Capture modifier keys pressing ( Control, Alt, Shift o CMD )

Question

I know how to detect key pressing. All keys except Control, Alt, Shift and CMD.

How can i detect when this keys are being pressed.

Thanks in advance.

Answer 1

If you want to detect these keys in something like a NSView object, have a look at the NSResponder class. When you overwrite a NSView class (or one of its sublcasses), you can overwrite keyDown:(NSEvent *)theEvent(Apple Documentation). When you call [theEvent modifierFlags], a NSUInteger bitfield is returned, which you can then evaluate.

For instance, with

if ([theEvent modifierFlags] & NSCommandKeyMask) {
   ...
}

See Apple's Cocoa Event-handling Guide, especially the section "Handling Key Events" for more information.

Answer 2

in

- (void) flagsChanged: (NSEvent *)theEvent

[theEvent keyCode] gives a number for CRTL, SHIFT, ALT, etc, so you only need to toggle a variable for those modifiers, set to 0 at start.

if you use OpenGL you may need to set:

-(BOOL) canBecomeKeyWindow