Using a system hotkey in a Visual C # program

1. First introduce System.Runtime.InteropServices

using System.Runtime.InteropServices;

2. Declare two API functions inside the class, and their positions are equivalent to the member variables of the class.

[System.Runtime.InteropServices.DllImport("user32.dll")] //申明API函数
public static extern bool RegisterHotKey(
IntPtr hWnd, // handle to window
int id, // hot key identifier
uint fsModifiers, // key-modifier options
Keys vk // virtual-key code
);
[System.Runtime.InteropServices.DllImport("user32.dll")] //申明API函数
public static extern bool UnregisterHotKey(
IntPtr hWnd, // handle to window
int id // hot key identifier
);

3. Define a Keymodifiers enumeration so that the key combinations appear

public enum KeyModifiers
{
　None = 0,
　Alt = 1,
　Control = 2,
　Shift = 4,
　Windows = 8
}

4. In class constructor out registry system hotkey

example, the following example registers four hot keys:

public MainForm()
{
　InitializeComponent();
　RegisterHotKey(Handle, 100, 2, Keys.Left); // 热键一:Control +光标左箭头
　RegisterHotKey(Handle, 200, 2, Keys.Right); / /热键一:Control +光标右箭头
　RegisterHotKey(Handle, 300, 2, Keys.Up); // 热键一:Control +光标上箭头
　RegisterHotKey(Handle, 400, 2, Keys.Down); // 热键一:Control +光标下箭头
　....;
}

5. Rewrite the WndProc () method to invoke the procedure by monitoring system messages

Example:

protected override void WndProc(ref Message m)//监视Windows消息
{
　const int WM_HOTKEY = 0x0312; //如果m.Msg的值为0x0312那么表示用户按下了热键
　switch (m.Msg)
　{
　　case WM_HOTKEY:
　　ProcessHotkey(m); //按下热键时调用ProcessHotkey()函数
　　break;
　}
　base.WndProc(ref m); //将系统消息传递自父类的WndProc
}

5. Needless to say, we will then need to implement the Processhotkey function:

//按下设定的键时调用该函数
private void ProcessHotkey(Message m)
{
　IntPtr id = m.WParam; //IntPtr用于表示指针或句柄的平台特定类型
　//MessageBox.Show(id.ToString());
　string sid = id.ToString();
　switch (sid)
　{
　　case "100": DecreseVolumnb(); break; // 按下Control +光标左箭头,调用函数DecreseVolumnb();
　　case "200": AddVolumnb(); break; // 按下Control +光标右箭头,调用函数AddVolumnb()
　　case "300":// 按下Control +光标上箭头,显示窗体
　　　this.Visible = true;
　　　break;
　　case "400":// 按下Control +光标下箭头,隐藏窗体
　　　this.Visible = false;
　　　break;
　}
}

It is obvious that the following function DECRESEVOLUMNB () is implemented separately; and ADDVOLUMNB (); Can.

6. Finally, don't forget to cancel the registration of the hotkey when the program exits

private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
{
　UnregisterHotKey(Handle, 100); //卸载第1个快捷键
　UnregisterHotKey(Handle, 200); //缷载第2个快捷键
　UnregisterHotKey(Handle, 300); //卸载第3个快捷键
　UnregisterHotKey(Handle, 400); //缷载第4个快捷键
}

The above is the whole process of using a system hotkey in a C # program.