Re: OK on Enter, not Return

FROM : Douglas Davidson
DATE : Fri Jun 06 21:26:56 2008

On Jun 6, 2008, at 11:19 AM, Andrew Merenbach wrote:

> I believe that you might do some magic with -keyDown: -- I'm sure 
> that someone else will have more knowledge about this -- but bear in 
> mind that the latest-gen MacBooks (of which I have one) do not have 
> separate Return and Enter keys -- just one.  (Maybe the fn button 
> changes it, but even if so, users would have to figure that out.) 
> What about making alt-Enter/alt-Return add a newline, while leaving 
> Return and Enter both to do the job of activating the OK button? 
> Hope this helps, even if only a little!


Here is something I wrote on this before:

Here is the normal sequence when a text view receives key events:

NSTextView's keyDown: passes events to interpretKeyEvents:, which is 
where they enter key binding and input management.  They come out 
either as insertText: or as doCommandBySelector: (see NSResponder.h 
for these three methods).

In particular, non-text keys like enter or return will (with the 
standard key bindings) end up using doCommandBySelector: to call 
methods like insertNewline: on the NSTextView.

If you are using an NSTextView, you should be able to implement the 
text view delegate method

- (BOOL)textView:(NSTextView *)aTextView doCommandBySelector:
(SEL)aSelector;

and examine the selector.

If you are using an NSTextField or similar control, you can implement 
their delegate method

- (BOOL)control:(NSControl *)control textView:(NSTextView *)textView 
doCommandBySelector:(SEL)aSelector;

If you wish to do something different at this point, you might (for 
example) look at the current event and ascertain whether it is a key 
down and if so, what key it is.

In most cases you don't actually want to intervene at keyDown: time. 
That's because keyDown: takes place before all of the key binding and 
input management that is necessary in general to make sense of 
keystrokes; it would be easy, for example, for you to break input 
methods like those used for East Asian text.  One possibility would be 
to use a keyDown: override to determine whether a particular keystroke 
is enter or return, but not to make any modifications at that point; 
instead, you could use that information to set a flag that would later 
be used at doCommandBySelector time.

Douglas Davidson