From: Henri Verbeet Subject: Re: [PATCH] d2d: Suppress last empty segment also for D2D1_FIGURE_END_OPEN Message-Id: Date: Mon, 3 Jan 2022 21:29:20 +0100 In-Reply-To: <60816640.FJ5EEuTH9u@pebbles> References: <20211230221854.18968-1-stefan.bruens@rwth-aachen.de> <26473716.ikUS8UAcQo@bacchus> <60816640.FJ5EEuTH9u@pebbles> On Mon, 3 Jan 2022 at 17:59, Stefan Brüns wrote: > Seems my explanation was somewhat unclear ... > > I do not want to remove the last vertex (p3), but the last segment. In the > current code, vertex_type[3] (using your example) for p3->p0 is always marked > as TYPE_LINE (see EndFigure code). In case of p0 == p3, this causes troubles > in the intersection code. In case p0 != p3, the p3->p0 segment must be a line > (for intersection tests and filling), regardless if END_OPEN or END_CLOSED. > The only difference between OPEN or CLOSED is the stroking of the p3->p0 > segment. > I think I see what you mean. You're right, we need the implicit segment for e.g. filling, so the current d2d_geometry_intersect_self() behaviour is correct in that regard. > What seems to work quite fine is setting the TYPE for the last vertex > (vertex_type[3]) to either TYPE_LINE for non-coincident p3/p0, or TYPE_END > (newly added type) otherwise. (TYPE_NONE is already overloaded and can't be > used.) > > For my current approach, see > https://build.opensuse.org/package/view_file/ > home:StefanBruens:branches:Emulators/wine/0003-d2d1-Skip-last-empty-segment- > in-intersection-tests.patch?expand=1&rev=19 > I think that approach should work, yes. Alternatives would be introducing a D2D_FIGURE_FLAG_ flag for this or just explicitly checking for coinciding start and end vertices in d2d_geometry_intersect_self(). Those alternatives have their advantages and disadvantages, but ultimately are largely equivalent. I don't have a clear favourite, so in that regard your (new) patch is fine. I would however request to please include a small test for the issue this fixes; both to demonstrate the issue and to prevent future regressions. Henri