Re: PATCH cairo-www: Simpler explanation for how to get sharp, single-pixel-wide lines
Guillermo Rodriguez <[email protected]>
| Newsgroups | gmane.comp.lib.cairo |
|---|---|
| Message-ID | <CABDcavYdG=3=srJGAn+s6v=aUyD_7ieHs02ZdBK_LDs43ZEUfw@mail.gmail.com> |
2017-05-17 11:24 GMT+02:00 Lawrence D'Oliveiro <[email protected]>: > On Wed, 17 May 2017 10:47:46 +0200, Guillermo Rodriguez wrote: > >> This simpler explanation fails to explain why this "problem" >> occurs ... > > It occurs because of anti-aliasing. No. It occurs because integer coordinates map to points half way between sample point locations, as the original text adequately explains. > >> ... and what is the rationale behind the current design. > > You want me to include a rationale for anti-aliasing? I don't want you to do anything. The original text explains perfectly why the design is like it is ("[...] so that fills align nicely, at the cost that some strokes do not"). > >> It also fails to discuss alternatives such as adjusting endpoints by >> 0.5, which allows you to get sharp, single-pixel-wide lines without >> turning off antialiasing, which in many cases is undesirable. > > Let me refresh your memory about the question in the FAQ: Not needed. > > Question: Whenever I try drawing with a line-width of 1.0, my > horizontal/vertical lines come out fat and blurry (eg. 2 pixels > wide and half-intensity). What's wrong? > > Note that it only discusses “horizontal/vertical” lines. This is the > specific situation where turning off antialiasing is the simplest > solution. It may be the simplest, but it is not the only one, and in many cases not the best one either. The solution proposed in the original text also solves the problem without the need to turn off antialiasing. Guillermo -- cairo mailing list [email protected] https://lists.cairographics.org/mailman/listinfo/cairo