I am working on a WPF application that has a Panel within a WindowsFormHost. The panel contains graphics that need to be redrawn every so often, and the code that draws these graphics is located within an OnPaint() event. The problem is, the OnPaint() event never seems to fire. To debug, I added a button to my form and used the button's click event handler to call the Invalidate() event. Even when I call Invalidate(), I can't seem to get the Paint event to fire. My code-behind looks like this:
public MainWindow()
{
InitializeComponent();
}
private void myPanel_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
/// Draw stuff
}
private void Button_Click(object sender, RoutedEventArgs e)
{
myPanel.Invalidate();
}
And my XAML looks like this:
<Window x:Class="MyProject.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
Title="MainWindow" Height="350" Width="525">
<Grid>
<StackPanel Name="stackPanel">
<Button Content="Button" Click="Button_Click"/>
<WindowsFormsHost x:Name="windowsFormsHost" >
<WindowsFormsHost.Child>
<wf:Panel x:Name="myPanel" Paint="myPanel_Paint"/>
</WindowsFormsHost.Child>
</WindowsFormsHost>
</StackPanel>
</Grid>
I've read through this: WindowsFormHost Paint Event Not Firing
...but we don't seem to be having the same problem, as my XAML does reference my Paint event handler, and OnPaint() still doesn't fire.
I have already tried adding myPanel.Update() to my Button_Click event, beneath my call to myPanel.Invalidate(). That also doesn't work.
What am I doing wrong here? Is it possible that Invalidate() is not really invalidating?
Related
Recently I have been experimenting with WPF. I was building a little program, but then I stumbled across a little problem. I tried to call the Window_Closing method from the code behind, it told me that I needed to give it cerntain parameters, but I don't have those parameters in the method I am trying to call it from.
This is my code:
private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
// My Window Closing code
}
private void Application_Exit(object sender, RoutedEventArgs e)
{
// Here is where I am trying to call it, giving a empty parameter with it.
// But it doesn't seem to work.
Window_Closing(null, EventArgs.Empty)
}
What I want
If a cenrtain button is called, I want the Window_Closing event to be called.
Anyone who knows the solution?
In your Designer, click on the Button and open its property window. There you select the "Events" - the "lightning" and choose the Click event to execute your Window_Closing method. There is a drop down in which you should be able to select it. If not, enter your method name there and press "Enter" to let VS generate the code-behind method.
Add "Window_Closing" & "Close_Click" in the XAML file (MainWindow.xaml) as follows.
<Window x:Class="WpfApp1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfApp1"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800" Closing="Window_Closing">
<Grid>
<Button x:Name="Close" Content="Close" Click="Close_Click" Width="100" Height="30"/>
</Grid>
Then in the code behind file (MainWindow.xaml.cs) add the following code. Here the window close command is called from the button click event handler which in turn closes the window, and then the 'Window_Closing' event handler will be automatically called.
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
}
private void Close_Click(object sender, RoutedEventArgs e)
{
Close();
}
}
Just close the window. Then the event will be called automatically, thats what it is there for to begin with.
And as it seems, you try calling it from your Application_Exit, which closes all the windows ... so .... What is your problem?
Just put a breakpoint in the Window_Closing and see, that is executed automatically. If not, maybe you should add the eventhander to all the windows Window_Closing events.
I am creating an application in WPF that relies on multi-touch and, although I can receive multiple touch points, the WPF controls do not behave as expected when multiple touches occur at the same time.
I created a simple test WPF application using buttons for visualization to ensure it wasn't anything in my project causing the issue.
The XAML:
<Window x:Class="TouchSample3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:TouchSample3"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Grid TouchDown="Grid_TouchDown">
<Button x:Name="button1" Content="Button" HorizontalAlignment="Left" Margin="108,86,0,0" VerticalAlignment="Top" Width="70" Height="70" Click="button1_Click" TouchDown="button1_TouchDown"/>
<Button x:Name="button2" Content="Button" HorizontalAlignment="Left" Margin="322,86,0,0" VerticalAlignment="Top" Width="70" Height="70" Click="button2_Click" TouchDown="button2_TouchDown"/>
</Grid>
</Window>
and here is my MainWindow:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
Console.WriteLine("Button 1 clicked.");
}
private void button2_Click(object sender, RoutedEventArgs e)
{
Console.WriteLine("Button 2 clicked.");
}
// TouchDown events
private void button1_TouchDown(object sender, TouchEventArgs e)
{
Console.WriteLine("Button 1 Touch Down.");
}
private void button2_TouchDown(object sender, TouchEventArgs e)
{
Console.WriteLine("Button 2 Touch Down.");
}
}
When I perform a single touch on either button it fires as expected, the TouchDown event, and Click event along with the button animation occur.
However, when I attempt to do two touches simultaneously (one finger held down, another one pressing), the TouchDown events get fired but the the Click events and the button animations do not happen.
It clearly registers the touch points but I don't understand why it doesn't perform actions/events to the WPF controls when touches happen simultaneously.
Any help or direction would be appreciated.
I think thats because the old version of Click event is not prepared well for a multi-touch wpf application. It is primary classified as a mouse event, since the TouchDown is touch event primary so it support the multi-touch feature.
Here I have sample window with a grid. I need to capture event when key is pressed. But it is not raising when I click grid area and then press key. It will work only if Textbox is focused. I know it will work if I capture it from Window. But I have other application with few usercontrols and I need to capture it from distinct ones. I tried to set Focusable.false for Window and true for Grid but it not helps.
Any solutions?
<Window x:Class="Beta.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" Closed="Window_Closed_1" Focusable="False">
<Grid KeyDown="Grid_KeyDown_1" Focusable="True">
<TextBox x:Name="tbCount" HorizontalAlignment="Left" Height="35" Margin="310,49,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="83"/>
</Grid>
Right this is weird. This is clearly a focus problem, still I can not understand why the grid do not take Focus, even when we click on it.
Though there is a workaround: create an handler for the loaded event of the grid:
<Grid x:Name="theGrid" KeyDown="Grid_KeyDown_1" Focusable="True" Loaded="TheGrid_OnLoaded">
And then force focus in your code behind:
private void TheGrid_OnLoaded(object sender, RoutedEventArgs e)
{
theGrid.Focus();
}
Your keydown event will work after that.
Hope it helps.
I had the same issue with a Universal Windows Platform (UWP) app. I attached the event to a grid in XAML but it would only work when the focus was on the TextBox. I found the answer (not just a workaround) on MSDN: https://social.msdn.microsoft.com/Forums/en-US/56272bc6-6085-426a-8939-f48d71ab12ca/page-keydown-event-not-firing?forum=winappswithcsharp
In summary, according to that post, the event won't fire because when focus to the TextBox is lost, it's passed higher up so the Grid won't get it. Window.Current.CoreWindow.KeyDown should be used instead. I've added my event handlers to the page loaded event like this:
private void Page_Loaded(object sender, RoutedEventArgs e)
{
Window.Current.CoreWindow.KeyDown += coreWindow_KeyDown;
Window.Current.CoreWindow.KeyUp += CoreWindow_KeyUp;
}
This works as expected for me.
I tried using the Focus Method too, to no avail, until I set the Focusable property to true ( It was default to False. )
I had the same problem, I've used PreviewKeyDownevent and it worked for me.
I'm trying to set up a WPF window so that it can accept different types of data via Drag and Drop. If I make a new project and set the window to the following:
<Window x:Class="DropShare.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300" AllowDrop="True" DragEnter="Window_DragEnter">
<Grid>
</Grid>
</Window>
And set the code-behind to:
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
private void Window_DragEnter(object sender, DragEventArgs e)
{
}
}
I only ever get DragEnter firing for files. It never fires for anything else - text, images, etc.
Is there something I'm missing? All the tutorials I've read have seemed to suggest this is all that's needed as the DragEnter event handler let's me state what I accept.
So your code works fine for me. But try this...
In your Window:
<Label Background="Purple" HorizontalAlignment="Center" VerticalAlignment="Center" Content="Drag from here!" MouseDown="Label_MouseDown"/>
and in your code behind:
private void Label_MouseDown(object sender, MouseButtonEventArgs e)
{
DragDrop.DoDragDrop(this, "This is just a test", DragDropEffects.All);
}
Then drag from the label into the window and see if your event fires.
If this works, it may have something to do with the permissions level between Visual Studio and your outside environment (possibly).
See:
https://superuser.com/questions/59051/drag-and-drop-file-into-application-under-run-as-administrator
In WPF drag and drop feature always has to deal with DragDrop Class, Please check here how to do drag and drop across applications
I have this simple UserControl:
<UserControl x:Class="WPFTreeViewEditing.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<TextBlock Text="Hello, world!" KeyDown="TextBlock_KeyDown" />
</Grid>
</UserControl>
I want to handle TextBlock.KeyDown event. So, I've added an event handler to the code-behind:
public partial class UserControl1 : UserControl
{
public UserControl1()
{
InitializeComponent();
}
private void TextBlock_KeyDown(object sender, KeyEventArgs e)
{
MessageBox.Show("Key up!");
}
}
but it doesn't fire. What's wrong?
UPDATE.
PreviewKeyDown doesn't fire too.
This UserControl is used in HierarchicalDataTemplate then:
<Window x:Class="WPFTreeViewEditing.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WPFTreeViewEditing"
Title="MainWindow" Height="265" Width="419">
<Grid>
<TreeView ItemsSource="{Binding}">
<TreeView.Resources>
<HierarchicalDataTemplate DataType="{x:Type local:ViewModel}" ItemsSource="{Binding Items}">
<local:UserControl1 />
</HierarchicalDataTemplate>
</TreeView.Resources>
</TreeView>
</Grid>
</Window>
From the documentation for UIElement.KeyDown:
Occurs when a key is pressed while focus is on this element.
You're using TextBlock which doesn't have the focus, so your KeyDown event will be handled by another control.
You can switch to TextBox and appy some styles so it'll look and behave like TextBlock, but you'll be able to get the focus and handle the event.
You should use PreviewKeyDown event instead of KeyDown event.
Ok, even though this question was posted a long time ago I had the same problem and found a way to get KeyDown events working, though it might not be what you're looking for I'll post the code to help future people with the same problem.
First thing first a KeyDown event handler in an Xaml Object will only fire off if that object has focus. Therefore you need a CoreWindow event handler, it's kind off the same thing but it will always run no matter what object or thing has focus. The following will be the code.
//CLASS.xaml.h
ref class CLASS{
private:
Platform::Agile<Windows::UI::Core::CoreWindow> window;
public:
void KeyPressed(Windows::UI::Core::CoreWindow^ Window, Windows::UI::Core::KeyEventArgs^ Args);
//CLASS.xaml.cpp
CLASS::CLASS(){
InitializeComponent();
window = Window::Current->CoreWindow;
window->KeyDown += ref new TypedEventHandler
<Windows::UI::Core::CoreWindow^, Windows::UI::Core::KeyEventArgs^>(this, &CLASS::KeyPressed);
};
void CLASS::KeyPressed(Windows::UI::Core::CoreWindow^ Window, Windows::UI::Core::KeyEventArgs^ Args){
SimpleTextBox->Text = Args->VirtualKey.ToString();
};
Basically you want a value to hold your window and use that to create a new TypedEventHandler. For safety you'll generally want to do this in your class' constructor a function that's only called once the moment the class starts (I still prefer the constructor though).
You can use this method to create an event handler for any event. Just change the "KeyDown" for another attribute like KeyUp, PointerMoved, PointerPressed and change the "&CLASS::KeyPressed" to the name of the function you want to be fired the moment you get an event of a corresponding type.