CODEWITHSUNDEEP
x11
Jatin
Jatin

Reputation: 31724

Get event's in X11

I am using Canon SDK to get the events from the camera. In the SDK, we register a callback function, which is called when a particular event occurs. I have built a Java wrapper, which communicates with the SDK.

But when the event is triggered, my window doesn't get the event directly. Infact on windows, this is how I get the event and dispatch it to myself:

private static final User32 lib = User32.INSTANCE;
boolean hasMessage = lib.PeekMessage( msg, null, 0, 0, 1 ); // peek and remove
if( hasMessage ){
lib.TranslateMessage( msg ); 
lib.DispatchMessage( msg ); //message gets dispatched and hence the callback function is     called
}

Basically one peeps if the window has received an event or not and then proceeds. On Mac, one can do it using Cocoa by having a NSApplication and WindowServer sends events if any.

I am looking for similar alternative using X11. Any sample code/link will suffice.

PS: This a follow up question to this.

Upvotes: 0

Views: 1506

Answers (1)

user1129682
user1129682

Reputation: 1091

I suppose you are looking for XPeekEvent. The Xlib is very well documented and the manpage for XNextEvent(3) says:

The XPeekEvent function returns the first event from the event queue,
but it does not remove the event from the queue.  If the queue is
empty, XPeekEvent flushes the output buffer and blocks until an event
is received.  It then copies the event into the client-supplied XEvent
structure without removing it from the event queue.

Example code for displaying a basic Xwindow and a main event loop for handling events can be found (for example) on wikibooks.

Upvotes: 2

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