Font Validation window

Both PostScript and TrueType impose some restrictions on the data that define a font. Before you save a font you should do a quick check (well... it's not always quick) to insure that you are not breaking any rules.

Validating a font can take a long time. So FontForge caches the validation state of each glyph (saving it to the sfd file so it is valid across invocations) and will only validate those glyphs which have changed since the last validation. This means that although the first validation may be slow, subsequent validations will probably be very fast -- so don't be discouraged by the time it takes to do this the first time.

(If, for some reason, you need to revalidate, then right clicking in the window will give you a menu where "Revalidate All" is an option).

The Validation window will recheck the state of the font as you edit it. So if you leave the window open you will see glyphs popping into the window and out of it as you create and fix problems.

If you double click on a line in the window then FontForge will open an outline glyph editing window for that glyph, and run a small version of Element->Find Problems to help you track down exactly where in the glyph the error(s) occurred.

If you right click, you will get a popup menu which has various options which may fix some of the problems in the glyph. There are also options to:

I say that these options "may" fix problems. Let me give some examples where they can't.

There is another pair of entries in the menu which sort of postpone dealing with the issue. Consider the glyphs Aring, Ccedilla and Oogonek. Frequently these glyphs are designed so that the accent will overlap the base letter. One would like to leave the glyph as being made up of references, but one would like to get rid of the overlap when the font is generated. There is a special flag in Element->Glyph Info->Unicode->Mark for Unlink, Remove Overlap before Save which will make fontforge unlink a glyph's references, and then run Element->Remove Overlap on them just before saving them. Then after saving it will reverse the operation and leave you with the original references.

So there are a pair of menu items (one for the current glyph, one for all glyphs that meet certain criteria) which will set this flag for the relevant glyph(s). Once this flag is set FontForge will no longer report that the glyph self-intersects.