WPF中如何实现PictureBox全屏显示（视频预览场景）

嘿，我来帮你搞定WPF里嵌套PictureBox实现视频全屏的问题！因为你是用WindowsFormsHost把WinForms的PictureBox嵌入到WPF界面中，所以得结合WPF窗口控制和WinForms控件的布局逻辑来实现，具体步骤如下：

步骤1：完善XAML布局 #

首先给你的WindowsFormsHost加个命名，方便后台代码访问；再添一个全屏触发按钮：

<!-- 给WindowsFormsHost添加x:Name -->
<WindowsFormsHost x:Name="videoWinFormsHost" Grid.Row="3" Grid.Column="4" Grid.ColumnSpan="2" Grid.RowSpan="2" Background="Black">
    <wf:PictureBox BorderStyle="FixedSingle" x:Name="pictureBox1"/>
</WindowsFormsHost>

<!-- 添加全屏按钮，放在你觉得合适的布局位置 -->
<Button x:Name="btnToggleFullScreen" Content="全屏" Click="BtnToggleFullScreen_Click" Margin="10"/>

步骤2：后台代码实现全屏/退出全屏逻辑 #

先定义变量保存原本的窗口和布局状态，避免退出全屏时界面混乱：

// 保存窗口原本的状态与边界
private WindowState _originalWindowState;
private Rect _originalWindowBounds;
// 保存WindowsFormsHost原来的布局参数
private int _originalColSpan;
private int _originalRowSpan;
private GridLength _originalRowHeight;
private GridLength _originalColWidth;

然后写按钮点击事件的处理逻辑，分全屏和退出全屏两种场景：

private void BtnToggleFullScreen_Click(object sender, RoutedEventArgs e)
{
    var parentGrid = (Grid)videoWinFormsHost.Parent;
    
    // 判断当前是否处于全屏状态
    if (WindowState == WindowState.Maximized && WindowStyle == WindowStyle.None)
    {
        // 退出全屏：恢复窗口与布局
        WindowState = _originalWindowState;
        WindowStyle = WindowStyle.SingleBorderWindow;
        Left = _originalWindowBounds.Left;
        Top = _originalWindowBounds.Top;
        Width = _originalWindowBounds.Width;
        Height = _originalWindowBounds.Height;
        
        // 把WindowsFormsHost放回原来的Grid位置
        Grid.SetRow(videoWinFormsHost, 3);
        Grid.SetColumn(videoWinFormsHost, 4);
        Grid.SetColumnSpan(videoWinFormsHost, _originalColSpan);
        Grid.SetRowSpan(videoWinFormsHost, _originalRowSpan);
        // 恢复Grid的行高与列宽
        parentGrid.RowDefinitions[3].Height = _originalRowHeight;
        parentGrid.ColumnDefinitions[4].Width = _originalColWidth;
        
        // 恢复PictureBox的显示模式
        pictureBox1.Dock = DockStyle.None;
        pictureBox1.SizeMode = PictureBoxSizeMode.Normal;
        
        btnToggleFullScreen.Content = "全屏";
    }
    else
    {
        // 进入全屏：先保存当前状态
        _originalWindowState = WindowState;
        _originalWindowBounds = new Rect(Left, Top, Width, Height);
        _originalColSpan = Grid.GetColumnSpan(videoWinFormsHost);
        _originalRowSpan = Grid.GetRowSpan(videoWinFormsHost);
        _originalRowHeight = parentGrid.RowDefinitions[3].Height;
        _originalColWidth = parentGrid.ColumnDefinitions[4].Width;
        
        // 设置窗口为无边框全屏
        WindowState = WindowState.Maximized;
        WindowStyle = WindowStyle.None;
        
        // 让WindowsFormsHost占满整个Grid
        Grid.SetRow(videoWinFormsHost, 0);
        Grid.SetColumn(videoWinFormsHost, 0);
        Grid.SetColumnSpan(videoWinFormsHost, parentGrid.ColumnDefinitions.Count);
        Grid.SetRowSpan(videoWinFormsHost, parentGrid.RowDefinitions.Count);
        // 让Grid的所有行和列均匀占满空间
        foreach (var rowDef in parentGrid.RowDefinitions)
        {
            rowDef.Height = new GridLength(1, GridUnitType.Star);
        }
        foreach (var colDef in parentGrid.ColumnDefinitions)
        {
            colDef.Width = new GridLength(1, GridUnitType.Star);
        }
        
        // 让PictureBox填满整个WindowsFormsHost
        pictureBox1.Dock = DockStyle.Fill;
        pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage; // 视频拉伸适配全屏
        
        btnToggleFullScreen.Content = "退出全屏";
    }
}

步骤3：添加ESC快捷键退出全屏（可选） #

为了提升用户体验，可以添加ESC键退出全屏的功能，重写窗口的OnKeyDown方法：

protected override void OnKeyDown(KeyEventArgs e)
{
    base.OnKeyDown(e);
    // 如果当前是全屏状态，按ESC直接退出
    if (e.Key == Key.Escape && WindowState == WindowState.Maximized && WindowStyle == WindowStyle.None)
    {
        BtnToggleFullScreen_Click(null, null);
    }
}

注意事项 #

• 如果你用的是第三方视频播放控件（比如基于DirectShow/FFmpeg的WinForms播放控件），可能需要额外调用控件自身的全屏方法，或者确保渲染上下文能适配新的大小，避免出现黑屏、画面错位等问题
• 测试时要验证窗口状态恢复是否正常，比如原本窗口是正常大小还是最大化，退出全屏后要准确回到初始状态

内容的提问来源于stack exchange，提问作者JINESH