[HECnet] Downloadble fonts into an VT220?

[Johnny Billquist]

On 2013-09-18 11:43, Sampsa Laine wrote:

To point out a few (maybe obvious) things.
Sixel graphics is not the same as soft fonts. Soft fonts are defined in a very sixel-like format, but you cannot get a sixel graphics image and display it on such a terminal.


I was just going to paint the bitmap canvas into the Terminal.app window, that should work right?

Not sure what you mean here. Sixel is a bitmap format. On pixel per bit. Six bits per byte. Each group of six pixels are done vertically, but the stream of bytes are done horizontally. So you get one band six pixels wide at a time. If you want to do colors with sixel you need to do several passes. Each pass do one color.

The VT330 and VT340 were the last terminals who could deal with this. Obviously a lot of DEC printers also did sixel graphics.

The soft fonts on the other hand defines characters. You can have a maximum of 96 characters defined. So that is one limit. Each character however, can look any way you want. The software that converts gif for a VT320 finds common patterns to decide what characters to define, and then use those characters to paint the picture. So there are obviously going to be imperfections in the picture when viewed on a VT320.

How to paint any kind of graphics into Terminal.app windows are beyond me. But if you want to play with soft fonts, or sixel graphis (or ReGIS), you need to intercept the incoming byte stream to Terminal.app, and then interpret that stuff to pull out what you are expected to display.

	Johnny