Adafruit GFX with OLED flickering at custom fonts

Hi! I am sorry to bother- but a whole weekend wasnt enough to find a solution..now I hope someone here may enlighten me:-)

So- I am using a 128x128 color OLED with a SSD1351 chip. I am using the Adafruit GFX and the Adafruit SSD1352 lib. I am using also a custom font. All on a Arduino Nano.

So far so good.

When I am now updating my OLED with some new Senor values the chaos begins.

" tft.print(fukt); "

Standard solution to not write a big number mash is ti define .setTextColor(WHITE,BLACK); so that the Background is also written. BUT this only works with the standard fonts.

So I have to make a rectangle, fill it and write my new value...which leads to ugly flickering.

So I read about writing the screen to the memory and then update it- but i wasnt able to find more about bulk pixel writing and buffering.

I tried some other lib like ssd13xx- which behaves nicer. Sadly I am not able to get my fonts in and the documentation is not really...so I dont get it.

So- how can I get rid of the flickering? Is there maybe a tft.write and tft. refresh function like in ssd1302? I cant find information about it. Just the .display(); is rejected when compiling.

HELP! :-)

if nobody knows..than maybe knows someone how I can change fonts in the ssd13xx library? That would help to get arround the Issue

The GFX tutorials show you how to fetch the background area to repaint. A minimal rectangle to fill. You only need to redraw the text when it changes. Most likely you are talking about 2 to 6 digit fields. And I bet that not every digit changes.

Note that many proportional fonts use a constant width for digits. Obviously letters vary greatly e.g. W is wider than i.

The GFX library only draws FreeFonts in transparent mode. Yes, you could use some custom text drawing functions to draw in rubout mode.

David.

I am just refilling one digit at a time and sadly- yes its to slow- you can see it clearly flickering. Speed and Position might change 2-3 times a second, that makes the whole thing a big disco with all the flickering in different places while updating the values. So right now i wonder a bit how all others do with these displays..the fonts included in GFX get not the full potential out of the resolution and with the custom fonts everybody is about to end up here...but I feel quite alone with this question...so I am doing probably something wrong.

Has someone experience with this rubbout mode? And how to change the drawing funnction.