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如何使用电源管理功能（PowerEnuimerate）获取电源设置。

c#.netwindowsdesktop
5
我需要让我的应用程序读取系统在关闭显示器、进入睡眠或休眠之前等待的时间。据我所知，我需要使用电源管理功能（http://msdn.microsoft.com/en-us/library/aa373163%28v=vs.85%29.aspx）。特别是，看起来我需要使用PowerEnumerate方法（http://msdn.microsoft.com/en-us/library/aa372730%28v=vs.85%29.aspx）。
我对如何做到这一点感到非常困惑。首先，我正在使用C＃进行操作，但代码似乎是C ++。其次，C ++代码似乎没有真正告诉你如何具体读取我想要的不同超时时间。
请注意，我是Windows编程和C＃的新手。大部分经验都是Java和Android方面的。
谢谢。
3个回答
13

我在MSDN上找到了一个关于如何在VB中使用PowerEnumerate函数的示例。

我已将示例转换为C#，并在循环中的每个视频设置输出中添加了友好名称。您可以将 GUID_VIDEO_SUBGROUP 更改为其他子组之一以查看其他设置。

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Text;

namespace TestProject
{
    class PowerEnumerator
    {
        private static Guid NO_SUBGROUP_GUID = new Guid("fea3413e-7e05-4911-9a71-700331f1c294");
        private static Guid GUID_DISK_SUBGROUP = new Guid("0012ee47-9041-4b5d-9b77-535fba8b1442");
        private static Guid GUID_SYSTEM_BUTTON_SUBGROUP = new Guid("4f971e89-eebd-4455-a8de-9e59040e7347");
        private static Guid GUID_PROCESSOR_SETTINGS_SUBGROUP = new Guid("54533251-82be-4824-96c1-47b60b740d00");
        private static Guid GUID_VIDEO_SUBGROUP = new Guid("7516b95f-f776-4464-8c53-06167f40cc99");
        private static Guid GUID_BATTERY_SUBGROUP = new Guid("e73a048d-bf27-4f12-9731-8b2076e8891f");
        private static Guid GUID_SLEEP_SUBGROUP = new Guid("238C9FA8-0AAD-41ED-83F4-97BE242C8F20");
        private static Guid GUID_PCIEXPRESS_SETTINGS_SUBGROUP = new Guid("501a4d13-42af-4429-9fd1-a8218c268e20");

        [DllImport("powrprof.dll")]
        static extern uint PowerEnumerate(
            IntPtr RootPowerKey,
            IntPtr SchemeGuid,
            ref Guid SubGroupOfPowerSetting,
            uint AccessFlags,
            uint Index,
            ref Guid Buffer,
            ref uint BufferSize);

        [DllImport("powrprof.dll")]
        static extern uint PowerGetActiveScheme(
            IntPtr UserRootPowerKey,
            ref IntPtr ActivePolicyGuid);

        [DllImport("powrprof.dll")]
        static extern uint PowerReadACValue(
            IntPtr RootPowerKey,
            IntPtr SchemeGuid,
            IntPtr SubGroupOfPowerSettingGuid,
            ref Guid PowerSettingGuid,
            ref int Type,
            ref IntPtr Buffer,
            ref uint BufferSize
            );

        [DllImport("powrprof.dll", CharSet = CharSet.Unicode)]
        static extern uint PowerReadFriendlyName(
            IntPtr RootPowerKey,
            IntPtr SchemeGuid,
            IntPtr SubGroupOfPowerSettingGuid,
            IntPtr PowerSettingGuid,
            StringBuilder Buffer,
            ref uint BufferSize
            );

        [DllImport("kernel32.dll")]
        static extern IntPtr LocalFree(
            IntPtr hMem
            );

        private const uint ERROR_MORE_DATA = 234;

        public static void GetCurrentPowerEnumerateVistaAPI()
        {
            IntPtr activeGuidPtr = IntPtr.Zero;
            try
            {
                uint res = PowerGetActiveScheme(IntPtr.Zero, ref activeGuidPtr);
                if (res != 0)
                    throw new Win32Exception();

                //Get Friendly Name
                uint buffSize = 0;
                StringBuilder buffer = new StringBuilder();
                Guid subGroupGuid = Guid.Empty;
                Guid powerSettingGuid = Guid.Empty;
                res = PowerReadFriendlyName(IntPtr.Zero, activeGuidPtr,
                    IntPtr.Zero, IntPtr.Zero, buffer, ref buffSize);

                if (res == ERROR_MORE_DATA)
                {
                    buffer.Capacity = (int)buffSize;
                    res = PowerReadFriendlyName(IntPtr.Zero, activeGuidPtr,
                        IntPtr.Zero, IntPtr.Zero, buffer, ref buffSize);
                }

                if (res != 0)
                    throw new Win32Exception();

                Console.WriteLine("ReadFriendlyName = " +
                    buffer.ToString());

                //Get the Power Settings
                Guid VideoSettingGuid = Guid.Empty;
                uint index = 0;
                uint BufferSize = Convert.ToUInt32(Marshal.SizeOf(typeof(Guid)));

                while (
                    PowerEnumerate(IntPtr.Zero, activeGuidPtr, ref GUID_VIDEO_SUBGROUP,
                    18, index, ref VideoSettingGuid, ref BufferSize) == 0)
                {
                    uint size = 4;
                    IntPtr temp = IntPtr.Zero;
                    int type = 0;
                    res = PowerReadACValue(IntPtr.Zero, activeGuidPtr, IntPtr.Zero,
                        ref VideoSettingGuid, ref type, ref temp, ref size);

                    IntPtr pSubGroup = Marshal.AllocHGlobal(Marshal.SizeOf(GUID_VIDEO_SUBGROUP));
                    Marshal.StructureToPtr(GUID_VIDEO_SUBGROUP, pSubGroup, false);
                    IntPtr pSetting = Marshal.AllocHGlobal(Marshal.SizeOf(VideoSettingGuid));
                    Marshal.StructureToPtr(VideoSettingGuid, pSetting, false);

                    uint builderSize = 200;
                    StringBuilder builder = new StringBuilder((int)builderSize);
                    res = PowerReadFriendlyName(IntPtr.Zero, activeGuidPtr,
                        pSubGroup, pSetting, builder, ref builderSize);
                    Console.WriteLine(builder.ToString() + " = " + temp.ToString());

                    index++;
                }
            }
            finally
            {
                if (activeGuidPtr != IntPtr.Zero)
                {
                    IntPtr res = LocalFree(activeGuidPtr);
                    if (res != IntPtr.Zero)
                        throw new Win32Exception();
                }
            }
        }
    }
}

这段代码的输出结果为：

电源设置

看起来我们正在使用一堆.dll文件。我在哪里可以找到它们的文档？ - Andi Jay
根据MSDN的PowerEnumerate页面（请参见页面底部），powrprof.dll似乎包含在较新版本的Windows（Vista及更高版本）中，并且kernel32.dll（LocalFree函数）至少从XP开始就是Windows的一部分：LocalFree on MSDN。 - endofzero
1
我正在尝试示例代码，但我注意到当我在“电源选项”对话框中更改单个设置时，重新运行示例时不会反映出更改。例如，我使用平衡计划，并将“最小处理器状态”从5％更改为100％，但输出始终显示5％。这是有什么原因吗？我该如何获取正确的值？ - sjlewis
1

我在寻找类似解决方案时遇到了这篇文章，并发现并纠正了一些错误。

我的IDE（Visual Studio 2019）需要一个主函数，所以我不得不弄清楚这个相当复杂的代码中应该放置在哪里。最后，我尝试将GetCurrentPowerEnumerateVistaAPI()重命名为Main()。我还结合了@Martijn Spaan的修复方法，稍作修改。不是使用ref settingGuid，而是使用ref videoSettingGuid。

现在它看起来像这样，并且按预期运行：

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Text;

namespace TestProject
{
    class PowerEnumerator
    {
        private static Guid NO_SUBGROUP_GUID = new Guid("fea3413e-7e05-4911-9a71-700331f1c294");
        private static Guid GUID_DISK_SUBGROUP = new Guid("0012ee47-9041-4b5d-9b77-535fba8b1442");
        private static Guid GUID_SYSTEM_BUTTON_SUBGROUP = new Guid("4f971e89-eebd-4455-a8de-9e59040e7347");
        private static Guid GUID_PROCESSOR_SETTINGS_SUBGROUP = new Guid("54533251-82be-4824-96c1-47b60b740d00");
        private static Guid GUID_VIDEO_SUBGROUP = new Guid("7516b95f-f776-4464-8c53-06167f40cc99");
        private static Guid GUID_BATTERY_SUBGROUP = new Guid("e73a048d-bf27-4f12-9731-8b2076e8891f");
        private static Guid GUID_SLEEP_SUBGROUP = new Guid("238C9FA8-0AAD-41ED-83F4-97BE242C8F20");
        private static Guid GUID_PCIEXPRESS_SETTINGS_SUBGROUP = new Guid("501a4d13-42af-4429-9fd1-a8218c268e20");

        [DllImport("powrprof.dll")]
        static extern uint PowerEnumerate(
            IntPtr RootPowerKey,
            IntPtr SchemeGuid,
            ref Guid SubGroupOfPowerSetting,
            uint AccessFlags,
            uint Index,
            ref Guid Buffer,
            ref uint BufferSize);

        [DllImport("powrprof.dll")]
        static extern uint PowerGetActiveScheme(
            IntPtr UserRootPowerKey,
            ref IntPtr ActivePolicyGuid);

        [DllImport("powrprof.dll")]
        static extern uint PowerReadACValue(
            IntPtr RootPowerKey,
            IntPtr SchemeGuid,
            IntPtr SubGroupOfPowerSettingGuid,
            ref Guid PowerSettingGuid,
            ref int Type,
            ref IntPtr Buffer,
            ref uint BufferSize
            );

        [DllImport("powrprof.dll", CharSet = CharSet.Unicode)]
        static extern uint PowerReadFriendlyName(
            IntPtr RootPowerKey,
            IntPtr SchemeGuid,
            IntPtr SubGroupOfPowerSettingGuid,
            IntPtr PowerSettingGuid,
            StringBuilder Buffer,
            ref uint BufferSize
            );

        [DllImport("kernel32.dll")]
        static extern IntPtr LocalFree(
            IntPtr hMem
            );

        private const uint ERROR_MORE_DATA = 234;

        public static void Main()
        //public static void GetCurrentPowerEnumerateVistaAPI()
        {
            IntPtr activeGuidPtr = IntPtr.Zero;
            try
            {
                uint res = PowerGetActiveScheme(IntPtr.Zero, ref activeGuidPtr);
                if (res != 0)
                    throw new Win32Exception();

                //Get Friendly Name
                uint buffSize = 0;
                StringBuilder buffer = new StringBuilder();
                Guid subGroupGuid = Guid.Empty;
                Guid powerSettingGuid = Guid.Empty;
                res = PowerReadFriendlyName(IntPtr.Zero, activeGuidPtr,
                    IntPtr.Zero, IntPtr.Zero, buffer, ref buffSize);

                if (res == ERROR_MORE_DATA)
                {
                    buffer.Capacity = (int)buffSize;
                    res = PowerReadFriendlyName(IntPtr.Zero, activeGuidPtr,
                        IntPtr.Zero, IntPtr.Zero, buffer, ref buffSize);
                }

                if (res != 0)
                    throw new Win32Exception();

                Console.WriteLine("ReadFriendlyName = " +
                    buffer.ToString());

                //Get the Power Settings
                Guid VideoSettingGuid = Guid.Empty;
                uint index = 0;
                uint BufferSize = Convert.ToUInt32(Marshal.SizeOf(typeof(Guid)));

                while (
                    PowerEnumerate(IntPtr.Zero, activeGuidPtr, ref GUID_VIDEO_SUBGROUP,
                    18, index, ref VideoSettingGuid, ref BufferSize) == 0)
                {
                    uint size = 4;
                    IntPtr temp = IntPtr.Zero;
                    int type = 0;

                    // My chenges
                    IntPtr pSubGroup = Marshal.AllocHGlobal(Marshal.SizeOf(GUID_VIDEO_SUBGROUP));
                    res = PowerReadACValue(IntPtr.Zero, activeGuidPtr, pSubGroup, ref VideoSettingGuid, ref type, ref temp, ref size);
                    // end my changes

                    Marshal.StructureToPtr(GUID_VIDEO_SUBGROUP, pSubGroup, false);
                    IntPtr pSetting = Marshal.AllocHGlobal(Marshal.SizeOf(VideoSettingGuid));
                    Marshal.StructureToPtr(VideoSettingGuid, pSetting, false);

                    uint builderSize = 200;
                    StringBuilder builder = new StringBuilder((int)builderSize);
                    res = PowerReadFriendlyName(IntPtr.Zero, activeGuidPtr,
                        pSubGroup, pSetting, builder, ref builderSize);
                    Console.WriteLine(builder.ToString() + " = " + temp.ToString());

                    index++;
                }
            }
            finally
            {
                if (activeGuidPtr != IntPtr.Zero)
                {
                    IntPtr res = LocalFree(activeGuidPtr);
                    if (res != IntPtr.Zero)
                        throw new Win32Exception();
                }
            }
            Console.ReadLine();
        }
    }
}
1
然而，被接受的答案仍然有效，我想指出其中存在一个错误，导致它枚举所有默认值而不是实际值。
在读取AC值时，还需要传递子组GUID：
res = PowerReadACValue(IntPtr.Zero, activeGuidPtr, pSubGroup, ref settingGuid, ref type, ref temp, ref size);
我正在读取电池设置，但无论设置是否为默认值，它始终返回零... - McGuireV10
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