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Trapping Return - Serious problem ?
Posted: Tuesday 13th April 2021 2:54pm
by Doctor Watson
I need to ‘trap’ the Return, F1 and other function keys, but that doesn’t seem to work. Or I’m doing something wrong and I don’t see it.
What follows here comes straight from the Gambas help that pops up when you’re typing code.
But there may be a surprise ...
So I made the following test on an otherwise empty form.
- Put Button1 on a Form
- Added Gambas class file (as copied from Gambas help)
PUBLIC SUB Button1_KeyPress()
IF Key.Alt THEN
Button1.Text = " True " & CString(Time)
ELSE
Button1.Text = " False " & CString(Time)
ENDIF
END
When I run this, it just seems to ignore the IF condition.
Whatever key I hit – be it a function key, numeric, abc – it jumps to the 'False' text.
But when I hit the Alt key, it STILL reports false. So it seems it doesn’t recognize the Alt key.
I tried this for other function keys – Enter, F1, Esc, … - with the same result.
Tried it with a ValueBox. Same error.
Surprise ! When I change Key.Alt to
Key.AltKey, whatever key I hit on my keyboard suddenly returns TRUE !
The on-screen help gives a warning : “Keys may have functions assigned to them by OS or other programs; you could close/... your program/other programs/system.”
So I made sure no other programmes were running. Even re-booted my computer a couple of times to make sure. Still the same result.
Any ideas? This is essential for my programme to function.
Re: Trapping Return - Serious problem ?
Posted: Tuesday 13th April 2021 4:48pm
by PJBlack
Public Sub Form_KeyPress()
' KeyPress with Alt Key event will often pass through to this Form event.
Dim altSet As Boolean
Try altSet = Key.Alt
altSet = IIf( Error , False, altSet)
If altSet Then
Debug CString(Time) & " True: Alt key is being held down"
Else
Debug CString(Time) & " False: Alt key was not held down"
Endif
End
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 2:11am
by Doctor Watson
Hi PJBlack
I tried your code - deleted the useless Cstring(Time)
Unfortunately the same strange things occur.
When pressing Alt or any other key, console indicates “Test.Form_KeyPress.22: False: Alt key was not held down”.
I then changed the code to test other function keys. And here’s the strange part : whichever key I try, the result is always the same. With some keys the result is False, with others it’s True.
Then I noticed something : when changing the Key.[Name] the list of available keynames is shown.
They are preceded by a blue or red dot.
When I try a blue-dotted one, like Key.Alt, Key.Shift, the result is False.
When choosing a red-dotted one, like Key.Return, Key.F1, the result is True.
And, as I said, whichever key on the keyboard I press.
There are even KeyNames that don't seem to exist, such as AltGrKey.
I haven’t the foggiest idea of what those red and blue dots stand for, but could we be looking at a bug?
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 7:05am
by stevedee
Doctor Watson wrote: ↑Wednesday 14th April 2021 2:11am
...Then I noticed something : when changing the Key.[Name] the list of available keynames is shown.
They are preceded by a blue or red dot.
When I try a blue-dotted one, like Key.Alt, Key.Shift, the result is False.
When choosing a red-dotted one, like Key.Return, Key.F1, the result is True.
And, as I said, whichever key on the keyboard I press.
There are even KeyNames that don't seem to exist, such as AltGrKey.
I haven’t the foggiest idea of what those red and blue dots stand for, but could we be looking at a bug?
Take a close look at the
red &
blue list of options and you will notice that the
reds are
Constants and the
blues are
Properties.
- Key_help.png (60.96 KiB) Viewed 5300 times
On my UK laptop keyboard the
<AltGr> key is on the right-hand side of the
spacebar. What kind of keyboard layout do you have?
You cannot use
Key.AltKey in your code example because it returns an Integer.
Your basic code moved to
Form_KeyPress() seems to work for me:-
Public Sub Form_KeyPress()
If Key.Alt Then
Me.Text = " True " & CString(Time)
Else
Me.Text = " False " & CString(Time)
Endif
End
If your code is part of a bigger project, just do a quick test project with the minimum code to see if it works. Step through the code using the <
F8> key to make sure it is not failing for some other reason.
You could also use this code to check that keys are returning the correct values:-
Public Sub Form_KeyPress()
Dim varKey As Variant
varKey = Key.Code
Me.Caption = "Last key: " & varKey
End
...but take note of the warning message in the .Code help screen:-
- Key_help_warning.png (48.67 KiB) Viewed 5300 times
...however, this may still provide some useful diagnostic information.
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 1:25pm
by grayghost4
maybe this will help you :
Public Sub Form_KeyPress() ' or Button1_KeyPress()
If Key.Code = Key.AltKey Then
Button1.Text = " True " & CString(Time)
Else
Button1.Text = " False " & CString(Time)
Endif
Me.Caption = "Last key: " & Key.Code
End
or this :
Public Sub Form_KeyPress()
Select Case Key.Code
Case Key.Return
Button1.TEXT = "RETURN "
Case Key.AltKey
Button1.Text = " ALT "
End Select
Me.Caption = "Last key: " & Key.Code
End
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 3:24pm
by cogier
I have been trying to work out exactly what you are after without success, however, I notice the line PUBLIC SUB Button1_KeyPress(). If you want the key to be activated by the Return key then set the Button Property Default to True. You can also activate the Button with the Esc key by setting the Button Property Cancel to True.
Another simple way to set a shortcut for the Button is to add an & to the Button Text Property. e.g. Button1.Text = "&Click me!" will underline the 'C' and allow you to use the shortcut Alt+C to activate the key.
If all of us are missing the point can you give us an idea what the program, and you hope to achieve.
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 3:33pm
by Doctor Watson
Hurray! Grayghhost4,
That does the trick indeed. That is, for the ‘red-dotted’ keys in the list, those returning an Integer, as mentioned by Steve. And those are just the ones I need.
How simple can it be, but it still doesn’t explain why some different approaches won’t work.
Steve, the AltGrKey is, just as on your keyboard first right of the space bar. It’s a Logitech and it’s AltGr works perfectly. Just tested it with Grayghhost4’s code and still gives the error : “Unknown symbol ‘AltGrKey ‘in class ‘Key’ in Form1”.
I’m going to do a test run on all function keys to find out if there are any more surprises.
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 3:47pm
by Doctor Watson
Hi Steve and Cogier
Our posts just have come through together.
I will test what you suggest, but as I just wrote, Grayghhost4’s solution seems to work fine.
The mayor keys I need throughout in my program are the F1, used to enter a help screen or pop-up, and the Return key.
And here’s what perhaps started this all : on my keyboard, the ‘Return’ key is named ‘Enter’.
If I find something else, I’ll let you know.
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 4:37pm
by cogier
on my keyboard, the ‘Return’ key is named ‘Enter’.
The 'Return' key (1) is on the main keyboard and the 'Enter' (2) key is on the numeric keyboard.
Re: Trapping Return - Serious problem ?
Posted: Wednesday 14th April 2021 11:07pm
by BruceSteers
AltGrKey does not work. (it broken in gambas)
the right alt key is actually called ISO_Level3_Shift (the Windows keys are called Super)
It's a pain dealing with it
it's hex value with gtk will be 0xfe03 (as per keysymdef.h)
If Key.Code = &hfe03&
with qt it's integer value is 16781571 (annoyingly a different value than gtk)
If Key.Code = 16781571
and then there's wayland that gambas key.class (and Desktop.SendKeys) do not support well.
Gambas Key.class has limitations with the right AltGr key and also it cannot define between left or right Alt/Shift/Ctrl keys
You can do it by manually checking out the key values
Ie.
Public Sub Form_KeyPress()
Print Str(Key.Code)
End
Run that and hit the key you want to register and make a note of it's code then you can test for that value.
Key codes are not so well supported as keyboards vary throughout the world and gui toolkits like gtk/qt/wayland/etc all vary the codes they give.