Visual Basic .NET

How to Show and Hide Controls

This tutorial is part of an ongoing lesson. Click
if you haven’t yet created a menu.

This tutorial is part of an ongoing lesson. Click
if you haven’t yet created a menu.

The items on our view menu are:

View Textboxes
View Labels
View Images

Although these are not terribly practical examples of what to place on a View
menu, they will help us to demonstrate a few useful techniques. The
first of these is how to show and hide controls.

 

The View Textboxes menu item

Controls on a form can be hidden or shown as the need arises. The process is
quite easy. Access the code for your View Textboxes menu item. Type the
following for the menu item:

Textbox1.Visible = False
Textbox2.Visible = False

Run your code and test it out. Click View > View Textboxes. The two
textboxes you added should disappear.

To hide a control, simply set it’s Visible property to False. If you want to
get it back, show a control by setting the Visible property to True.

A good idea is to have the ability to toggle a control on and off: One click
of a menu item could hide the control, and a second click could show it again.
You can do that with your menus.

Each item on your menu has a Checked property. If set to True, you’ll see a
tick appear next to the menu item. As in the image below:

The selected menu item has a tick next to it

You can use this Checked property as a toggle: If the menu item is ticked,
display the textbox; if it’s not ticked, hide the textbox.

Delete or comment out the line of code for your View Textboxes menu item. Add
the following line in its place (this assumes that you’ve Named your View Textboxes
menu item as mnuViewTextboxes. If you’ve named it something else, changed the
part before the full stop):

mnuViewTextboxes.Checked = Not mnuViewTextboxes.Checked

This line toggles the Tick on and off. The part before the equals sign sets
the Checked property of our menu item. The part after the equals sign sets it
to whatever it’s NOT at the moment. So if Checked is True, it’s NOT False. In
which case, set it to False.

Run your code and test it out. Click View > View Textboxes. Have
a look at the menu again, and you’ll see a tick appear. Click View > View
Textboxes
again and the tick will disappear.

We can show the textboxes if there’s a tick next to View Textboxes. Just test
the value of the Checked property in an If Statement. Add this If Statement
just below your first line:

If mnuViewTextboxes.Checked = True Then

TextBox1.Visible = True
TextBox2.Visible = True

Else

TextBox1.Visible = False
TextBox2.Visible = False

End If

So the If Statement examines the Checked property of the menu item. If it’s
True, make the textboxes Visible ; Else, we set the Visible property of the
textboxes to False.

Before you run your code, return to the Form view by holding Shift + F7 on
your keyboard. When you have your form displayed, and not the code, click on
textbox1 to select it. In the property box, locate the Visible property
and set it to False. Do the same for texbox2. When your form runs, the
two textboxes will then be hidden.

Now run your programme and test out your new menu. Click View > View
Textboxes
and see if they toggle on and off.

Exercise

Add two labels to your form. Write code to toggle the labels on and off. The
two labels should disappear with the textboxes. And they should reappear when
the menu item is toggled to the on position

In the next part, we’ll see how we can insert images. We’ll use the View Images
menu for that.

Kaynak : https://www.homeandlearn.co.uk/NET/nets4p11.html ‘sitesinden alıntı

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