c# - SetTarget 与 RegisterName/SetTargetName

Question

这是一个简单的程序，它为 Line 形状的 Y2 属性设置动画。请注意，我使用 SetTarget 方法来定位 Line。这个程序运行良好。

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace SoGeneratingAnimatedLine
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            var canvas = new Canvas();

            Content = canvas;

            var sb = new Storyboard();

            var line = new Line()
            {
                X1 = 10, Y1 = 10,
                X2 = 90, Y2 = 10,
                Stroke = Brushes.Black,
                StrokeThickness = 2
            };

            canvas.Children.Add(line);

            var animation = new DoubleAnimation(10, 90, new Duration(TimeSpan.FromMilliseconds(1000)));

            sb.Children.Add(animation);

            Storyboard.SetTarget(animation, line);
            Storyboard.SetTargetProperty(animation, new PropertyPath(Line.Y2Property));

            MouseDown += (s, e) => sb.Begin(this);
        }
    }
}

这是一个类似的程序，它为 LineGeometry 的 EndPoint 设置动画，这是 Path 的 Data:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace SoGeneratingAnimatedLine
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            var canvas = new Canvas();

            Content = canvas;

            var sb = new Storyboard();

            var lineGeometry = 
                new LineGeometry(new Point(10, 10), new Point(90, 10));

            var path = new Path()
            {
                Stroke = Brushes.Black,
                StrokeThickness = 2,
                Data = lineGeometry
            };

            canvas.Children.Add(path);

            var animation =
                new PointAnimation(
                    new Point(90, 10),
                    new Point(90, 90),
                    new Duration(TimeSpan.FromMilliseconds(1000)));

            sb.Children.Add(animation);

            Storyboard.SetTarget(animation, lineGeometry);
            Storyboard.SetTargetProperty(animation, new PropertyPath(LineGeometry.EndPointProperty));

            MouseDown += (s, e) => sb.Begin(this);
        }
    }
}

第二个版本不有效。但是，如果我替换行:

Storyboard.SetTarget(animation, lineGeometry);

与:

RegisterName("geometry", lineGeometry);
Storyboard.SetTargetName(animation, "geometry");

然后动画运行。

为什么第二个程序的 SetTarget 版本不起作用？什么时候可以使用 SetTarget 而不是 RegisterName/SetTargetName 组合？这两种方法有什么区别？

Answer 1

根本不需要 Storyboard。只需调用 BeginAnimation直接在 LineGeometry 上:

lineGeometry.BeginAnimation(LineGeometry.EndPointProperty, animation);