Board index » cppbuilder » Handling navigation keys in TFrame

2007-10-14 01:12:50 AM
cppbuilder45
Hi all! How do I handle navigation keys (arrow keys, tab et c) when a
component inside a TFrame is in focus?
Some details about my program: I have a TFrame descendant (TMyFrame)
to which I have added a TPaintBox at design time. I also have a TForm
descendant (TMyForm) to which I have added a TPageControl. In the
program, at run-time, I create an instance of TMyFrame and attach it
to a TTabSheet which also has been created dynamically, and then I add
the tabsheet to the page control in TMyForm. Now, when the user
presses a navigation key, for example an arrow key, and the paintbox
is in focus, I would like to handle that keypress somewhere, but I
have failed so far.
I have tried:
* Using a custom TPaintBox component where I have published
OnKeyDown, but the handler never gets called.
* Assigning OnKeyDown to a handler dynamically in TMyFrame, but that
handler never gets called either.
* Setting KeyPreview to true in TMyForm and adding an OnKeyDown
handler there. Here's where it's getting interesting. If I press a non-
navigation key, for example the space key, the handler is always
called. But if I press a navigation key, the handler is called only if
a component outside the frame is in focus. The case navigation key AND
component in frame in focus doesn't work.
* Defining an action in TMyForm whose shortcut key is the navigation
key I want to handle. This actually works - the action handler is
called, but it also consumes the key so that it doesn't work in TEdits
et c in other places in the program.
I'm using C++Builder 6. Any insight into this problem will be greatly
appreciated.
 

OK, I solved the problem when I realized that it doesn't have to do
with TFrame at all, but with that navigation keys generally don't fire
OnKeyDown events. The solution was to add a handler for CM_DIALOGKEY
in TMyForm.
On 13 Okt., 19:12, XXXX@XXXXX.COM wrote: