Showing/Closing forms in wpf - wpf

Question

Im developing an application using wpf template I have these 2 windows:
MainWindow.xaml and
JungleTimer.vb which is a Windows Form
I have a button in my main windows which shows JungleTimer form using this code:
Dim JungleTimer As New JungleTimer
JungleTimer.Show()
But as you see, clicking this button multiple times will show multiple JungleTime form.
I tried to use this code to check if JungleTimer is visible but it doesn't work:
Dim JungleTimer As New JungleTimer
If JungleTimer.Visible = False Then
JungleTimer.Show()
End If
I also need the code to close the JungleTimer form.

Answer 1

As you are creating a new JungleTimer each time you click the button you will always get a new instance of the window. What you need to do is declare a field within the class of the type JungleTimer. Initially this will be null (Nothing). When you click the button, check if this field has a value or is still null. If still null, set it to a new JungleTimer and show it. If it isn't null, activate the existing window without creating a new instance. you'll also need to detect when the window closes so that you can set the field back to null.
For a demo, create a new WPF application with two windows, MainWindow (the main window) and JungleTimer.
XAML for MainWindow:
<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<StackPanel VerticalAlignment="Center">
<Button Width="100" Height="30" Click="Jungle_Click">Jungle Me</Button>
<Button Width="100" Height="30" Click="DeJungle_Click">De-Jungle Me</Button>
</StackPanel>
VB for MainWindow (sorry if it's clumsy, I haven't done VB for ten years or so):
Class MainWindow
Private WithEvents _jungleTimer As JungleTimer
Private Sub Jungle_Click(sender As Object, e As RoutedEventArgs)
If _jungleTimer Is Nothing Then
_jungleTimer = New JungleTimer
_jungleTimer.Show()
Else
_jungleTimer.Activate()
End If
End Sub
Private Sub DeJungle_Click(sender As Object, e As RoutedEventArgs)
If Not _jungleTimer Is Nothing Then
_jungleTimer.Hide()
_jungleTimer = Nothing
End If
End Sub
Private Sub CloseHandler() Handles _jungleTimer.Closed
_jungleTimer = Nothing
End Sub
End Class
XAML for JungleWindow:
<Window x:Class="JungleTimer"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="JungleTimer" Height="300" Width="300">
<Grid>
<Label HorizontalAlignment="Center" VerticalAlignment="Center">
Jungle!
</Label>
</Grid>