[Solved] Active screen

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orgin

Posted on: 2009/5/6 21:26 #1

Supreme Council

Is there any way to determine which screen is active at the moment?

Trying to figure out on which screen a mouse click was made.

Edit: I just noticed that struct IntuitionBase contains struct Screen*ActiveScreen. Is it legal in os4 to peek the struct IntuitionBase directly?

Edited by orgin on 2009/5/8 13:23:24

Vacca foeda. Sum, ergo edo

Mr Bobo Cornwater

xeron

Re: Active screen

Posted on: 2009/5/6 22:55 #2

Not too shy to talk

@orgin

AFAIK IntuitionBase->ActiveScreen is the only way to know. There is also FrontScreen (from memory!). I don't think actually using these fields is recommended, but i don't know any other way..

centaurz

Re: Active screen

Posted on: 2009/5/6 23:08 #3

Just popping in

@orgin

No problem with this if you LockIBase() / UnLockIBase().

BillE

Re: Active screen

Posted on: 2009/5/8 12:05 #4

Quite a regular

@xeron

> AFAIK IntuitionBase->ActiveScreen is the only way...

How do you get around the following error message.

'struct Library' has no member named 'ActiveScreen'

Bill.

orgin

Re: Active screen

Posted on: 2009/5/8 13:22 #5

Supreme Council

@BillE

You need to typecast:


struct Screen *active;

     BPTR lock = IIntuition->LockIBase(0);

     active = ((struct IntuitionBase *)IntuitionBase)->ActiveScreen;

     IIntuition->UnlockIBase(lock);

Vacca foeda. Sum, ergo edo

Mr Bobo Cornwater

orgin

Re: [Solved] Active screen

Posted on: 2009/5/8 13:24 #6

Supreme Council

@all

Set to solved, though I didn't get a conclusive answer if it's okey to peek the structure directly.

Vacca foeda. Sum, ergo edo

Mr Bobo Cornwater

centaurz

Re: [Solved] Active screen

Posted on: 2009/5/8 14:48 #7

Just popping in

@orgin

From intuition autodoc, intuition.library/LockIBase

Quote:

[...]
Grabs Intuition internal semaphore so that caller may examine
IntuitionBase safely. This function is not a magic "fix all my
race conditions" panacea.
The idea here is that you can get the locks Intuition needs before
such IntuitionBase fields as ActiveWindow and FirstScreen are
changed, or linked lists of windows and screens are changed.

[...]

orgin

Re: [Solved] Active screen

Posted on: 2009/5/8 14:50 #8

Supreme Council

@centaurz

Which isn't conclusive to me. But it's moot anyway, I need to do it and now it's done.

Vacca foeda. Sum, ergo edo

Mr Bobo Cornwater

centaurz

Re: [Solved] Active screen

Posted on: 2009/5/8 14:53 #9

Just popping in

@orgin

What do you mean by "not conclusive" ?

BillE

Re: Active screen

Posted on: 2009/5/8 15:13 #10

Quite a regular

@orgin

Quote:

orgin wrote:
@BillE

You need to typecast:

active = ((struct IntuitionBase *)IntuitionBase)->ActiveScreen;

Thanks for that. It is more or less what I tried, but I was missing the outer set of brackets. It works now

Bill

jahc

Re: Active screen

Posted on: 2009/5/9 7:25 #11

Not too shy to talk

@orgin

Thanks for the code. I didnt know this existed.. so I've used it in my Alt Tab Switcher program. Uploaded to os4depot.net already. :)

From the readme:
Thanks to Orgin and Xeron on www.amigans.net for providing code for detecting
the active screen!

Changes
-------
v1.9
- Previously, opening the Alt Tab Switcher window would jump to the screen
where it was last closed. So if you used the switcher to switch to Screen A,
then used RAmiga+M to get to Screen B, pressing Alt+Tab again would make
Screen A appear and the AltTabSwitcher GUI would appear on that screen.
This has now been fixed!
AltTabSwitcher will now always appear on the CURRENT screen.

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