WPF MultiBinding Converter Object Type - c#

I have bound the Checked event of a checkbox to a method. I am also passing two Command Parameters to that method through a converter (implementing IMultiValueConverter). In the code below, the two CommandParameter bindings are of type bool and type string respectively.
<CheckBox Name="cbTopLeftHeader" Content="Top Left Header">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Checked">
<i:InvokeCommandAction Command="{Binding IncludeCheckedCommand}">
<i:InvokeCommandAction.CommandParameter>
<MultiBinding Converter="{StaticResource MultiBindingConverter}" ConverterParameter="IncludeChecked">
<Binding ElementName="cbTopLeftHeader" Path="IsChecked"></Binding>
<Binding Source="{StaticResource TopLeft}"></Binding>
</MultiBinding>
</i:InvokeCommandAction.CommandParameter>
</i:InvokeCommandAction>
</i:EventTrigger>
</i:Interaction.Triggers>
</CheckBox>
Why is it that if I replace the line:
<Binding ElementName="cbTopLeftHeader" Path="IsChecked"></Binding>
With:
<Binding RelativeSource="{RelativeSource Self}" Path="IsChecked"></Binding>
In my converter the IsChecked parameter changes from type bool to type DependencyProperty (DependencyProperty.UnsetValue)?
How can I achieve passing the Checked property without having the element bind to itself by name?


Get rid the interaction trigger and use the Command and CommandParameter properties of the CheckBox:
<CheckBox Name="cbTopLeftHeader" Content="Top Left Header" Command="{Binding IncludeCheckedCommand}">
<CheckBox.CommandParameter>
<MultiBinding Converter="{StaticResource MultiBindingConverter}" ConverterParameter="IncludeChecked">
<Binding RelativeSource="{RelativeSource Self}" Path="IsChecked"/>
<Binding Source="{StaticResource TopLeft}"></Binding>
</MultiBinding>
</CheckBox.CommandParameter>
</CheckBox>
Or stick with your current approach of binding to the CheckBox using ElementName. {RelativeSource Self} of an InvokeCommandAction is not a CheckBox.

Related

C# WPF Same Command for Multiple events

I have a WPF application in C# that follows MVVM pattern. I have a written the following code in xaml for double click event in a datagrid that will invoke a command.
<DataGrid.InputBindings>
<MouseBinding Gesture="LeftDoubleClick"
Command="{Binding LoadDetailGridCommand}">
<MouseBinding.CommandParameter>
<MultiBinding Converter="{StaticResource Converter}">
<Binding ElementName="dgInvDetails" Path="SelectedItem"/>
<Binding ElementName="dgInvDetails" Path="CurrentColumn"/>
</MultiBinding>
</MouseBinding.CommandParameter>
</MouseBinding>
</DataGrid.InputBindings>
I want the same to be triggered when enter key is pressed. Do I have to use the same code with KeyBinding and set Enter key for the same command or is there any better way of doing this?
Thanks in Advance!

If you want to reuse the binding, you could define it as a resource:
<Window.Resources>
<local:MultiConverter x:Key="Converter" />
<MultiBinding x:Key="binding" Converter="{StaticResource Converter}">
<Binding ElementName="dgInvDetails" Path="SelectedItem"/>
<Binding ElementName="dgInvDetails" Path="CurrentColumn"/>
</MultiBinding>
</Window.Resources>
...and then use a custom markup extension to reference it:
<DataGrid.InputBindings>
<KeyBinding Key="Return" Command="{Binding LoadDetailGridCommand}"
CommandParameter="{local:BindingResourceExtension binding}" />
<MouseBinding Gesture="LeftDoubleClick" Command="{Binding LoadDetailGridCommand}"
CommandParameter="{local:BindingResourceExtension binding}" />
</DataGrid.InputBindings>

You need to specify key binding for enter key.
Try below
<DataGrid>
<DataGrid.InputBindings>
<KeyBinding Command="{Binding LoadDetailGridCommand}" Key="Enter" >
<KeyBinding.CommandParameter>
<MultiBinding Converter="{StaticResource Converter}">
<Binding ElementName="dgInvDetails" Path="SelectedItem"/>
<Binding ElementName="dgInvDetails" Path="CurrentColumn"/>
</MultiBinding>
</KeyBinding.CommandParameter>
</KeyBinding>
</DataGrid.InputBindings>
</DataGrid>

ConvertBack is not called

I'm trying to write a universal control in which I can pass different data models (all implement INotifyPropertyChanged) with a converter. The data is passed in the control without problems and is displayed correctly (some of it also uses IMultivalueConverts, which work flawlessly). Although the data is modified, the IMultiValueConverter of the MainControl is not called.
The universal control should just show rectangles calculated from coordinates in an ObservableCollection.
I put DebugConverters on all bindings, and everything seems to be updated except the ConvertBack to the top. The SourceUpdate from the ListBox is also called.
I tried this converter with different NotifyOn...Updated, Mode and UpdateSourceTrigger, I always see the values changing in the control, but never the ConvertBack of the Main Control.
The partial data template used (Updates are done correctly), all the DegreeTo... converters are called both ways
<DataTemplate x:Key="RectangleWithLabel">
<Canvas IsHitTestVisible="True">
<Rectangle x:Name="RectangleROI" MouseLeftButtonDown="myCanvas_PreviewMouseLeftButtonDown" >
<!--
<Rectangle.Visibility>
<Binding Path="ROI" Converter="{StaticResource NullToVisibilityConverter}"/>
</Rectangle.Visibility>
-->
<Canvas.Left>
<MultiBinding Converter="{StaticResource DegreeToScreenPixelConverterH}" Mode="TwoWay" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged" >
<Binding Path="ROI.Begin.PosH" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" />
<Binding Path="DataContext.UsedCoordinateSystem" RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type UserControl}}" NotifyOnSourceUpdated="True" Mode="TwoWay" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged" />
</MultiBinding>
</Canvas.Left>
<Canvas.Top>
<MultiBinding Converter="{StaticResource DegreeToScreenPixelConverterV}" Mode="TwoWay" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged">
<Binding Path="ROI.Begin.PosV" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" />
<Binding Path="DataContext.UsedCoordinateSystem" RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type UserControl}}" NotifyOnSourceUpdated="True" Mode="TwoWay" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged"/>
</MultiBinding>
</Canvas.Top>
<Rectangle.Width>
<MultiBinding Converter="{StaticResource DegreeToScreenPixelWidthConverter}" Mode="TwoWay" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged">
<Binding Path="ROI.Begin.PosH" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" />
<Binding Path="ROI.End.PosH" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" />
<Binding Path="DataContext.UsedCoordinateSystem" RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type UserControl}}" NotifyOnSourceUpdated="True" Mode="TwoWay" NotifyOnTargetUpdated="True"/>
</MultiBinding>
</Rectangle.Width>
<Rectangle.Height>
<MultiBinding Converter="{StaticResource DegreeToScreenPixelHeightConverter}" Mode="TwoWay" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged">
<Binding Path="ROI.Begin.PosV" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True"/>
<Binding Path="ROI.End.PosV" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" />
<Binding Path="DataContext.UsedCoordinateSystem" RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type UserControl}}" NotifyOnSourceUpdated="True" Mode="TwoWay" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged"/>
</MultiBinding>
</Rectangle.Height>
<Rectangle.Fill>#33FF0000</Rectangle.Fill>
<Rectangle.Stroke>#FF00FF00</Rectangle.Stroke>
<Rectangle.IsHitTestVisible>true</Rectangle.IsHitTestVisible>
</Rectangle>
The List View containing all the data:
<ListView ItemsSource="{Binding Rectangles, Mode=TwoWay, NotifyOnTargetUpdated=True, NotifyOnSourceUpdated=True, NotifyOnValidationError=True, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" x:Name="listBox" Width="{Binding ActualWidth, ElementName=ImageControl, Mode=OneWay,UpdateSourceTrigger=PropertyChanged}" Height="{Binding ActualHeight, ElementName=ImageControl, Mode=OneWay,UpdateSourceTrigger=PropertyChanged}" Background="{x:Null}" BorderBrush="{x:Null}" Foreground="{x:Null}" ItemTemplate="{StaticResource RectangleWithLabel}" MouseMove="ListBox_MouseMove" DataContextChanged="ListBox_DataContextChanged" SourceUpdated="ListBox_SourceUpdated" IsSynchronizedWithCurrentItem="True" TargetUpdated="ListBox_TargetUpdated" />
The call to the ImageViewer from the parent, here the converter is called on the way to the ImageViewer, but the ConvertBack is never called:
<common:ImageViewer x:Name="ctrlImage" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" >
<common:ImageViewer.DataContext>
<MultiBinding Converter="{StaticResource ConverterWhichIsOnlyCalledOneWay}" Mode="TwoWay" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True" UpdateSourceTrigger="PropertyChanged">
<Binding Path="." UpdateSourceTrigger="PropertyChanged" Mode="TwoWay" NotifyOnSourceUpdated="True" NotifyOnTargetUpdated="True"/>
</MultiBinding>
</common:ImageViewer.DataContext>
</common:ImageViewer>
How can I get the ConvertBack to be called?
EDIT:
I made an overview of the controls and the converters. I think I was wrong, that the ConvertBack should be called, everything is updating, even without the big converter. But I'm still stuck when adding some elements to the ObservableCollection. When I add some values, the values appear in the DataContext of the MainWindow. But the Converter is not triggered. When I add the Observable.Count as Binding to the Big Converter, the update is triggered, but all bindings are lost.
Changes from the original code were: Changing all internal variables to DependencyProperties, this made updates reliable for the single entries in the ObservableCollection.
Overview of the GUI and the used converters

Time to answer the question myself:
I was wrong when assuming that a changes travels down throught the converter when there is a direct connection between two elements.
So if I have an element (just consider it as a leave of a tree) in a deeply nested and it is once displayed once through a converter (which changes some other objects) and the same time without a converter, the element is updated without calling the converter. WPF is so clever to see that the value is the same and does not pipe the change through the converter up and down.

What is the order of setting properties in XAML?

I have a TextBlock with two properties (Text and Foreground) bound to the same ViewModel property.
Both also have converters. One of the converters checks the Text property and returns a 'dash' if the value is NaN. The other checks that the value is above, below or equals zero and accordingly sets the foreground to different colors.
XAML example:
<TextBlock>
<TextBlock.Text>
<Binding Path="AvgDistance" StringFormat="{}{0:N1}"
Converter="{x:Static converter:ValueToDash.Instance}"/>
</TextBlock.Text>
<TextBlock.Foreground>
<MultiBinding Converter="{x:Static converter:ValueToColor.Instance}">
<Binding Path="AvgDistance"/>
<Binding ElementName="currentPeriod" Path="IsChecked" />
</MultiBinding>
</TextBlock.Foreground>
</TextBlock>
Now I need that the ValueToDash converter fired before the ValueToColor converter, but it is always vice versa.
The Foreground property seems to be always set first, and only then the Text property is set.
Why is it so? And is it possible to reverse the order of setting?

You shouldn't rely on the order in which the properties are being set.
What you could do instead is to add another binding to your MultiBinding that binds to the Text property of the TextBlock:
<TextBlock>
<TextBlock.Text>
<Binding Path="AvgDistance" StringFormat="{}{0:N1}"
Converter="{x:Static converter:ValueToDash.Instance}"/>
</TextBlock.Text>
<TextBlock.Foreground>
<MultiBinding Converter="{x:Static converter:ValueToColor.Instance}">
<Binding Path="AvgDistance"/>
<Binding ElementName="currentPeriod" Path="IsChecked" />
<Binding Path="Text" RelativeSource="{RelativeSource Self}"/>
</MultiBinding>
</TextBlock.Foreground>
</TextBlock>
Then the ValueToColor converter will be invoked (again) whenever the Text property is set to some new value.

Binding the Value of StringFormat

I have a Textbox with a Value and a Unit bound like this:
<TextBox Text="{Binding Path=Value,StringFormat='{}{0} mm'}" />
The Unit mm should be also bound to the ViewModel Property Unit. This can be done via a Multibinding:
<TextBox>
<TextBox.Text>
<MultiBinding StringFormat="{}{0} {1}">
<Binding Path="Value"
Mode="TwoWay" />
<Binding Path="Unit"
Mode="OneWay" />
</MultiBinding>
</TextBox.Text>
</TextBox>
But with this I lose my Two Way Binding and I don't want to edit the Unit aswell. If ths user deletes "8 mm" and enteres an "8" the binding should automatically reevaluate the binding and add the unit as it is done via normal string format binding.
So finally I need something like this:
<TextBox>
<TextBox.Text>
<Binding Path="Value"
StringFormat="{Binding Path=ValueUnitStringFormat}" />
</TextBox.Text>
</TextBox>
But unfortunally StringFormat Property on BindingBase is not a DependencyProperty.
Anyone got a solution for this?

multi binding in wpf

I am trying to do multiple binding in wpf.
here is my code:
<CheckBox>
<CheckBox.IsChecked>
<MultiBinding Converter="{View:MultiConvertorOr}">
<Binding ElementName="txtbox1" Path="Text" Converter="{View:TextToBool}" Mode="TwoWay">
<Binding RelativeSource="{RelativeSource AncestorType={x:Type ListBoxItem}}" Path="IsSelected" Mode="TwoWay">
</MultiBinding>
</CheckBox.IsChecked>
</CheckBox>
My goal is when I enter text I want the checkbox to be checked (what happens) and the listBoxItem to be selected. (this part is not working).
I also want to keep the binding between the itemListBox and the checkBox (this also works).
Any Ideas how can I do what I want? maybe with event triggers or something like it?
Thanks ahead.

Categories

Resources