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.
Related
Is there a method which initiates on focus change and can be overridden?
My goal is for the program to fetch closest data automatically from database to input fields whenever user changes his focus/presses enter or tab when on corresponding field. I'm still looking for a way to do this when user selects an item by mouse.
I'm aware that this could be implemented on mouse click but I refuse to believe that there is not a general method for focus change.
What about something like this:
foreach(Control ctrl in this.Controls)
{
ctrl.Enter += new EventHandler(Focus_Changed); // Your method to fire
}
Iterate through all controls and add a enter-event. Bind this handler to your method.
Edit:
Just in case you are wondering why "Enter" and not "LostFocus" or something like that: From my knowledge not every control got focus-events. As I've seen so far "Enter" is presented for all. Maybe there are exceptions. Should be checked out...
You could use Control.Enter event and Control.Leave event for that purpose.
See on MSDN Control.Enter and
Control.Leave.
textBox1.Enter += textBox1_Enter;
textBox1.Leave += textBox1_Leave;
private void textBox1_Enter(object sender, System.EventArgs e)
{
// the control got focus
}
private void textBox1_Leave(object sender, System.EventArgs e)
{
// the control lost focus
}
How can I check that whether mouse pointer is pointing a button or some other control?
I want to perform a particular task when mouse hover/move a button.
I know I can set event on individual button. But isn't it possible to check the pointed/hover control is button?
The sender argument in an event method should have the information you need...
private void MyEventHandler(object sender, EventArgs args) {
if(sender is Button) {
//Do some stuff
}
}
I'm not sure if you mean: can I do this without event handlers for MouseHover in individual controls. If so, the answer is no.
But you can attach each contol's MouseHover event to just one event handler that could look like the one in Chris's answer. For convenience you could even do that programmatically by looping through the controls in the form's load event. (assuming this is winforms)
I have this simple code, where when the user leaves the TextBox control, TreeView gets focused:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
this.treeView1.Nodes.Add("A");
this.treeView1.Nodes[0].Nodes.Add("A.A");
this.treeView1.Nodes.Add("B");
this.treeView1.Nodes[0].Nodes.Add("B.A");
}
private void textBox1_Leave(object sender, EventArgs e)
{
System.Diagnostics.Debug.WriteLine("Leave..");
this.treeView1.Focus();
}
}
If we execute this code the Leave event is fired twice:
Leave..
Leave..
But if we set focus to other control, only one Leave event is fired.
Is that a problem of the TreeView? Do you know any workaround? Should we report this to Microsoft?
Thanks,
RG
this.treeView1.Focus();
Do not use the Focus() method in an event handler that's called because of a focusing event, like Leave. If you need to prevent a focus change then use the Validating event instead. Setting e.Cancel = true stops it.
But do note that this isn't very logical to do so for a TreeView, there isn't anything the user can do to alter the state of the control. You'll trap the user. Maybe that was the intention, do make sure the user can still close the window. If not then you might need the FormClosing event to force e.Cancel back to false.
Given that there is no code there to wire up the event I'm guessing you did it from the designer which means a line of code such as
textBox1.Leave += new EventHandler(textBox1_Leave);
will have been added to the Form1.designer.cs, check this file to ensure the line doesn't exist more than once as for each time this line is run you will get an event trigger, so if you run the line 3 times the Leave event will fire 3 times when you leave the textbox!
HTH
OneShot
I have a TextBox on a WinForm and I want to execute some code every time someone presses a key inside of that TextBox. I'm looking at the events properties menu, and see the KeyDown event, but don't know how to add code to it.
You need to add an event handler for that event. So in the properties menu, double-click on the field beside the KeyDown event and Visual Studio will create an event handler for you. It'll look something like this:
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
// enter your code here
}
You can also subscribe to events yourself without using the Properties window. For example, in the form's constructor:
textBox1.KeyDown += HandleTextBoxKeyDownEvent;
And then implement the event handler:
private void HandleTextBoxKeyDownEvent(object sender, KeyEventArgs e)
{
// enter your code here
}
These answers will have visual studio generate the event and bind it behind the scenes in the Designer.cs file.
If you want to know how to bind events yourself, it looks like this.
MyTextBox.KeyDown += new KeyEventHandler(MyKeyDownFunction)
private function MyKeyDownFunction(object sender, KeyEventArgs e) {
// your code
}
If done this way, the new KeyEventHandler() part is optional. You can also use lambdas to avoid boilerplate code.
MyTextBox.KeyDown += (s, e) => {
// s is the sender object, e is the args
}
Doubleclick the textfield next to it.
I assume you are in Visual Studio. One way would be to double click on the empty textbox on the right of the KeyDown event: VS will generate the code for you.
You need to add a handler to the event.
Double-click the KeyPress event in the textbox's Properties window to make Visual Studio generate an event handler in the code file.
You can then put any code you want to inside the event handler function. You can check which key was pressed by writing e.KeyCode.
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;