How to Dynamically Update Label with TextBox As Input Changes - vb.net

I have a spelling application that I am building in VB.Net, where I have a textbox receiving simple input (spelling words), and a label which will show the output. What I want to accomplish is when I enter something in the textbox, I can see it in my label - as I am typing into the textbox.
I will admit that I don't know what I'm doing, as I've never tried this before, so I don't know to begin in terms of setting up what I need to do. I know that I'll need some variable to hold my String input, and will probably need some type of loop, but beyond that, I am lost. The only other example is in C#, and doesn't help me any.
Can anyone give me a simple model to work off of, so I can put the approach into memory? For now, all I have is code stub from my TextChanged event handler:
Private Sub txtSpell_TextChanged(sender As Object, e As EventArgs) Handles txtSpell.TextChanged
'Set variables to hold values.
Dim someText As String
'Connect the label and textbox.
lblShowInput.Text = txtWordInput.Text
'Process loop to populate the label from textbox input.
for '(This is where I am lost on the approach)
End Sub

I know that I'll need some variable to hold my String input, and will
probably need some type of loop
I don't think you'll need a loop, or the variable to hold the value. You almost have it:
Private Sub txtSpell_TextChanged(sender As Object, e As EventArgs) Handles txtSpell.TextChanged
'Connect the label and textbox.
lblShowInput.Text = txtSpell.Text
End Sub
In the code you provided, you are referencing an object named txtWordInput inside your txtSpell text changed event handler. If you are entering the text in the txtWordInput input, you'll want to handle this in the txtWordInput textChanged event handler:
Private Sub txtWordInput_TextChanged(sender As Object, e As EventArgs) Handles txtWordInput.TextChanged
'Connect the label and textbox.
lblShowInput.Text = txtWordInput.Text
End Sub
Follow-up:
The TextChanged event is the correct event for this.
In your code, you are assigning lblShowInput.Text to txtWordInput.Text, but in the txtSpell TextChanged event handler.
You want to be in the TextChanged event handler for whatever TextBox you would like to use to update the label, as the text is changing.
To give a better example, I have created a simple Winforms VB application that has only a textbox named InputTextBox and a label named Output Label.
The Form:
The Code:
Public Class Form1
Private Sub InputTextBox_TextChanged(sender As System.Object, e As System.EventArgs) Handles InputTextBox.TextChanged
OutputLabel.Text = InputTextBox.Text
End Sub
End Class
Explanation:
InputTextBox_TextChanged is the method name generated by Visual Studio for our event handler
Handles InputTextBox.TextChanged ties the method to an actual event it is handling.
When the InputTextBox text property is changed (typically by user input), whatever we have in our InputTextBox_TextChanged Sub will execute. In this case, I am assigning the Text of OutputLabel to the Text of the InputTextBox
Output:
Resources:
I've uploaded this simple demo to GitHub if you'd like a closer look.
Take a look at the TextChanged documentation

Related

How to create something similar to google style currency converter with VB.NET

Ok I have a bit of a weird question here. I have a program similar to a currency converter (it performs a mathematical function in order to produce a value to go in another textbox). What I want it to be able to do is identify the last textbox that you edited (there are 4) and then update the rest based on what you have inputted, the user then must be able to change a different textbox to change all of them.
If anyone can get me started on how to do it or even some sample code that would be much appreciated, thanks!
Sorry if I'm not making sense, just have a look at the google currency converter and think that with two more editable boxes.
This might be what you want if I understand you correctly.
In the form class, you have a variable called lastTextBoxChangedName which keeps track of which text box was the last to be edited.
Next there is an event handler which will fire when any of the four TextBoxes are changed. This merely updates lastTextBoxChangedName.
When you have finihed editing a textbox, and tab to the next one or click on something that causes a TextBox to lose input focus, the next event handler executes. This looks at lastTextBoxChangedName to see which was the last edited TextBox and you can insert your update code to replace the comments in the Select Case block.
Public Class Form1
Dim lastTextBoxChangedName As String
Private Sub TextBox_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged, TextBox2.TextChanged, TextBox3.TextChanged, TextBox4.TextChanged
lastTextBoxChangedName = sender.name
End Sub
Private Sub TextBox1_LostFocus(sender As Object, e As EventArgs) Handles TextBox1.LostFocus, TextBox2.LostFocus, TextBox3.LostFocus, TextBox4.LostFocus
updateTextBoxes()
End Sub
Private Sub updateTextBoxes()
Select Case lastTextBoxChangedName
Case "TextBox1"
'do updates appropriate to textbox1 changed
Case "TextBox2"
'do updates appropriate to textbox2 changed
Case "TextBox3"
'do updates appropriate to textbox3 changed
Case "TextBox4"
'do updates appropriate to textbox4 changed
End Select
End Sub
End Class
However, if you already have separate event handlers for each TextBox, don't add that first event handler for TextBox_TextChanged, just add the line ..
lastTextBoxChangedName = sender.name
into each handler.

VB.net, Being able to select text in a richtextbox without losing focus?

VB.net .. Currently I have two controls, one richtextbox and a textbox. The RTB is readonly, and also HideSelection is set to false.
The textbox is generic, it allows for input (to send data).
I want to be able to select things in the richtextbox without losing focus in the textbox. There is a client called 'mushclient' that does this, and it works pretty well. The text is still selected, but it doesn't lose the focus on the chatbar to type in.
I don't exactly know however how to prevent 'focus' though. At the moment it breaks flow when you are in game but want to copy something, you'll have to click the textbox again to start typing again. I understand I could setfocus after clicking the RTB, but this feels overall a bit odd. I was wondering if there is a more elegant solution.
Thanks!
This seems to work well for me. The TextBox does loose focus, but as soon as the Mouse_UP event fires, the selected text is copied to the clipboard and focus is sent back to the text box.
Public Class Form1
Dim LostFocusControl As Control
Private Sub RichTextBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles RichTextBox1.MouseUp
If RichTextBox1.SelectedText.Length > 0 Then
Clipboard.SetText(RichTextBox1.SelectedText)
End If
If Not IsNothing(LostFocusControl) Then
LostFocusControl.Focus()
End If
End Sub
Private Sub ControlLostFocus(sender As Object, e As EventArgs) Handles TextBox1.LostFocus
LostFocusControl = Sender
End Sub
End Class
The code is a bit longer than it could be, but this makes it easier if later on you want to change the control that focus is returned to. To change the control that you want to return focus to, just change the name of the control that the handler is subscribed to e.g
Change
Private Sub ControlLostFocus(sender As Object, e As EventArgs) Handles TextBox1.LostFocus
To
Private Sub ControlLostFocus(sender As Object, e As EventArgs) Handles Listbox1.LostFocus
or whatever the name of the control is that you want to return focus to.

How to make this more efficient?

Private Sub btnOne_Click(sender As Object, e As EventArgs) Handles btnOne.Click
txtAnswer.AppendText(1)
End Sub
So this is my code (It's for 0 through to 9 and a dot for decimal points).
I'm working on calculator for an assignment, my question is, can I make this more efficient so I don't have a lot code doing the same thing?
I had considered setting up a function to read the contents of the buttons and add them to the textbox, but then the operation buttons and clear buttons would just add to the textbox instead of performing the code assigned to them.
you can create one method for the numeric buttons and add their value to the Tag Object. Then you can just reference the tag object to append to the text
Private Sub NumericButtons_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim btn As Button
btn = sender
txtAnswer.AppendText(btn.Tag)
End Sub
You could create a function just like that, but it should read the number from the sender's Text property, and only assign the number buttons to that function in the OnClick event.
The other buttons will have their own OnClick methods, and you should make a generic function like in this case when you find a common behavior in some of them. Perhaps you could do another generic function for all + - / x operators, it that's appropriate.

Value of global variable won't change

I have a variable whose scope needs to be global, because it needs to be called in a function as well as in a button press. So I declared the variable in a Module so it would be global.
The problem is that the value of this variable needs to be equal to the value of the text property of a textbox in the form.
Here you can download the VB.net demonstration of my problem: http://db.tt/DDxQJDXl
Below is an explanation of what happens
You enter a string into the textbox, in this case I entered "Hello". Then you click the button and it displays what you wrote.
You click OK in that message box and change the value in the textbox. In this case I changed it to "Goodbye". Then I hit the button again, but the variable did not change values and the messagebox displays "Hello" again.
Here is the entire source code:
Module Module1
Public strDataValue = frmTest.txtDataValue.Text
End Module
Public Class frmTest
Private Sub btnTest_Click(sender As System.Object, e As System.EventArgs) Handles btnTest.Click
MsgBox(strDataValue)
End Sub
End Class
Note: This is just a demonstration of a problem I'm having in a much larger program so the variable does have to be global.
You need to set the value of the field to the new value in the TextBox:
Private Sub btnTest_Click(sender As System.Object, e As System.EventArgs) Handles btnTest.Click
strDataValue = txtDataValue.Text
MsgBox(strDataValue)
End Sub
The field will not change values by itself.
The value of strDataValue won't automatically change when txtDataValue.Text changes. You need to update strDataValue manually, either when the textbox loses focus, or when you click the Test button.
You could also have a public property, which automatically returns the actual value as long as the form is open.
Public ReadOnly Property DataValue() As String
Get
Return frmTest.txtDataValue.Text
End Get
End Property
You need to assign value of txtDataValue.Text to your variable strDataValue in better performance
Using of Timer object or TextChenged event not recommended
Any change of txtDataValue.Text can assign after end of editing action
for me best solution: Leave or LostFocus events
Private Sub txtDataValue_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtDataValue.Leave
strDataValue = txtDataValue.Text
End Sub

Dynamically adding and using types in vb.net

I am making a program which dynamically adds objects, such as a button or a checkbox to a form.
For each instance, a handler is added so a certain function is called for the Click event of each object.
Now, when that handler is called, how can I manipulate the object that fired off the Click event? The Sender object is useless here as I cannot change the location, text, parent, nothing at all.
Since the objects are being created dynamically, their instance name is unfortunately always going to be the same, therefore I cannot simply do things like button1.Text = "Button 1".
I really do not want to create a new subroutine for every type since the actions that would be performed are the same...so how can I manipulate these objects?
There are, at last count, 27 different object types which are being manipulated, and which I want to be manipulated by a single sub.
Thanks for the help!
It sounds like the sender is what you want, as this will be the object that fired off the Click event. You just need to figure out a way to cast it to the required type.
If you are just manipulating location, text and parent, then casting to Control will be enough:
Dim c As Control = CType(sender, Control)
Otherwise you will need to cast to the specific type which means you will need different routines per type.
Another option is to turn on late binding, which I believe in VB is Option Strict Off. Then you can refer to control properties even without the casting -- .NET will look for the property at runtime (and, be warned, will throw an exception if the property's not there).
Cast the sender to Control & you can do what you want (all your objects are Controls right?)
If you know the type of input that called the handler, then you can use typecasting to solve your issue:
Sub General_OnClick(ByVal sender As Object, ByVal e As EventArgs)
Dim b As Button = sender
b.Text = "Hello World!"
End Sub
If you don't, which you don't seem you, you might try casting to Control instead, this may give you enough control, depending on what you need to do. If not, you can always do something like:
Sub General_OnClick(ByVal sender As Object, ByVal e As EventArgs)
If TypeOf sender Is Button Then
Dim b As Button = sender
b.Text = "Hello World!"
Else If TypeOf sender Is TextBox Then
Dim tb As TextBox = sender
tb.Text = "Goodbye cruel world!"
End If
End Sub
EDIT: Updated to translate into VB.Net