I'm working on c# WinForm.
I have an custom UserControl : MyControl : UserControl, INotifyPropertyChanged. I attached a method on event on event VisibleChanged : this.VisibleChanged += new System.EventHandler(this.MyControl_VisibleChanged);
My application have some pages, each page is a control like MyControl. Top of MainWindows contains Button, used to switch tab.
My problem is that my function MyControl_VisibleChanged is called only when Visible is changing to true. I added a test in a tab to check MyControl.Visible, when I select the other tab, MyControl.Visible is false but no event is raised.
I've try to define a new property Visible for this control but value is never set, only the base value is modify.
Can you help me to find a solution ?
This is a quirk in the way Visible works, explained here. His solution was to use properties that he has complete control over, but you could instead have a method allowing the tab switches to tell their children to raise their VisibleChanged event that extra time.
The first two answers to this question may also be useful.
When I build a vb.net winforms application in VS2010, I can double click on a control on my form and it takes me to the code window. Then there are dropdown lists at the top left and top right of the code window that allow me to select the control and the event that I want to handle...
If the event handler already is already in use/defined/coded, it takes me there, otherwise it defines a new handler method with a standard naming convention (_click(blah blah blah))...
But for some reason when I build a c# application, there is no such "cheat"... call me lazy, but I don't like having to type code that I don't need to, and since the functionality exists in VS to "just do it", why can't I do it in a C# app...???
Maybe there is just a setting I need to find... anyone know of such a setting..???
Thanks
In VS2010's C# mode, similar functionality is enabled by default. Double-clicking on a control in the visual form designer will create a default event handler for that form in the code window. This may not always be the event that you would like to handle, however. If that is the case, right-click the control in the form designer and select Properties from the context menu. A property grid will appear that contains a list of all of the control's properties and events. Click on the lightning-bolt icon at the top of this grid to select the Events tab. From here, double-clicking on any of the event rows will automatically create a new event handler for the control in the code window.
I need to hook up an event that shows a WPF Popup control when a TextBox has focus and a keyboard shortcut is clicked. For instance. When typing in the TextBox field, the user can press ALT+H for help, to get a popup dialog showing input help. Pressing ALT+H "outside" the TextBox should not open the popup.
Any ideas?
Looks like a job for an Attached Event.
From MSDN:
The concept of
an attached event enables you to add a handler for a particular event
to an arbitrary element rather than to an element that actually
defines or inherits the event. In this case, neither the object
potentially raising the event nor the destination handling instance
defines or otherwise "owns" the event.
You can find details here, on the MSDN
Use command binding:
ApplicationCommands.Help.InputGestures.Add(new KeyGesture(Key.H, ModifierKeys.Alt));
this.CommandBindings.Add(new CommandBinding(ApplicationCommands.Help, Help_Executed, Help_Enabled));
In function Help_Executed do some operations
In function Help_Enabled check if textbox selected, do e.CanExecute = true;
InputGestures assign ALT-H for help
.NET newbie alert
Using Visual C# 2008 Express Edition I have accidentally created a click event for a button. I then deleted the automatically-created method code, which resulted in an error saying that the function, which had now been referenced in the form loading code, could no longer be found.
Deleting the following line from the Form1.Designer.cs file's InitializeComponent() function...
this.btnCopy.Click += new System.EventHandler(this.btnCopy_Click);
... seems to do the trick, however, it makes me feel very dirty because of the following warning at the beginning of the #region:
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
I haven't been able to find a way to do this using the form designer, which I assume is the means implied by this warning. What is the correct way to do this?
You do have to be careful when working in the designer.cs files but you don't have to feel dirty about it (when I make the same mistake it is just easier to fix it the designer.cs file). You can do it visually like this:
Open the form in the form designer.
In the form designer, click the button of interest.
Press F4 (or right click the button and then click properties). The properties pane should show up.
At the top of the properties pane, click the lightning bolt. This shows the events for the button.
Find the click event and clear its handler.
Okay, I am usually the one advocating the use of notepad2 or some other text editor to perform coding tasks.
But, since you ask how to do so in the Designer...
Open the form where the erroneous event was added to a control.
Select the control.
Right-click, select "Properties".
Change to "Events" by selecting the button with the lighting-bolt icon.
Select the event you need to remove.
After placing the mouse in the box which is showing the event handler method name, delete all of the text in that box and press enter. This will remove the event handler and the delegate assignment for this event on your control.
The only caveat being: if you wish to preserve your event handler method (i.e. it is not auto-generated by Visual Studio) - you probably want to avoid deleting the assignment in this manner. Because when I say that it removes the event handler - I should say that the declaration of the event handler method in "Form1.cs" (for example) will be deleted as well.
Rep steps:
create example .NET form application
put a TextBox on the form
wire a function up to the TextBox's Enter event
When you run this application, the Control.Enter event fires when focus first goes to the TextBox. However, if you click away into another application and then click back into the test application, the event will not fire again.
So moving between applications does not trigger Enter/Leave.
Is there another alternative Control-level event that I can use, which will fire in this scenario?
Ordinarily, I would use Form.Activated. Unfortunately, that is troublesome here because my component is hosted by a docking system that can undock my component into a new Form without notifying me.
What are you trying to do in the Enter event?
I can't find another control-level event that fires in your example program but when my test app does regain focus, the control that last had focus still has it.
Interesting question but it needs a little more context.
If I try your example and click outside the control on another window, desktop, etc, I can get the Got and Lost Focus events to fire, but if you're only trying to click within a form or a control with only 1 control, these event will never be fired because it is the only thing to focus on. Neither will Entered or left, unless you change the dynamics or overload the controls, you cannot get this to happen
In your example, I think you need another control. The reason being is that the first control (tabIndex 0) is the one with focus. With no other control to switch focus to, this control will always be focused, and therefore can never be entered. Switching to another application or form will not change the focus or active control in this form so when you return you will still not get the event fired.
With added controls control.entered should work fine. If this is your only control, why not call the event on formLoad, or TextChanged, when the form gets focus?
Thanks, I'll give some background.
My control is a UserControl that contains a grid and a toolbar. A user will typically launch several of these controls to view different slices of the system's data.
There are several keyboards shortcuts that can launch actions from the selected row in the current grid. However, it is a requirement that these keyboard shortcuts should apply not only to the currently focused grid. If the user is currently focused on one of the many other areas of the application, then this keyboard shortcut should still work, and it should be routed to the last focused grid.
So I wired a function to the Control.Enter event of my UserControl to basically say LastFocusedGrid = this.
And it would work, except for the docking and undocking...
See, these controls are hosted inside an application with docking features, somewhat similar to visual studio.
By default, the control launches as a tab within the main working area of the application, similar to the way a source file opens in visual studio.
However, the user can "rip out" a tab by grabbing the tab header and dragging it out of the main application. At this point, the application creates a new "float form" to host the control. Switching between the main application and this float form is the same as switching between apps, for the purposes of the Control.Enter and Form.Activated events.
At that point we have the "one control within a form" scenario simulated with the example application described in the original post.
Now, there are some ways around this. I could leverage the Form.Activated event, which DOES fire when switching between forms. If you add an event in the test application to the Form's Activated event, you will see that it works great.
The problem is that my UserControl's relationship with its parent Form is fluid, making the solution somewhat complicated. I tried wiring up to "this.ParentForm.Activated" which worked okay. The problem is when do you call this? What happens when you are undocked/redocked? I ended up with a nasty bunch of code with things like "previousParentForm" so that I could unhook from the old form, and then I was still facing the problem that the docking system doesn't notify me when my parent Form is being changed, so I was going to have to make a bunch of changes there, too.
These problems are not unsolvable, but if there is a simpler control-level "parent form was activated" event, then that would be a lot more elegant.
That's rather long, but I hope it clarifies the situation.
So when creating your grid, can you not set the KeyPressed, or KeyUp, etc. event? If so, all the grids can make use of the same event handler. Just make sure that when you get into the event handler to do something like:
Grid currentGrid = (Grid)sender;
Then you should be able to apply that block of code to any grid that gets sent in without having to worry about keeping track.
Since all the event handler really is, it's location is a mute point really as long as everything you need to execute it is accessible.
Frye, the problem is that the keyboard shortcuts should work no matter where the user is in the application. They are gloabl commands, handled at the top level, and then routed to the "last focused grid."
So handling the keystrokes at the grid level will not help.
To be more specific, assume user launches grids A, B, and C. But he also launches other controls X, Y, and Z that have nothing to do with my code.
User clicks on A, then on C. Then he clicks on Y, then on Z. With focus on Z, he hits my keyboard shortcut. In this case, grid C should respond since it was the last grid the user was focused in.
It sounds like the issue that you're having is not directly related to the Enter event and more to the point, if you have controls "that have nothing to do with your code" then you really aren't looking at a control level event.
Guess I wasn't clear.
My control lives in a container application. So do other unrelated controls by other teams. Think of it like visual studio -- my control is the code editing tab, but there is also the pending changes list and the properties window, which cohabitate with the source files but aren't directly related.
The keyboard shortcut is handled by the container application. Then it should be routed to the last one of my controls that the user was focused on.
Maintaing this "LastFocusedGrid" reference is what I do in the Enter event.
If you want to see similar functionality at work in visual studio, try this:
open a few source files
navigate to the "Start Page" tab.
Hit Ctrl-F and search "current document" for some string
Notice that the serach feature auto-navigates to the LAST FOCUSED source file to perform the search.
So even though you weren't focused in the source file, the ctrl-F command was processed by visual studio and routed to the last focused source file tab.
Now try the same thing with Ctrl-G. It doesn't work unless you are focused directly in the source file.
My keyboard commands need to work like Ctrl-F here, not like Ctrl-G. That is why I don't just capture the keyboard events directly in my control.
Does that clarify or make things worse?
Have you tried just a simple Control.GotFocus?
in this example if you toggle between clicking the textboxes neither the enter or got focus will do as expected, however if you click the child forms instead both will behave as expected.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
namespace EnterBrokenExample
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Form Form1 = new Form();
Form c1 = new Form();
Form c2 = new Form();
Form1.IsMdiContainer = true;
c1.MdiParent = Form1;
c2.MdiParent = Form1;
c1.Show();
c2.Show();
TextBox tb1 = new TextBox();
c1.Controls.Add(tb1);
tb1.Enter += ontbenter;
tb1.Text = "Some Text";
tb1.GotFocus += ongotfocus;
TextBox tb2 = new TextBox();
c2.Controls.Add(tb2);
tb2.Enter += ontbenter;
tb2.Text = "some other text";
tb2.GotFocus += ongotfocus;
Application.Run(Form1);
}
static void ontbenter(object sender, EventArgs args)
{
if (!(sender is TextBox))
return;
TextBox s = (TextBox)sender;
s.SelectAll();
}
static void ongotfocus(object sender, EventArgs args)
{
if (!(sender is TextBox))
return;
TextBox s = (TextBox)sender;
s.SelectAll();
}
}
}