单独的动画起作用，情节提要(storyboard)不起作用.为什么?

问题描述

TL:DR; 故事板完全没有动画.为什么?

TL:DR; Storyboard doesn't animate at all. Why?

我正在尝试创建一个情节提要，以动画化渐变中所有渐变停靠点的偏移，并将它们从左向右移动.

I am attempting to create a storyboard which will animate the offsets of all the gradient stops within a gradient, shifting them from the left to the right.

我确定这只是一个愚蠢的语法或参数错误，或者是我的某个地方，但我找不到它.

I'm certain this is just a stupid syntax or argument error or something someplace on my part but I can't find it.

这是XAML:

<Window
    x:Class="GradientShifting.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:GradientShiftDerping"
    mc:Ignorable="d" Title="MainWindow" Height="350" Width="525"
    AllowsTransparency="True" WindowStyle="None">
    <Window.Background>
        <LinearGradientBrush EndPoint="1,1" StartPoint="0,0">
            <GradientStop Color="Black" Offset="0"/>
            <GradientStop Color="White" Offset="1"/>
        </LinearGradientBrush>
    </Window.Background>
</Window>

这是背后的代码:

using System;
using System.Linq;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Animation;

namespace GradientShifting {
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window {
        private Storyboard _sbGradientShifter = new Storyboard( );
        public MainWindow( ) {
            InitializeComponent( );
            this.Loaded += new RoutedEventHandler(
                ( S, E ) => this.SetupGradientShift( ) );
        }

    private void SetupGradientShift( ){
        GradientBrush BackBrush = this.Background as GradientBrush;
        if ( BackBrush != null ) {
            /* Ordering by offset is important because
               the last color in the gradient requires
               special consideration. */
            DoubleAnimationUsingKeyFrames DAUKF;
            GradientStopCollection GSC = new GradientStopCollection(
                BackBrush.GradientStops.OrderBy( GS => GS.Offset ) );
            foreach( GradientStop GS in GSC ){
                DAUKF = new DoubleAnimationUsingKeyFrames( ) {
                    KeyFrames = new DoubleKeyFrameCollection( ){
                        new LinearDoubleKeyFrame(
                            1.0D, KeyTime.FromPercent( 1.0D )
                }, Duration = TimeSpan.FromSeconds( 3 )
            };

            //Something I am doing from here...
            this._sbGradientShifter.Children.Add( DAUKF );

            Storyboard.SetTarget( DAUKF, GS );

            Storyboard.SetTargetProperty(
                DAUKF, new PropertyPath( GradientStop.OffsetProperty ) );
        }
        this._sbGradientShifter.Begin( this ); //THIS DOES NOTHING.
    }
}

因此，再次-此代码无效.我已经能够通过调用 GradientStop.BeginAnimation 来启动情节提要中包含的动画，但是 Storyboard.Begin 无效.

So, again - this code doesn't work. I have been able to start the the animation included within the storyboard by calling GradientStop.BeginAnimation, however Storyboard.Begin does not work.

推荐答案

出于某些原因， Storyboard.SetTarget 仅适用于 FrameworkElement s或 FrameworkContentElement s.要执行所需的操作，您可以像在"hack"中一样自行启动单个动画(IMO是一种完全合理的动画制作方法).

For some reason, Storyboard.SetTarget only works with FrameworkElements or FrameworkContentElements. To do what you want, you can either start the individual animations yourself as you have in your "hack" (a perfectly reasonable way of doing animations, IMO).

或者您可以为所有目标注册名称，例如:

Or you can register names for all your targets, e.g.:

foreach (var gs in gsc)
{
    var name = "GS_" + Guid.NewGuid().ToString("N");
    RegisterName(name, gs);
    Storyboard.SetTargetName(caukf, name);
}

如果您决定直接调用动画，则实际上不需要将它们保存在单独的列表中.创建它们后，请立即在第一个循环中立即启动它们.

If you decide to invoke the animations directly, you really don't need to save them in a separate list. Just start them immediately in the first loop as soon as they are created.

如果需要更多协调，例如暂停动画，使用名称范围，高级定时或从XAML进行动画处理，则故事板非常有用.但是对于您来说，简单的时间表似乎就足够了.

Storyboards are great if you need more coordination, such as pausing animations, using name scopes, advanced timing or animate from XAML. But in your case it seems simple Timelines would be adequate.

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