Arrow keys don't seem to match Keys.Down

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G

Guest

This has to be something silly but...

I have a breakpoint at the start of my KeyDown event handler where I want to
check for the Down Arrow key (which I can't seem to match)

When I press the Down Arrow key on the arrow keypad of my keyboard, I get

e.KeyCode == RButton | ShiftKey
and
e.KeyData == RButton | ShiftKey | Alt

but,
Keys.Down == Back | Space

so my check if (e.KeyCode == Keys.Down) is testing False

??
 
This has to be something silly but...

I have a breakpoint at the start of my KeyDown event handler where I want to
check for the Down Arrow key (which I can't seem to match)

When I press the Down Arrow key on the arrow keypad of my keyboard, I get

e.KeyCode == RButton | ShiftKey
and
e.KeyData == RButton | ShiftKey | Alt

but,
Keys.Down == Back | Space

so my check if (e.KeyCode == Keys.Down) is testing False

??
Click to expand...

I put together a quick little application in VS 2005 and was able to
get the KeyDown event to catch the Keys.Down KeyCode. Could you show
the rest of the event and where you subscribe to the event in your
code?
 
Justin,

In TaskControl.Designer.cs ...

this.KeyDown += new
System.Windows.Forms.KeyEventHandle(this.TaskControl_KeyDown);


In TaskControl.cs ...

private void TaskControl_KeyDown(object sender, KeyEventArgs e)
{
-> currentState.KeyDown(sender, e);
e.Handled = true;
}

Break at "->" ...
<immediate window...>
e.KeyCode
RButton | ShiftKey
e.KeyData
RButton | ShiftKey | Alt
Keys.Down
Back | Space
 
Justin,

In TaskControl.Designer.cs ...

this.KeyDown += new
System.Windows.Forms.KeyEventHandle(this.TaskControl_KeyDown);

In TaskControl.cs ...

private void TaskControl_KeyDown(object sender, KeyEventArgs e)
{
-> currentState.KeyDown(sender, e);
e.Handled = true;
}

Break at "->" ...
<immediate window...>
e.KeyCode
RButton | ShiftKey
e.KeyData
RButton | ShiftKey | Alt
Keys.Down
Back | Space
Click to expand...

MarcG,

Nothing major seems to be wrong with your code. When you subscribe to
the event it should be "KeyEventHandler" instead of "KeyEventHandle"
but I'm guessing that's just a typo b/c your project wouldn't compile
like that.

This is just a guess, but are you pressing the down arrow that is part
of the number pad on your keyboard? I know that the number 2 which is
the down arrow will give a KeyCode of "RButton | ShiftKey | Space".
Try a few letters and let me know what KeyCode is coming through for
each of them. Also, below you'll find my code that is working,
hopefully this will help but it looks very similar to what you have.

TextBox textBox1 = new TextBox();
this.textBox1.KeyDown += new
System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);

private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.Down)
{
MessageBox.Show("it was KeyDown, KeyCode, and
Keys.Down");
}
}
 
Hi MarcG,

I performed a test based on your description but didn't reproduce the
problem you mentioned.

I create a WinForms application project and subscribe the KeyDown event of
the form. In the KeyDown event handler, I can detect if the Down Arrow key
is pressed by checking whether the e.KeyCode equals to Keys.Down or not.

In addition, when the Num Lock is locked and then the Down Arrow key in the
number pad is pressed, the e.KeyCode equals to Keys.NumPad2.

The following is the code of my test.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.KeyDown += new KeyEventHandler(Form1_KeyDown);
}

void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Down)
{
MessageBox.Show("You have pressed the Down Arrow key!");
}
}
}

FYI, if there're controls on the form, to get the KeyDown event of the form
to be raised when the user presses a key, we should set the KeyPreview
property of the form to true.

I notice that you mentioned the control 'TaskControl' in your sample code.
Is it a custom control in your project? If your problem is still not
resolved, you may send me your sample project that could just reproduce the
problem. To get my actual email address, remove 'online' from my displayed
email address.

Sincerely,
Linda Liu
Microsoft Online Community Support

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Linda, Justin,

So this is cute, and now I'm really confused...

In my app, I have a form and at runtime I select a user control and place it
on the form. The specific user control I pick is in fact derived from a base
usercontrol that I created.

The KeyPreview property of the form itself is FALSE and the keydown event
handler is set up in the derived usercontrol. Neither the base control or the
form have any key related event handlers set up. The user control covers the
entire form which itself is maximized.

Now, what is weird is this.... I tried to create a sample, starting first
with just a default form, and I set a keydown event handler on it. I was
surprised when it did not detect the arrow keys at all. Going to the docs, I
worked out that I needed to set up a KeyPreview event handler where I could
check for the arrow keys and set e.IsInputKey to true. I did this, set a
breakpoint in the KeyDown handler, and lo and behold, it went off when I hit
the down arrow key and the test (e.KeyCode==Keys.Down) ran TRUE and
e.KeyCode.ToString was "Back | Space"

So, I removed all event handlers from my sample form, built an empty base
usercontrol and derived a usercontrol from it. Using the designer, I added a
KeyDown event handler. This matched by previous design. In the form, after
InitializeComponent(), I new'd my derived usercontrol and added it to the
form.

When I ran it and hit the down arrow key, my breakpoint in the KeyDown
handler DID NOT go off. I then added a PreviewKeyDown event handler and set
e.IsInputKey=true for the down arrow. When I reran the test, the downarrow
was trapped and matched properly in the keyDown event handler.

NOW, the control that made me post this problem in the first place DOES NOT
have a PreviewKeyDown event handler, nor does its base control, nor does the
form that the control is loaded into. Also, the form itself has
KeyPreview=false.

In this configuration, my KeyDown event handler DOES execute when the down
arrow is hit, BUT the keyCode is "RButton | ShiftKey", NOT "Back | Space"

When I went back and added a PreviewKeyDown event handler to my control and
with the following internal code:

if (e.KeyCode == Keys.Down)
{
e.IsInputKey = true;
}

my KeyDown event handler did successfully match e.KeyCode==Keys.Down

So, somehow my KeyDown event handler was getting invoked when I hit the down
arrow key (when it should not have been because I had no PreviewKeyDown
handler), and the KeyCode value was getting mangled.

Any thoughts??
I am running VS2005 but without SP1 (which made my entire VS environment
unusable and I had to completely remove and reinstall VS).

Thx
Marc
 
Hi MarcG,

Firstly, it is recommended to handle the keyborad stroke events within a
form level, i.e. we should subscribe and handle the KeyDown event of the
form. If there're controls on the form, the form's KeyDown event won't be
raised when the user presses a key. To get the form informed of the key
stroke, we should set the form's KeyPreview property to true.

In addition, as you have mentioned, when the user presses some certain
keys, such as the TAB, RETURN, ESCAPE, and arrow keys are handled by
controls on the form automatically. To have these keys raise the KeyDown
event, you must override the IsInputKey method in each control on your
form. The code for the override of the IsInputKey would need to determine
if one of hte special keys is pressed and return a value of true.

To sum up:

1. Create a WinForm application project.
2. Add a UserControl into the project. Override the IsInputKey method in
the UserControl and return true in the override method.
3. Build the project. Drag&drop the UserControl onto the form.
4. Set the KeyPreview property of the form to true.
5. Subscribe and handle the KeyDown event of the form.
6. Build the project.

Run the program. When I press the Down Arrow key, the KeyDown event of the
form is raised and the e.KeyCode equals to Keys.Down.

Hope this helps.
If you have any question, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support
 
Linda,

I (now) understand the rules, although I'm not sure where I should have gone
to find the design pattern.

My app now works properly, although I've chosen to tie all event handlers
and properties to the user control and not the form, since for me, the form
is an artifact of my development environment and the one I'm using here isn't
the one that the control will reside on eventually.

I'm still interested in the weird behaviour I got from my initial design. My
KeyDown handler should never have been invoked and I can't come up with ANY
explaination for

e.KeyCode == RButton | ShiftKey
and
e.KeyData == RButton | ShiftKey | Alt

Any thoughts on (a) why the handler got called, and (b) what
"RButton|ShiftKey" means??

Thanks for the help.

Marc
 
Hi Marc,

Since I couldn't reproduce the werid behaviour you got from your initial
design, could you please send me a sample project that could just reproduce
the problem?

To get my actual email address, remove 'online' from my displayed email
address.

Only after I can reproduce the problem on my side, I may give you possible
assistance.

Thank you for your understanding and cooperation!

Sincerely,
Linda Liu
Microsoft Online Community Support
 
Linda,

You suggested this earlier, and when I started to do that, I got exactly the
correct behaviour. There's obviously something screwy in my actual project,
and I don't think you'd want to sort through the whole thing.

I now have a PreviewKeyDown event handler in place and everything seems to
be working - that is, I've masked whatever is actually wrong. Much as I hate
to do it, I think I'm going to just "declare victory" and move on.

Thanks for your help.

Marc
 
Hi Marc,

Thank you for your prompt response.

I am sorry that I asked for a sample project twice, because it seems to me
that you'd like to make clear the weird behavior you got from your initial
design. However, if I couldn't reproduce the problem on my side, it's hard
for me to explain this matter.

Since you have known how to address this matter correctly, you may let it
go. If you reproduce the problem some day, you may re-open this particular
issue or post a new issue and we will continue to work with you.

Good luck to your project and have a nice weekend!

Sincerely,
Linda Liu
Microsoft Online Community Support
 
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