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Forum Index : Microcontroller and PC projects : CMM2: Redefining fonts characters in runtime

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LeoNicolas

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Joined: 07/10/2020
Location: Canada
Posts: 504

Posted: 07:33am 12 Jan 2021

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Is it possible to change the fonts characters shape in runtime?

This is something I did a lot in my old MSX to draw my games backgrounds only using text. I used to update the characters changing directly the characters table in memory using the poke command.

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10310

Posted: 08:48am 12 Jan 2021

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If you re-download V5.07.00b3 then you can use the command

MM.INFO(FONT ADDRESS n)

This gives the address of font n in memory

If you load a font from file to font 8 then this will be in RAM and could be "hacked"

In addition you can use

MM.INFO(FONT POINTER n)

This one can really get you into trouble. This gives you the address of the pointer to font n

so you could create a font in an integer array and then do something like

dim b%(1000)
' code to create a font in b%()
poke word mm.info(font pointer 12),peek(varaddr b%())
font 12

Edited 2021-01-12 19:19 by matherp

CircuitGizmos

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Joined: 08/09/2011
Location: United States
Posts: 1427

Posted: 04:52pm 12 Jan 2021

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"This one can really get you into trouble."

An exciting thing to debug, for sure.

Micromites and Maximites! - Beginning Maximite

johnd
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Joined: 22/10/2020
Location: United States
Posts: 30

Posted: 05:40pm 12 Jan 2021

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I don't think this will mimic the text mode of the older computers (and maybe this isn't what you want anyways). Since CMM2 only supports graphic screens, whatever text is drawn to the screen will stay that way until it is redrawn or erased. So if you print some 'A' characters to the screen, then change the font's 'A' char to look like a pacman, all the 'A's previously on the screen will still be 'A's. That won't change until you re-print the new 'A' pacman char to the screen -- and in that case, why not just use offscreen graphics and the blit command.

On the vintage computers, I also like the ability to dynamically change the font and have it instantly updated on the screen (I think the old Ultima on the C64 used this mode from what I remember for the various animations of water and other stuff). But remember that in text mode, a chip was constantly refreshing the screen output with the text glyph data. The CMM2 doesn't do that. It displays screen memory, and unless YOU update the screen by drawing new glyphs, nothing will change.

Anyways, if your only interested in a font that can be updated dynamically so you can print out more than 255 characters using the same font, then what I said above doesn't relate and is moot.

vegipete

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Joined: 29/01/2013
Location: Canada
Posts: 1132

Posted: 06:08pm 12 Jan 2021

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Quote "This one can really get you into trouble."

An exciting thing to debug, for sure.

With great power comes great responsibility.

Perfect for a font editing program.

Visit Vegipete's *Mite Library for cool programs.

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