Re: [Tuxpaint-devel] Polygon fill messing with other tools drawing

[Bill K. <nb...@so...>]

On Sun, Apr 07, 2024 at 03:11:09PM +0200, Pere Pujal i Carabantes wrote:
> Hi all,
> 
> Tested the new polyfill stuff, it is nice :)
> 
> Just found a minor problem:

"Minor" X-D


> Start Tux Paint, select the Polygon Fill tool.
> select another tool and draw something.
> Return to the Polygon Fill tool, see how everything you had drawn is lost.
> 
> The problem is polyfill_snapshot being kept and later blit into the canvas via
> set_color() -> draw_preview() before switchin()
> 
> We could clean up polyfill_snapshot at switchout() and recreate it at each swcithin() or
> we could set some marker, mark it at switchout, clean it up at switchin() and only blit polyfill_snapshot
> if the marker allows it, that would allow to reuse polyfill_snapshot and not destroy/recreate it
> at each switchout()/switchin() cycle.

For now, I've set a variable to tell whether switchin() has been
called yet.  To me, it seems strange that I'm calling a Magic tool's
set_color() BEFORE its switchin() has been called.  But rather than
change that (and potentially break lots of other tools), I've opened a
ticket. :-)

  https://sourceforge.net/p/tuxpaint/bugs/286/

I also addressed an issue I already knew about, where the in-progress
polygon preview (the lines and big red & green boxes) would remain on
the canvas when switching to a different tool.

I believe I solved that by simply blitting the tool's own snapshot
back to the canvas on switchout().  (And since it makes a fresh
snapshot after every polygon has been completed, this works.)

Adjustments like this may help some of the other Magic tools that
"act weird" when you're in the middle of using them, but then
switch away.

I've also thought it might be nice to provide a way for Magic
tools to say "I can handle the 'Undo' command myself", e.g.
for Filled Polygon tool, it would remove the most-recently
added point.  Then, if there's no more work for them to do,
they can tell Tux Paint that it should do it's normal Undo
process.

Prior to that, I also thought it might be interesting to provide a
way for Magic tools to provide an 'overlay' SDL_Surface which
Tux Paint would draw on top everything else, rather than having
to abuse the main `canvas` surface to draw previews, crosshairs,
grids, etc.

Things are getting tricky. :)

-bill!