[Freeciv-Dev] (PR#81) overstretched map doesn't get updated properly

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

[rp - Thu Jul 29 07:39:09 1999]:

> It is possible to make the displayed map wider than the actual one.
> It will
> wrap
> around and the initial display is correct, but updates do not happen
> corectly.
> The possibility of having to update the same tiles in two places is
> not being
> taken inso account, it seems.
> <P>
> Few players display more than the minimum width of 40 tiles on their
> screen so
> this
> isn't very urgent.  Two 1M jpg images are available at
> http://www.freeciv.org/~hop/wrap1.jpg and wrap2.jpg to illustrate the
> problem.

This actually happens because of a bug in map_to_canvas_pos for non-iso
view.

If map_view_x0 = 0 then map_to_canvas_pos with x=20 will give you
canvas_x=20*NORMAL_TILE_WIDTH.  But x=100 will not give you
canvas_x=20*NORMAL_TILE_WIDTH the way it should - it will give
canvas_x=100*NORMAL_TILE_WIDTH.  Thus the tile will be erronously drawn
twice (erronously because it doesn't happen anywhere else and thus is
never updated).

This is fixed by PR#4681.

PR#4679 is also related - it leads to city names (but not whole tiles)
being drawn and never updated

jason