No kerning when using diskfont.library

[matsp888]

Regarding the rendering of Compugraphic outline fonts, in case anyone's interested and knows what I'm talking about, one thing i've noticed is that using diskfont.library and the Text() function doesn't make use of any kerning information. You'll have to use the Bullet engine directly, and blit to the raster port yourself.

Perhaps it's logical not to make use of any kerning information when using diskfont.library, since it's also used to produce bitmaps outside of any program. And you don't know beforehand which character pairs will be used in that situation.

[Thomas Richter]

Originally Posted by matsp888

Regarding the rendering of Compugraphic outline fonts, in case anyone's interested and knows what I'm talking about, one thing i've noticed is that using diskfont.library and the Text() function doesn't make use of any kerning information.

It does not because it cannot. The Amiga font subsystem design is from the 80's. Characters have a common height, and an individual width, but the graphics.library font system knows nothing about kerning. All the diskfont.library does is that it creates - by means of an external font engine - a bitmap font from an outline/scalable font, so it is all bitmaps in the end. As graphics knows nothing about kerning, and graphics renders the text, diskfont knows nothing about kerning either, and the information is lost between the font engine (typically, bullet.library) and diskfont.

[Bruce Abbott]

Originally Posted by Thomas Richter

graphics knows nothing about kerning

That's not entirely true - bitmap fonts have 'kerning', but the values are fixed and not adjusted according to character pairs.

For Compugraphic kerning to work with existing graphics functions, every character pair would have to be passed through to the font engine, then the returned kerning info put into the bitmap font for graphics library to use. This would have to be done one character at a time, which might be a big performance hit and tricky to implement transparently. Better to just create a normal bitmap font for compatibility, and allow applications to use the font engine directly if they need true kerning.

Originally Posted by matsp888

You'll have to use the Bullet engine directly,

I actually had trouble finding out how to do this! Eventually found the information and some sample code on the Developer CD V1.1 in Amiga Mail Vol2 section V-23 "Using Compugraphic Typefaces with Bullet" (had to use the PC because I don't have a CDROM drive on any of my current Amigas...).

[Thomas Richter]

Originally Posted by Bruce Abbott

That's not entirely true - bitmap fonts have 'kerning', but the values are fixed and not adjusted according to character pairs.

That is what one calls "no kerning".