<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Canvas Width="400" Height="400">
<Button MinWidth="100" Content="A Button">
<Button.RenderTransform>
<MatrixTransform x:Name="myMatrixTransform">
<MatrixTransform.Matrix >
<Matrix />
</MatrixTransform.Matrix>
</MatrixTransform>
</Button.RenderTransform>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<MatrixAnimationUsingPath Storyboard.TargetName="myMatrixTransform" Storyboard.TargetProperty="Matrix" IsOffsetCumulative="True" Duration="0:0:5" RepeatBehavior="2x">
<MatrixAnimationUsingPath.PathGeometry>
<PathGeometry Figures="M 10,100 C 35,0 135,0 160,100 180,190 285,200 310,100"/>
</MatrixAnimationUsingPath.PathGeometry>
</MatrixAnimationUsingPath>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
</Canvas>
</Window>
如何在Button动画的路径上绘制轨迹？
之前曾问过类似的问题，但没有答案。
Painting a trail over a Path in WPF
附言： xaml或背后的代码（C＃或VB）对我来说都是可以接受的。
答案 0 :(得分：0)
首先，我对WPF中的这类内容不太熟悉。
不过，我试图为您的问题找到解决方案，并得出以下结果。
我估算了通过许多单个点的真实路径，以便可以使用这些点绘制路径的特定部分。
注意：这远非完美，只是一个快速解决方案。
public class PortionPath : Shape
{
#region Geometry
private static readonly DependencyProperty GeometryProperty =
DependencyProperty.Register("Geometry", typeof(Geometry), typeof(PortionPath),
new PropertyMetadata(Geometry.Empty, null, CoerceGeometry));
private Geometry Geometry => (Geometry)GetValue(GeometryProperty);
private static object CoerceGeometry(DependencyObject d, object baseValue)
{
PortionPath portionPath = (PortionPath) d;
int firstPoint = (int)(portionPath.PointCollection.Length * portionPath.From);
int lastPoint = (int)(portionPath.PointCollection.Length * portionPath.To);
if (firstPoint == 0 && lastPoint == portionPath.PointCollection.Length)
{
return portionPath.Data;
}
if (firstPoint == lastPoint)
{
return Geometry.Empty;
}
PathFigure pathFigure = new PathFigure();
var pointCollection = portionPath.PointCollection.Skip(firstPoint).Take(lastPoint - firstPoint).ToArray();
if (pointCollection.Length > 0)
{
pathFigure.StartPoint = pointCollection[0];
if (pointCollection.Length > 1)
{
Point[] array = new Point[pointCollection.Length - 1];
for (int i = 1; i < pointCollection.Length; i++)
{
array[i - 1] = pointCollection[i];
}
pathFigure.Segments.Add(new PolyLineSegment(array, true));
}
}
PathGeometry polylineGeometry = new PathGeometry();
polylineGeometry.Figures.Add(pathFigure);
return polylineGeometry;
}
#endregion
#region PointCollection
private static readonly DependencyProperty PointCollectionProperty =
DependencyProperty.Register("PointCollection", typeof(Point[]), typeof(PortionPath),
new PropertyMetadata(new Point[0], PointCollectionChanged, CoercePointCollection));
private Point[] PointCollection => (Point[]) GetValue(PointCollectionProperty);
private static void PointCollectionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
d.CoerceValue(GeometryProperty);
}
private static object CoercePointCollection(DependencyObject d, object baseValue)
{
PortionPath portionPath = (PortionPath) d;
var path = portionPath.Data;
var steps = portionPath.Steps;
var g = path.GetFlattenedPathGeometry(portionPath.Tolerance, ToleranceType.Absolute);
List<Point> pointCollection = new List<Point>();
var step = 1.0 / steps;
for (double i = 0; i <= 1; i += step)
{
g.GetPointAtFractionLength(i, out Point p, out _);
pointCollection.Add(p);
}
return pointCollection.ToArray();
}
#endregion
#region Tolerance
private static readonly DependencyProperty ToleranceProperty =
DependencyProperty.Register("Tolerance", typeof(double), typeof(PortionPath),
new PropertyMetadata(0.000001, ToleranceChanged));
public double Tolerance
{
get => (double) GetValue(ToleranceProperty);
set => SetValue(ToleranceProperty,value);
}
private static void ToleranceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
d.CoerceValue(PointCollectionProperty);
}
#endregion
#region Data
public static DependencyProperty DataProperty = DependencyProperty.Register("Data", typeof(Geometry),
typeof(PortionPath), new FrameworkPropertyMetadata(Geometry.Empty, FrameworkPropertyMetadataOptions.AffectsRender, DataChanged));
public Geometry Data
{
get => (Geometry)GetValue(DataProperty);
set => SetValue(DataProperty, value);
}
private static void DataChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
d.CoerceValue(PointCollectionProperty);
}
#endregion
#region Steps
public static DependencyProperty StepsProperty = DependencyProperty.Register("Steps", typeof(int),
typeof(PortionPath), new FrameworkPropertyMetadata(1000, FrameworkPropertyMetadataOptions.AffectsRender, StepsChanged));
public int Steps
{
get => (int)GetValue(StepsProperty);
set => SetValue(StepsProperty, value);
}
private static void StepsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
d.CoerceValue(PointCollectionProperty);
}
#endregion
#region From
public static DependencyProperty FromProperty = DependencyProperty.Register("From", typeof(double),
typeof(PortionPath), new FrameworkPropertyMetadata(0.0, FrameworkPropertyMetadataOptions.AffectsRender, FromChanged, CoerceFrom));
public double From
{
get => (double)GetValue(FromProperty);
set => SetValue(FromProperty, value);
}
private static void FromChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
d.CoerceValue(ToProperty);
d.CoerceValue(GeometryProperty);
}
private static object CoerceFrom(DependencyObject d, object baseValue)
{
switch (baseValue)
{
case double doubleValue:
if (doubleValue > 1.0) return 1.0;
if (doubleValue < 0.0) return 0.0;
return doubleValue;
default:
return 1.0;
}
}
#endregion
#region To
public static DependencyProperty ToProperty = DependencyProperty.Register("To", typeof(double),
typeof(PortionPath), new FrameworkPropertyMetadata(1.0, FrameworkPropertyMetadataOptions.AffectsRender, ToChanged, CoerceTo));
public double To
{
get => (double) GetValue(ToProperty);
set => SetValue(ToProperty,value);
}
private static void ToChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
d.CoerceValue(GeometryProperty);
}
private static object CoerceTo(DependencyObject d, object baseValue)
{
PortionPath portionPath = (PortionPath) d;
switch (baseValue)
{
case double doubleValue:
if (doubleValue > 1.0) return 1.0;
if (doubleValue < 0.0 || doubleValue < portionPath.From) return portionPath.From;
return doubleValue;
default:
return 1.0;
}
}
#endregion
protected override Geometry DefiningGeometry => Geometry;
}
<Canvas Width="400" Height="400">
<Button MinWidth="100" Content="A Button">
<Button.RenderTransform>
<MatrixTransform x:Name="myMatrixTransform">
<MatrixTransform.Matrix >
<Matrix />
</MatrixTransform.Matrix>
</MatrixTransform>
</Button.RenderTransform>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<MatrixAnimationUsingPath Storyboard.TargetName="myMatrixTransform" Storyboard.TargetProperty="Matrix" IsOffsetCumulative="True" Duration="0:0:5">
<MatrixAnimationUsingPath.PathGeometry>
<PathGeometry Figures="M 10,100 C 35,0 135,0 160,100 180,190 285,200 310,100"/>
</MatrixAnimationUsingPath.PathGeometry>
</MatrixAnimationUsingPath>
<DoubleAnimation From="0" To="1" Storyboard.TargetName="PortionPath" Storyboard.TargetProperty="To" Duration="0:0:5"/>
<DoubleAnimation From="0" To="1" Storyboard.TargetName="PortionPath" Storyboard.TargetProperty="From" BeginTime="0:0:1" Duration="0:0:5"/>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
<local:PortionPath x:Name="PortionPath" From="0" To="0" Stroke="Red" Data="M 10,100 C 35,0 135,0 160,100 180,190 285,200 310,100" />
</Canvas>
欢迎提出任何改进此解决方案的建议