Audio Book Player

using System;
using System.Runtime.InteropServices;
using System.Collections.Generic;
using System.IO;
using Microsoft.Win32;
using System.Text;

// this helper class encapsulates various API calls and methods
// that work fine (after numerous trial-and-error) on my device
// (ASUS MyPal 639) but may not perform on other devices and may
// need device adaptation
public enum ePlaySoundFlags
{
    SND_ALIAS = 0x10000,
    SND_FILENAME = 0x20000,
    SND_RESOURCE = 0x40004,
    SND_SYNC = 0x0,
    SND_ASYNC = 0x1,
    SND_NODEFAULT = 0x2,
    SND_MEMORY = 0x4,
    SND_LOOP = 0x8,
    SND_NOSTOP = 0x10,
    SND_NOWAIT = 0x2000,
    SND_VALIDFLAGS = 0x17201F,
    SND_TYPE_MASK = 0x170007
};

public class cASUS639DeviceSpecifics : cBaseDeviceSpecifics
{
    // System power status structure
    [StructLayout(LayoutKind.Sequential)]
    internal struct SYSTEM_POWER_STATUS_EX
    {
        public byte ACLineStatus;
        public byte BatteryFlag;
        public byte BatteryLifePercent;
        public byte Reserved1;
        public uint BatteryLifeTime;
        public uint BatteryFullLifeTime;
        public byte Reserved2;
        public byte BackupBatteryFlag;
        public byte BackupBatteryLifePercent;
        public byte Reserved3;
        public uint BackupBatteryLifeTime;
        public uint BackupBatteryFullLifeTime;
    }

    [DllImport("coredll.dll")]
    public extern static int SetSystemPowerState(IntPtr psState, int StateFlags,
        int Options);
    [DllImport("coredll.dll")]
    public extern static int PlaySound(string szSound, IntPtr hMod, int flags);
    [DllImport("coredll")]
    public static extern int waveOutSetVolume(IntPtr hMod, int lVolume);
    [DllImport("coredll")]
    public static extern int waveOutGetVolume(IntPtr hMod, ref int lVolume);
    [DllImport("Coredll.dll")]
    internal static extern bool GetSystemPowerStatusEx(ref SYSTEM_POWER_STATUS_EX pstatus, bool fUpdate);
    [DllImport("coredll.dll")]
    public static extern void SystemIdleTimerReset();
    [DllImport("Aygshell.dll")]
    public static extern void SHIdleTimerReset();
    [DllImport("coredll.dll")]
    public static extern int SystemParametersInfo(uint uiAction,
        uint uiParam, ref uint pvParam, uint fWinIni);

    // constants
    private const int POWER_STATE_OFF = (int)(0x00020000);
    private const int POWER_FORCE = (int)(0x00001000);
    private const uint SPI_GETSCREENSAVETIMEOUT = 14;
    private const uint SPI_SETSCREENSAVEACTIVE = 17;
    // Backlight registry constants
    private const String BACKLIGHT_ROOT_KEY = "ControlPanel";
    private const String BACKLIGHT_SUB_KEY = "BackLight";
    private const String BACKLIGHT_ENTRY = "BatteryTimeout";
    private const int BACKLIGHT_DEFAULT_VALUE = 30;
    // sound related vars
    private string PLAYLIST_READY_FILE = "";
    private const String BEEP_ROOT_KEY = "ControlPanel\\Notifications\\Default";
    private const String BEEP_VALUE = "Wave";
    private const String BEEP_PATH = "\\Windows\\";
    private const String BEEP_DEFAULT_FILE = "Notify";

    // play notification beep
    public override void Beep()
    {
        string str = "";
        if (PLAYLIST_READY_FILE == "")
        {
            RegistryKey RK = null;
            try
            {
                RK = Registry.CurrentUser.OpenSubKey(BEEP_ROOT_KEY, true);
                str = (String)RK.GetValue(BEEP_VALUE,
                    BEEP_DEFAULT_FILE);
                PLAYLIST_READY_FILE = (File.Exists(BEEP_PATH + str + ".wav"))?
                    BEEP_PATH + str + ".wav": "-";

            }
            catch
            {
                PLAYLIST_READY_FILE = "-";
            }
            finally
            {
                if (RK != null) RK.Close();
            }
        }

        str = (PLAYLIST_READY_FILE == "-") ? "" : PLAYLIST_READY_FILE;
        ePlaySoundFlags flag = (str == "")? 
            ePlaySoundFlags.SND_ALIAS: ePlaySoundFlags.SND_FILENAME;
        PlaySound(str, IntPtr.Zero, (int)(ePlaySoundFlags.SND_ASYNC | flag));
    }
    // get/set the wave master volume
    // the master volume is a 2-word value representing the left and right
    // value in each word. value is between 0 and maxvalue of a word - 64k
    // we use pecentage values and convert from and to with the help of
    // functions later in this class
    // we set both the left and right parts to the same level
    public override int Volume
    {
        get
        {
            // get volume into v
            int v = 0;
            waveOutGetVolume(IntPtr.Zero, ref v);
            // convert to percentage
            return NativeVolToPercent(v);
        }
        set
        {
            // set after converting from percentage to native values
            waveOutSetVolume(IntPtr.Zero, PercentToNativeVol(value));
        }
    }
    // convert percentage to device volume values
    private int PercentToNativeVol(int percent)
    {
        int i = (int)(((0xFFFF * 1.0) * percent) / 100.0);
        return i + i * 0x10000;
    }
    // convert device volume values to percentage
    private int NativeVolToPercent(int vol)
    {
        int i = (vol & 0xFFFF);
        return (int)(i * 100.0 / (0xFFFF * 1.0));
    }
    // power and backlight functions
    public override long PowerOffThreshold
    {
        get
        {
            // get device screensave timeout 
            uint timeout = uint.MaxValue;
            SystemParametersInfo(SPI_GETSCREENSAVETIMEOUT, 0, ref timeout, 0);
            // set desired threshold
            return (timeout < 30) ? 20 : timeout - 20;
        }
    }
    // keep system runnung
    public override void PreventAutoPowerOff()
    {
        SystemIdleTimerReset();
        SHIdleTimerReset();
    }
    // get power state
    public override PowerState PowerAndBatteryState
    {
        get
        {
            SYSTEM_POWER_STATUS_EX system_power_status_ex = new SYSTEM_POWER_STATUS_EX();
            GetSystemPowerStatusEx(ref system_power_status_ex, true);
            return new PowerState((system_power_status_ex.ACLineStatus == 1),
                system_power_status_ex.BatteryLifePercent);
        }
    }
    // power off device
    public override void PowerOff()
    {
        SetSystemPowerState((IntPtr)null, POWER_STATE_OFF, POWER_FORCE);
    }
    // get/set backlight timeout
    public override int BacklightTimeout
    {
        get
        {
            int blto = 0;
            RegistryKey RK = null;
            RegistryKey SRK = null;
            try
            {
                RK = Registry.CurrentUser.OpenSubKey(BACKLIGHT_ROOT_KEY, true);
                SRK = RK.OpenSubKey(BACKLIGHT_SUB_KEY, true);
                blto = (int)SRK.GetValue(BACKLIGHT_ENTRY,
                    BACKLIGHT_DEFAULT_VALUE);
            }
            catch
            {
            }
            finally
            {
                if (SRK != null) SRK.Close();
                if (RK != null) RK.Close();
            }
            return blto;
        }
        set
        {
            RegistryKey RK = null;
            RegistryKey SRK = null;
            try
            {
                RK = Registry.CurrentUser.OpenSubKey(BACKLIGHT_ROOT_KEY, true);
                SRK = RK.OpenSubKey(BACKLIGHT_SUB_KEY, true);
                SRK.SetValue(BACKLIGHT_ENTRY, value, RegistryValueKind.DWord);
            }
            catch
            {
            }
            finally
            {
                if (SRK != null) SRK.Close();
                if (RK != null) RK.Close();
            }
        }
    }
}