我想创建一个从其当前宽度到0的条形（矩形）动画，该动画将用作倒计时的可视化。
最后，它看起来应该像这样：
现在，我在动画中设置了启动动画的触发器（该部分已经起作用）。
Winsoc我有几点，我不在这里工作：
无法冻结此情节提要板时间轴树以供跨线程使用。
我也尝试使用ProgressBar代替，但是我无法使其动画流畅。更改值时总会出现一些小的步骤，因此对我来说这并不是一个选择。
欢迎您提供任何帮助，谢谢。
当我需要依赖于Widths之类的动态动画时，我总是将它们作为附加行为或自定义控件代码在代码中进行处理。
这使您可以在代码中创建Storyboard，设置其所有动态属性，然后启动它。
在这种情况下，动画一旦开始播放，就等于控件开始的大小。如果用户在运行窗口时调整其大小，则动画将不会自动缩放。但是，您确实可以做到这一点。我刚刚实现了您简单的DoubleAnimation。
以下是您的案例的有效示例：
XAML
<Window x:Class="WpfApp4.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApp4"
Title="MainWindow"
Width="800"
Height="450"
UseLayoutRounding="True">
<Window.DataContext>
<local:MainWindowViewModel />
</Window.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Control x:Name="CountDownVisual"
Grid.Row="1"
Height="30"
Margin="0">
<Control.Template>
<ControlTemplate>
<Grid x:Name="RootElement">
<Grid x:Name="CountDownBarRootElement"
local:CountDownBarAnimationBehavior.IsActive="{Binding ShowUiTimer}"
local:CountDownBarAnimationBehavior.ParentElement="{Binding ElementName=RootElement}"
local:CountDownBarAnimationBehavior.TargetElement="{Binding ElementName=CountDownBar}">
<Rectangle x:Name="CountDownBar"
HorizontalAlignment="Left"
Fill="#FFA4B5BF" />
</Grid>
</Grid>
</ControlTemplate>
</Control.Template>
</Control>
</Grid>
</Window>
附加行为
using System;
using System.Windows;
using System.Windows.Media.Animation;
using System.Windows.Threading;
namespace WpfApp4
{
public static class CountDownBarAnimationBehavior
{
private static Storyboard sb;
#region IsActive (DependencyProperty)
public static readonly DependencyProperty IsActiveProperty = DependencyProperty.RegisterAttached("IsActive",typeof(bool),typeof(CountDownBarAnimationBehavior),new FrameworkPropertyMetadata(false,OnIsActiveChanged));
public static bool GetIsActive(DependencyObject obj)
{
return (bool)obj.GetValue(IsActiveProperty);
}
public static void SetIsActive(DependencyObject obj,bool value)
{
obj.SetValue(IsActiveProperty,value);
}
private static void OnIsActiveChanged(DependencyObject d,DependencyPropertyChangedEventArgs e)
{
if (!(d is FrameworkElement control))
{
return;
}
if((bool)e.NewValue)
{
if (GetParentElement(control) != null)
{
StartAnimation(control);
}
else
{
// If IsActive is set to true and the other properties haven't
// been updated yet,defer the animation until render time.
control.Dispatcher?.BeginInvoke((Action) (() => { StartAnimation(control); }),DispatcherPriority.Render);
}
}
else
{
StopAnimation();
}
}
#endregion
#region ParentElement (DependencyProperty)
public static readonly DependencyProperty ParentElementProperty = DependencyProperty.RegisterAttached("ParentElement",typeof(FrameworkElement),new FrameworkPropertyMetadata(null,OnParentElementChanged));
public static FrameworkElement GetParentElement(DependencyObject obj)
{
return (FrameworkElement)obj.GetValue(ParentElementProperty);
}
public static void SetParentElement(DependencyObject obj,FrameworkElement value)
{
obj.SetValue(ParentElementProperty,value);
}
private static void OnParentElementChanged(DependencyObject d,DependencyPropertyChangedEventArgs e)
{
if(!(d is FrameworkElement fe))
{
return;
}
// You can wire up events here if you want to react to size changes,etc.
}
private static void OnParentElementSizeChanged(object sender,SizeChangedEventArgs e)
{
if (!(sender is FrameworkElement fe))
{
return;
}
if (GetIsActive(fe))
{
StopAnimation();
StartAnimation(fe);
}
}
#endregion
#region TargetElement (DependencyProperty)
public static readonly DependencyProperty TargetElementProperty = DependencyProperty.RegisterAttached("TargetElement",new FrameworkPropertyMetadata(null));
public static FrameworkElement GetTargetElement(DependencyObject obj)
{
return (FrameworkElement)obj.GetValue(TargetElementProperty);
}
public static void SetTargetElement(DependencyObject obj,FrameworkElement value)
{
obj.SetValue(TargetElementProperty,value);
}
#endregion
private static void StartAnimation(DependencyObject d)
{
var parent = GetParentElement(d);
var target = GetTargetElement(d);
if (parent == null || target == null)
{
return;
}
sb = new Storyboard();
var da = new DoubleAnimation();
Storyboard.SetTarget(da,target);
Storyboard.SetTargetProperty(da,new PropertyPath("Width"));
da.AutoReverse = false;
da.Duration = new Duration(new TimeSpan(0,1,0));
da.From = parent.ActualWidth;
da.To = 0d;
sb.Children.Add(da);
sb.Begin();
}
private static void StopAnimation()
{
sb?.Stop();
}
}
}