【发布时间】：2015-05-13 08:03:15
【问题描述】：
我正在寻找在 ControlTemplate 中包含的控件上以代码隐藏方式启动动画的方法。
在我的应用程序中，我有从 ObservableCollection 创建的自定义模板按钮（播放菜单角色）：
MainMenuViewModel：
/// <summary>
/// Menu items list
/// </summary>
private ObservableCollection<MenuItem> _items;
....
/// <summary>
/// Menu items list property
/// </summary>
public ObservableCollection<MenuItem> Items
{
get { return _items; }
set { _items = value; }
}
主菜单视图：
<UserControl x:Class="OfficeTourismeBrantome.Views.MainMenuView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="800" d:DesignWidth="300">
<UserControl.Resources>
<Style x:Key="MenuItemButtonStyle" TargetType="Button">
<Setter Property="FontSize" Value="60" />
<Setter Property="FontFamily" Value="Segoe" />
<Setter Property="FontWeight" Value="UltraLight" />
<Setter Property="Foreground" Value="#FFEBEDEA" />
<!--<Setter Property="Height" Value="{Binding MenuLayout.MenuItemSize.Height}" />-->
<Setter Property="HorizontalContentAlignment" Value="Right" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<ControlTemplate.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard Name="themeSelectionAnimation">
<DoubleAnimation
Storyboard.TargetName="coloredRectangle"
Storyboard.TargetProperty="Width"
From="30.0"
To="250.0"
Duration="0:0:0.3" />
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</ControlTemplate.Triggers>
<Canvas HorizontalAlignment="Stretch" ClipToBounds="False" >
<ContentPresenter Canvas.Left="{Binding MenuLayout.MenuItemLeftMargin}" HorizontalAlignment="Center"
VerticalAlignment="Center" Canvas.ZIndex="1"/>
<TextBlock
Text="{Binding SecondaryText}"
Canvas.Top="50"
Canvas.Left="10"
FontSize="30"
FontWeight="ExtraLight"
FontStyle="Italic"
Canvas.ZIndex="1"
/>
<Rectangle
Canvas.Top="30"
Canvas.Left="10"
Name="coloredRectangle"
Width="30"
Height="10"
Canvas.ZIndex="0"
Fill="{Binding Color}"/>
</Canvas>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Storyboard x:Key="themeUnselectionAnimation">
<DoubleAnimation
Storyboard.TargetProperty="Width"
From="250.0"
To="30.0"
Duration="0:0:0.15" />
</Storyboard>
</UserControl.Resources>
<ItemsControl Name="menuButtonContainer" ItemsSource="{Binding Items}" Margin="{Binding MenuLayout.MenuMargin}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Vertical" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button
Style="{StaticResource ResourceKey=MenuItemButtonStyle}"
Margin="{Binding ElementName=menuButtonContainer,
Path=DataContext.MenuLayout.MenuItemMargin}"
Height="{Binding ElementName=menuButtonContainer,
Path=DataContext.MenuLayout.MenuItemSize.Height}"
Content="{Binding Text}"
Command="{Binding ElementName=menuButtonContainer,
Path=DataContext.ChangeThemeCommand}"
CommandParameter="{Binding Id}"
/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</UserControl>
正如您在上面的代码中看到的，我在按钮单击时自动触发了动画。当单击集合中的另一个按钮（选择另一个菜单项）时，我想反向播放它。要播放的动画是名为 themeUnselectionAnimation 的动画。
第一个问题：有没有办法只在 XAML 中做到这一点？我不确定，因为需要按下另一个按钮才能触发它。
以下是我的想法：
- 在
Button（这是我的菜单项）命令操作中，发送一条消息，让订阅者知道菜单项正在改变。 - 在
MainMenuViewcode-behind 中注册。 - 从那里启动动画。
到目前为止，我的问题是为动画设置目标控件。为此，我需要在ControlTemplate 中找到名为coloredRectangle 的Rectangle。该怎么做？
下面是我对应上述步骤的代码：
第 1 步：发送消息（我使用的是 MVVM Light 框架）
/// <summary>
/// Delegates that handles theme change process and tasks
/// </summary>
/// <param name="themeId">the new active theme</param>
private void ChangeTheme(int themeId)
{
// Set current active theme as inactive, if one is selected.
// Exception use because of Single implementation that throw an InvalidOperationException if not item is found
try
{
MenuItem currentTheme = Items.Single(x => x.IsActive == true);
// Check if this is current theme. If it is, we do nothing.
if(currentTheme.Id == themeId)
return;
// If current theme is set and new theme id is not the same, disable the old one
currentTheme.IsActive = false;
// Set new theme as active
Items.Single(x => x.Id == themeId).IsActive = true;
// Finally, launch unselection animation
// Send message and register to it in view code behind
// Create inner message
ThemeChangeNotification innerMessage = new ThemeChangeNotification();
innerMessage.NewThemeId = themeId;
innerMessage.OldThemeId = currentTheme.Id;
NotificationMessage<ThemeChangeNotification> message =
new NotificationMessage<ThemeChangeNotification>(innerMessage, "");
// Send message
Messenger.Default.Send(message);
}
catch (InvalidOperationException exception)
{
// Set first theme selection as active
Items.Single(x => x.Id == themeId).IsActive = true;
}
}
第 2 步：注册消息
Messenger.Default.Register<NotificationMessage<ThemeChangeNotification>>(this, ChangeThemeAnimation);
第 3 步：从 index/id 到达 Button 并启动动画（不工作）
/// <summary>
/// Theme change message delegate
/// </summary>
/// <param name="e">The ThemeChangeNotification message</param>
private void ChangeThemeAnimation(NotificationMessage<ThemeChangeNotification> message)
{
var buttonTheme = menuButtonContainer.ItemContainerGenerator.ContainerFromIndex(message.Content.OldThemeId) as FrameworkElement;
var rectangle = buttonTheme.FindName("coloredRectangle") as Rectangle;
Storyboard sb = this.FindResource("themeUnselectionAnimation") as Storyboard;
Storyboard.SetTarget(sb, rectangle);
sb.Begin();
}
非常感谢您的回答！
【问题讨论】：
-
绝对应该有一种比您正在尝试的更好（更直接）的方法。例如：在项目视图模型中有一个类似“IsSelected”的属性——并使用
DataTrigger来触发 XAML 中的动画。另一个例子：使用重新模板化的ListBox而不是 ItemsControl（因为您的控件显然需要项目选择的概念）。 -
谢谢 McGarnagle，Trigger 似乎是我最好的尝试。正如您所说，我将使用重新模板化的 ListBox。感谢您的建议！
标签： c# wpf mvvm binding wpf-animation