我是 WPF 和 C# 新手。我在一个简单的 WPF 应用程序中使用 MediaElement 来播放循环视频，并使用 Storyboard。
现在在这个项目中我遇到了一个大问题。 MediaElement 中播放的视频会阻止屏幕保护程序启动。但就我而言，我需要正常的窗口行为。 (自动屏保、自动注销等。)
即使 MediaElement 中正在播放视频，如何才能再次显示正常的屏幕保护程序？
代码很简单: 主窗口:
<Window x:Name="BrutusView" x:Class="BRUTUS_Panel_View.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:BRUTUS_Panel_View"
mc:Ignorable="d"
Title="3nb BRUTUS Side Panel Player" Height="320" Width="256" HorizontalAlignment="Center" VerticalAlignment="Center" Left="0" Top="0" Deactivated="BrutusView_Deactivated" LostFocus="BrutusView_LostFocus" Loaded="BrutusView_Loaded" WindowStyle="ToolWindow" ResizeMode="CanResize" Icon="F:\Dokumente\Visual Studio 2015\Projects\BRUTUSConfig\BRUTUSConfig\3nb.ico" Topmost="True" ShowInTaskbar="False" ShowActivated="False" Visibility="Visible">
<Grid>
<MediaElement x:Name="myMediaElement" LoadedBehavior="Manual" HorizontalAlignment="Center" VerticalAlignment="Center" IsMuted="True" Stretch="UniformToFill">
<MediaElement.Triggers>
<EventTrigger RoutedEvent="MediaElement.Loaded">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard>
<MediaTimeline Source="C:\Animations\1.mp4" Storyboard.TargetName="myMediaElement" RepeatBehavior="Forever" />
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</MediaElement.Triggers>
</MediaElement>
</Grid>
</Window>
C#:
using System;
using System.Linq;
using System.Windows;
using System.Windows.Forms;
using System.Windows.Threading;
namespace BRUTUS_Panel_View
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void BrutusView_Loaded(object sender, RoutedEventArgs e)
{
}
private void BrutusView_Deactivated(object sender, EventArgs e)
{
BrutusView.Topmost = true;
}
private void BrutusView_LostFocus(object sender, RoutedEventArgs e)
{
BrutusView.Topmost = true;
}
}
}
最佳答案
Answer 包含两种解决方案:(i) 基于 UWP DisplayRequest 类，(ii) 基于更通用的自定义 ScreenSaverManager 类。
<强>1。 UWP DisplayRequest 类
Windows 提供了直接方法来请求暂停屏幕保护程序，并且成功调用它可以保证屏幕保护程序不会由于用户不活动(即在媒体播放期间)而启动。通过再次启用屏幕保护程序的方法可以实现相反的操作。这两种方法都在 Windows 10(UWP 运行时)中可用，并且可以通过 Windows.System.Display.DisplayRequest 类访问。下面发布了如何在 UWP 应用程序之外(在 WPF 桌面应用程序中)使用它的示例。
在使用代码之前，有必要将以下引用添加到在 Visual Studio 中创建的标准 WPF 应用程序中:(i) 来自目录的 Windows.winmd:C:\Program目录中的文件 (x86)\Windows Kits\10\UnionMetadata 和 (ii) System.Runtime.WindowsRuntime.dll:C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETCore\v4.5.1(或 v4.5)。
在播放过程中暂停或启用屏幕保护，将播放事件的启动和停止 Hook 到相关方法。
using System;
using System.Windows;
using System.Windows.Controls;
using Windows.System.Display;
namespace SuspendScreenSaverWpf
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
private DisplayRequest mDisplayRequest;
public MainWindow()
{
InitializeComponent();
}
private void SuspendButton_Click(object sender, RoutedEventArgs e)
{
Button b = sender as Button;
if (b != null)
{
try
{
if (mDisplayRequest == null)
{
// This call creates an instance of the displayRequest object
mDisplayRequest = new DisplayRequest();
}
}
catch (Exception ex)
{
this.MessageBoard.Content = $"Error Creating Display Request: {ex.Message}";
}
if (mDisplayRequest != null)
{
try
{
// This call activates a display-required request. If successful,
// the screen is guaranteed not to turn off automatically due to user inactivity.
mDisplayRequest.RequestActive();
this.MessageBoard.Content = $"Display request activated - ScreenSaver suspended";
this.EnableButton.IsEnabled = true;
this.SuspendButton.IsEnabled = false;
}
catch (Exception ex)
{
this.MessageBoard.Content = $"Error: {ex.Message}";
}
}
}
}
private void EnableButton_Click(object sender, RoutedEventArgs e)
{
Button b = sender as Button;
if (b != null)
{
if (mDisplayRequest != null)
{
try
{
// This call de-activates the display-required request. If successful, the screen
// might be turned off automatically due to a user inactivity, depending on the
// power policy settings of the system. The requestRelease method throws an exception
// if it is called before a successful requestActive call on this object.
mDisplayRequest.RequestRelease();
this.MessageBoard.Content = $"Display request released - ScreenSaver enabled.";
this.SuspendButton.IsEnabled = true;
this.EnableButton.IsEnabled = false;
}
catch (Exception ex)
{
this.MessageBoard.Content = $"Error: {ex.Message}";
}
}
}
}
}
}
<Window x:Class="SuspendScreenSaverWpf.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:SuspendScreenSaverWpf"
mc:Ignorable="d"
Title="MainWindow ScreenSaver management demo" Height="350" Width="525">
<Grid>
<Button x:Name="SuspendButton" IsEnabled="true" Content="Suspend ScreenSaver" HorizontalAlignment="Left" Margin="73,250,0,0" VerticalAlignment="Top" Width="150" Click="SuspendButton_Click"/>
<Button x:Name="EnableButton" IsEnabled="False" Content="Enable ScreenSaver" HorizontalAlignment="Left" Margin="298,250,0,0" VerticalAlignment="Top" Width="150" Click="EnableButton_Click"/>
<Label x:Name="MessageBoard" Content="Example project demonstrating how to disable ScreenSaver on Windows 10" HorizontalAlignment="Left" Height="78" Margin="73,39,0,0" VerticalAlignment="Top" Width="375"/>
</Grid>
</Window>
有关引用程序集以访问 Windows 10 UWP API 的另一条说明可以在 UwpDesktop NuGet package 的网页上找到。 。 UwpDesktop 包本身似乎在至少最近两次 Windows 10 Creators 更新期间没有得到维护，但如果针对 10.0.14393 API，它仍然有用。
有关如何在 C/C++ 代码中使用此方法的示例，请参阅 SDL Library 的存储库
<强>2。自定义 ScreenSaverManager 类
问题的挑战性部分与 System.Windows.Controls.MediaElement 控件的未记录行为有关，该控件在媒体播放期间暂停屏幕保护程序。尽管从用户观看电影的角度来看，阻止屏幕保护程序的激活是一个很好的做法，但在某些应用程序中这是不可取的。由于安全原因或当播放媒体不是最重要的应用程序功能时，强制禁用屏幕保护程序或锁定工作站并不是一个好的做法。微软应该提供一个公共(public)属性或方法来控制这个功能。
为了避免任何黑客攻击，我尝试仅使用 Win32 和 .NET/WPF 公共(public) API 来解决问题。最简单但最有效的解决方案是基于创建我们自己的 ScreenSaverManager，它复制操作系统功能并按需强制执行原始屏幕保护程序行为(自动屏幕保护程序和自动注销等 )。首先 ScreenSaverManager 读取当前 session 设置，并根据这些设置开始执行 session 策略，绕过 MediaElement 用于阻止屏幕保护程序和 session 锁定的方法。
using System;
using System.Timers;
namespace ManageScreenSaver.MediaElementWpf
{
public class ScreenSaverManager
{
private static ScreenSaverManager _Manager;
public static ScreenSaverManager Instance
{
get
{
if (_Manager != null)
return _Manager;
_Manager = new ScreenSaverManager();
return _Manager;
}
}
private TimeSpan _ScreenSaverTimeout;
private bool _IsScreenSaverSecure;
private Timer _Timer;
protected ScreenSaverManager()
{
_ScreenSaverTimeout = NativeMethods.ScreenSaverTimeout;
_IsScreenSaverSecure = NativeMethods.IsScreenSaverSecure;
_Timer = new Timer(_ScreenSaverTimeout.TotalMilliseconds/2);
_Timer.AutoReset = false;
_Timer.Elapsed += Timer_Elapsed;
_Timer.Start();
}
private void Timer_Elapsed(object sender, ElapsedEventArgs e)
{
var lastInput = NativeMethods.GetLastUserInputTimeInterval();
MainWindow.Console.WriteLine($"Last user input interval: {lastInput}");
if (lastInput >= _ScreenSaverTimeout)
{
StartScreenSaver();
}
else
{
_Timer.Interval = _ScreenSaverTimeout.Subtract(lastInput).TotalMilliseconds + 100;
_Timer.Start();
}
}
private void StartScreenSaver()
{
if (_IsScreenSaverSecure)
{
NativeMethods.LockWorkStationSession();
}
else
{
var result = NativeMethods.SendMessage((IntPtr) 0xffff, (uint) WindowMessage.WM_SYSCOMMAND, (uint) WmSysCommandParam.ScSCREENSAVE, 0);
}
}
}
}
互操作方法在单独的类NativeMethods中定义:
using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
namespace ManageScreenSaver.MediaElementWpf
{
public static class NativeMethods
{
public const uint SPI_GETSCREENSAVETIMEOUT = 0x000E;
public const uint SPI_SETSCREENSAVETIMEOUT = 0x000F;
public const uint SPI_GETSCREENSAVEACTIVE = 0x0010;
public const uint SPI_SETSCREENSAVEACTIVE = 0x0011;
public const uint SPI_SETSCREENSAVERRUNNING = 0x0061;
public const uint SPI_SCREENSAVERRUNNING = SPI_SETSCREENSAVERRUNNING;
public const uint SPI_GETSCREENSAVERRUNNING = 0x0072;
public const uint SPI_GETSCREENSAVESECURE = 0x0076;
public const uint SPI_SETSCREENSAVESECURE = 0x0077;
public const uint SPIF_UPDATEINIFILE = 0x0001;
public const uint SPIF_SENDWININICHANGE = 0x0002;
public const uint SPIF_SENDCHANGE = SPIF_SENDWININICHANGE;
[DllImport("user32.dll", CallingConvention = CallingConvention.Winapi, PreserveSig = true, SetLastError = true)]
internal static unsafe extern bool SystemParametersInfo(uint uiAction, uint uiParam, void* pvParam, uint fWinIni);
[DllImport("user32.dll", CallingConvention = CallingConvention.Winapi, CharSet = CharSet.Unicode, PreserveSig = true, SetLastError = true)]
internal static extern IntPtr DefWindowProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled);
[DllImport("user32.dll", SetLastError = true)]
static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);
[DllImport("User32.dll", SetLastError = true)]
internal static extern int SendMessage(IntPtr hWnd, uint msg, uint wParam, uint lParam);
[DllImport("user32.dll", SetLastError = true)]
internal static extern bool LockWorkStation();
public static TimeSpan GetLastUserInputTimeInterval()
{
LASTINPUTINFO lastInputInfo = new LASTINPUTINFO();
lastInputInfo.cbSize = (uint)Marshal.SizeOf(lastInputInfo);
if (!GetLastInputInfo(ref lastInputInfo))
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
uint ticks = (uint)Environment.TickCount;
var idleMiliseconds = ticks - lastInputInfo.dwTime;
return idleMiliseconds > 0 ? TimeSpan.FromMilliseconds((double)idleMiliseconds) : default(TimeSpan);
}
public static void LockWorkStationSession()
{
if (!LockWorkStation())
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
}
public static bool IsScreenSaverActive
{
get
{
bool enabled = false;
unsafe
{
var result = SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, &enabled, 0);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return enabled;
}
}
}
public static bool IsScreenSaverRunning
{
get
{
bool enabled = false;
unsafe
{
var result = SystemParametersInfo(SPI_GETSCREENSAVERRUNNING, 0, &enabled, 0);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return enabled;
}
}
}
public static bool IsScreenSaverSecure
{
get
{
bool enabled = false;
unsafe
{
var result = SystemParametersInfo(SPI_GETSCREENSAVESECURE, 0, &enabled, 0);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return enabled;
}
}
}
public static TimeSpan ScreenSaverTimeout
{
get
{
int timeout = 0;
unsafe
{
var result = SystemParametersInfo(SPI_GETSCREENSAVETIMEOUT, 0, &timeout, 0);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return TimeSpan.FromSeconds(timeout);
}
}
}
}
[Flags]
public enum WindowMessage : uint
{
WM_COMMAND = 0x0111,
WM_SYSCOMMAND = 0x0112,
}
public enum WmSysCommandParam : uint
{
ScSIZE = 0xF000,
ScMOVE = 0xF010,
ScMINIMIZE = 0xF020,
ScMAXIMIZE = 0xF030,
ScNEXTWINDOW = 0xF040,
ScPREVWINDOW = 0xF050,
ScCLOSE = 0xF060,
ScVSCROLL = 0xF070,
ScHSCROLL = 0xF080,
ScMOUSEMENU = 0xF090,
ScKEYMENU = 0xF100,
ScARRANGE = 0xF110,
ScRESTORE = 0xF120,
ScTASKLIST = 0xF130,
ScSCREENSAVE = 0xF140,
ScHOTKEY = 0xF150,
ScDEFAULT = 0xF160,
ScMONITORPOWER= 0xF170,
ScCONTEXTHELP = 0xF180,
ScSEPARATOR = 0xF00F,
}
}
最后有一个关于如何在 WPF 应用程序中使用 ScreenSaverManager 的示例:
<Window x:Class="ManageScreenSaver.MediaElementWpf.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:ManageScreenSaver.MediaElementWpf"
mc:Ignorable="d"
Title="MainWindow" Height="570" Width="550" MinHeight="570" MinWidth="550" MaxHeight="570" MaxWidth="550">
<Grid Margin="0,0,0,0">
<MediaElement x:Name="myMediaElement" Width="530" Height="270" LoadedBehavior="Manual" HorizontalAlignment="Center" VerticalAlignment="Center" IsMuted="True" Stretch="Fill" Margin="10,52,10,197" >
<MediaElement.Triggers>
<EventTrigger RoutedEvent="MediaElement.Loaded">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard>
<MediaTimeline Source="..\..\BigBuckBunny_320x180.mp4" Storyboard.TargetName="myMediaElement" RepeatBehavior="Forever" />
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</MediaElement.Triggers>
</MediaElement>
<Button x:Name="SuspendButton" IsEnabled="true" Content="Suspend ScreenSaver" HorizontalAlignment="Left" Margin="74,489,0,0" VerticalAlignment="Top" Width="150" Click="SuspendButton_Click" RenderTransformOrigin="0.501,2.334"/>
<Button x:Name="EnableButton" IsEnabled="true" Content="Enable ScreenSaver" HorizontalAlignment="Left" Margin="302,489,0,0" VerticalAlignment="Top" Width="150" Click="EnableButton_Click" RenderTransformOrigin="0.508,1.359"/>
<Label x:Name="MessageBoard" Content="Example project demonstrating how to disable ScreenSaver on Windows 10" HorizontalAlignment="Left" Height="25" Margin="44,10,0,0" VerticalAlignment="Top" Width="432"/>
<TextBox x:Name="TextBox" Text="" HorizontalAlignment="Center" HorizontalContentAlignment="Left" Height="110" Margin="10,342,10,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="510"/>
</Grid>
</Window>
using System;
using System.Timers;
using System.Windows;
using System.Windows.Controls;
using Windows.System.Display;
namespace ManageScreenSaver.MediaElementWpf
{
public partial class MainWindow : Window
{
private DisplayRequest mDisplayRequest;
internal static TextBoxWriter Console;
private static ScreenSaverManager _ScreenSaverManager;
public MainWindow()
{
InitializeComponent();
Console = new TextBoxWriter(this.TextBox);
_ScreenSaverManager = ScreenSaverManager.Instance;
PrintSSaverStatus(" MainWindow.ctor");
}
private void PrintSSaverStatus(string apendedText = "")
{
Console.WriteLine(GetScreenSaverStatusMessage() + apendedText);
}
private void SuspendButton_Click(object sender, RoutedEventArgs e)
{
Button b = sender as Button;
if (b != null)
{
EnsureDisplayRequest();
if (mDisplayRequest != null)
{
try
{
// This call activates a display-required request. If successful,
// the screen is guaranteed not to turn off automatically due to user inactivity.
mDisplayRequest.RequestActive();
this.MessageBoard.Content = $"Display request activated - ScreenSaver suspended";
this.EnableButton.IsEnabled = true;
this.SuspendButton.IsEnabled = false;
}
catch (Exception ex)
{
this.MessageBoard.Content = $"Error: {ex.Message}";
}
PrintSSaverStatus(" SuspendButton_Click");
}
}
}
private void EnsureDisplayRequest()
{
try
{
if (mDisplayRequest == null)
{
// This call creates an instance of the displayRequest object
mDisplayRequest = new DisplayRequest();
}
}
catch (Exception ex)
{
this.MessageBoard.Content = $"Error Creating Display Request: {ex.Message}";
}
}
private void EnableButton_Click(object sender, RoutedEventArgs e)
{
Button b = sender as Button;
if (b != null)
{
EnsureDisplayRequest();
if (mDisplayRequest != null)
{
try
{
// This call de-activates the display-required request. If successful, the screen
// might be turned off automatically due to a user inactivity, depending on the
// power policy settings of the system. The requestRelease method throws an exception
// if it is called before a successful requestActive call on this object.
mDisplayRequest.RequestRelease();
this.MessageBoard.Content = $"Display request released - ScreenSaver enabled.";
this.SuspendButton.IsEnabled = true;
this.EnableButton.IsEnabled = false;
}
catch (Exception ex)
{
this.MessageBoard.Content = $"Error: {ex.Message}";
}
PrintSSaverStatus(" EnableButton_Click");
}
}
}
private string GetScreenSaverStatusMessage()
{
string message = $"Screen Saver is: \"{{0}}\", \"{{1}}\", timeout: \"{{2}}\" {DateTime.UtcNow}";
message = String.Format(message,
NativeMethods.IsScreenSaverActive ? "active" : "inactive",
NativeMethods.IsScreenSaverSecure ? "secure" : "not secure",
NativeMethods.ScreenSaverTimeout);
return message;
}
}
}
仍然缺少一个小实用程序，即 WPF 控制台:
using System;
using System.IO;
using System.Text;
using System.Windows.Controls;
namespace ManageScreenSaver.MediaElementWpf
{
public class TextBoxWriter : TextWriter
{
private TextBox _TextBox;
private string _NewLine = "\n";
public TextBoxWriter(TextBox target)
{
if (target == null)
throw new ArgumentNullException(nameof(target));
_TextBox = target;
}
public override Encoding Encoding => new UTF8Encoding(false);
public override string NewLine { get => _NewLine; set => _NewLine = value; }
public override void Write(string value)
{
_TextBox.Dispatcher.InvokeAsync(
() => _TextBox.AppendText(value)
);
}
public override void WriteLine(string value)
{
_TextBox.Dispatcher.InvokeAsync(
() => _TextBox.AppendText(value + NewLine)
);
}
}
}
注意:这不是生产就绪的代码。有必要实现错误处理、系统和监视器电源事件处理、登录和注销处理:工作站 session 启动和结束、 session 中屏幕保护程序配置更改。
此方法有一些限制，当通过 RDP 连接到远程计算机时将不起作用，但当通过控制台连接到 Hyper-V 中的 Windows VM 时将起作用。
关于c# - 在媒体播放期间通过 C# 中的 WPF 应用程序在 Windows 上启用屏幕保护程序，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47063185/