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WPF UserControl Child Component Event Handler

I have a UserControl that contain let's say a button (or any other object).
<UserControl x:Class="StackOverFlowQuestion.UserControlButton"
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"
xmlns:local="clr-namespace:StackOverFlowQuestion"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<Button
x:Name="Button1"
Content="Click me for testing"/>
</Grid>
</UserControl>
and I want to access that Button's(Or any Object) Click Event or any Event form the parent that contains the UserControl.
<Window x:Class="StackOverFlowQuestion.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:StackOverFlowQuestion"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Grid>
<local:UserControlButton/>
</Grid>
</Window>
Thanks.

It's quite easy. Just put a public event to the UserControl (code behind) for it could be accessible from outside of UserControl and do forward the Click event from your button.
public partial class UserControlButton : UserControl
{
public event RoutedEventHandler ButtonClick;
private void UsrCtlButton_Click(object sender, RoutedEventArgs e)
{
ButtonClick?.Invoke(sender, e);
}
}
XAML of UserControl:
<Button x:Name="Button1" Content="Click me for testing" Click="UsrCtlButton_Click"/>
XAML where UserControl being used:
<local:UserControlButton ButtonClick="Some_event_handler_to_handle_Button_Click"/>

WPF Navigate from frame in window to Usercontrol and pass parameters to it

I have a modern window in WPF/C# application, in which I added a modern frame:
<mui:ModernWindow x:Class="MyApp.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mui="http://firstfloorsoftware.com/ModernUI"
WindowStartupLocation="CenterScreen"
Style="{StaticResource EmptyWindow}">
<Window.Resources>
</Window.Resources>
<Grid>
<Menu x:Name="menu" Height="62" VerticalAlignment="Top" >
<MenuItem x:Name="miHome" Header="Home" Click="MenuItem_Home" IsChecked="True" Width="60" FontSize="14" />
<MenuItem x:Name="miClients" Header="Clients" FontSize="14" Click="MenuItem_Clients" Width="65"/>
<MenuItem x:Name="miSuppliers" Header="Suppliers" FontSize="14" Click="MenuItem_Suppliers" Width="81"/>
<MenuItem x:Name="miReports" Header="Reports" FontSize="14" Click="MenuItem_Reporting" Width="71"/>
</Menu>
<mui:ModernFrame Margin="0,75,10,10" x:Name="frame">
</mui:ModernFrame>
</Grid>
I have MenuItems in my application, when I click on Suppliers item, I fill the frame with a usercontrol, like this:
frame.Source = new Uri("/Pages/Suppliers.xaml", UriKind.Relative);
Where Suppliers.xaml design is:
<UserControl
x:Class="MyApp.LinksBar.Suppliers"
xmlns:MyApp="clr-namespace:MyApp"
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"
xmlns:mui="http://firstfloorsoftware.com/ModernUI"
mc:Ignorable="d"
d:DesignHeight="575" d:DesignWidth="905">
<UserControl.Resources>
</UserControl.Resources>
<Grid Name="Grid">
<mui:ModernButton x:Name="btnmakePayment" Content="Make Payment" Click="btnMakePayment_Click" Grid.Row="2" HorizontalAlignment="Right" VerticalAlignment="Top"/>
</Grid>
</UserControl>
When I click on "Make Payment" button, I navigate to another UserControl (MakePayment.xaml):
private void btnMakePayment_Click(object sender, RoutedEventArgs e)
{
NavigationCommands.GoToPage.Execute(new Uri("/Actions/MakePayment.xaml", UriKind.Relative), this);
}
MakePayment.xaml design is:
<UserControl
xmlns:local="clr-namespace:MyApp.Actions" x:Class="MyApp.Actions.MakePayment"
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"
xmlns:mui="http://firstfloorsoftware.com/ModernUI" xmlns:System="clr-namespace:System;assembly=mscorlib" xmlns:MyApp="clr-namespace:MyApp"
mc:Ignorable="d"
Loaded="MakePayment_Loaded"
d:DesignHeight="600" d:DesignWidth="866" >
<UserControl.Resources>
</UserControl.Resources>
<Grid DataContext="{StaticResource makePaymentViewSource}" Name="Grid">
<Grid.RowDefinitions>
</Grid.RowDefinitions>
<Label Content="Total" VerticalContentAlignment="Center" HorizontalAlignment="Left" VerticalAlignment="Top"/>
// More design code here ...
</Grid>
</UserControl>
Here comes my question:
I need to pass parameters from Suppliers UserControl to MakePayment UserControl.
How to programmatically pass the parameters in Suppliers and read them in MakePayment?
Thank you.

If you can bind one to the other, that is what you should be doing. By far, the easiest way to make two UserControls "communicate" (or share properties that both can do stuff with) is to define a DependencyProperty on each and bind them two-way.
This way, both always have access to the same value and both can do stuff with it.
Take my own control as an example:
<UserControl x:Class="MyControls.MasterContainerControl"
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"
xmlns:local="clr-namespace:MyControls"
mc:Ignorable="d"
x:Name="masterContainerControl">
<local:ContainerControl SomeProperty="{Binding ElementName=masterContainerControl, Path=SomeProperty}">
<local:ContainerControl.Another>
<local:AnotherControl SomeProperty="{Binding ElementName=masterContainerControl, Path=SomeProperty"/>
</local:ExplorerBase.AddressBar>
<local:ContainerControl.Some>
<local:SomeControl SomeProperty="{Binding ElementName=masterContainerControl, Path=SomeProperty"/>
</local:ContainerControl.Some>
</local:ContainerControl>
</UserControl>
This, of course, all assumes MasterContainerControl, ContainerControl, AnotherControl, and SomeControl all have a DependencyProperty called SomeProperty, and then the bindings seal the deal.
Note: Make sure the default values are defined in MasterContainerControl because those will override the values MasterContainerControl binds to.
If I misunderstood your issue, please let me know.

hide control while resizing window in wpf

I'm trying to hide a control during a window resize because it's not behaving right otherwise. However in WPF there doesn't seem to be any OnBeginResize-ish event.
Any suggestions how to achieve this in WPF?

Bind a property(Notifiable) to your window width so when the width changes Setter of this property will be invoked and within this setter you can have the logic to hide your control.
<Window x:Class="SiemensEnergy.Frw.Main.Client.UI.Views.MainWindowView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:viewmodel="clr-namespace:SiemensEnergy.Frw.Main.Client.UI.ViewModels"
Title="MainWindow" mc:Ignorable="d" xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
Width="{Binding WindowWidthProperty, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
</Window>

Window_SizeChanged?
<Window x:Class="TestControls.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:m="clr-namespace:WFControls;assembly=WFControls"
xmlns:ff="clr-namespace:WFControls.Fernfracht;assembly=WFControls"
Title="MainWindow" Height="350" Width="525" SizeChanged="Window_SizeChanged">
<DockPanel>
</DockPanel>
</Window>

How to send data from one User Control to another User Control?

Say I have these two User Controls. How would I pass data entered in the TextBox from ControlOneto the TextBox in ControlTwo when the Button in ControlOne is clicked?
<UserControl x:Class="Project.ControlOne"
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>
<StackPanel Orientation="Horizontal">
<TextBox x:Name="MyTextBox" HorizontalAlignment="Center" VerticalAlignment="Center" Width="100" />
<Button HorizontalAlignment="Center" VerticalAlignment="Center" Content="Send" Click="Button_Click" />
</StackPanel>
</Grid>
</UserControl>
...
namespace Project
{
public partial class ControlOne : UserControl
{
public ControlOne()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
}
}
}
<UserControl x:Class="Project.ControlTwo"
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>
<StackPanel Orientation="Horizontal">
<TextBox x:Name="MyTextBox" HorizontalAlignment="Center" VerticalAlignment="Center" Width="100" />
</StackPanel>
</Grid>
</UserControl>

Your two user controls should have no knowledge of each other (unless one contains the other). That's why you can't "pass data" between them. The idea behind a user control is that you can drop it anywhere as many times as needed. If ControlOne knew about ControlTwo, what would happen if you used them separately? Or had three ControlTwos in the same place?
The layer which contains both of them should be the one to read a value from one and set it to the other. If you want it to happen on the button press, you should look into event handling so the parent can know when the control's button is pressed.

ContextMenuOpening event not trigered

I have a button with a context menu, but I just can get the ContextMenuOpening event to triger.
<Button Name="a_button"
ContextMenu="{StaticResource MyContextMenu}"
ContextMenuOpening="MyContextMenu_Opening" >
</Button>
private void MyContextMenu_Opening(object sender, ContextMenuEventArgs e)
{
// doesnt get here.
}
Any ideas how to make this work ?
Thanks.

ContextMenuOpening event must be handled on an ancestor of the ContextMenu not on the ContextMenu itself. If you try handling it on the ContextMenu the event only fires when you right click once ContextMenu is already open.

I've just checked your code and it works perfectly.
Here is my full xaml:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Window.Resources>
<ContextMenu x:Key="MyContextMenu">
<MenuItem Header="Send" />
</ContextMenu>
</Window.Resources>
<Grid>
<Button Name="a_button"
ContextMenu="{StaticResource MyContextMenu}"
ContextMenuOpening="MyContextMenu_Opening" >
</Button>
</Grid>
</Window>
And *.cs:
private void MyContextMenu_Opening(object sender, ContextMenuEventArgs e)
{
}