by joe_blaze » April 22nd, 2009, 7:24 pm
Sometimes VisualAPL programmers report that the "font is corrupted" when displaying APL characters.
VisualAPL, just like any other .Net language, is entirely Unicode-based. The positions of the "APL" glyphs in a Unicode font used by VisualAPL are those which were established by internation standards prepared many years ago.
When APL characters appear to be "corrupted" it generally means that the rendering mechanism, e.g. text editor, printer, forum software, Windows configuration, Visual Studio configuration. etc. has been set by the user, or by default, to a font which does not have the APL glyphs implemented. This occurs even with fonts described as "Unicode fonts", because often a font is designed to support a limited number of the many glyphs defined in the international Unicode standards.
This is one of the reasons that VisualAPL provides the APLNext.ttf font to be sure that the VisualAPL programmer has available typography which implements the APL glyphs in the positions of the font defined by internation Unicode standards.
Legacy APL implementations generally did not have a Unicode basis. Instead they developed a proprietary font which usurped other glyphs in pre-existing, general-use fonts and replaced those glyphs with APL glyphs.
With a Unicode-based implementation, this usurpation is not necessary because internation Unicode standards have reserved a section of the Unicode code numbers and associated font positions for the complete set of APL glyphs.
Recently other Unicode fonts purporting to support APL glyphs have circulated on the Internet which do not follow the internation Unicode standards. These fonts are thus proprietary to a specific APL implementation.