C# WPF入门学习主线篇（三十四）—— 图形和动画

图形和动画是WPF的重要组成部分，能够大幅提升应用程序的用户体验。本篇博客将详细介绍WPF中图形和动画的使用方法，涵盖基本图形绘制、动画创建及多媒体的应用。通过本文，你将学习如何利用Shapes、Brushes、Transforms等绘制和处理图形，如何使用Storyboard和各种动画类创建动态效果，以及如何在WPF中集成音频和视频。

一、图形绘制

1. 使用Shapes绘制基本图形

WPF提供了多个Shape类，用于绘制基本图形，如线条、矩形和椭圆。以下是几个常用的图形绘制示例。

1.1 绘制线条

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Graphics Demo" Height="350" Width="525">
    <Grid>
        <Canvas>
            <Line X1="10" Y1="10" X2="100" Y2="100" Stroke="Black" StrokeThickness="2"/>
        </Canvas>
    </Grid>
</Window>

1.2 绘制矩形

<Canvas>
    <Rectangle Width="100" Height="50" Fill="Blue" Stroke="Black" StrokeThickness="2" Canvas.Left="50" Canvas.Top="50"/>
</Canvas>

1.3 绘制椭圆

<Canvas>
    <Ellipse Width="100" Height="50" Fill="Red" Stroke="Black" StrokeThickness="2" Canvas.Left="200" Canvas.Top="50"/>
</Canvas>

2. 使用Brushes和Transforms

WPF提供了丰富的Brushes和Transforms来处理图形的填充和变换。

2.1 使用Brushes

<Canvas>
    <Rectangle Width="100" Height="50" Canvas.Left="50" Canvas.Top="150">
        <Rectangle.Fill>
            <LinearGradientBrush>
                <GradientStop Color="Yellow" Offset="0"/>
                <GradientStop Color="Orange" Offset="1"/>
            </LinearGradientBrush>
        </Rectangle.Fill>
    </Rectangle>
</Canvas>

2.2 使用Transforms

<Canvas>
    <Rectangle Width="100" Height="50" Fill="Green" Stroke="Black" StrokeThickness="2" Canvas.Left="50" Canvas.Top="250">
        <Rectangle.RenderTransform>
            <RotateTransform Angle="45" CenterX="50" CenterY="25"/>
        </Rectangle.RenderTransform>
    </Rectangle>
</Canvas>

二、动画

1. 动画基础

WPF的动画系统可以创建复杂的动画效果，主要通过Storyboard和各种Animation类实现。

1.1 创建简单动画

<Canvas>
    <Rectangle Width="100" Height="50" Fill="Blue" Canvas.Left="50" Canvas.Top="50">
        <Rectangle.Triggers>
            <EventTrigger RoutedEvent="Rectangle.Loaded">
                <BeginStoryboard>
                    <Storyboard>
                        <DoubleAnimation Storyboard.TargetProperty="(Canvas.Left)" From="50" To="300" Duration="0:0:5"/>
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </Rectangle.Triggers>
    </Rectangle>
</Canvas>

2. 使用动画创建动态效果

通过组合多个动画，可以实现复杂的动态效果。

<Canvas>
    <Rectangle Width="100" Height="50" Fill="Blue" Canvas.Left="50" Canvas.Top="50">
        <Rectangle.Triggers>
            <EventTrigger RoutedEvent="Rectangle.Loaded">
                <BeginStoryboard>
                    <Storyboard>
                        <DoubleAnimation Storyboard.TargetProperty="(Canvas.Left)" From="50" To="300" Duration="0:0:5" AutoReverse="True" RepeatBehavior="Forever"/>
                        <DoubleAnimation Storyboard.TargetProperty="(Canvas.Top)" From="50" To="200" Duration="0:0:5" AutoReverse="True" RepeatBehavior="Forever"/>
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </Rectangle.Triggers>
    </Rectangle>
</Canvas>

三、多媒体

1. 在WPF中使用音频和视频控件

WPF提供了MediaElement控件，用于播放音频和视频文件。

1.1 播放音频

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Media Player" Height="200" Width="400">
    <Grid>
        <MediaElement Name="audioPlayer" LoadedBehavior="Manual" UnloadedBehavior="Stop" Width="0" Height="0"/>
        <Button Name="playPauseButton" Content="Play" Click="PlayPauseButton_Click" Width="100" Height="30" VerticalAlignment="Center" HorizontalAlignment="Center"/>
    </Grid>
</Window>

using System;
using System.Windows;

namespace WpfApp
{
    public partial class MainWindow : Window
    {
        private bool isPlaying = false; // 跟踪播放状态

        public MainWindow()
        {
            InitializeComponent();
            audioPlayer.Source = new Uri("zaijiana.mp3", UriKind.Relative);
        }

        private void PlayPauseButton_Click(object sender, RoutedEventArgs e)
        {
            if (isPlaying)
            {
                audioPlayer.Pause();
                playPauseButton.Content = "Play";
            }
            else
            {
                audioPlayer.Play();
                playPauseButton.Content = "Pause";
            }
            isPlaying = !isPlaying; // 切换播放状态
        }
    }
}

1.2 播放视频

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Media Demo" Height="350" Width="525">
    <Grid>
        <MediaElement Name="videoPlayer" Source="video.mp4" LoadedBehavior="Manual" UnloadedBehavior="Stop" Width="300" Height="200"/>
        <Button Content="Play Video" Click="PlayVideo_Click" Width="100" Height="30" VerticalAlignment="Bottom"/>
    </Grid>
</Window>

1.3 代码后台播放控制

private void PlayAudio_Click(object sender, RoutedEventArgs e)
{
    audioPlayer.Play();
}

private void PlayVideo_Click(object sender, RoutedEventArgs e)
{
    videoPlayer.Play();
}

四、总结

本文详细介绍了如何在WPF中使用图形和动画，涵盖了基本图形的绘制、动画效果的创建以及多媒体的应用。通过掌握这些技术，你可以创建更为丰富和生动的WPF应用程序，提升用户体验。希望通过本文的讲解，你能更好地理解和应用WPF中的图形和动画功能。

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