The 768Kb backgroung image raw file loading for 4,5 sec from SD card.
myFiles.load(0, 0, 800, 480, "blue_wall.raw", 1);
When I push a button for new sub page and call the clrScr() I wont reaload the image and wait 4,5 sec again and again. How can I use again without reload.
Or how can I clear just a layer with fix background?
There are 5 inch displays with CPLD. These can store two whole screens. And display either one instantly.
The regular 5 inch displays only have memory for a single screen (the one that is being displayed)
Think about it. Let's say that your screen has a portrait of Donald Trump as a background.
You display temperature, PH, ... etc with the text and digits written transparently over the background.
When the temperature changes, you just need to draw a fresh background in the small area occupied by the text. It is reasonable to store these small areas in SRAM. Or even on the SD card.
Small areas take less time to draw (and load from SD)