Font and Font Size Control

[rmills]

Trying to figure out how the library handles the fonts. EVE_cmd_text_burst() takes "int16_t font" but there is not reference to what that variable refers too? The examples only use 26 to 29, others seem to just draw boxes. I found some functions for loading fonts but nothing about controlling the size.

Are the loaded font/fonts a fixed size or is there a way to control them in the display list?

Is it possible to mix a very large font size with a small size?

[RudolphRiedel]

While you are correct that there is very little documentation included here, the reason is that most of the functions are implemented exactly as described in the FT81x / BT81x programming guides and they are not doing anything functional, they just provide a way to send a stream of bytes in the required format to the chip.

And Bridgetek provides the documentation:
https://brtchip.com/ic-module/document/programming-guides/
https://brtchip.com/ic-module/wp-content/uploads/sites/3/2021/10/FT81X_Series_Programmer_Guide.pdf
https://brtchip.com/ic-module/wp-content/uploads/sites/3/2021/10/BRT_AN_033_BT81X-Series-Programming-Guide.pdf

That said, what the number for the font actually refers to is a bitmap-handle and there 32 of them so the range is 0-31.
I really have no idea why the parameter is an int16_t, but this is what the command requires.
By default the bitmap-handles 16 to 31 point to the ROM fonts and 26 to 31 are different sized versions of the same font.
All the fonts, ROM or custom, are a collection of bitmaps so there is no practical way to scale their size.

And the only way to mix different font sizes is to use separate commands.
There is no degree symbol in the ROM fonts for example, as in "21°C".
And the number of characters for FT8xx is limited to 127.
Instead of using a custom font and replacing some symbol I simply have a FT81x print "21 C" first and then "o" in a smaller font.
The tricky bit is just to figure out where to place it.

With BT81x though UTF-8 custom fonts are possible.

The CMD_SETFONT2 is used to register a custom font with a bitmap-handle.
And for this command the parameter to hold 0 to 31 has a type of uint32_t.
Most likely to avoid the need to shuffle bytes around to form 32 bit words for the other parameters.

[rmills]

Oh sorry, I had NewHavens docs and they were just different. Their library is implemented a lot differently. Looking at the BRT docs I understand why you have it the way you do. Looks like I need to create a new font, I'm on an FT812, I will have look and see if I can figure out that process. If I can figure out how to get a large font, I think I have the rest sorted out.

[RudolphRiedel]

How large are we talking about?
The FT81x have three more fonts numbered 32, 33 and 34, these only need to be assigned to a bitmap-handle, CMD_ROMFONT does this. Beyond these you need a custom font.