I was trying to document gfx-functions numerous times, but some functions always had been my kryptonite.
One such function was
gfx.deltablit, which I didn't understand, how to use, until the last two days.
Long story short, I made a tool, with which I can test the function to see, how it works, including finding useful defaults, that simply display a picture in its normal, unaltered way.
So here it is:
https://github.com/Ultraschall/ultra..._displayer.lua
It asks you to select a picture to show. This will be displayed and you can alter the indvidual parameters using the arrow-keys.
For finer/bigger stepsize, combine arrowkeys with ctrl, shift or ctrl+shift.
Hit F1 to get, what else is possible.
WIth this tool, you can experiment quite easily with gfx.deltablit and get a clue, how it works and how to use it.
Have fun with it