playing with ArrayBuffer and led matrix... i'm confused

Hello (again),

well, i apology for this stupid question, but i'm a bit confused with the use of arraybuffer.

i'm working with a custom font, a slanted font design that need lot of process to write nicely on a screen.
i've used a pdc8544 display for testing purpose, and i'm now satisfied by my customdrawString().

my idea (and that perhaps the problem, i don't know)
is to draw String (that need some process time) in a quite long arrayBuffer (for a sentence, between 20 and 60 chars) and copy a part of it on a display (a simple led matrix, 20mm with TM1640, or bigger with a max7219)

my question is about copying a part of an arrayBuffer on the display.

I saw bufferArrayView.slice but i'm in sort of panic, cause i do not understand any example i saw.
In the MDN, it's to abstract for me!
And i don't know how to use it!
and it said, it produce a simple array... therefor how to transfer it to display (and it is here you laugh)

if i drawString in a certain arrayBuffer, how to copy a part of this buffer (only 8x8) in an other (the display)?
I can not do that.
Sure, many of you will laugh at this, but that's how it is.

I tried to use graphic.scroll () (as @MaBe, suggest in an other post) but it only scrolls the displayed pixels, so only the 8 pixels of the display.
Even if I try to create a larger buffer let g = Graphics.createArrayBuffer(64,8,1);. (i suposse the display driver have his own buffer (8x8), that's why)
It doesn't work.

i certainly missed something...

let g;

function sendData() {
  // reset le buffer, ajoute la font, ecrit la chaine de caractères
  g.clear(); // efface le buffer (TM1640)
  g.setFont4x6();
  g.drawString("hello",0,0);
  g.setContrast(7); /* val entre 0 et 7 - TM1640*/
  // mise à jour du display
  g.flip();
  setTimeout(scroll, 1000);

}
function scroll() {
  g.scroll(-1,0);
  g.flip();
  setTimeout(scroll, 200);
}

function onInit() {
  require("Font4x6").add(Graphics);
  g = require("TM1640").connect({din: B15, clk: B13});
  setTimeout(sendData, 100);
}

would you have some compassion to explain to me how to do it?

i'm able to drw in an arrayBuffer but not copy a part.

thanks very much.

é.

1 Attachment