How can I bind the value cross the window? - wpf

Question

Here is the XAML:
<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">
<Grid>
<TextBox Text="{Binding CB+Width,RelativeSource={RelativeSource AncestorType={x:Type Window}},Mode=TwoWay}"></TextBox>
</Grid>
</Window>
And here is code-behind:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace WpfApp1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
TB = new TextBox();
TB.Width = 200;
}
public ComboBox CB
{
get { return (ComboBox)GetValue(CBProperty); }
set { SetValue(CBProperty, value); }
}
// Using a DependencyProperty as the backing store for CB. This enables animation, styling, binding, etc...
public static readonly DependencyProperty CBProperty =
DependencyProperty.Register("CB", typeof(ComboBox), typeof(MainWindow), null);
}
}
In fact, the DependencyProperty is a custom control, but I replace it as a ComboBox for easy to explain my problem to you.
The custom control is not in the same window and I want to bind its value such as Width to the TextBox.
The custom control is in a different window. That means there are two windows, window 1 and window 2. The custom control is in window 1 and the textbox is in window 2. I do this because one is the main window and the other is the setting window. Whenever the setting window changes the setting, you can see it in the main window at once. So I use a DependencyProperty to store the custom control which in a different window and wanna bind it to the textbox.
Now how can I do it? Would you please help me? Thank you.

Answer 1

It LOOKs like you want your textbox to show the width property of the Window? (or some other control in the future and just testing). If you apply an x:Name value to a control, you can reference that control directly in the XMAL and then properties directly on that. No need for any custom other control with your own dependency property... something like.
<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"
x:Name="myOuterWindowControl" >
<Grid>
<TextBox Text="{Binding ElementName=myOuterWindowControl, Path=Width, Mode=TwoWay,
UpdateSourceTrigger=LostFocus}" Height="30" Width="70"
HorizontalAlignment="Left" VerticalAlignment="Top"/>
<TextBox Height="30" Width="70"
HorizontalAlignment="Left" VerticalAlignment="Top" Margin="0,50,0,0"/>
</Grid>
</Window>
Now I actually added an extra textbox control so there is more than one control in the XAML to allow focus to change. Reason. I set the textbox to allow mode as Two-Way binding. The window will push to the textbox, but you can also type in a value to the textbox and when the LOST FOCUS happens, it pushes the value back to the window and you can dynamically change the width (or other property height, coloring, whatever).
Is this more in line with what you were trying to get at?