Subj : Re: GUI implementation
To   : apam
From : fusion
Date : Tue May 23 2023 04:46:24

On 23 May 2023, apam said the following...
 
 ap> I think I should only be drawing things that are either visible or
 ap> changed, but I just can't wrap my head around how to do this without
 ap> making it just as complex as just redrawing everything.

just spitballing here but:

as a window moves, have a function for each window to tell it what is happening. follow the z-order from top to bottom. if your new window's right side is now 420 and your next window down in the z-order used to be overlapped from 421-430 that window's expose function is called and can redraw itself that tiny bit. what the message might look like for each window:

window zorder1: i'm exposing 421w-430w
window zo2: okay i'll redisplay that but part of it isn't in my window. i'll tell the next window down
window zo3: you're telling me 421w-430w 510h-515h is now exposed. i'm there so i'll redraw that little bit. 5 lines arent in my window though. i'll tell the next window down
window zo4: i'm nowhere near you guys. i'll pass it along unchanged
window zo5: those are my lines. i'll redraw them.
xx no further unclaimed exposures xx

cheat and force the icons on the bottom of the z-order of the window list, or make the desktop a window

for updating a window (text scrolling in the bg or something) probably just
send an expose message to the whole window rectangle.. but then you might
need code for exposing 4 rectangles in one go (like if a small window like a
calculator is right on top in the middle of a text editor)

i duno. never implemented that type of thing myself, but seems like a reasonable method to me.

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