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。

 1 <Window x:Class="WPFdemo12.MainWindow"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6         xmlns:local="clr-namespace:WPFdemo12"
 7         mc:Ignorable="d"
 8         Title="MainWindow" Height="350" Width="525">
 9     <Window.Resources>
10         <Style x:Key="Style">
11             <Style.Triggers>
12                 <Trigger Property="Control.IsFocused" Value="True">
13                     <Setter Property="Control.Background" Value="Red" />
14                 </Trigger>
15             </Style.Triggers>
16         </Style>
17     </Window.Resources>
18     <Grid>
19         <WrapPanel>
20             <Button Content="button1" Height="20" Width="500" Margin="3"  Style="{StaticResource Style}"></Button>
21             <Button Content="button2" Height="20" Width="500" Margin="3"></Button>
22         </WrapPanel>
23     </Grid>
24 </Window>

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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

 1 <Window x:Class="WPFdemo12.Window1"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6         xmlns:local="clr-namespace:WPFdemo12"
 7         mc:Ignorable="d"
 8         Title="Window1" Height="300" Width="300">
 9     <Window.Resources>
10         <Style x:Key="Styled">
11             <Style.Triggers>
12 
13                 <MultiTrigger>
14                     <MultiTrigger.Conditions>
15                         <Condition Property="Control.IsFocused" Value="True"/>
16                         <Condition Property="Control.IsMouseOver" Value="True"/>
17                     </MultiTrigger.Conditions>
18                     <MultiTrigger.Setters>
19                         <Setter Property="Control.Foreground" Value="Red" />
20                     </MultiTrigger.Setters>
21                 </MultiTrigger>
22             </Style.Triggers>
23         </Style>
24     </Window.Resources>
25     <Grid>
26         <WrapPanel>
27             <Button Content="button1" Height="20" Width="500" Margin="3"  Style="{StaticResource Styled}"></Button>
28             <Button Content="button2" Height="20" Width="500" Margin="3"></Button>
29         </WrapPanel>
30     </Grid>
31 </Window>

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三，事件触发器

用于处理动画

 1 <Window x:Class="WPFdemo12.Window2"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6         xmlns:local="clr-namespace:WPFdemo12"
 7         mc:Ignorable="d"
 8         Title="Window2" Height="300" Width="300">
 9     <Window.Resources>
10        
11         <Style TargetType="{x:Type Button}">
12             <Style.Triggers>
13                 <!--事件触发器：当 window 加载时，触发-->
14                 <EventTrigger RoutedEvent="Window.Loaded">
15                     <EventTrigger.Actions>
16                         <!--同样的，启动动画并将动画分发给目标对象和属性-->
17                         <BeginStoryboard>
18                             <Storyboard>
19                                 <DoubleAnimation Storyboard.TargetProperty="Width" From="0" To="100" Duration="0:0:5"/>
20                             </Storyboard>
21                         </BeginStoryboard>
22                     </EventTrigger.Actions>
23                 </EventTrigger>
24             </Style.Triggers>
25         </Style>
26     </Window.Resources>
27 
28     <StackPanel Margin="5">
29         <Button Padding="20" Margin="5" >666666</Button>
30       
31     </StackPanel>
32 </Window>

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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。

 1 <Window x:Class="WPFdemo12.Window3"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6         xmlns:local="clr-namespace:WPFdemo12"
 7         mc:Ignorable="d"
 8         Title="Window3" Height="300" Width="300">
 9     <Window.Resources>
10 
11         <Style TargetType="{x:Type Button}">
12             <Style.Triggers>
13                 <!--触发条件：当 name 值为 bt 的控件的焦点属性值为 True 时-->
14                 <DataTrigger Binding="{Binding IsFocused, ElementName=bt}" Value="True">
15                     <Setter Property="Background" Value="Blue"></Setter>
16                     <DataTrigger.EnterActions>
17                         <!--同样的，启动动画并将动画分发给目标对象和属性-->
18                         <BeginStoryboard>
19                             <Storyboard>
20                                 <DoubleAnimation Storyboard.TargetProperty="Width" 
21                                     From="100" To="500" Duration="0:0:4"/>
22                             </Storyboard>
23                         </BeginStoryboard>
24                     </DataTrigger.EnterActions>
25                 </DataTrigger>
26             </Style.Triggers>
27         </Style>
28     </Window.Resources>
29     <Grid>
30         <Button Name="bt" Content="66666" Margin="30"></Button>
31     </Grid>
32 </Window>

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多重数据绑定跟多重绑定类似。