I set the datacontext dynamically in code. I would like a button on screen to be enabled/disabled depending if DataContext == null or not. I can do it in code when I assign the DataContext but it would be better if I can bind like that :)
You should be able to use a DataTrigger on the button style to disable your button when the DataContext is null. The other option is to bind the IsEnabled property to the DataContext and use a value converter to return false if DataContext is null and true otherwise.
With trigger:
<Button>
<Button.Style>
<Style TargetType="{x:Type Button}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=DataContext, RelativeSource={RelativeSource Self}}" Value="{x:Null}">
<Setter Property="IsEnabled" Value="false"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
With converter:
Converter:
public class DataContextSetConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return value != null;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
And use it
<UserControl.Resources>
<local:DataContextSetConverter x:Key="dataContextSetConverter"/>
</UserControl.Resources>
...
<Button IsEnabled="{Binding Path=DataContext, RelativeSource={RelativeSource Self}, Converter={StaticResource dataContextSetConverter}}"/>
This should do it:
<Button Content="ButtonName">
<Button.Style>
<Style TargetType="{x:Type Button}">
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=DataContext}" Value="{x:Null}">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
Related
I have a checkbox which looks something like this (have removed many things to make it short) -
<CheckBox IsChecked="{Binding functionABC, Mode=TwoWay}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Checked">
<i:InvokeCommandAction Command="{Binding Path=XYZ}"/>
</i:EventTrigger>
<i:EventTrigger EventName="Unchecked">
<i:InvokeCommandAction Command="{Binding Path=XYZ}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</CheckBox>
Now, I have to map the window title of app to 2 different values depending on checked or unchecked. I could have done it normally, but there is a trigger set already for both states, and I don't know how to work around it.
Use a Style with a DataTrigger
<!-- !!! remove the Title property from the Window declaration !!! -->
<Window
...>
<Window.Style>
<Style TargetType="Window">
<Style.Triggers>
<DataTrigger Binding="{Binding functionABC}" Value="True">
<Setter Property="Title" Value="True Title" />
</DataTrigger>
<DataTrigger Binding="{Binding functionABC}" Value="False">
<Setter Property="Title" Value="False Title" />
</DataTrigger>
</Style.Triggers>
</Style>
</Window.Style>
...
</Window>
Update
As thatguy suggested this style can be simplified by
<!-- !!! remove the Title property from the Window declaration !!! -->
<Window
...>
<Window.Style>
<Style TargetType="Window">
<Setter Property="Title" Value="False Title" />
<Style.Triggers>
<DataTrigger Binding="{Binding functionABC}" Value="True">
<Setter Property="Title" Value="True Title" />
</DataTrigger>
</Style.Triggers>
</Style>
</Window.Style>
...
</Window>
sample project on github
You can use an special IValueConverter
public class BooleanToCustomConverter : MarkupExtension, IValueConverter
{
public string? TrueValue { get; set; }
public string? FalseValue { get; set; }
public object? Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is bool b)
return b ? TrueValue : FalseValue;
return Binding.DoNothing;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
return this;
}
}
and use that within your Binding
<Window
...
Title="{Binding functionABC, Mode=OneWay, Converter={local:BooleanToCustomConverter TrueValue='True Value', FalseValue='False Value'}}"
...>
...
</Window>
sample project on github
I am currently facing a small issue with my DataGridTextColumn.
I want to display a tooltip at a DataGridTextColumn but only if the text is not empty.
How can I achieve this? The code that I am currently using:
<DataGridTextColumn IsReadOnly="True" Header="Person" Binding="{Binding SomeBinding, TargetNullValue='-'}" Width="Auto"
CellStyle="{StaticResource SomeStyle}"/>
With the style
<Style x:Key="SomeStyle"
TargetType="DataGridCell" BasedOn="{StaticResource InactiveStyle}">
<Style.Setters>
<Setter Property="ToolTip" Value="{Binding Path=SomeBinding}"/>
</Style.Setters>
</Style>
This code does provide me the tooltip, however, it is also showing the tooltip when there is no text. If there are any questions, please let me know and I can help you.
Try to add data triggers for string.Empty and null:
<Style x:Key="SomeStyle" TargetType="DataGridCell"
BasedOn="{StaticResource InactiveStyle}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=SomeBinding}" Value="">
<Setter Property="ToolTip" Value="{x:Null}"/>
</DataTrigger>
<DataTrigger Binding="{Binding Path=SomeBinding}" Value="{x:Null}">
<Setter Property="ToolTip" Value="{x:Null}"/>
</DataTrigger>
</Style.Triggers>
<Style.Setters>
<Setter Property="ToolTip" Value="{Binding Path=SomeBinding}"/>
</Style.Setters>
</Style>
Here is an approach :
//Create a class which inherits from IValueConverter
public class CellToolTipConverter : IValueConverter
{
#region IValueConverter Membres
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string stringValue = (string)value;
if (!string.IsNullOrEmpty(stringValue))
return "Your tooltip";//As you are in a c# class, you have many possibilities.
else
return string.Empty;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
#endregion
}
//In your xaml :
//Declare your namespace
xmlns:CustomClasses="clr-namespace:YourAssamblyName.YourNameSpaceOfConverterClass"
<UserControl.Resources>
<CustomClasses:CellToolTipConverter x:Key="CustomToolTipConverter"/>
</UserControl.Resources>
//In your grid view
<GridView.RowStyle>
<Style TargetType="{x:Type telerik:GridViewRow}">
<Setter Property="MyCustomToolTipProperty" Value="{Binding YourProperty, Converter=
{StaticResource CustomToolTipConverter}}"/>
</Style>
</GridView.RowStyle>
I'm trying to style a rectangle inside of a listview item, based on a data-field of the listview item object.
To return a boolean I'm converting the integer from daydata.workload to a boolean uasing a IValueConverter.
I'm getting no exception, the rectangle is just not affected by the DataTrigger. The other style rules are working fine.
<Window.Resources>
<cv:numConverter x:Key="capacityConverter" />
<Window.Resources>
-
<ListView Name="weekView" ItemsSource="{Binding dayList}" ItemTemplate="{StaticResource DefaultTemplate}" >
<ListView.Resources>
<Style TargetType="Rectangle" x:Key="capacityBG">
<Setter Property="Stroke" Value="#FFE2E2E2" />
<Setter Property="Width" Value="180" />
<Setter Property="Height" Value="10" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=dayList.workload, Converter={StaticResource capacityConverter}, ConverterParameter=12}">
<DataTrigger.Value>true</DataTrigger.Value>
<Setter Property="Fill" Value="Red"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ListView.Resources>
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"></StackPanel>
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemContainerStyle>
<Style TargetType="{x:Type ListViewItem}">
<Setter Property="Background" Value="Transparent" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListViewItem}">
<ContentPresenter />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ListView.ItemContainerStyle>
</ListView>
-
<Rectangle Style="{DynamicResource capacityBG}" VerticalAlignment="Top" Grid.Row="0" />
-
public class numConverter : IValueConverter
{
object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return ((int)value) > val;
}
object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
public int val { get; set; }
}
-
public class dayData
{
public DateTime date { get; set; }
public int workload { get; set; }
public List<job> jobs { get; set; }
}
The problem here is that values entered for the converter parameter and the data trigger value are treated as string. You need to specify the type for each one of these values like shown below:
xmlns:sys="clr-namespace:System;assembly=mscorlib"
<Style.Triggers>
<DataTrigger>
<DataTrigger.Binding>
<Binding Path="WorkLoad" Converter="{StaticResource capacityConverter}">
<Binding.ConverterParameter>
<sys:Int32>12</sys:Int32>
</Binding.ConverterParameter>
</Binding>
</DataTrigger.Binding>
<DataTrigger.Value>
<sys:Boolean>true</sys:Boolean>
</DataTrigger.Value>
<Setter Property="Fill" Value="Red"/>
</DataTrigger>
</Style.Triggers>
Then you can cast converter parameter to an int to make the comparison.
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return (int)value > (int)parameter;
}
I came across a situation where I want to avoid using converter in multibinding, below is the xaml source snippet from my current code. Below code works perfectly fine, but IS IT POSSIBLE to avoid converter first place ??
ViewModel:
public MainViewModel()
{
Cars = new List<string>() { "Audi", "BMW", "Ferrari", "Ford" };
Models = new List<string>() { "Model 1", "Model 2" };
IsOptionEnable = false;
}
public bool IsOptionEnable { get; private set; }
public List<string> Models { get; private set; }
public List<string> Cars { get; private set; }
Main window xaml:
<Grid>
<ComboBox HorizontalAlignment="Left" VerticalAlignment="Top" Width="120" Margin="87.2,44.8,0,0"
ItemsSource="{Binding Cars}"
SelectedItem="{Binding SelectedItm}"
Style="{StaticResource ModelsComboBox}">
</ComboBox>
</Grid>
Resource dictionary:
<Style x:Key="ModelsComboBox" TargetType="ComboBox">
<Setter Property="ItemContainerStyle">
<Setter.Value>
<Style TargetType="ComboBoxItem">
<Setter Property="IsEnabled">
<Setter.Value>
<MultiBinding Converter="{StaticResource ModelToBoolConverter}">
<Binding/>
<Binding Path="DataContext.IsOptionEnable" RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type ComboBox}}"/>
</MultiBinding>
</Setter.Value>
</Setter>
</Style>
</Setter.Value>
</Setter>
</Style>
Multivalue converter:
internal sealed class ModelToBoolConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
bool enable = true;
if ((values[0] != null && values[0] != DependencyProperty.UnsetValue) &&
(values[1] != null && values[1] != DependencyProperty.UnsetValue))
{
var comboboxItemText = values[0] as string;
if ((comboboxItemText == "Ferrari") && (bool)values[1] == false)
{
enable = false;
}
}
return enable;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotSupportedException();
}
}
You can use MultiDataTrigger in this case.
<Style TargetType="ComboBox">
<Setter Property="IsEnabled" Value="True" />
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding}" Value="Ferrai"/>
<Condition Binding="{Binding Path=DataContext.IsOptionEnable, RelativeSource={RelativeSource AncestorType=ComboBox}}" Value="False" />
</MultiDataTrigger.Conditions>
<MultiDataTrigger.Setters>
<Setter Property="IsEnabled" Value="False" />
</MultiDataTrigger.Setters>
</MultiDataTrigger>
</Style.Triggers>
</Style>
You can use MultiDataTrigger to achieve the same.
Resource dictionary:
<Style x:Key="ModelsComboBox" TargetType="ComboBox">
<Setter Property="ItemContainerStyle">
<Setter.Value>
<Style TargetType="ComboBoxItem">
<Setter Property="IsEnabled" Value="True"/>
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding}" Value="Ferrari"/>
<Condition Binding="{Binding Path=DataContext.IsOptionEnable,
RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ComboBox}}}"
Value="False"/>
</MultiDataTrigger.Conditions>
<Setter Property="IsEnabled" Value="False"/>
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Setter.Value>
</Setter>
</Style>
I have a way of doing this now using code-behind and changing visibility of 'panels' , but I wonder if this can be done in a straight xaml way?
You should be able to bind this using ElementName, along with an IValueConverter that converts true/false to Visibility:
<Grid>
<Grid.Resources>
<local:BoolToVisibilityConverter x:Key="BoolToVisibilityConverter" />
</Grid.Resources>
<UserControl Visibility="{Binding ElementName=toggle,
Path=IsChecked,
Converter={StaticResource BoolToVisibilityConverter}}"
/>
<ToggleButton x:Name="toggle" />
</Grid>
And the converter:
public class BoolToVisibilityConverter: IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var isChecked = (bool)value;
return isChecked ? Visibility.Visible : Visibility.Collapsed;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Here you can do it like below.. you can have both your usercontrol and togglebutton as the content of a parent Contentcontrol and use DataTemplate triggers to set visibility of user control depending on checked status of ToggleButton
<ContentControl>
<ContentControl.ContentTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<local:myusercontrol x:Name="control"/>
<ToggleButton Content="click" x:Name="toggleBtn"/>
</StackPanel>
<DataTemplate.Triggers>
<Trigger Property="IsChecked" Value="false" SourceName="toggleBtn">
<Setter Property="Visibility" Value="Visible" TargetName="control"/>
</Trigger>
<Trigger Property="IsChecked" Value="true" SourceName="toggleBtn">
<Setter Property="Visibility" Value="Collapsed" TargetName="control"/>
</Trigger>
</DataTemplate.Triggers>
</DataTemplate>
</ContentControl.ContentTemplate>
</ContentControl>