调节电脑声音，并调出电脑音量显示条，实时显示

【核心代码】

using CoreAudioApi;
using SuperClassServer;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace PCVolumeControl
{
   /// <summary>
   /// 电脑音量控制类
   /// </summary>
   public static class VolumeControl
    {     
        /// <summary>
        /// volume -2 静音 -1解除静音
        /// </summary>
        /// <param name="volume"></param>
        public static void SetVolume(int volume)
        {
            if (volume == -2)
            {
                Mute();
            }
            if (volume >= 0)
            {
                SetSYSTEMVolume(volume);
            }
        }
        #region 控制系统的声音
        [DllImport("user32.dll")]
        static extern void keybd_event(byte bVk, byte bScan, UInt32 dwFlags, UInt32 dwExtraInfo);
        [DllImport("user32.dll")]
        static extern Byte MapVirtualKey(UInt32 uCode, UInt32 uMapType);
        private const byte VK_VOLUME_MUTE = 0xAD;
        private const byte VK_VOLUME_DOWN = 0xAE;
        private const byte VK_VOLUME_UP = 0xAF;
        private const UInt32 KEYEVENTF_EXTENDEDKEY = 0x0001;
        private const UInt32 KEYEVENTF_KEYUP = 0x0002;
        /// <summary>
        /// 改变系统音量大小，增加
        /// </summary>
        static void VolumeUp()
        {
            keybd_event(VK_VOLUME_UP, MapVirtualKey(VK_VOLUME_UP, 0), KEYEVENTF_EXTENDEDKEY, 0);
            keybd_event(VK_VOLUME_UP, MapVirtualKey(VK_VOLUME_UP, 0), KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
        }
        /// <summary>
        /// 改变系统音量大小，减小
        /// </summary>
        static void VolumeDown()
        {
            keybd_event(VK_VOLUME_DOWN, MapVirtualKey(VK_VOLUME_DOWN, 0), KEYEVENTF_EXTENDEDKEY, 0);
            keybd_event(VK_VOLUME_DOWN, MapVirtualKey(VK_VOLUME_DOWN, 0), KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
        }
        /// <summary>
        /// 改变系统音量大小，静音
        /// </summary>
        static void Mute()
        {
            keybd_event(VK_VOLUME_MUTE, MapVirtualKey(VK_VOLUME_MUTE, 0), KEYEVENTF_EXTENDEDKEY, 0);
            keybd_event(VK_VOLUME_MUTE, MapVirtualKey(VK_VOLUME_MUTE, 0), KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, 0);
        }

        /// <summary>
        /// 改变电脑的音量
        /// </summary>       
        /// <param name="targetValue">目标音量值</param>
        public static void ChangeVolume(float targetValue)
        {
            //先通过CoreAudioApi得到当前音量值
            CoreAudioApi.MMDeviceEnumerator devices = new MMDeviceEnumerator();
            MMDevice device = devices.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia);
            //MasterVolumeLevelScalar为0-1范围的值
            float currentValue = device.AudioEndpointVolume.MasterVolumeLevelScalar * 100;
            int offset = (int)(targetValue - currentValue);           
            //如果没有改变
            if (offset == 0)
            {
                return;
            }
            //如果是增大
            else if (offset > 0)
            {
                //得到需要改变的次数，因为每次改变的值是2
                int changeNum = (int)(offset / 2);
                //如果目标值是100
                if (targetValue == 100)
                {
                    //改变的次数加1，是因为当改变的次数除不尽时，取整会少一个，加一可以避免加不到100
                    changeNum  = 1;
                }
                for (int i = 0; i < changeNum; i  )
                {
                    VolumeUp();
                }
            }
            else
            {
                //得到需要改变的次数，因为每次改变的值是2
                int changeNum = (int)(offset / 2);
                //如果目标值是0
                if (targetValue == 0)
                { 
                    //改变的次数加1，是因为当改变的次数除不尽时，取整会少一个，加一可以避免减不到0
                    changeNum -= 1;
                }
                for (int i = 0; i < -changeNum; i  )
                {
                    VolumeDown();
                }
            }
        }


        /// <summary>
        /// 设置系统声音
        /// </summary>
        /// <param name="volume"></param>
        /// 
        static int now_volume = 0; //记录当前系统音量
        static void SetSYSTEMVolume(int volume)
        {
            int half_volume = volume / 2; //目标音量

            if (half_volume < now_volume)
            {

                for (int i = 0; i <= 50; i  )
                {
                    VolumeDown();
                }
            }
            else
            {

                for (int i = 0; i <= half_volume; i  )
                {
                    VolumeUp();
                }
            }
            now_volume = half_volume;
        }
        #endregion
    }
    
}