[Freeciv-Dev] (PR#3509) undraw_segment shouldn't use update_map_canvas

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

In undraw_segment(), in iso-view update_map_canvas() is called on 
several tiles; this redraws either a 1x2, 2x1, or 2x2 area.  In the most 
common case (a diagonal move - most goto routes follow diagonals) it 
draws a 2x2 area.

In non-iso mode, two individual refresh_tile_mapcanvas calls are made 
(with the possibility for additional calls).

The advantage of using refresh_tile_mapcanvas is that the city 
descriptions can easily be redrawn afterwards.  In other words, if we 
did two refresh_tile_mapcanvas calls for iso-view, we could avoid having 
the city descriptions overwritten by goto lines.

The 2x2 redraw means (parts of) 14 different tiles (4 + 10 partials) 
must be redrawn; a 2x1 or 1x2 means 10 tiles must be redrawn (2 + 8 
partials).  A single call to refresh_tile_mapcanvas means parts of 7 
tiles must be redrawn.  Thus I conclude two tiles to 
refresh_tile_mapcanvas are not substantially slower than a single 
update_map_canvas (and my tests are consistent with this).

jason

Index: client/mapview_common.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/client/mapview_common.c,v
retrieving revision 1.32
diff -u -r1.32 mapview_common.c
--- client/mapview_common.c     2003/02/22 02:48:30     1.32
+++ client/mapview_common.c     2003/02/23 10:24:03
@@ -761,16 +761,10 @@
     assert(0);
   }
 
-  if (is_isometric) {
-    /* somewhat inefficient */
-    update_map_canvas(MIN(src_x, dest_x), MIN(src_y, dest_y),
-                     src_x == dest_x ? 1 : 2,
-                     src_y == dest_y ? 1 : 2,
-                     TRUE);
-  } else {
-    refresh_tile_mapcanvas(src_x, src_y, TRUE);
-    refresh_tile_mapcanvas(dest_x, dest_y, TRUE);
+  refresh_tile_mapcanvas(src_x, src_y, TRUE);
+  refresh_tile_mapcanvas(dest_x, dest_y, TRUE);
 
+  if (!is_isometric) {
     if (NORMAL_TILE_WIDTH % 2 == 0 || NORMAL_TILE_HEIGHT % 2 == 0) {
       if (dir == DIR8_NORTHEAST) {
        /* Since the tile doesn't have a middle we draw an extra pixel