XAML
<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">
<Grid>
<TabControl x:Name="TabControl1">
<TabItem Header="General"/>
<TabItem Header="Security" />
<TabItem Header="Details" />
</TabControl>
</Grid>
</Window>
vb.net
Class MainWindow
Private Sub TabControl1_SelectionChanged(sender As Object, e As SelectionChangedEventArgs) Handles TabControl1.SelectionChanged
System.Media.SystemSounds.Asterisk.Play()
End Sub
End Class
I want to play sound when User clicks every TabItem.
The codes above play sound during Window is opening which I dont want.
So, how to prevent playing sound during Window is opening?
There is the property IsLoaded in Window, that can be used for that purpose.
You could check for the value of IsLoaded to determine whether to play the sound or not (it may well be that there are syntactic errors, my VB.NET is not that good ;) )
Class MainWindow
Private Sub TabControl1_SelectionChanged(sender As Object, e As SelectionChangedEventArgs) Handles TabControl1.SelectionChanged
If IsLoaded Then
System.Media.SystemSounds.Asterisk.Play()
End If
End Sub
End Class
The first selection of the first tab should occur before Loaded is called, hence IsLoaded should be false and no sound should be played.
Related
There are many explanation in google, but I still struggling to implement mouse events.
I have tried to use MouseEnter="Canvas1_MouseEnter" in canvas properties, but it doesn't work.
I tried to add manually, . it doesn't work.
I also tried to use AddHandler Canvas1.MouseEnter, AddressOf Canvas1_MouseEnter in Private Sub main_Loaded(sender As Object, e As RoutedEventArgs) Handles main.Loaded method, it doesn't work too.
Then I tried to move AddHandler Canvas1.MouseEnter, AddressOf Canvas1_MouseEnterto Public Sub InitializeComponent() in MainWindow.g.i.vb file. it didn't work
I have no idea how to implement mouse events. :(
so I tried to implement MouseEnter to the form it self, the event called properly.
Does it mean z-order matter?
Here is the xaml file
<Window x:Name="main" x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="620.242" Width="827.423">
<Grid HorizontalAlignment="Left" Height="575" Margin="10,10,0,0" VerticalAlignment="Top" Width="807">
<Canvas x:Name="Canvas1" HorizontalAlignment="Left" Height="555" Margin="794,368,-774,-348" VerticalAlignment="Top" Width="787" />
</Grid>
</Window>
and the hanlder sub
'this code generated automatically
Private Sub Canvas1_MouseEnter(sender As Object, e As MouseEventArgs)
MessageBox.Show("event called")
End Sub
How could I implement mouse event to my canvas?
Any help appreciated :)
UI elements in WPF do not receive mouse events (without mouse capture) outside their rendered area. A Panel (like your Canvas) does not render anything outside the area of its child elements unless you define a non-null value for its Background property.
You may set a Background for your Canvas like shown below, which makes it render the entire area defined by its ActualWidth and ActualHeight with a transparent brush:
<Canvas x:Name="Canvas1" Background="Transparent"
MouseEnter="Canvas1_MouseEnter" ... />
Your canvas does not have the MouseEnter event. Use it like this
<Grid>
<Canvas HorizontalAlignment="Left" Height="158" Margin="191,85,0,0" VerticalAlignment="Top"
Width="221" Background="#FF575757" MouseEnter="Canvas_MouseEnter"/>
</Grid>
And then the Sub for the Event:
Private Sub Canvas_MouseEnter(sender As Object, e As MouseEventArgs)
MessageBox.Show("Hello?")
End Sub
I need to run some part of application in background and allow user to update the UI while the sub is running in the background. I searched and I found out that in WPF I should use Dispatcher. Problem is even when I use dispatcher still my GUI is not usable till the all subs will finish. I attached a code here so you can have better perspective of what I mean.
For example in this code when a user run the application, system should run a new thread that will change the text of first textbox while use can update the text of the second textbox.
I am wondering if I am doing this right or not. Can anybody help me with this?
<Window x:Class="Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:src="clr-namespace:testDispacher"
Title="Window1" Height="300" Width="300" Loaded="Window_Loaded">
<Grid>
<StackPanel>
<TextBlock>UCtextbox:</TextBlock>
<src:ToBeRunByDispacherUC x:Name="UC1" />
<TextBlock>Windowstxtbox:</TextBlock>
<TextBox x:Name="txtBox2" Width="100" Height="30"/>
</StackPanel>
</Grid>
Class Window1
Delegate Sub runSub()
Dim setTxt As runSub
Public Sub New()
InitializeComponent()
setTxt = AddressOf UC1.setTxtBox
End Sub
Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
UC1.IsEnabled = False
Dispatcher.Invoke(setTxt, Windows.Threading.DispatcherPriority.Background)
End Sub
End Class
<UserControl x:Class="ToBeRunByDispacherUC"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
<TextBox x:Name="txtBox1" Width="100" Height="30"/>
</Grid>
Partial Public Class ToBeRunByDispacherUC
Public Sub setTxtBox()
Dim j As Integer = 0
For i As Integer = 0 To 10
j += 1
System.Threading.Thread.Sleep(1000)
Next
txtBox1.Text = "End"
Me.IsEnabled = True
End Sub
End Class
The dispatcher should be used to update UI objects from a separate thread, it does not actually spawn up the thread for you. If you are using .NET 4.0 or higher, you can use the TPL library to spawn your thread, do your work, then update your UI object via the dispatcher from the background thread.
Task.Factory.StartNew(Sub() DoBackgroundWork())
Then, inside DoBackgroundWork whenever you want to update your UI...
Dispatcher.BeginInvoke(Sub() txtBox1.Text = "End")
you can call to the general application.
Application.Current.Dispatcher.Invoke()
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.
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>
Well, someone can tell me why this exception occurs in these conditions?
Test Window
<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>
<ComboBox
Name="cmbTest"
IsEditable="True"
SelectionChanged="ComboBox_SelectionChanged">
</ComboBox>
</StackPanel>
</Window>
Code behind
Class MainWindow
Sub New()
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
Dim source As New ObservableCollection(Of String)()
source.Add("AAA")
source.Add("BBB")
source.Add("CCC")
cmbTest.ItemsSource = source
End Sub
Private Sub ComboBox_SelectionChanged(sender As System.Object, e As System.Windows.Controls.SelectionChangedEventArgs)
Keyboard.Focus(cmbTest)
End Sub
End Class
Now, if you type AAA and then Ctrl+Z, ComboBox control raise this exception:
Cannot Undo or Redo while undo unit is open.
Someone can explain why?!? How it would be possible to avoid it?
"The Undo method does not work with the KeyPress or TextChanged events."
This has gotten me before.
Source: http://msdn.microsoft.com/en-us/library/system.windows.forms.textboxbase.undo.aspx
I am using an AutoCompleteBox UserControl that uses a listbox inside of a Popup. Everything works fine, the user can type in, view suggested results, and click the result which retrieves information.
i have been trying to add arrow key event handlers so they can scroll down through the listbox that pops up with up and down arrows, and hit enter to select a result.
I have a PreviewKeyDown event on the TextBox the user types in, and inside of that:
If e.Key = Key.Up Then
txtNamesListBox.Focus()
End If
If e.Key = Key.Down Then
txtNamesListBox.Focus()
End If
The event fires and i can reach these functions by setting a break point, however it doesnt set the focus to the ListBox that pops up, and i cant scroll through the results at all. is this even possible and am i way off in my attempt? I am at a loss, thanks!
You need to get a reference of the ScrollViewer residing inside ListBox template and use it to scroll content.
Something like following should do. (NOTE: I have not tested this code.)
Example:
ScrollViewer scrollViewer = (ScrollViewer)txtNamesListBox.Template.FindControl("ScrollViewer");
// call methods on scrollViewer
Edit:
Worked out simpler soultion. Idea is wrapping the ListBox with a ScrollViewer and disabling ListBox's scrolling.
Example:
XAML:
<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"
Loaded="Window_Loaded">
<Grid>
<StackPanel>
<RepeatButton Click="ScrollUp">Scroll Up</RepeatButton>
<ScrollViewer Name="scrollViewer"
ScrollViewer.VerticalScrollBarVisibility="Hidden"
MaxHeight="200">
<ListBox Name="txtNamesListBox"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
ScrollViewer.VerticalScrollBarVisibility="Disabled"></ListBox>
</ScrollViewer>
<RepeatButton Click="ScrollDown">Scroll Down</RepeatButton>
</StackPanel>
</Grid>
</Window>
Code Behind:
Class MainWindow
Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
txtNamesListBox.ItemsSource = Enumerable.Range(1, 50).Select(Function(i As Int32) i.ToString())
End Sub
Private Sub ScrollDown(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset + 10)
End Sub
Private Sub ScrollUp(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset - 10)
End Sub
End Class