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C# GraphX highlight vertex on click

I'm using GraphX for .NET and I'm trying to highlight a vertex when the user clicks on it.
I registered for the VertexSelected event:
public class MyGraphArea : GraphArea<Node, Edge, MiniFlowGraph>
{
public MyGraphArea()
{
VertexSelected += VertexSelected_MarkVertex;
}
private void VertexSelected_MarkVertex(object sender,VertexSelectedEventArgs args)
{
HighlightBehaviour.SetHighlighted(args.VertexControl, true);
}
}
But nothing happened in the UI. So I tried to add multiple options:
To the constructor I added:
EnableVisualPropsApply = true;
HighlightBehaviour.SetIsHighlightEnabled(this, true);
SetVerticesHighlight(true, GraphControlType.VertexAndEdge);
I also registered to the Loaded event and added this code:
foreach (var item in VertexList)
HighlightBehaviour.SetIsHighlightEnabled(item.Value, true);
Then I added the line SetVerticesHighlight(true, GraphControlType.VertexAndEdge) to the VertexSelected event, just for case.
But nothing happened.
I'm looking at the source code, and I can't find anything else.

I believe you just need to add the following lines of code:
Graph.SetEdgesHighlight(true, GraphControlType.VertexAndEdge);
Graph.SetVerticesHighlight(true, GraphControlType.VertexAndEdge, EdgesType.All);
I was playing around with the WindowsFormsProject example, and I added these lines just before the return statement of the method Form1.GenerateWpfVisuals(). I did not had to subscribe to any event. However, the standard behavior will highlight vertices and edges on mouse hover, not on mouse click.
The default Gold color is used for the highlighting is defined in template.xaml:
<!-- VERTEX CONTROL -->
...
<Style.Triggers>
<Trigger Property="controls:HighlightBehaviour.Highlighted" Value="True">
<Setter Property="Background" Value="Gold"/>
<Setter Property="BorderThickness" Value="7"/>
</Trigger>
</Style.Triggers>
...
<!-- EDGE CONTROL -->
...
<Style.Triggers>
<Trigger Property="controls:HighlightBehaviour.Highlighted" Value="True">
<Setter Property="Foreground" Value="Gold"/>
<Setter Property="StrokeThickness" Value="5"/>
</Trigger>
</Style.Triggers>

Set Grid's IsMouseOver to True in C#

I have a style with a Trigger for IsMouseOver, and I want to trigger that Trigger (heh) from C#. How can this be done? Thanks in advance!

You can create a DataTrigger and then bind to a property in your ViewModel.
First create a bool property that will advise the View whether it should 'show' or 'not show' your style.
public bool GridTrigger
{
get { return this.gridTrigger; }
set { // raise a PropertyChange event, as per normal
}
And then add the DataTrigger to the XAML
<Grid.Triggers>
<DataTrigger Binding="{Binding GridTrigger}" Value="True">
<Setter Property="Style" Value="{StaticResource MyMouseOverStyle"/>
</DataTrigger>
</Grid.Triggers>
This obviously assumes you are using MVVM!

WPF programmatically setting fields as required

I am fairly new to WPF but have spent time researching WPF validation, and have not yet seen a good approach to conditional validation.
To simplify the situation greatly, let's say I have two textboxes and a submit button. The user enters a string in the first textbox. If the user enters, for example "ABC", then the second textbox should be a required field (I'd want the background to be a light blue color, to signify this), and the submit button should be disabled until that textbox is populated.
How can this be done? Is there an easy way to add/remove validations in runtime? 'DataAnnotations' (http://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.aspx) seemed like a good starting place, however I can't mark a field with the [Required] attribute, as the field won't always be required. Basically, I need something like 'Required if Field1 = 'ABC'
Thanks!

I would handle it using MVVM and here is a sample for that.
Implement IDataError Info on the class and that will implement two properties Error and this[string columnName] you can implement the second property with your binding errors that you want
public class MainViewModel:ViewModelBase,IDataErrorInfo
{
public string Error
{
}
public string this[string columnName]
{
get
{
string msg=nulll;
switch(columnName)
{
case "MyProperty": //that will be your binding property
//choose your validation logic
if(MyProperty==0||MyProperty==null)
msg="My Property is required";
break;
}
return msg;
}
}
Also Set ValidateOnErrors=True in binding of a textbox. here ColumnName is the name of the property that is changed and that has ValidateOnErrors set to true. Check here and put up the conditions and return message then you will see the errors on the tooltip when you put this style in your Resources.
<UserControl.Resources>
<Style TargetType="{x:Type TextBox}">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true" >
<Setter Property="Foreground" Value="Red"/>
<Setter Property="Background" Value="MistyRose"/>
<Setter Property="BorderBrush" Value="Red"/>
<Setter Property="BorderThickness" Value="1.0"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self},Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
</Style>
</UserControl.Resources>
and here is a sample of the textbox
<TextBox Text="{Binding UpdateSourceTrigger=PropertyChanged, Mode=TwoWay,
Path=PropertyName,ValidatesOnDataErrors=True}" Name="textBox1">
<Validation.ErrorTemplate>
<ControlTemplate>
</ControlTemplate>
</Validation.ErrorTemplate>
</TextBox>

I would just handle this logic in your ViewModel (assuming you're using an MVVM pattern, if not just in your code-behind).
Fire some logic on the TextChanged event for the first textbox that ultimately sets the appropriate properties. Essentially I'm saying code this validation manually. Once you start getting into more complex validation logic like this your going to start running into the limitations of the validation frameworks / declarative validation.

How do I change the color of Cell in WPF DataGrid based on a property of the object in itemsource?

I have a very simple object called CellData. Is defined as:
public sealed class CellData
{
internal string DisplayText
{
get;
set;
}
public string Color
{
get;
set;
}
public override string ToString()
{
return this.DisplayText;
}
}
I can get it to display using the WPF toolkit DataGrid just fine. However, I want to be able to change the background color of each cell based on what data is in the cell. I'm having trouble understanding what type of binding I need to do because I can't see to get to the CellData object in my DataTrigger. I have tried the following, and several other variations but I can't get it to work:
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=(CellData).Color, Mode=OneWay}" Value="1">
<Setter Property="Background" Value="Red" />
<Setter Property="Foreground" Value="White" />
</DataTrigger>
I am pretty new to XAML databidinding so any suggestions would be greatly appreciated. Thank you.

I'm guessing you have a RowData object that contains several CellData objects, that you have bound the ItemsSource of the DataGrid to a list of RowData objects, and that you are using DataGridTextColumns or other DataGridBoundColumns bound to the properties on RowData, maybe just by using AutoGenerateColumns="True".
The problem is that the DataContext for the cell is actually the RowData, not the CellData. The Binding is only used for the Text property of the TextBlock and TextBox. This is useful if you want to have the triggers based on other properties of the RowData object, but makes it difficult in scenarios like yours where you have a rich data structure for the cell data.
If you are creating the columns explicitly, you can just use the property for the column again in the trigger:
<DataGridTextColumn Binding="{Binding Foo}">
<DataGridTextColumn.CellStyle>
<Style TargetType="DataGridCell">
<Style.Triggers>
<!-- DataContext is the row, so start
binding path with Foo property -->
<DataTrigger Binding="{Binding Foo.Color}" Value="1">
<Setter Property="Background" Value="Red" />
<Setter Property="Foreground" Value="White" />
</DataTrigger>
</Style.Triggers>
</Style>
</DataGridTextColumn.CellStyle>
</DataGridTextColumn>
Unfortunately, this won't let you share the style between columns since it is specific to the column name. If you want to do that, you may need to create a custom DataGridColumn subclass that has a property of type Binding that it applies to the DataContext property of the object returned by GenerateElement and GenerateEditingElement.
(Using a Binding with RelativeSource of Self as you did in your sample gives you the element in the visual tree rather than its DataContext, which won't help you get to the CellData object.)

You can use a ValueConverter: create a binding between the cell's background color and the Color property of your object, then add a ValueConverter to ensure that your data is properly converter to the object needed to set the background.

WPF Extended TextBox design question

I want to derive from System.Windows.Controls.TextBox and provide this functionality.
IsEnabledProperty.OverrideMetadata(typeof(MyTextBox), new FrameworkPropertyMetadata(
new PropertyChangedCallback(delegate(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
MyTextBox tb = o as MyTextBox;
if (tb != null && !tb.IsEnabled)
{
tb.SetValue(TextProperty, null);
tb.OnLostFocus(new RoutedEventArgs(LostFocusEvent, typeof(MyTextBox)));
}
}
)));
The problem is that if I write a Custom Control, nothing will be displayed when using it, but I don't want to write my custom Template. I want to use the original one.
How would you do that, please ?

Check and see if your control overrides the DefaultStyleKeyProperty
DefaultStyleKeyProperty.OverrideMetadata
If that is the case, it will expect to find a style somewhere. Remove that override and you should be seeing normal TextBox behaviour!
If it does not, you can always base your new Textbox style on your old style, like so:
<Style TargetType="{x:Type Your:YourTextBox}" BasedOn="{StaticResource {x:Type TextBox}}" />
Place it in a ResourceDictionary somewhere, and it should work as well!
Hope this helps!

There is a much simpler option, here. Just use a DataTrigger to set your TextBox's Text to null (or empty) when the TextBox.IsEnabled is false:
<Style TargetType="TextBox">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsEnabled}" Value="False">
<Setter Property="Text" Value="" />
</DataTrigger>
</Style.Triggers>
</Style>