I have a textBox on my main Window and I have a user control with Images (Bitmaps). Through a mouse click on an Image, a value is calculated. This value should be displayed on the textBox in the main window.
1) without data binding
How could I access the textBox object on the main window from the user control. It works the other way round, i.e. I can access a user control textBox from the main window using the name of the user control and the textBox to access the textBox such as usercontrol1.textBoxName.
But it seems to me that I cannot access a main window textBox from the usercontrol such as mainWindow.textBoxName because the user control does not know the main Window and has no main Window object. Is this correct?
2) with data binding
It probably works with data binding. But what I tried so far did not work. In the main window XAML:
TextBox Text="{Binding Path=usercontrol1.GetCycleNumber()}" Name="cycleNumberBox"
in mainWindow.cs:
public partial class MainWindow : Window , INotifyPropertyChanged
I added the INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
public void CycleChanged()
{
this.cycleNumber = usercontrol1.GetCycleNumber();
if (this.cycleNumberBox.Text != cycleNumber)
{
this.cycleNumberBox.Text = cycleNumber;
RaisePropertyChanged("cycleNumber");
}
}
usercontrol1.cs
Now I would have to signal a change with
RaisePropertyChanged("cycleNumber");
in the user control. However, I cannot access this method.
Since I spent days already to figure this out, I would be glad for any help.
I am beginner and it is my first project. Thank you!
If you have a user control that needs to share a piece of data with main window (or for any container of the user control), your best bet is to use data binding.
Expose a dependency property on the user control. In your case, it looks like CycleNumber.
Internally,the user control can use this dependency property as needed. If it's a calculated field, you may want to use the RegisterReadOnly() method to register the dependency property.
2a. To have other controls access the value in CycleNumber, you can either use ElementBinding to bind to the dependency property, or
2b. have the dependency propery bound to a value in your ViewModel (or other structure if you're not following the MVVM pattern).
If you need more to go on, I can come up with some sample code for you.
Hope that helps.
Sergio
Related
I have status bar control in the main winodw. I have a user control placed in the main window.My user conrtorl has buttons .
say if i click the button in the user control ,I need to update the main window status bar .
I am following MVVM pattern. I am not sure how to achive this. I am beginner in wpf.
You need to use Dependency Property to send something to Main Control from UserControl.
For eg: If you want to change the text of a textblock present in the Main Window from a button Click present in USerControl.
You need to bind your DependencyProperty to the TextBlock TEXT property to reflect the change and your USERCONTROL must Implement INotifyPropertyChange
Make this DependencyProperty in your UserControl
public static readonly DependencyProperty TextProperty = DependencyProperty.Register("WriteText", typeof(string), typeof(UserControlnameSpace)) //Write Namespace of your UserControl where I mentioned
public string WriteText
{
get { return (bool)GetValue(TextProperty ); }
set
{
SetValue(TextProperty , value);
}
}
ButtonClick event present in USERCONTROL
public void Button_Click(object sender, RoutedEventArgs e)
{
WriteText="Hie"; //Write what you want to display on MainWindow.
}
ViewModel:-
private string _txtContent;
public string TxtContent
{
get
{
return _txtContent;
}
set
{
_txtContent = value;
RaisePropertyChanged("TxtContent");
}
}
Main Window:-
<TextBlock Text="{Binding TxtContent,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>
Where you are including your UserControl:-Include this property
<UserControl WriteText={Binding TxtContent Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />
You can set the DataContext(viewmodel) of the user control same as that of Main Window. Keep a property in viewModel and Bind that Property in the user control. So whenever anything changes in the Control that property will automatically be updated in the View Model which can be used by the Main
I would suggest that the usercontrol works with its own viewmodel. The main windows has a main controller which is responsible to initialize a Status bar messenger service and the user control view model uses that service.
User control's view model is bound to the button's actions via RelayCommand and on executing action it uses the status bar service to update the status.
This is enable your status bar on the main window to work with multiple user controls/pages of your application.
I asked a similar question a while back here WPF MVVM User Control. I got some answers, but they were way off, so I guess I wasn't clear in what I want to do....
I am working on a WPF application using MVVM. The app is built using a component based approach, so I have some user controls that I've defined that will be used throughout the application. As an example, I have an Address control. I want to use it an multiple places throughout the application. Here's an example. See here:
http://sdrv.ms/1aD775H
The part with the green border is the Address control. The control has its own View Model.
When I place it on a window or other control, I need to tell it the PK of the customer to load addresses for. So I created a Customer ID DependencyProperty:
public partial class AddressView : UserControl
{
public AddressView()
{
InitializeComponent();
}
public static DependencyProperty CustomerIdProperty = DependencyProperty.Register("CustomerId", typeof(int), typeof(AddressView),
new UIPropertyMetadata(0, AddressView.CustomerIdPropertyChangedCallback, AddressView.CustomerIdCoerce, true));
public int CustomerId
{
// THESE NEVER FIRE
get { return (int)GetValue(CustomerIdProperty); }
set { SetValue(CustomerIdProperty, value); }
}
private static void CustomerIdPropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs args)
{
// THIS NEVER FIRES
AddressView instance = (AddressView)d;
instance.CustomerId = (int)args.NewValue;
}
enter code here
private static object CustomerIdCoerce(DependencyObject d, object value)
{
return value; // <=== THIS FIRES ON STARTUP
}
}
Then in the MainWindowView I have:
<vw:AddressView Grid.Row="1"
Grid.Column="0"
x:Name="AddressList"
CustomerId="{Binding ElementName=TheMainWindow, Path=SelectedCustomer.Id, Mode=TwoWay}"/>
Note my comments in the user control's CS. The Coerce fires on startup. The callback never fires, nor do the CustomerId getter or setter.
What I would like to happen seems simple, I just can't make it work....
When a customer is selected the CustomerId should be passed to the Address UserControl. Then in the VM for the Address UserControl should handle getting & saving the data.
So, again, 2 questions:
1) Anyone see what's wrong?
2) How does the UserControl DP send the PK to the ViewModel?
If anyone's interested, my sample project is here: http://sdrv.ms/136bj91
Thanks
Your CustomerId getter and setter will never fire in this situation. They are there simply as helper methods in case you want to access the CustomerIdProperty property from your code behind.
Your CustomerIdPropertyChangedCallback method will not fire because your binding expression is incorrect. You need to bind to the DataContext of MainWindow and not the window itself:
...
CustomerId="{Binding ElementName=TheMainWindow, Path=DataContext.SelectedCustomer.Id}"
...
Also, make sure that you are calling the INotifyPropertyChanged PropertyChanged event when the property bound to the ComboBox is changed.
Try this :
CustomerId="{Binding RelativeSource={RelativeSource FindAncestor,
AncestorType={x:Type Window}}, Path=DataContext.YourSelectedItem.TheProperty}"
I am not sure how to manage your seleted item in window, so please change yourSelectedItem.TheProperty accordingly.
I'm trying to host a Visio ActiveX object in a WPF application.
To do this, I created a Windows user control project where I add the Visio object. This windows user control is then hosted on an WPF user control in an WindowsFormsHost object.
<WindowsFormsHost Name="wfHost" Grid.Row="1">
<wf:VisioUserControl FileNamePath="?"/>
</WindowsFormsHost>
What I would like to do is to bind the value of the FileNamePath member to the value of a TextBox element which defines the path.
The project follows the MVVM pattern, so there is no way that I can access the VisioUserControl object in my ViewModel.
The solution I was thinking about is to bind the FileNamePath member to the value of the TextBox that contains the path, but it is not a DependencyProperty and it seems that I'm not able to define one in the code behind of the windows user control.
So, is there any workaround to perform this binding?
Thanks in advance.
You can solve this by creating a UserControl that wraps your VisioUserControl (I wrote a simple tutorial on UserControl creation here). You can then add a FileNamePath dependency property to your UserControl. In the property changed handler of this dependency property, set the FileNamePath property on the VisioUserControl that this user control wraps.
Ok I have created an example of a WPF usercontrol that is hosting a Winforms control, with a dependency property that is bound to the winforms control's text property.
public partial class ActiveXObjectHoster : UserControl
{
private static System.Windows.Forms.Label testObject;
public ActiveXObjectHoster()
{
InitializeComponent();
testObject = new System.Windows.Forms.Label();
windowsFormsHost1.Child = testObject;
}
#region Properties
public static DependencyProperty FileNameProperty = DependencyProperty.Register("FileName", typeof(string), typeof(ActiveXObjectHoster), new UIPropertyMetadata("",new PropertyChangedCallback(OnFileNamePropertyChanged)));
public string FileName
{
get { return (string)GetValue(FileNameProperty); }
set
{
SetValue(FileNameProperty, value);
}
}
private static void OnFileNamePropertyChanged(
DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
testObject.Text = (string)e.NewValue;
}
#endregion
}
Here is the xaml of the control (its very simple)
<UserControl xmlns:my="clr-namespace:System.Windows.Forms.Integration;assembly=WindowsFormsIntegration"
x:Class="WPFTestApp2.Controls.ActiveXObjectHoster"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Name="ObjectHost"
Height="100" Width="100">
<Grid>
<my:WindowsFormsHost x:Name="windowsFormsHost1" />
</Grid>
</UserControl>
What you need to do is change the test object from a Label to whatever Visio object you were using. Then in the property callback change the text property to the filename or whatever property you wanted.
As mentioned above this is done in the code behind, but that is fine for a user control, its completely decoupled from whatever thing is using it, you just need to bind to the filename property of the control.
Here is a link to a project I created showing how the control is used. There is a textbox whos text is bound to the FileName property, which changes the Winforms Labels text.
You can place this in a Winforms Usercontrol if you want to use it in winforms (like you mentioned in your reply to my comment)
Try replacing the label for your control and see if it works.
Why not implement a UserControl to wrap the WindowsFormHost and the Visio user control? Then you cann add a Dependency Property, and implement in the code behind a handler for the PropertyChangedCallback, and appropiately interact with the WinForms control
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 am little new to Command binding so this might be a trivial question to many. I know that we can add Command bindings in xaml of a window and give its correspondng property in viewmodel. This viewmodel will be given to the DataContext of the window. Something like the following
--app.xaml.cs
mainWindow.DataContext = viewModel;
-- xaml
lt;Button Grid.Row="1" HorizontalAlignment="Right" Margin="0,3,18,3" Name="button1" Width="110"
Command="{Binding LoadCommand}">_Load</Button>
-- viewmodel
/// <summary>
/// Gets the load command.
/// </summary>
/// <value>The load command.</value>
public ICommand LoadCommand
{
get
{
if (m_LoadCommand == null)
{
m_LoadCommand = new RelayCommand(param => CanLoad(), param => Load());
}
return m_LoadCommand;
}
}
Here the relaycommand is a class which implements ICommand interface. CanLoad() and Load() are the methods which will get executed for canexecute and execute action of the relaycommand respectively. This is the click event of the button which is handled.
I have a user control which has a custom routedevent registered in it and the user control is then used on a window. I am currently adding the event handler explicitly in code.
//hook up event listeners on the actual UserControl instance
this.ucCustomEvent1.CustomClick += new RoutedEventHandler(ucCustomEvent_CustomClick);
//hook up event listeners on the main window (Window1)
this.AddHandler(UserControlThatCreatesEvent.CustomClickEvent, new RoutedEventHandler(ucCustomEvent_CustomClick));
I dont want to hook up the routedevent explicitly in code but in the xaml in the similar way as in the button example. I have uploaded the working sample code here for your perusal.
I'm not sure I fully understand your question but I hope one of my answers below helps you out.
To attach a "direct" event handler in XAML, just do the following:
<c:MyUserControl x:Name="uc1" CustomClick="uc1_CustomClickHandler"/>
To hook up a handler for the (routed) event of one element (e.g. the CustomClick event in your example) to another element (e.g. the parent window):
<Window c:MyUserControl.CustomClick="ucCustomEvent_CustomClick"/>
Now, if you want to tie up an event in your UI to a Command in your ViewModel, you will need attached behaviors to do that. There are lots of frameworks around featuring different implementations of this. Here's one you can try out: http://sachabarber.net/?p=514. It will allow you to do something like the following in your code:
<c:MyUserControl local:CommandBehavior.RoutedEventName="MyCustomClick"
local:CommandBehavior.TheCommandToRun="{Binding MyViewModelCommand}"/>
Hope this helps.