"James H. Cloos Jr." wrote: > > >>>>> "Sergey" == Sergey Babkin <[EMAIL PROTECTED]> writes: > > Sergey> just make the hinting instructions work in terms of > Sergey> full pixels. Then multiply whatever coordinates they produce > Sergey> by 2 or 4 to convert them into subpixels. > > Freetype itself could work wither way, but that is how Xft handles aa. > > Except that the specified axis is expanded by 3, not 2 or 4. > > That said, many users find the fonts look better when freetype is told > not to hint them. I find some fonts are best w/ the hinting/ > instructing and some are better w/o.
As far as I understand from looking at the FreeType page, it has a problem with fonts having many unneccessary intermediate points on the curves. If you look again at the example in http://ttf2pt1.sf.net/SNAPSHOT/dust.ps.gz you can see a lot of red dots on the black curves. The problem is that if you move the endpoints of the curve around according to the hinting, you change not the whole curve but only its section to the next intermediate point. The result is a monstrous bulge. Worse yet, many TTF fonts have curves crossing the vertical or horizontal tangents (i.e. the curve goes up and then down, without interrupting at the topmost point). Adobe has described these problems in the Type1 specification and strongly advised how to design the outlines properly. On the other hand, most of the TTF font designers don't seem to know about them. To do hinting of any reasonable quality the outlines have to be cleaned up in advance co conform to Adobe's rules, similarly to what is shown on the diagrams. The diagrams are the result of the algorithm in ttf2pt1 that replaces these short curve fragments with one [almost] identical long curve. The algorithm works on the cubic Bezier curves but I believe can be adapted to the quadratic curves just as well or better. The downside is that it works by sequential approximation and thus is not very fast, so it's better to be ran in advance rather than when opening a font. -SB _______________________________________________ Fonts mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/fonts
