Smart and Simple refresh - difference?

[Bloodwych]

Can someone please clarify the difference between “Smart” and “Simple” refresh. Scalos and SmartWB readme files contradict one another:

Scalos Windowtype:

smart refresh: in general slower but no flicker.

simple refresh: faster and less memory demanding, some more flickering.

SmartWB:

It forces to Workbench windows to open in smart-refresh mode instead of slow, ugly-look simple-refresh.

I really don’t know why gurus in C= decided to use simple-refresh - it saves some memory, but the speed gain worth that.

Hmmmm. Which is correct? MUI also has a setting for smart and simple so I’d like to know which to use. Currently Scalos is set to Simple and MUI Smart, which are thier default settings.

[thomas]

Simple-refresh ist like Windows: when part of the window has to be redrawn (e.g. because you moved another window out of the way), the application gets a signal and has to redraw itself.

With smart-refresh Intuition saves the hidden parts of the window in a buffer and if these parts become visible again, the buffers are copied back. The application does not need to care about refreshing.

Regarding speed, one or the other might be faster. Letting the application redraw itself might be fast if there is not much to do. But if there are lots of lines and dots to be drawn (not just a big image), you can usually watch the window refreshing itself (just like Windows windows).

With smart-refresh the redraw has always the same speed, no matter how much has to be refreshed. It is always a copying of rectangular image parts. On an old A500 or even with AGA this might be slower, but with graphics cards and fast processors this will almost always be much quicker than simple-refresh. However, the buffers might take some memory. In the old Kick 1.3 days these buffers were said to take the same amount of memory as the whole screen for resizable windows. I don't know if this is still true or ever was.

[Bloodwych]

Nice detailed info Thomas. That at least helps me to make an informative choice.

Do you know if the Blitter does the redrawing for damaged/covered windows in Smart refresh also, using less CPU?

Ultimately I want to know the best settings for Scalos and MUI in a) AGA native screen b) P96 screen. I’d imagine MUI is best left to smart with its complex details.

Scalos is confusing – it’s hard to test which is faster on an emulator! I’ve tried opening several windows and cycling through them using the depth gadget, but can’t notice any difference. I remember using SmartWB (smart refresh) on my A1200 in normal (non-scalos) workbench and depth cycling was considerably faster, at the sacrifice of a little ram as you said.

Unless anyone knows better, I guess I’ll just leave Scalos on Simple as this was its default choice, uses less memory, claims to be confusingly faster in the readme and I’m unable to test the benefits of setting it to Smart.

[thomas]

Do you know if the Blitter does the redrawing for damaged/covered windows in Smart refresh also, using less CPU?

On native Amiga sceens yes, certainly, unless you have FBlit installed. On graphics cards it depends on the driver and the card. If the driver has support for 2d acceleration and the card has some kind of "block image transferrer", then it will probably be used.

IMHO smart refresh is faster in most cases. As I mentioned in my previous post, there often are situations where you can watch a window redraw itself on simple refresh.

I usually use smart refresh in my applications because it is easier to handle. If the OS is smart, the application does not need to be.

[Bloodwych]

Thanks for the info Thomas, helpful as always.