Any way to have a screen buffer, and/or save screenshots of the display to an SD card?

[iamsako]

So I am making a drawing program with the touchscreen and it works, but as of now I am just drawing directly onto the screen buffer (I don't know if that's the right term). Basically, if I draw any UI, it will overwrite whatever was drawn on the canvas. I want to figure out a way to have a separate screen buffer for the canvas that I can draw to with the touchscreen, so that I can then draw UI on top without affecting what's drawn on the canvas itself, if that makes sense.

I also want to be able to save the canvas buffer (or a regular screenshot) to the SD card as a .bmp file or something. Ideally the image should be in .png format for my goal of being able to post directly from the ESP32 to platforms like Mastodon, Bluesky etc (as those platforms currently don't allow uploading of .bmp files), but I know libraries like PNGenc exist, so hopefully that's a solvable thing.

I can share my current code and more details about my project later, if necessary. I don't have much free time to work on it, I only started on it yesterday while procrastinating on other work I'm supposed to do. If what I'm trying to do is just not possible with the hardware or something, please let me know. I am still somewhat of a beginner when it comes to C code and microcontrollers like the ESP32. I've lightly tinkered with Arduino and PIC microcontrollers before, but this is the hardest I've pushed one processing-wise so far and I don't quite have a feel for the processor's limitations yet. I know the display's 320x240 resolution is quite large for a microcontroller like this, so I'm worried about the screen/canvas buffer not being possible, or too slow.