一个操作系统声音的类。控制系统声音

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
namespace WaveLib
{
    public class AudioMixerHelper
    {
        public const int MMSYSERR_NOERROR = 0;
        public const int MAXPNAMELEN = 32;
        public const int MIXER_LONG_NAME_CHARS = 64;
        public const int MIXER_SHORT_NAME_CHARS = 16;
        public const int MIXER_GETLINEINFOF_COMPONENTTYPE = 0x3;
        public const int MIXER_GETCONTROLDETAILSF_VALUE = 0x0;
        public const int MIXER_GETLINECONTROLSF_ONEBYTYPE = 0x2;
        public const int MIXER_SETCONTROLDETAILSF_VALUE = 0x0;
        public const int MIXERLINE_COMPONENTTYPE_DST_FIRST = 0x0;
        public const int MIXERLINE_COMPONENTTYPE_SRC_FIRST = 0x1000;
        public const int MIXERLINE_COMPONENTTYPE_DST_SPEAKERS =
             (MIXERLINE_COMPONENTTYPE_DST_FIRST + 4);
        public const int MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE =
             (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 3);
        public const int MIXERLINE_COMPONENTTYPE_SRC_LINE =
             (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 2);
        public const int MIXERCONTROL_CT_CLASS_FADER = 0x50000000;
        public const int MIXERCONTROL_CT_UNITS_UNSIGNED = 0x30000;
        public const int MIXERCONTROL_CONTROLTYPE_FADER =
             (MIXERCONTROL_CT_CLASS_FADER | MIXERCONTROL_CT_UNITS_UNSIGNED);
        public const int MIXERCONTROL_CONTROLTYPE_VOLUME =
             (MIXERCONTROL_CONTROLTYPE_FADER + 1);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerClose(int hmx);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerGetControlDetailsA(int hmxobj, ref 
              MIXERCONTROLDETAILS pmxcd, int fdwDetails);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerGetDevCapsA(int uMxId, MIXERCAPS
             pmxcaps, int cbmxcaps);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerGetID(int hmxobj, int pumxID, int
             fdwId);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerGetLineControlsA(int hmxobj, ref 
              MIXERLINECONTROLS pmxlc, int fdwControls);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerGetLineInfoA(int hmxobj, ref 
              MIXERLINE pmxl, int fdwInfo);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerGetNumDevs();
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerMessage(int hmx, int uMsg, int
             dwParam1, int dwParam2);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerOpen(out int phmx, int uMxId,
             int dwCallback, int dwInstance, int fdwOpen);
        [DllImport("winmm.dll", CharSet = CharSet.Ansi)]
        private static extern int mixerSetControlDetails(int hmxobj, ref 
              MIXERCONTROLDETAILS pmxcd, int fdwDetails);
        public struct MIXERCAPS
        {
            public int wMid;
            public int wPid;
            public int vDriverVersion;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAXPNAMELEN)]
            public string szPname;
            public int fdwSupport;
            public int cDestinations;
        }
        public struct MIXERCONTROL
        {
            public int cbStruct;
            public int dwControlID;
            public int dwControlType;
            public int fdwControl;
            public int cMultipleItems;
            [MarshalAs(UnmanagedType.ByValTStr,
                  SizeConst = MIXER_SHORT_NAME_CHARS)]
            public string szShortName;
            [MarshalAs(UnmanagedType.ByValTStr,
                  SizeConst = MIXER_LONG_NAME_CHARS)]
            public string szName;
            public int lMinimum;
            public int lMaximum;
            [MarshalAs(UnmanagedType.U4, SizeConst = 10)]
            public int reserved;
        }
        public struct MIXERCONTROLDETAILS
        {
            public int cbStruct;
            public int dwControlID;
            public int cChannels;
            public int item;
            public int cbDetails;
            public IntPtr paDetails;
        }
        public struct MIXERCONTROLDETAILS_UNSIGNED
        {
            public int dwValue;
        }
        public struct MIXERLINE
        {
            public int cbStruct;
            public int dwDestination;
            public int dwSource;
            public int dwLineID;
            public int fdwLine;
            public int dwUser;
            public int dwComponentType;
            public int cChannels;
            public int cConnections;
            public int cControls;
            [MarshalAs(UnmanagedType.ByValTStr,
                  SizeConst = MIXER_SHORT_NAME_CHARS)]
            public string szShortName;
            [MarshalAs(UnmanagedType.ByValTStr,
                  SizeConst = MIXER_LONG_NAME_CHARS)]
            public string szName;
            public int dwType;
            public int dwDeviceID;
            public int wMid;
            public int wPid;
            public int vDriverVersion;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAXPNAMELEN)]
            public string szPname;
        }
        public struct MIXERLINECONTROLS
        {
            public int cbStruct;
            public int dwLineID;
            public int dwControl;
            public int cControls;
            public int cbmxctrl;
            public IntPtr pamxctrl;
        }
        private static bool GetVolumeControl(int hmixer, int componentType,
             int ctrlType, out MIXERCONTROL mxc, out int vCurrentVol)
        {
            // This function attempts to obtain a mixer control. 
            // Returns True if successful. 
            MIXERLINECONTROLS mxlc = new MIXERLINECONTROLS();
            MIXERLINE mxl = new MIXERLINE();
            MIXERCONTROLDETAILS pmxcd = new MIXERCONTROLDETAILS();
            MIXERCONTROLDETAILS_UNSIGNED du = new
                 MIXERCONTROLDETAILS_UNSIGNED();
            mxc = new MIXERCONTROL();
            int rc;
            bool retValue;
            vCurrentVol = -1;
            mxl.cbStruct = Marshal.SizeOf(mxl);
            mxl.dwComponentType = componentType;
            rc = mixerGetLineInfoA(hmixer, ref mxl,
                 MIXER_GETLINEINFOF_COMPONENTTYPE);
            if (MMSYSERR_NOERROR == rc)
            {
                int sizeofMIXERCONTROL = 152;
                int ctrl = Marshal.SizeOf(typeof(MIXERCONTROL));
                mxlc.pamxctrl = Marshal.AllocCoTaskMem(sizeofMIXERCONTROL);
                mxlc.cbStruct = Marshal.SizeOf(mxlc);
                mxlc.dwLineID = mxl.dwLineID;
                mxlc.dwControl = ctrlType;
                mxlc.cControls = 1;
                mxlc.cbmxctrl = sizeofMIXERCONTROL;
                // Allocate a buffer for the control 
                mxc.cbStruct = sizeofMIXERCONTROL;
                // Get the control 
                rc = mixerGetLineControlsA(hmixer, ref mxlc,
                    MIXER_GETLINECONTROLSF_ONEBYTYPE);
                if (MMSYSERR_NOERROR == rc)
                {
                    retValue = true;
                    // Copy the control into the destination structure 
                    mxc = (MIXERCONTROL) Marshal.PtrToStructure(
                         mxlc.pamxctrl, typeof(MIXERCONTROL));
                }
                else
                {
                    retValue = false;
                }
                int sizeofMIXERCONTROLDETAILS =
                    Marshal.SizeOf(typeof(MIXERCONTROLDETAILS));
                int sizeofMIXERCONTROLDETAILS_UNSIGNED =
                    Marshal.SizeOf(typeof(MIXERCONTROLDETAILS_UNSIGNED));
                pmxcd.cbStruct = sizeofMIXERCONTROLDETAILS;
                pmxcd.dwControlID = mxc.dwControlID;
                pmxcd.paDetails =
                    Marshal.AllocCoTaskMem(sizeofMIXERCONTROLDETAILS_UNSIGNED);
                pmxcd.cChannels = 1;
                pmxcd.item = 0;
                pmxcd.cbDetails = sizeofMIXERCONTROLDETAILS_UNSIGNED;
                rc = mixerGetControlDetailsA(hmixer, ref pmxcd,
                    MIXER_GETCONTROLDETAILSF_VALUE);
                du = (MIXERCONTROLDETAILS_UNSIGNED) Marshal.PtrToStructure(
                    pmxcd.paDetails, typeof(MIXERCONTROLDETAILS_UNSIGNED));
                vCurrentVol = du.dwValue;
                return retValue;
            }
            retValue = false;
            return retValue;
        }
        private static bool SetVolumeControl(int hmixer, MIXERCONTROL mxc,
             int volume)
        {
            // This function sets the value for a volume control. 
            // Returns True if successful 
            bool retValue;
            int rc;
            MIXERCONTROLDETAILS mxcd = new MIXERCONTROLDETAILS();
            MIXERCONTROLDETAILS_UNSIGNED vol = new
                 MIXERCONTROLDETAILS_UNSIGNED();
            mxcd.item = 0;
            mxcd.dwControlID = mxc.dwControlID;
            mxcd.cbStruct = Marshal.SizeOf(mxcd);
            mxcd.cbDetails = Marshal.SizeOf(vol);
            // Allocate a buffer for the control value buffer 
            mxcd.cChannels = 1;
            vol.dwValue = volume;
            // Copy the data into the control value buffer 
            mxcd.paDetails = Marshal.AllocCoTaskMem(Marshal.SizeOf(
                 typeof(MIXERCONTROLDETAILS_UNSIGNED)));
            Marshal.StructureToPtr(vol, mxcd.paDetails, false);
            // Set the control value 
            rc = mixerSetControlDetails(hmixer, ref mxcd,
                 MIXER_SETCONTROLDETAILSF_VALUE);
            if (MMSYSERR_NOERROR == rc)
            {
                retValue = true;
            }
            else
            {
                retValue = false;
            }
            return retValue;
        }
        public static int GetVolume()
        {
            int mixer;
            MIXERCONTROL volCtrl = new MIXERCONTROL();
            int currentVol;
            mixerOpen(out mixer, 0, 0, 0, 0);
            int type = MIXERCONTROL_CONTROLTYPE_VOLUME;
            GetVolumeControl(mixer,
                 MIXERLINE_COMPONENTTYPE_DST_SPEAKERS, type, out volCtrl, out 
                   currentVol);
            mixerClose(mixer);
            return currentVol;
        }
        public static void SetVolume(int vVolume)
        {
            int mixer;
            MIXERCONTROL volCtrl = new MIXERCONTROL();
            int currentVol;
            mixerOpen(out mixer, 0, 0, 0, 0);
            int type = MIXERCONTROL_CONTROLTYPE_VOLUME;
            GetVolumeControl(mixer,
                 MIXERLINE_COMPONENTTYPE_DST_SPEAKERS, type, out volCtrl, out 
                   currentVol);
            if (vVolume > volCtrl.lMaximum)
                vVolume = volCtrl.lMaximum;
            if (vVolume < volCtrl.lMinimum)
                vVolume = volCtrl.lMinimum;
            SetVolumeControl(mixer, volCtrl, vVolume);
            GetVolumeControl(mixer,
                 MIXERLINE_COMPONENTTYPE_DST_SPEAKERS, type, out volCtrl, out 
                   currentVol);
            if (vVolume != currentVol)
            {
                throw new Exception("Cannot Set Volume");
            }
            mixerClose(mixer);
        }
    }
}