更改屏幕的滤色器以与多台显示器一起使用
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【中文标题】更改屏幕的滤色器以与多台显示器一起使用【英文标题】：Change colour filter of screen to work with multiple monitors 【发布时间】：2015-06-29 07:06:34 【问题描述】：我已经编写了一个程序来更改屏幕的滤色器，类似于 Flux 所做的方式（显示的代码在主要问题 from here 中）。但是，我的几个用户说它不会影响具有两个或更多显示器的其他屏幕。我将如何修改代码以使其正常运行？
【问题讨论】：
它在有两个显示器的机器上什么都不做，还是抛出错误？它只改变一个屏幕吗？用户体验如何？ 它显然对第二个屏幕没有任何作用。 【参考方案1】：你可以这样做
-
获取所有连接的监视器
将 get/set 函数应用到 Graphics（或其 HDC）。
注册
MonitorInfoInvalidated 事件以重新申请，如果监视器信息失效。
如果您已经依赖于Windows.Forms dll，或者不介意承担这种依赖关系，您可以使用它的Screen 类，正如@HansPassant 在他的answer 中指出的那样。在这种情况下，您将为 SystemEvents.DisplaySettingsChanged 注册一个事件处理程序以触发重新应用您的 get/set 函数，并且您将使用对 CreateDC 和 DeleteDC 的互操作调用从 Screen.DeviceName 获取/释放设备上下文句柄 (IntPtr)财产。下面的代码显示了一个围绕这个类的包装器，它有助于做到这一点：
/// <summary>
/// This is an alternative that uses the Windows.Forms Screen class.
/// </summary>
public static class FormsScreens
public static void ForAllScreens(Action<Screen, IntPtr> actionWithHdc)
foreach (var screen in Screen.AllScreens)
screen.WithHdc(actionWithHdc);
public static void WithHdc(this Screen screen, Action<Screen, IntPtr> action)
var hdc = IntPtr.Zero;
try
hdc = CreateDC(null, screen.DeviceName, null, IntPtr.Zero);
action(screen, hdc);
finally
if (!IntPtr.Zero.Equals(hdc))
DeleteDC(hdc);
private const string GDI32 = @"gdi32.dll";
[DllImport(GDI32, EntryPoint = "CreateDC", CharSet = CharSet.Auto)]
static extern IntPtr CreateDC(string lpszDriver, string lpszDevice, string lpszOutput, IntPtr lpInitData);
[DllImport(GDI32, CharSet = CharSet.Auto)]
private static extern bool DeleteDC([In] IntPtr hdc);
如果您不想对Windows.Forms dll 产生新的依赖，下面的ConnectedMonitors 类提供了相同的功能：
/// <summary>
/// This is the version that is not dependent on Windows.Forms dll.
/// </summary>
public static class ConnectedMonitors
private static readonly bool _isSingleMonitor = GetSystemMetrics(SM_CMONITORS) == 0;
private static Lazy<List<MonitorInfo>> _monitors = new Lazy<List<MonitorInfo>>(GetMonitors, true);
public static event Action MonitorInfoInvalidated;
public class MonitorInfo
public readonly IntPtr MonitorHandle;
public readonly IntPtr DeviceContextHandle;
public readonly string DeviceName;
public readonly bool IsPrimary;
public readonly Rectangle Bounds;
public readonly Rectangle WorkArea;
public void WithMonitorHdc(Action<MonitorInfo, IntPtr> action)
var hdc = DeviceContextHandle;
var shouldDeleteDC = IntPtr.Zero.Equals(hdc);
try
if (shouldDeleteDC)
hdc = CreateDC(null, DeviceName, null, IntPtr.Zero);
action(this, hdc);
finally
if (shouldDeleteDC && !IntPtr.Zero.Equals(hdc))
DeleteDC(hdc);
internal MonitorInfo(
IntPtr hMonitor,
IntPtr hDeviceContext,
string deviceName,
bool isPrimary,
Rectangle bounds,
Rectangle workArea)
this.MonitorHandle = hMonitor;
this.DeviceContextHandle = hDeviceContext;
this.DeviceName = deviceName;
this.IsPrimary = isPrimary;
this.Bounds = bounds;
this.WorkArea = workArea;
public static void CaptureScreen(MonitorInfo mi, string fileName)
CaptureScreen(mi).Save(fileName);
public static Bitmap CaptureScreen(MonitorInfo mi)
Bitmap screenBmp = default(Bitmap);
mi.WithMonitorHdc((m, hdc) =>
screenBmp = new Bitmap(m.Bounds.Width, m.Bounds.Height, PixelFormat.Format32bppArgb);
using (var destGraphics = Graphics.FromImage(screenBmp))
var monitorDC = new HandleRef(null, hdc);
var destDC = new HandleRef(null, destGraphics.GetHdc());
var result = BitBlt(destDC, 0, 0, m.Bounds.Width, m.Bounds.Height, monitorDC, 0, 0, unchecked((int)BITBLT_SRCCOPY));
if (result == 0)
throw new Win32Exception();
);
return screenBmp;
public static IEnumerable<MonitorInfo> Monitors
get return _monitors.Value;
private static List<MonitorInfo> GetMonitors()
// Get info on all monitors
var cb = new EnumMonitorsCallback();
EnumDisplayMonitors(IntPtr.Zero, IntPtr.Zero, cb.Callback, IntPtr.Zero);
// Register for events invalidating monitor info.
SystemEvents.DisplaySettingsChanging += OnDisplaySettingsChanging;
SystemEvents.UserPreferenceChanged += OnUserPreferenceChanged;
// Return result.
return cb.Monitors;
private class EnumMonitorsCallback
public List<MonitorInfo> Monitors = new List<MonitorInfo>();
public bool Callback(IntPtr hMonitor, IntPtr hdcMonitor, ref RECT lprcMonitor, IntPtr lparam)
// Get its info
var info = new MONITORINFOEX();
info.Size = Marshal.SizeOf(typeof(MONITORINFOEX));
GetMonitorInfo(hMonitor, ref info);
// Decode the info
var isPrimary = (hMonitor == (IntPtr)PRIMARY_MONITOR) || ((info.Flags & MONITORINFOF_PRIMARY) != 0);
var bounds = Rectangle.FromLTRB(info.Monitor.Left, info.Monitor.Top, info.Monitor.Right, info.Monitor.Bottom);
var workArea = Rectangle.FromLTRB(info.WorkArea.Left, info.WorkArea.Top, info.WorkArea.Right, info.WorkArea.Bottom);
var deviceName = info.DeviceName.TrimEnd('\0');
// Create info for this monitor and add it.
Monitors.Add(new MonitorInfo(hMonitor, hdcMonitor, deviceName, isPrimary, bounds, workArea));
return true;
private static void OnDisplaySettingsChanging(object sender, EventArgs e)
InvalidateInfo();
private static void OnUserPreferenceChanged(object sender, UserPreferenceChangedEventArgs e)
InvalidateInfo();
private static void InvalidateInfo()
SystemEvents.DisplaySettingsChanging -= OnDisplaySettingsChanging;
SystemEvents.UserPreferenceChanged -= OnUserPreferenceChanged;
var cur = _monitors;
_monitors = new Lazy<List<MonitorInfo>>(GetMonitors, true);
var notifyInvalidated = MonitorInfoInvalidated;
if (notifyInvalidated != null)
notifyInvalidated();
#region Interop
private const string USER32 = @"user32.dll";
private const string GDI32 = @"gdi32.dll";
private const int PRIMARY_MONITOR = unchecked((int)0xBAADF00D);
private const int MONITORINFOF_PRIMARY = 0x00000001;
private const int SM_CMONITORS = 80;
private const int BITBLT_SRCCOPY = 0x00CC0020;
private const int BITBLT_CAPTUREBLT = 0x40000000;
private const int BITBLT_CAPTURE = BITBLT_SRCCOPY | BITBLT_CAPTUREBLT;
[StructLayout(LayoutKind.Sequential)]
private struct RECT
public int Left;
public int Top;
public int Right;
public int Bottom;
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct MONITORINFOEX
public int Size;
public RECT Monitor;
public RECT WorkArea;
public uint Flags;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string DeviceName;
delegate bool EnumMonitorsDelegate(IntPtr hMonitor, IntPtr hdcMonitor, ref RECT lprcMonitor, IntPtr dwData);
[DllImport(USER32, CharSet=CharSet.Auto)]
private static extern bool EnumDisplayMonitors(IntPtr hdc, IntPtr lprcClip, EnumMonitorsDelegate lpfnEnum, IntPtr dwData);
[DllImport(USER32, CharSet = CharSet.Auto)]
private static extern bool GetMonitorInfo(IntPtr hMonitor, ref MONITORINFOEX lpmi);
[DllImport(USER32, CharSet = CharSet.Auto)]
private static extern int GetSystemMetrics(int nIndex);
[DllImport(GDI32, EntryPoint = "CreateDC", CharSet = CharSet.Auto)]
static extern IntPtr CreateDC(string lpszDriver, string lpszDevice, string lpszOutput, IntPtr lpInitData);
[DllImport(GDI32, CharSet = CharSet.Auto)]
private static extern bool DeleteDC([In] IntPtr hdc);
[DllImport(GDI32, CharSet = CharSet.Auto)]
public static extern int BitBlt(HandleRef hDC, int x, int y, int nWidth, int nHeight,
HandleRef hSrcDC, int xSrc, int ySrc, int dwRop);
#endregion
您的用例的使用示例，使用稍微修改的SetLCDbrightness 方法：
private bool SetLCDbrightness(IntPtr hdc, Color c)
short red = c.R;
short green = c.G;
short blue = c.B;
unsafe
short* gArray = stackalloc short[3 * 256];
short* idx = gArray;
short brightness = 0;
for (int j = 0; j < 3; j++)
if (j == 0) brightness = red;
if (j == 1) brightness = green;
if (j == 2) brightness = blue;
for (int i = 0; i < 256; i++)
int arrayVal = i * (brightness);
if (arrayVal > 65535) arrayVal = 65535;
*idx = (short)arrayVal;
idx++;
// For some reason, this always returns false?
bool retVal = SetDeviceGammaRamp(hdc, gArray);
return false;
调用如下：
// ConnectedMonitors variant
public void SetBrightness(Color c)
foreach (var monitor in ConnectedMonitors.Monitors)
monitor.WithMonitorHdc((m, hdc) => SetLCDbrightness(hdc, c));
// Variant using the Windows.Forms Screen class
public void SetBrightness(Color c)
var setBrightness = new Action<Screen, IntPtr>((s, hdc) => SetLCDbrightness(hdc, c));
FormsScreens.ForAllScreens(setBrightness);
请注意，它还允许进行一些其他有趣的事情，例如截屏：
var n = 0;
foreach (var m in ConnectedMonitors.Monitors)
ConnectedMonitors.CaptureScreen(m, string.Format(@"c:\temp\screen0.bmp", n++));
【讨论】：
哇，没想到会这么复杂——很棒的工作。当我尝试编译时出现一个问题 - 我得到：“找不到类型或命名空间名称‘Lazy’”。不幸的是，我无法“解决”这个问题。 @DanW 类System.Lazy<T> 可以在System 命名空间中找到。确保您有 using System; 声明。它从 .NET 4 开始可用。如果您使用的是旧版本的 .NET，创建一个简单的替换实现应该不难。
是的，由于潜在的更大用户群，我倾向于将 .NET 3.5 用于我的所有程序。创建它需要超过 5-10 行代码供您添加吗？如果是这样，我会看看我是否可以为这个程序切换到 .NET 4。
@DanW 你可以找到一个here。它有超过 10 行代码，所以我想是时候升级到更新的 .NET 版本了；-)
哈哈，很公平 - 我会捏它。顺便问一下，你的答案与汉斯的优劣相比如何？【参考方案2】：
当机器有多个显示适配器时，您的代码无法工作，这种情况并不少见。所以 GetDC() 不正确，您需要改为 pinvoke CreateDC()，将屏幕名称（如 @"\\.\DISPLAY1"）作为第一个参数传递，其余为空。使用 DeleteDC() 进行清理。
使用Screen.DeviceName 属性获取设备名称，Screen.AllScreens() 枚举监视器。你可能应该订阅 SystemEvents.DisplaySettingsChanged 事件来检测用户启用了监视器，我没有硬件来检查这个。
【讨论】：
谢谢。就利弊而言，您的答案与 Alex 的答案相比如何？老实说，我可能不是第一个应该判断赏金获胜者的人。尽管就我个人而言，我需要您的答案更加充实，最好是使用代码。顺便说一句，我相信你知道，但以防万一它有什么不同，请注意 GetDC() 不用于写入屏幕颜色的方法，只读取它。也许你的意思是 GetHdc()？ 我不明白他为什么把它弄得这么复杂，使用 Screen 类很容易。 @HansPassant，你说得对，这可以使用 Windows 窗体Screens 类来完成，它与我的回答中的 ConnectedMonitors 类几乎相同。这是我在一个软件中使用的东西，它不需要任何其他对 Windows 窗体的依赖，并且具有额外的功能来确定显示设备是否可拆卸、活动、它们的物理尺寸是什么、支持的分辨率......如果 OP 不需要阻止对 Windows 窗体的依赖，则使用其 Screens 类的解决方案同样可以正常工作。我会相应地更新我的答案。以上是关于更改屏幕的滤色器以与多台显示器一起使用的主要内容，如果未能解决你的问题，请参考以下文章
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