【WPF属性笔记】【DataTrigger】

WPF属性笔记系列

第一章 【WPF属性笔记】【IsHitTestVisible】
第二章 【WPF属性笔记】【DataTrigger】

---

---

前言

关于WPF属性DataTrigger的学习笔记。

---

一、DataTrigger介绍

• WPF中，根据数据的值不同，UI的界面随之改变（显示控件、隐藏控件以及改变控件的其他属性），这时我们可以用DataTrigger触发器

二、DataTrigger的使用

下面的案例实现功能，根据条件（数据的值）不同时，显示不同的按钮。
从案例的运行效果图中可以看到，当Condition的值变化时，将会触发xaml中的事件，从而改变控件原本的显示状态。

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>

通知类

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);
        }
    }
}

实体类

public class Core : ProperyChangeBase
{
    public string Condition
    {
        get => _Condition;
        set { SetProperty(ref _Condition, value); }
    }
    private string _Condition = "条件1";
}

C# 代码：

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";
}

展现效果：

总结

不积硅步，何以至千里