I am using Expresion Blend 3 and created a new user control in my project. I want a storyboard to run if a custom property of that user control is triggered like with the ones shown here in the list..
I learnt you need a dependency property, but my understanding there is limited. Here's the basic code I set up with property "IsAwesome" as an example..
Partial Public Class simpleControl
Public Sub New()
MyBase.New()
Me.InitializeComponent()
End Sub
Public Shared ReadOnly IsAwesomeProperty As DependencyProperty = _
DependencyProperty.Register("IsAwesome", GetType(Boolean), GetType(simpleControl))
Public Property IsAwesome() As Boolean
Get
Return DirectCast(Me.GetValue(IsAwesomeProperty), Boolean)
End Get
Set(ByVal value As Boolean)
Me.SetValue(IsAwesomeProperty, value)
End Set
End Property
End Class
However, my property doesn't show in that list. What am I missing? Or is my entire approach wrong?
Any help or advice would be appreciated!
Cheers
I created a new Wpf project. Added a new UserControl (UserControl1) with a custom dependency property called Foo.
Then I opened Blend and added an instance of UserControl1 to Window1. I right clicked on UserControl1 and said EditTemplate | Edit a Copy.
This created a copy of my user control template in the Window.Resources. From within this new template I went up to the Triggers panel and clicked the button to add a new property trigger.
Right away Blend defaulted to selecting my property in the "Activated When" section.
alt text http://blog.BradCunningham.net/Images/ForumImages/CustomDPInBlend.png
You can grab my little sample app from here: http://blog.BradCunningham.net/SourceCode/ForumSamples/CustomDPInBlend.zip
Related
I have written a custom control based on a ListBox. It contains a default ItemTemplate which shows an image given to the ListBox by a custom dependency property. The control also contains a default image, which is used when the user doesn't give an image to the dependency property.
This works so far, but now I've found a little problem and I don't know how to fix that.
When I use my custom control in the XAML designer, it first shows the default image. When I set the image's dependency property to an other image, the new image is immediately shown in the XAML designer.
But when I remove the XAML attribute for the new image again, the XAML designer only shows a white rectangle instead of the default image.
I assume it's because with setting the image's dependency property to some value and then removing it I nulled the value. But even when I check for null in the CoerceCallback and give back the default image when the coerced value is null, doesn't work.
What's the best way to support fallback values for dependency properties?
TestControl.vb
Public Class TestControl
Inherits ListBox
Private Shared _defaultResources As ResourceDictionary
Shared Sub New()
_defaultResources = New ResourceDictionary
_defaultResources.Source = New Uri("...")
End Sub
Public Shared ReadOnly TestProperty As DependencyProperty = DependencyProperty.Register(NameOf(TestControl.Test),
GetType(ImageSource),
GetType(TestControl),
New FrameworkPropertyMetadata(Nothing,
AddressOf TestControl.OnTestChanged,
AddressOf TestControl.OnTestCoerce))
Public Property Test As ImageSource
Get
Return DirectCast(MyBase.GetValue(TestControl.TestProperty), ImageSource)
End Get
Set(value As ImageSource)
MyBase.SetValue(TestControl.TestProperty, value)
End Set
End Property
Private Shared Sub OnTestChanged(d As DependencyObject, e As DependencyPropertyChangedEventArgs)
End Sub
Private Shared Function OnTestCoerce(d As DependencyObject, value As Object) As Object
If (value Is Nothing) Then
Return TryCast(_defaultResources.Item("TestImage"), ImageSource)
End If
Return value
End Function
Public Sub New()
Me.Test = TryCast(_defaultResources.Item("TestImage"), ImageSource)
End Sub
End Class
When I use that control like this
<local:TestControl ItemsSource="{Binding Items}" />
every item shows the default image at design time. When I change the XAML to
<local:TestControl ItemsSource="{Binding Items}"
Test="{StaticResource NewImage}" />
every item shows the new item at design time. But when I remove the Test="{StaticResource NewImage}" again, it doesn't go back to the default image.
Ok, after some testing (using this technique) I have discovered the source of your issue.
First of all, you are not using PropertyMetadata to set your default value, but instead the constructor. I assume you have a good reason to do so, but this essentially means that now you are relying on the coercion callback to set the default value.
However, it is not called (the framework assumes that your "true" default value - Nothing - doesn't need to be validated) after you remove the
Test="{StaticResource TestString}" line. Only the OnTestChanged
is called. This means we can use it to restore the default value:
void OnTestChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (e.NewValue is null)
{
((TestControl)d).Test = yourDefaultImage;
return;
}
//Actual "OnChanged" code
}
A clumsy solution indeed, but it works. Depending on your exact situation, you might also want to take a look at Binding's FallbackValue and TargetNullValue properties:
Test="{Binding Source={ }, FallbackValue={ }, TargetNullValue={ }}"
I have a winform custom control that looks like :
Public Class MyCustomControl
Inherits Control
Implements INotifyPropertyChanged
'Some textboxes...
private Textbox1 as textbox
private Textbox2 as textbox
private Textbox3 as textbox
'Control value
Property Value as MyCustomClass
get
'Extract some values from textboxes and return MyCustomClass (a separate custom object)
end get
Set(value As MyCustomClass)
'Set the values of the textboxes from the Value object
end Set
end Property
end class
I would like to insert this object in a winform and I would like my control to be "compatible" with errorProvider. Such that if I insert an errorProvider in the form and I call : errorProvider.SetError(MyCustomControl, "Error message"), it will show the error message on a specific text box in my custom control according to a custom logic.
Does anyone know which interface should be implemented or how to that please ?
Thanks. Cheers,
What you're trying to do would be better achieved with a UserControl, instead of inheriting directly from Control. (Having three TextBox instances inside your control is a good indication here.) In your UserControl you have a couple of options:
Add an ErrorProvider component and hook it up to each TextBox; or
For each TextBox expose it by making it public or via a public property, and then in your form hook it up to the form's ErrorProvider.
Ideally, you would use a BindingSource and data bind each TextBox, with the ErrorProvider.DataSource being set to your BindingSource.
here's my issue:
I made an UserControl containing a ListView called "lstMain".
I have a property inside my controller:
Public ReadOnly Property DataRowBoundColumns() As System.Windows.Forms.ListView.ColumnHeaderCollection
Get
Return Me.lstMain.Columns
End Get
End Property
In the designer I can edit such property BUT when I compile the value gets deleted.
This doesn't happen for the other properties, which are a String, an Integer and other objects (not arrays).
Can anyone help me?
The problem is that the data you provide through the collection editor in design mode, do not get serialized.Assuming that your custom control is called "MyCompositeControl" you should write something like the following.
Imports System.ComponentModel
Public Class MyCompositeControl
<DesignerSerializationVisibility(DesignerSerializationVisibility.Content)>
Public ReadOnly Property DataRowBoundColumns() As System.Windows.Forms.ListView.ColumnHeaderCollection
Get
Return Me.lstMain.Columns
End Get
End Property
End Class
I have a WPF application with form that has a textbox named "txtStatusWindow". I also have a vb.net class handed to me by a co-worker that needs to be called and executed by the code in my application code-behind. My co-worker insists that I will need to use common .net events to update the textbox on my form.
The separate vb.net class:
Public Class globalclass
Public Event txtStatusWindow(ByVal Text As String)
Public Sub InitializeProgram()
RaiseEvent txtStatusWindow("Updating something.")
System.Threading.Thread.Sleep(2000)
RaiseEvent txtStatusWindow("Updating something else.")
System.Threading.Thread.Sleep(2000)
RaiseEvent txtStatusWindow("Updating something other than else.")
System.Threading.Thread.Sleep(2000)
RaiseEvent txtStatusWindow("Updating something other than the else stuff.")
System.Threading.Thread.Sleep(2000)
End Sub
End Class
I need to be able to call the sub "InitializeProgram()" from my code-behind, and it needs to be able to update "txtStatusWindow.text" as it runs.
I told him that the updating of the text box can be done with data-binding, but I don't know how to integrate a separate class like this into my project, how to call methods in it, or how to cause it to update my text blocks through data binding.
I also suggested that the methods in this class aren't optimal for connecting to the WPF project anyway, but he just wrote it as an example to discover how to connect the two projects.
Eventually, I will need to integrate classes like these that will be running separate threads to update their data from a dynamic source, and cause many controls to update in my application.
So far, the only way we have been able to get this to work from my code-behind is this:
Partial Public Class SplashScreen
Dim NewText as String
Public WithEvents Globals As globalclass = New globalclass
Public Delegate Sub StringDelegate(ByVal Text As String)
Public SplashText As String
Public Sub New()
MyBase.New()
Me.InitializeComponent()
Me.Show()
Globals.InitializeProgram()
End Sub
Public Sub UpdateSplashscreenHandler(ByVal Text As String) Handles Globals.UpdateSplashScreen
StatusWindowText.Text = Text
End Sub
Notwithstanding the fact that the WPF screen "freezes" until the "globalclass InitializeProgram" method completes (txtStatusWindow.Text does not update while sub without using the esoteric "refresh" extension...), I fully believe we are going about this the wrong way.
There are precious few examples out there concerning the integration and then binding to objects in existing code. Thanks for examining our little quandary.
If this status window is in XAML and the status window is a UserControl, then add a StatusText dependency property to the status window. Then, in the XAML you can bind to the value of that property with something like:
<UserControl x:Name="MyStatusWindow" ...>
<TextBlock Text="{Binding Path=StatusText, ElementName=MyStatusWindow}" />
</UserControl>
Then, from your event, just update the value of that StatusText property.
(Is that even close to what you were asking?)
Also, about that freezing: Instead of doing that updating in the constructor of that class, you might want to do it from the Loaded event of that control. It will still be freezing, though, unless you move it to a separate thread. Right now, that's happening on the same thread that the UI message pump is running on. This is the Dispatcher for that UI.
I'm having one hell of a time trying to get my databinding to work correctly. I have reason to believe that what I'm trying to accomplish can't be done, but we'll see what answers I get.
I've got a UserControl. This UserControl contains nothing more than a button. Now within the code behind, I've got a property name IsBookmarked. When IsBookmarked is set, code is run that animates the look of the button. The idea is that you click the button and it visually changes. We'll call this UserControl a Bookmark control.
Now I have another control, which we'll call the FormControl. My FormControl contains a child Bookmark control. I've tried to do databinding on my Bookmark control, but it's not working. Here's some code to help you out.
This is the XAML and Loaded event handler of my control. As you can see it contains a child element that is a custom control (bookmark). So once this control loads, it's DataContext is set to an new instance of an Employee object. Silverlight also sets the DataContext property of my child bookmark control to the same instance. I've verified this by debugging. If my parent has a valid DataContext set then why can't my child control (bookmark) property databind to it?
<UserControl ......>
<q:Bookmark x:Name="BookMarkControl1" IsBookmarked="{Binding IsSiteBookmarked}" />
</UserControl>
public void Control_Loaded(object sender, EventArgs e)
{
DataContext = new Employee { IsSiteBookmarked = True };
}
This is my custom control below. Obviously it contains more than this, but for readability I've trimmed it down to the property I'm trying to databind to.
//this is the bookmark control. I've included this control within another control, and I'm trying to databind to properties within my parents DataContext
public partial class Bookmark : UserControl
{
bool _IsBookmarked= false;
public bool IsBookmarked
{
get {return _IsBookmarked;}
set {
_IsBookmarked= value;
SwitchMode(value);
}
}
}
UPDATE
Got some javascript errors that I should mention. Firebug reports a AG_E_PARSER_BAD_PROPERTY_VALUE exception. It doesn't seem like my databinding is even working yet.
Make your IsBookmarked property on the Bookmark control a dependency property.
I presume Control_Loaded is a part of your FormControl, in which case I'm not sure you are using DataContext properly. Best double check that.
UPDATE: Yes, you are using the DataContext properly. AG_E_PARSER_BAD_PROPERTY_VALUE indicates you need to make the IsBookmarked property a dependency property, like so:
Public Property IsBookmarked() As Boolean
Get
Return Me.GetValue(IsBookmarkedProperty)
End Get
Set(ByVal value As Boolean)
Me.SetValue(IsBookmarkedProperty, value)
End Set
End Property
Public Shared ReadOnly IsBookmarkedProperty As DependencyProperty = DependencyProperty.Register("IsBookmarked", GetType(Boolean), GetType(Bookmark), New PropertyMetadata(New PropertyChangedCallback(AddressOf OnIsBookmarkedPropertyChanged)))
Private Shared Sub OnIsBookmarkedPropertyChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
Dim cntrl As Bookmark = TryCast(d, Bookmark)
cntrl.SetIsBookmarked(e.NewValue)
End Sub
If you only need to store the value for later use, then you don't need to do anything in the OnIsBookmarkedPropertyChanged procedure, But I put some code there as an example anyway.
Good Luck!
I don't recall the exact order in which databinding is evaluated (and I'm too lazy to go look it up), but as I recall, it initially happens BEFORE the form's Loaded event fires, and without making the IsBookmarked property a dependency property, or at least using INotifyPropertyChanged, it may have trouble establishing the datacontext appropriately. I'd recommend either implementing INotifyPropertyChanged or making IsBookmarked a dependency property. DataBinding is tough enough to get right in the best of circumstances (see my long, bad-tempered rant about it here), and you'll just be making it more difficult on yourself if you aren't setting up your properties in the way that it expects.
The control exposes a IsSiteBookmarked property(which I believe should be a DependencyProperty) but the control is binding to a IsBookmarked which is not shown. Is this intentional? Have you checked your Visual Studio output window for binding errors?
Addition 1:
Since you have fixed the typo in your question and added that there is an error being reported.
Start by clearing up the AG_E_PARSER_BAD_PROPERTY_VALUE problem. Is there a line number and start position in the error message? Start looking there. One strategy is to start taking out XAML until there is no longer an error. This will narrow down the offending code.
Running in debug, mode check for binding errors in the output window.
You might want to also post the Employee class code, especially the IsSiteBookmarked property.
Typically when doing databinding to an object you will want to leverage the INotifyPropertyChanged interface and implement that so that the control can properly invalidate it's property value. Unless you use INotifyPropertyChanged with Mode=TwoWay then any code that changes your DataContext's IsSiteBookmarked will have no effect.