NULL, path_clear_active_helper, NULL, NULL);
+      path_traverse_path (path, NULL, path_set_flags_helper, NULL, tmp);
+
+   g_free (tmp);
 }
 
 
 /**************************************************************
- * Set of tools to draw the segments to the window
+ * Set of functions to draw the segments to the window
  */
 
 /* This is a CurveTraverseFunc */
@@ -840,10 +1300,13 @@ path_tool_draw_helper (Path *path, PathCurve *curve, PathSegment * segment, gpoi
    GDisplay * gdisp;
    PathTool * path_tool;
    DrawCore * core;
-   gint x1, y1, x2, y2, draw;
+   gint x1, y1, x2, y2;
+   gboolean draw = TRUE;
    
    if (!tool) {
+#ifdef PATH_TOOL_DEBUG
       fprintf (stderr, "Fatal Error: path_tool_draw_segment called without valid tool *\n");
+#endif PATH_TOOL_DEBUG
       return;
    }
    
@@ -852,15 +1315,8 @@ path_tool_draw_helper (Path *path, PathCurve *curve, PathSegment * segment, gpoi
    path_tool = (PathTool *) tool->private;
    core = path_tool->core;
    
-   draw = 1;
-   
    if (path_tool->draw & PATH_TOOL_REDRAW_ACTIVE)
-   {
+      draw = (segment->flags & SEGMENT_ACTIVE || (segment->next && segment->next->flags & SEGMENT_ACTIVE));
-      if (segment->flags & SEGMENT_ACTIVE || (segment->next && segment->next->flags & SEGMENT_ACTIVE))
-	 draw=1;
-      else
-	 draw=0;
-   }
 
    if (segment && draw) 
    {
@@ -880,8 +1336,10 @@ path_tool_draw_helper (Path *path, PathCurve *curve, PathSegment * segment, gpoi
          gdk_draw_line (core->win, core->gc, x1, y1, x2, y2);
       }
    }
+#ifdef PATH_TOOL_DEBUG
    else if (!segment)
       fprintf(stderr, "path_tool_draw_segment: no segment to draw\n");
+#endif PATH_TOOL_DEBUG
 }
 
 static void
@@ -892,11 +1350,14 @@ path_tool_draw (Tool *tool)
    PathTool * path_tool;
    PathCurve * cur_curve;
   
+#ifdef PATH_TOOL_DEBUG
    fprintf (stderr, "path_tool_draw\n");
+#endif PATH_TOOL_DEBUG
    
    gdisp = tool->gdisp_ptr;
    path_tool = tool->private;
    cur_path = path_tool->cur_path;
    
    path_traverse_path (cur_path, NULL, path_tool_draw_helper, NULL, tool);
+   
 }

app/tools/path_toolP.h

@@ -40,45 +40,46 @@ typedef enum { SEGMENT_LINE, SEGMENT_BEZIER } SegmentType;
 
 
 typedef struct _path_segment PathSegment;
+typedef struct _path_curve PathCurve;
+typedef struct _path Path;
+
+typedef struct _path_tool PathTool;
 
 struct _path_segment
 {
    SegmentType type;          /* What type of segment */
    gdouble x, y;              /* location of starting-point in image space  */
+   gpointer data;             /* Additional data, dependant of segment-type */
    
    guint32 flags;             /* Various Flags: Is the Segment active? */
 
+   PathCurve *parent;         /* the parent Curve */
    PathSegment *next;         /* Next Segment or NULL */
    PathSegment *prev;         /* Previous Segment or NULL */
 
-   gpointer data;             /* Additional data, dependant of segment-type */
 };
 
 
-typedef struct _path_curve PathCurve;
-
 struct _path_curve
 {
    PathSegment * segments;    /* The segments of the curve */
    PathSegment * cur_segment; /* the current segment */
+   Path * parent;             /* the parent Path */
    PathCurve * next;          /* Next Curve or NULL */
    PathCurve * prev;          /* Previous Curve or NULL */
 };
 
 
-typedef struct _path Path;
-
 struct _path
 {
    PathCurve * curves;        /* the curves */
    PathCurve * cur_curve;     /* the current curve */
    GString * name;            /* the name of the path */
    guint32 state;             /* is the path locked? */
+   PathTool * path_tool;      /* The parent Path Tool */
 };
 
 
-typedef struct _path_tool PathTool;
-
 struct _path_tool
 {
    gint click_pos;            /* where did the user click?         */
@@ -90,6 +91,14 @@ struct _path_tool
    PathCurve *click_curve;    /* was the click?                    */
    PathSegment *click_segment;
 
+   gint active_count;         /* How many segments are active?     */
+   /*
+    * WARNING: single_active_segment may contain non NULL Values
+    * which point to the nirvana. But they are important!
+    * The pointer is garantueed to be valid, when active_count==1
+    */
+   PathSegment *single_active_segment;  /* The only active segment */
+
    gint state;                /* state of tool                     */
    gint draw;                 /* all or part                       */
    DrawCore *core;            /* Core drawing object               */

app/tools/tools.c

@@ -520,7 +520,7 @@ ToolInfo tool_info[] =
     26,
     N_("/Tools/Path"),
     "",
-    (char **) measure_bits,
+    (char **) path_tool_bits,
     N_("Manipulate paths"),
     "ContextHelp/path",
     PATH_TOOL,