c# - Windows 如何决定显示屏幕保护程序

Question

Windows 有一个内部机制，通过检查用户交互性和其他任务(有人正在观看视频等)来决定何时显示屏幕保护程序(或关闭屏幕)。

是否有 Win API 允许我询问用户是否处于事件状态，或者他们最后一次处于事件状态是什么时候？

Answer 1

它被称为“空闲计时器”。您可以通过调用 CallNtPowerInformation() 来获取它的值，询问 SystemPowerInformation。返回的 SYSTEM_POWER_INFORMATION.TimeRemaining 字段告诉您空闲计时器还剩多少时间。 SystemExecutionState 请求会告诉您是否有任何线程调用了 SetThreadExecutionState() 来停止计时器，就像显示视频的应用所做的那样。

using System;
using System.Runtime.InteropServices;

public static class PowerInfo {
    public static int GetIdleTimeRemaining() {
        var info = new SYSTEM_POWER_INFORMATION();
        int ret = GetSystemPowerInformation(SystemPowerInformation, IntPtr.Zero, 0, out info, Marshal.SizeOf(info));
        if (ret != 0) throw new System.ComponentModel.Win32Exception(ret);
        return info.TimeRemaining;
    }

    public static int GetExecutionState() {
        int state = 0;
        int ret = GetSystemExecutionState(SystemExecutionState, IntPtr.Zero, 0, out state, 4);
        if (ret != 0) throw new System.ComponentModel.Win32Exception(ret);
        return state;
    }

    private struct SYSTEM_POWER_INFORMATION {
        public int MaxIdlenessAllowed;
        public int Idleness;
        public int TimeRemaining;
        public byte CoolingMode;
    }
    private const int SystemPowerInformation = 12;
    private const int SystemExecutionState = 16;
    [DllImport("powrprof.dll", EntryPoint = "CallNtPowerInformation", CharSet = CharSet.Auto)]
    private static extern int GetSystemPowerInformation(int level, IntPtr inpbuf, int inpbuflen, out SYSTEM_POWER_INFORMATION info, int outbuflen);
    [DllImport("powrprof.dll", EntryPoint = "CallNtPowerInformation", CharSet = CharSet.Auto)]
    private static extern int GetSystemExecutionState(int level, IntPtr inpbuf, int inpbuflen, out int state, int outbuflen);

}