Handle CMD+ in an NSView

Question

I'm trying to trap the CMD+ and CMD- keyboard actions in my NSView - to increase and decrease the font size of some custom text. For various reasons, I can't simply use an NSTextView. Does anyone know the correct way to handle this?

As I understand it, they are key equivalents for menu items. I can 'enable' the menu items by implementing changeFont: and I can trap the keypress by implementing performKeyEquivalent: but this seems a little bit of a hack. Also when changeFont does get called, it's not clear how I interpret the fact that it was called for CMD+/- since it simply sends me an NSFontManager. Makes me wonder if I'm handling the wrong message?

Thanks in advance.

Answer 1

Gerd (see comments above) got me sorted. In my changeFont handler I create a temp font of size 10 then pass it back to the font manager and check the size of the returned font. If it's bigger then CMD+ was pressed, if it was smaller then CMD- was pressed.

- (void)changeFont:(id)sender
{
    NSFontManager* fm = sender;

    NSFont* fntBefore = [NSFont systemFontOfSize:10];
    NSFont* fntAfter = [fm convertFont:fntBefore];

    CGFloat delta = fntAfter.pointSize - fntBefore.pointSize;
}