I am creating a UserControl, I want that when I click in a button from that Control a property (attriibute) modifies from my MainWindow. The UserControl is created from a separate project and built as a .dll.
I had tried the following:
Window l = Window.GetWindow(this);
The problem is that because my window is not being referenced I have no way to access it (the properties I had created) and I dont know how to do it. If I try to write "MainWindow" it says that it couldn't be found.
You can get window using Application.Current.MainWindow. It will return window object so make sure you typecast it to actual instance of your window.
Assuming actual instance is MainWindow, it can be accessed like this:
MainWindow window = (MainWindow)Application.Current.MainWindow;
You have a number of ways of accessing a reference to the main Window in WPF. There is the way that #Rohit Vats showed you:
MainWindow window = (MainWindow)Application.Current.MainWindow;
However, as you have noticed, this does not always work. Sometimes it can be fixed simply by setting the property to the MainWindow instance:
public MainWindow()
{
Loaded += MainWindow_Loaded;
}
private void MainWindow_Loaded(object sender, RoutedEventArgs e)
{
Application.Current.MainWindow = this;
}
You should now be able to access the MainWindow from this property. However, if that still doesn't work for some reason, then you can also try the Application.Windows property:
foreach (MainWindow window in Application.Windows.OfType<MainWindow>())
{
// Do something with window here
}
Related
My question is exactly like in the title.
I'm starting with Caliburn.Micro for MVVM approach (which also is new for me) and in every tutorial the first step is to remove the default MainWindow.xaml file and create a new UserControl file. Why is that? UserControl does not even accept a Title. Isn't it possible to build application using normal Windows? I already tried that, but with every launch I get error "Cannot find view for ViewModel", although both MainView.xaml and MainViewModel.cs are present. When I created a pair of USerControl and ViewModel for it, everything started to work as expected. So again, why Windows don't work?
It wouldn't really be a problem, but I'm thinking that some additions like Modern UI themes for WPF might not work without a window. I'm not sure of that.
Probably one solution would be to display a defined UserControl View inside of a Window, but it's just a workaround.
You could create your own custom shell window by creating a custom WindowManager:
public class CustomWindowManager : WindowManager
{
protected override Window CreateWindow(object rootModel, bool isDialog, object context, IDictionary<string, object> settings)
{
Window window = new Window();
window.Title = "custom...";
return window;
}
}
...that you register in your bootstrapper:
public class HelloBootstrapper : BootstrapperBase
{
...
protected override void Configure()
{
_container.Singleton<IWindowManager, CustomWindowManager>();
...
}
}
So I have a user control within a window. I need to be able (from user control) to retrieve the parent window left and top (in order to locate a new popup I'm opening from the child). I'm trying to do this by referencing the UserControl .Parent property but doesn't seem to work.
Any idea? Thanks!
Are you using MVVM? Are you concerned about writing code in the code behind? .Net 3.5 or 4.0?
From the UserControl Code behind you could use:
Window parentWindow = Window.GetWindow(userControlReference);
public partial class UserControl1 : UserControl
{
public UserControl1()
{
InitializeComponent();
Loaded += new RoutedEventHandler(UserControl1_Loaded);
//Window parrentWindow = Window.GetWindow(this);//don't add here the value will be null
}
void UserControl1_Loaded(object sender, RoutedEventArgs e)
{
Window parrentWindow = Window.GetWindow(this);
}
}
Background:
I have WPF application with a main window containing a user control. I want to pass a value from the main window to the user control.
In the Main window's constructor I have code:
public MainWindow()
{
InitializeComponent();
_vm = new MainWindowViewModel();
this.DataContext = _vm;
ucControl = new UserControl1("NameSet");
}
(ucControl is my user control)
User control has two constructors:
public UserControl1()
{
InitializeComponent();
this.ID = ID.GetNewID;
}
public UserControl1(string name)
{
InitializeComponent();
_vm = new UCViewModel(name);
this.DataContext = _vm;
this.ID = ID.GetNewID;
}
The problem is: although the second constructor (with parameter) is called, it is not loaded in the main window. I checked the ID (this.ID) in the user control's loaded event and I see the ID set in the default constructor and its DataContext is null. Because of this reason, I do not get the "name" string in my user control.
Any help please? Since I am using MVVM pattern I do not want to expose properties in user control (view) to be set from main window just for this.
You are instantiating the UserControl1 object twice:
Once within the XAML. The <uc:UserControl1> element instantiates a UserControl1 object, using the default constructor, and assigns it to the member ucControl.
You instantiate it again within the constructor of the MainWindow object
If you put a break point in the constructor of UserControl, you'll notice it is called twice. I assume WPF instantiate and initialize the XAML's UserControl (#1 from above) after you assign the dynamic UserControl (#2 from above), and this is why you see the former in the logical tree of MainWindow.
You should have only one instance. If you want to parameterized a user control, the canonical paradigm is what you mention that you don't want to do (why??). If you had such a property, you could set it in the XAML: <uc:UserControl1 x:Name="..." YourProperty="NameSet>
exposing such a property is a single line in the UserControl:
public YourProperty { get; set; }
If you insist of not having this line, you should do the following:
Remove the XAML's user control.
In main window, subscribe to the Loaded event
In the handler of the Loaded event, instantiate a new UserControl1 - with whatever constructor parameter that you want.
Manually add it to the Children array of the parent Grid element
Clearly this isn't my recommendation. In addition to the complexity, with the former method you'll also work very well with the Visual Studio designer.
I'm sure this is something very simple but I can't figure it out. I've searched here and on msdn and have been unable to find the answer. I need to be able to set the richtextboxes selection via richtextbox.Selection.Select(TextPointer1, Textpointer2).
Application.Current contains a collection of all windows in you application, you can get the other window with a query such as
var window2 = Application.Current.Windows
.Cast<Window>()
.FirstOrDefault(window => window is Window2) as Window2;
and then you can reference the control from your code, as in
var richText = window2.MyRichTextBox
Application.Current.Windows.OfType(Of MainWindow).First
You should be able to access controls on Window1 from Window2 code behind, if that's what you want. Generated fields are internal by default.
All you need is to name the control on Window1, like this:
<RichTextBox x:Name="richtextbox" ... />
In Window2 code behind:
var window = new Window1(); // or use the existing instance of Window1
window.richtextbox.Selection.Select(TextPointer1, Textpointer2);
A better option would be to encapsulate select operation in a method in code behind of Window1, to avoid giving away internal. Then you would have:
// Window1.cs
public void Select(int param1, int param2)
{
richtextbox.Selection.Select(param1, param2);
}
// Window2.cs
var window = new Window1(); // or use the existing instance of Window1
window.Select(TextPointer1, Textpointer2);
You cant access the texbox from another window as it is private to that window you can however work around this by exposing the RichTextBox as a public property on your window (hack)
public RichTextBox RichTextBox {
get{
//the RichTextBox would have a property x:Name="richTextbox" in the xaml
return richTextBox;
}
}
I have a user control where the XAML of the control can bind to the appropriate properties from the parent's data context like normal (the data context propagates in xaml).
For example, I have a window whose DataContext I am setting to ObjectA for example. My user control within the window is then try to access the properties within the dataContext
So my window's xaml and code behind can both see a non-null DataContext.
My control that DataContext propagates to can see a non-null DataContext in the Xaml but not in the code behind.
What is the proper way of handling this?
failing that if you need to check whether the DataContext is being set you can use the DataContextChanged
public partial class UserControl1 : UserControl
{
public UserControl1()
{
InitializeComponent();
DataContextChanged += new DependencyPropertyChangedEventHandler(UserControl1_DataContextChanged);
}
void UserControl1_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
{
// You can also validate the data going into the DataContext using the event args
}
}
Note it wont enter UserControl1_DataContextChanged until DataContext is changed from null to a different value.
Not sure if this answers your question but can be quite handy to use in debugging issues.
I think you are checking the 'DataContext' in the constructor of the UserControl. It will be null at the Constructor since the user control hasnt yet created while execution is in the constructor code. But check the property at Loaded event you will see the object properly.
public partial class UserControl1
{
public UserControl1()
{
this.InitializeComponent();
//DataContext will be null here
this.Loaded += new RoutedEventHandler(UserControl1_Loaded);
}
void UserControl1_Loaded(object sender, RoutedEventArgs e)
{
//Check DataContext Property here - Value is not null
}
}
I would check to see whether you are having a binding error at runtime. Add this namespace to your XAML:
xmlns:debug="clr-namespace:System.Diagnostics;assembly=System"
and check the debugger's Output window for relevant error messages.
Alternatively, can you show us more code?