WPF property notes series
Chapter 1 [WPF Property Notes] [IsHitTestVisible]
Chapter 2 [WPF Property Notes] [DataTrigger]
Article directory
Preface
Study notes on the WPF property DataTrigger.
1. Introduction to DataTrigger
- In WPF, depending on the value of the data, the UI interface changes accordingly (showing controls, hiding controls, and changing other properties of the controls). At this time, we can use the DataTrigger trigger.
2. Use of DataTrigger
The following case implements a function that displays different buttons according to different conditions (data values).
As can be seen from the running rendering of the case, when the value of Condition changes, the event in xaml will be triggered, thereby changing the original display state of the control.
xaml:
<Window.Resources>
<local:Core x:Key="core" />
<Style TargetType="{x:Type Button}">
<Setter Property="Margin" Value="5" />
<Setter Property="Padding" Value="0,8.5" />
<Setter Property="FontSize" Value="16" />
</Style>
</Window.Resources>
<Grid>
<ContentControl>
<ContentControl.ContentTemplate>
<DataTemplate>
<StackPanel>
<WrapPanel HorizontalAlignment="Center">
<Button Content="条件1" Click="Button_Click_1"/>
<Button Content="条件2" Click="Button_Click_2"/>
<Button Content="条件3" Click="Button_Click_3"/>
</WrapPanel>
<TextBlock Text="按钮列表" HorizontalAlignment="Center" FontSize="18"/>
<TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="Red" FontSize="16" Text="{Binding Source={StaticResource ResourceKey=core},Path=Condition}"/>
<CheckBox x:Name="cb1" IsChecked="True" HorizontalAlignment="Center" Visibility="Collapsed"/>
<TextBox x:Name="tb2" Text="666666" HorizontalAlignment="Center" Visibility="Collapsed"/>
<ComboBox x:Name="cbb3" HorizontalAlignment="Center" Visibility="Collapsed"/>
<Button x:Name="btn1" Content="编辑按钮1" Visibility="Collapsed"/>
<Button x:Name="btn2" Content="编辑按钮2" Visibility="Collapsed"/>
<Button x:Name="btn3" Content="编辑按钮3" Visibility="Collapsed"/>
</StackPanel>
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding Source={StaticResource ResourceKey=core},Path=Condition}" Value="条件1">
<Setter TargetName="cb1" Property="Visibility" Value="Visible" />
<Setter TargetName="btn1" Property="Visibility" Value="Visible"/>
</DataTrigger>
<DataTrigger Binding="{Binding Source={StaticResource ResourceKey=core},Path=Condition}" Value="条件2">
<Setter TargetName="tb2" Property="Visibility" Value="Visible" />
<Setter TargetName="btn1" Property="Visibility" Value="Visible"/>
<Setter TargetName="btn2" Property="Visibility" Value="Visible"/>
</DataTrigger>
<DataTrigger Binding="{Binding Source={StaticResource ResourceKey=core},Path=Condition}" Value="条件3">
<Setter TargetName="cbb3" Property="Visibility" Value="Visible" />
<Setter TargetName="btn1" Property="Visibility" Value="Visible"/>
<Setter TargetName="btn2" Property="Visibility" Value="Visible"/>
<Setter TargetName="btn3" Property="Visibility" Value="Visible"/>
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</ContentControl.ContentTemplate>
</ContentControl>
</Grid>
Notification class
public class ProperyChangeBase : INotifyPropertyChanged, INotifyPropertyChanging
{
public event PropertyChangedEventHandler? PropertyChanged;
public event PropertyChangingEventHandler? PropertyChanging;
public void NotifyPropertyChanged(string propertyName)
{
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public void NotifyPropertyChanging(string propertyName)
{
this.PropertyChanging?.Invoke(this, new PropertyChangingEventArgs(propertyName));
}
public void OnPropertyChanged(string propertyName)
{
NotifyPropertyChanged(propertyName);
}
public void OnPropertyChanging(string propertyName)
{
NotifyPropertyChanging(propertyName);
}
public void SetProperty([CallerMemberName] string? propertyName = null)
{
if (propertyName != null)
{
NotifyPropertyChanged(propertyName);
}
}
public void SetProperty<T>(ref T field, T newValue, [CallerMemberName] string? propertyName = null)
{
if (field != null && newValue != null)
{
SetProperty_Null(ref field, newValue, propertyName);
}
}
public void SetProperty_Null<T>(ref T field, T newValue, [CallerMemberName] string? propertyName = null)
{
if (!EqualityComparer<T>.Default.Equals(field, newValue))
{
if (string.IsNullOrEmpty(propertyName))
{
field = newValue;
return;
}
NotifyPropertyChanging(propertyName);
field = newValue;
NotifyPropertyChanged(propertyName);
}
}
public void SetProperty<T>(T oldValue, T newValue, Action<T> callback, [CallerMemberName] string? propertyName = null)
{
if (oldValue != null && newValue != null && !EqualityComparer<T>.Default.Equals(oldValue, newValue))
{
if (string.IsNullOrEmpty(propertyName))
{
callback(newValue);
return;
}
NotifyPropertyChanging(propertyName);
callback(newValue);
NotifyPropertyChanged(propertyName);
}
}
}
Entity class
public class Core : ProperyChangeBase
{
public string Condition
{
get => _Condition;
set {
SetProperty(ref _Condition, value); }
}
private string _Condition = "条件1";
}
C# code:
private Core core1 = new Core();
public MainWindow()
{
InitializeComponent();
if (this.FindResource("core") is Core thecore)
{
core1 = thecore;
}
core1.Condition = "条件3";
}
private void Button_Click_1(object sender, RoutedEventArgs e)
{
core1.Condition = "条件1";
}
private void Button_Click_2(object sender, RoutedEventArgs e)
{
core1.Condition = "条件2";
}
private void Button_Click_3(object sender, RoutedEventArgs e)
{
core1.Condition = "条件3";
}
Display effect:
Summarize
How can you reach a thousand miles without accumulating steps?