WPF学习笔记-触发器

一、简单触发器

可为任何依赖项属性关联简单触发器。例如，可通过响应Control类的IsFocused、IsMouseOver以及IsPressed属性的变化，创建鼠标悬停效果和焦点效果。

<Window x:Class="WPFdemo12.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WPFdemo12"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <Style x:Key="Style">
            <Style.Triggers>
                <Trigger Property="Control.IsFocused" Value="True">
                    <Setter Property="Control.Background" Value="Red" />
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <WrapPanel>
            <Button Content="button1" Height="20" Width="500" Margin="3"  Style="{StaticResource Style}"></Button>
            <Button Content="button2" Height="20" Width="500" Margin="3"></Button>
        </WrapPanel>
    </Grid>
</Window>

当触发多个触发器，改同一个属性时，最后一个触发器修改属性有效。

二、多条件触发器

有时候触发的条件不止一个，要满足多个时候，就需要多条件触发

<Window x:Class="WPFdemo12.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WPFdemo12"
        mc:Ignorable="d"
        Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <Style x:Key="Styled">
            <Style.Triggers>

                <MultiTrigger>
                    <MultiTrigger.Conditions>
                        <Condition Property="Control.IsFocused" Value="True"/>
                        <Condition Property="Control.IsMouseOver" Value="True"/>
                    </MultiTrigger.Conditions>
                    <MultiTrigger.Setters>
                        <Setter Property="Control.Foreground" Value="Red" />
                    </MultiTrigger.Setters>
                </MultiTrigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <WrapPanel>
            <Button Content="button1" Height="20" Width="500" Margin="3"  Style="{StaticResource Styled}"></Button>
            <Button Content="button2" Height="20" Width="500" Margin="3"></Button>
        </WrapPanel>
    </Grid>
</Window>

三，事件触发器

用于处理动画

<Window x:Class="WPFdemo12.Window2"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WPFdemo12"
        mc:Ignorable="d"
        Title="Window2" Height="300" Width="300">
    <Window.Resources>
       
        <Style TargetType="{x:Type Button}">
            <Style.Triggers>
                <!--事件触发器：当 window 加载时，触发-->
                <EventTrigger RoutedEvent="Window.Loaded">
                    <EventTrigger.Actions>
                        <!--同样的，启动动画并将动画分发给目标对象和属性-->
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetProperty="Width" From="0" To="100" Duration="0:0:5"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger.Actions>
                </EventTrigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>

    <StackPanel Margin="5">
        <Button Padding="20" Margin="5" >666666</Button>
      
    </StackPanel>
</Window>

四，数据触发器

当绑定数据满足某些条件时，数据触发器执行某些操作。

<Window x:Class="WPFdemo12.Window3"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WPFdemo12"
        mc:Ignorable="d"
        Title="Window3" Height="300" Width="300">
    <Window.Resources>

        <Style TargetType="{x:Type Button}">
            <Style.Triggers>
                <!--触发条件：当 name 值为 bt 的控件的焦点属性值为 True 时-->
                <DataTrigger Binding="{Binding IsFocused, ElementName=bt}" Value="True">
                    <Setter Property="Background" Value="Blue"></Setter>
                    <DataTrigger.EnterActions>
                        <!--同样的，启动动画并将动画分发给目标对象和属性-->
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetProperty="Width" 
                                    From="100" To="500" Duration="0:0:4"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </DataTrigger.EnterActions>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <Button Name="bt" Content="66666" Margin="30"></Button>
    </Grid>
</Window>

多重数据绑定跟多重绑定类似。