Here's the steps to reproduce the problem :
Create a c# project with a form with 1 control, let's say a textbox.
Using the properties window (lightning bolt thingy), add a "click" event.
Write some code in that method.
Using the properties window, remove the content of the "click" event cell.
I would like to know why is the code from step 3 has disapear (but not the method signature).
Normal behavior from the IDE ? Option in the "tools-options" menu ?
The method you created should remain even after it has been unhooked from the control's event. The only time VisualStudio will automatically remove the method is if the method is empty. Once you add custom code, the method should not be removed.
Related
Please help me to fix this problem in c#. Every time i accidentally click any Button,Text Box etc. it will go to the source code and when i delete the code, debug wont run, but when i put comment sign /* comment*/ the application will run.
Any one can help me on how to remove on click event.
this is what i want to remove
private void comboBox3_SelectedIndexChanged(object sender, EventArgs e)
{ }
Every time i delete this debug will prompt me. but when i using VB i can easily delete this no need to remove the button or txtbox etc.
Basically when you double click a control, the designer automatically create a the event handler.
It also automatically assigns the event handler to the control. It makes this change in the designer.cs file of your form. This is handeled for you.
Unfortunately, when you remove the code you pointed out, the function no longer exists. Therefore, the solutions fails to build because the reference to the function still exist in the. Designer.cs file.
You need to remove the reference in the designer.cs file:
"If you click on a control in the Form Designer, you see a list of event handlers that the designer is associating with the control in the Properties Window. Click on the lightning bolt at the top of the Window to see a listing of events. You will see method names next to events that the Form Designer is writing code for in the designer.cs file. Simply erase the name of the method for the event you wish to disconnect, hit Enter, done."
- https://social.msdn.microsoft.com/Forums/vstudio/en-US/a6f25488-b761-437f-8a65-e7e51dd4b382/remove-event-handler?forum=csharpgeneral
You would not have to do this in VB.net, as VB.net uses the handles command whereas c# performs a method like so:
button1.Click += new EventHandler(button1_Click);
Just simply remove the event from your element before deleting the method in your code:
There will be a line in form.designer.cs class just remove that.
comboBox3.SelectedIndexChanged+=new eventargs(comboBox3_SelectedIndexChanged);
Moreover, windows forms use CodDom to write a code to you have to be careful hope this will help you to learn more about creating windows form application.
https://learn.microsoft.com/en-us/dotnet/framework/winforms/controls/how-to-add-controls-to-windows-forms
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.
.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.
I recently switched over to C# from vb.NET and within visual studio found that hooking up events is extremely annoying. In VB I could select a control from a drop down on the top left and the event on the top right drop down and the method would automatically be created and attached to the control using "handles". I know that is not supported in C# but it seems I have to go through each control and add the events manually on the page and the codebehind. Is there an easier/faster way to do this like in VB or is it just how it is? Thanks!
Yes, there is! Click a control in Design view, then click on the "Events" button in the Properties window (see 1 in hand-annotated diagram below).
From here you can see a list of all the events available to that control. By typing a method name (see 2) and pressing enter, Visual Studio will create a method (if it doesn't already exist) and hook it up properly.
Alternatively, double-clicking in the field where you would type in the handler name causes Visual Studio to assign a default value.
You can setup events extremely fast in C# compared to VB. In the code window type the name of the instance and then event name then write += and press tab twice. That will hook up the event and create a method name accordingly that will handle the event.
For example write:
panel1.MouseClick +=
and then press tab once to insert the eventhandler and twice to both insert eventhandler and create the method for it.
alt text http://img136.imageshack.us/img136/7514/eventhandlercsharp.png