如何以编程方式更改系统卷

本文关键字：系统 方式更 编程 | 更新日期: 2023-09-27 18:15:37

我想更改系统的音量。我使用以下代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace shaped_form
{
    class VolumeChange
    {
        private const int APPCOMMAND_VOLUME_MUTE = 0x80000;
        private const int APPCOMMAND_VOLUME_UP = 0xA0000;
        private const int APPCOMMAND_VOLUME_DOWN = 0x90000;
        private const int WM_APPCOMMAND = 0x319;
        [DllImport("user32.dll")]
        public static extern IntPtr SendMessageW(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
        private void btnMute_Click(object sender, EventArgs e)
        {
            SendMessageW(**this.Handle * *, WM_APPCOMMAND, **this.Handle * *, (IntPtr)APPCOMMAND_VOLUME_MUTE);
        }
        private void btnDecVol_Click(object sender, EventArgs e)
        {
            SendMessageW(**this.Handle * *, WM_APPCOMMAND, **this.Handle * *, (IntPtr)APPCOMMAND_VOLUME_DOWN);
        }
        private void btnIncVol_Click(object sender, EventArgs e)
        {
            SendMessageW(**this.Handle * *, WM_APPCOMMAND, **this.Handle * *, (IntPtr)APPCOMMAND_VOLUME_UP);
        }
    }
}

但是我在突出显示的地方得到了一个错误，如"shaped_form.VolumeChange does not contain a definition for Handle"。

我从一些互联网资源得到这个代码。

如何以编程方式更改系统卷

你得到一个错误，因为this.Handle没有定义在一个普通的香草类，如VolumeChange类，你有那里。它来自system.windows.forms form类。

它需要，因为SendMessageW方法需要一个窗口句柄

因为你没有在你的新类中定义它，所以你不能使用它。

尝试在VolumeChange的构造函数中传递一个有效的窗口句柄，并使用它来调用SendMessageW 

public class VolumeChange
{
  private const int APPCOMMAND_VOLUME_MUTE = 0x80000;
  private const int APPCOMMAND_VOLUME_UP = 0xA0000;
  private const int APPCOMMAND_VOLUME_DOWN = 0x90000;
  private const int WM_APPCOMMAND = 0x319;
  private IntPtr windowHandle;

  public VolumeChange(IntPtr hwnd)
  {
     windowHandle = hwnd;
  }
  [DllImport("user32.dll")]
  public static extern IntPtr SendMessageW(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr    lParam);
  private void btnMute_Click(object sender, EventArgs e)
  {
    SendMessageW(windowHandle, WM_APPCOMMAND, windowHandle,(IntPtr)APPCOMMAND_VOLUME_MUTE);
  }
  private void btnDecVol_Click(object sender, EventArgs e)
  {
    SendMessageW(windowHandle, WM_APPCOMMAND, windowHandle,(IntPtr)APPCOMMAND_VOLUME_DOWN);
  }
  private void btnIncVol_Click(object sender, EventArgs e)
  {
    SendMessageW(windowHandle, WM_APPCOMMAND,windowHandle,(IntPtr)APPCOMMAND_VOLUME_UP);
  }
}

如果在构造函数中传递窗口句柄不是一个选项，(例如，如果您想使VolumeChange为静态)

查看GetActiveWindow (MSDN)

要展开Timothy的答案，您应该将类VolumeChange提取到它自己的类中，并在单击表单按钮时使用它。这样，如果你想改变音量从其他形式或类，你也可以。

基本上，你最终有两个类，你的Form类和实用程序类VolumeChanger。在创建VolumeChanger实例时，通过表单的Handle属性获取所需的Handle。 
public class VolumeChanger
{
    private const int APPCOMMAND_VOLUME_MUTE = 0x80000;
    private const int APPCOMMAND_VOLUME_UP = 0xA0000;
    private const int APPCOMMAND_VOLUME_DOWN = 0x90000;
    private const int WM_APPCOMMAND = 0x319;
    public VolumeChange(IntPtr hwnd)
    {
        Handle = hwnd;
    }
    public IntPtr Handle { get; private set; }
    [DllImport("user32.dll")]
    public static extern IntPtr SendMessageW(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
    public void Mute() {
        SendMessageW(Handle, WM_APPCOMMAND, Handle, (IntPtr)APPCOMMAND_VOLUME_MUTE);
    }
    public void IncreaseVolume() {
        SendMessageW(Handle, WM_APPCOMMAND, Handle, (IntPtr)APPCOMMAND_VOLUME_UP);
    }
    public void DecreaseVolume() {
        SendMessageW(Handle, WM_APPCOMMAND, Handle, (IntPtr)APPCOMMAND_VOLUME_DOWN);
    }
}
public class Form1 : Form {
    private VolumeChanger _volume;
    public Form1() {
        InitializeComponent();
        _volume = new VolumeChanger(Handle);
    }
    private void btnMute_Click(object sender, EventArgs e)
    {
        _volume.Mute();
    }
    private void btnDecVol_Click(object sender, EventArgs e)
    {
        _volume.DecreaseVolume();
    }
    private void btnIncVol_Click(object sender, EventArgs e)
    {
        _volume.IncreaseVolume();
    }
}
相关文章：