I want to detect when a key on the keyboard is pressed to execute a command. So that when I press the F key it does an action. How I can do it?
You need to process the keyboard events like KeyDown. These provide you with events on every key press or release.
Inside the Event handler you need to filter which key was pressed and execute whatever action needs to be done:
public void MyKeyDownEventHandler(object sender, KeyRoutedEventArgs e)
{
if (e.Key == 70)
{
MessageBox.Show("'F' key pressed");
}
}
Since the KeyDown event is bound to a control and will only be fired when the control has focus you need to think about from which control you want the event to be fired from. In order to get the event fired from everywhere in your app, this blog post provides a neat solution:
By registering the KeyDown event to all controls during startup of your app, it will always fire as long as your app is in focus since there is always one control in focus. To achieve this, add this to the OnStartup() method of your app (inside the app.xaml.cs):
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
EventManager.RegisterClassHandler(typeof(Control),
Control.KeyDownEvent,
new KeyEventHandler(MyKeyDownEventHandler));
base.OnStartup(e);
}
}
Related
I am developing an app for Windows 8.1
am using XAML + C#
I read the article this article in MSDN for Responding to keyboard interaction
I did as they say , but the problem is that the event occurs only when i press a key inside a TextBox
but i want the event to occur everywhere i press in the Page
Note: I use a laptop (no touch hardware)
XAML :
<Grid x:Name="GameGrid" Margin="0,0,0,0.111" KeyDown="Grid_KeyDown">
C# :
private void Grid_KeyDown(object sender, KeyRoutedEventArgs e)
{
if (e.Key == Windows.System.VirtualKey.A)
this.DoSomething();
}
Try registering an accelerator key instead of a key event on grid (it must have focus to fire the event):
http://msdn.microsoft.com/en-us/library/windows/apps/windows.ui.core.coredispatcher.acceleratorkeyactivated
Example:
Window.Current.Dispatcher.AcceleratorKeyActivated += ...
I have to process enter (among other keys) on win form without it producing error sound, but only if the currently active control didn't process it already.
So, when enter is pressed while in a TextBox or DateTimePicker, i want to process it with a form (without error sound), but if it is pressed, for example, in DataGridView i want it to be handled the way DataGridView does by default.
OnKeyUp solves my problem with handling only unhandled keystrokes (e.Handled) and ProcessCmdKey (this) solves sound problem, but neither solves both.
Any suggestions?
Kudos for the very interesting question. Unfortunately, I can't seem to find a global event handler for all key presses other than overriding ProcessCmdKey on the main form per this article. Only issue with this method is that the arguments passed into the event handler delegate don't define what control is creating the event :(
So, my only thought is that you need to assign your event handler to every single control in the application. I've written some code that should help show you how to do this. I'm not sure what the adverse effects may be of assigning a KeyPress event handler to every control on your page though, but it's the only feasible solution I see.
Code:
private void Form1_Load(object sender, EventArgs e)
{
AssignHandler(this);
}
protected void HandleKeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == (char)Keys.Enter && (sender != this.textBoxToIgnore || sender ! this.gridViewToIgnore))
{
PlaySound(); // your error sound function
e.Handled = true;
}
}
public void AssignHandler(Control c)
{
c.KeyPress += new KeyPressEventHandler(HandleKeyPress);
foreach (Control child in c.Controls)
{
AssignHandler(child);
}
}
Is there any standard way to route all Key events from the control A to other control B? I wish that the keyboard focus will still be on A however the event handler of A would trigger the all event handlers of B for the key events.
edit: Clarification: calling a specific event handler I wrote for B is not enough. I need to mimic the actual event. So for example I want that if a key is sent to a TextBox, it would be written to the TextBox. The solution given below does not do that (not to mention the fact that if new event handlers are added to B it completely fails).
I'm aware that WPF differentiates between logical focus and keyboard focus, but I need both focuses to remain on control A, but in a certain cases route its incoming event to other controls.
Couldn't you do something like this?
private void button1_Click(object sender, RoutedEventArgs e)
{
// Check if the event needs to be passed to button2's handler
if (conditionIsMet)
{
// Send the event to button2
button2.RaiseEvent(e);
}
else
{
// button1's "Click" code
}
}
private void button2_Click(object sender, RoutedEventArgs e)
{
// button2's "Click" code
}
Edit: Modified code to use the RaiseEvent() method to programmatically raise a specific event, rather than just calling the event handler for button2.
I'm implementing copy-paste in a Windows Forms application.
I need to enable/disable the bar-buttons for this two operations when the user changes the focused element in the application.
I can find the current focused control using something like this: http://www.syncfusion.com/FAQ/windowsforms/faq_c41c.aspx#q1021q, but how can I detect that the focused control has changed?
In your form load event handler you could also loop through all of the controls contained in the form and for each focusable control add an event handler for the Enter event:
private void Form1_Load(object sender, EventArgs e)
{
foreach (Control control in Controls)
{
control.Enter += ControlReceivedFocus;
}
}
void ControlReceivedFocus(object sender, EventArgs e)
{
Debug.WriteLine(sender + " received focus.");
}
My proposal is to use Application.Idle event.
Write logic that enables/disables your buttons in Application.Idle event.
Subscribe to Application.Idle event on form shown event
Check button availability on button click (so you never pass accidental click under heavy load)
Do not forget to remove Idle handler on form disposing (or closing), because this is static event
Using this technique you will always have correct buttons state, and you not need to worry about subscribing to many controls events to detect focus change. This is also light-weight approach, because Idle event is raised only when application is not busy.
I think you should add an event handler to the control (or if you have many of the same type, subclass it, and override the appropriate OnChange handler). This way you won't have to 'find' the focused control (it will be given as the sender parameter), and the event will only arise when the change actually happened.
To detect the focus on a control you can create this event:
void MyGotFocus(object sender, EventArgs e)
{
if (sender is TextBox)
{
//TODO YOUR OPERATION
//FOR EXAMPLE
(sender as TextBox).SelectAll();
}
}
and the next step is to associate the control and event by code:
myText1.GotFocus += MyGotFocus;
myText2.GotFocus += MyGotFocus;
I'm currently developing a custom control and realize that my code is being run twice. It is not really a huge issue (it is only a Focus method call). However, I would like to understand it.
From reading the MSDN description for click | onclick event, it states that:
Fires when the user clicks the left mouse button on the object.
So I added the OnClick event and the MouseClick events to handle both left and right clicking. But after debugging the code I found that the OnClick handles both left and right click events.
Why is OnClick handling both and do I need to keep both events in my code for some reason I'm overlooking?
protected override void OnClick(EventArgs e)
{
this.Focus();
base.OnClick(e);
}
private void CustomControl_MouseClick(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Right)
{
rightClickMenu(e);
}
}
According to MSDN, the Click event is called not only when the mouse is clicked, but also when the Enter button is pressed. If you only need to handle mouse clicks, I'd move all of your code in the MouseClick event. You can't do it the other way around because the Click event doesn't tell you which mouse button (if any) was clicked.
First of all, your link is incorrect, it links to HTML and DHTML Reference, not WinForms :)
Correct link is Control.MouseClick event
You need to override only one method. If you want to handle only mouse clicks - override OnMouseClick() and don't handle MouseClick event, otherwise - override OnClick() and don't override OnMouseClick().
You shouldn't need to have both events... Just keep the OnClick.
Also, I haven't done Windows Forms in quite a while, but I think there's a better way to accept focus than manually setting it on the click event, but I can't tell you specifically what it is... I think there's a property for it or something.
In Winforms, the Click event is raised when either mouse key is clicked.
If my memory serves me right, click does both mouseclick and the 'Enter' key or even setting focus on the control using the 'Tab' key and then using 'Space' or 'Enter' to "click" it.
If such behaviour is acceptable/desired, you may do the following.
I had this workaround for a DoubleClick event...
void ControlClick(object sender, EventArgs e)
{
MouseEventArgs mEvt=e as MouseEventArgs; // or (MouseEventArgs)e;
// now mEvt has the same properties as 'e' in MouseClick event
}
Hope this helps.
-Nurchi
The OnClick and CustomControl_MouseClick is the same event
You can have how many methods you want attached to an event ( this.Click += ...)