Question

如何在另一个应用程序中获取元素的wParam和lParam值？

//until the window procedure has processed the message. 
[DllImport("User32.dll")]
public static extern Int32 SendMessage(
    int hWnd,               // handle to destination window
    int Msg,                // message
    int wParam,             // first message parameter
    [MarshalAs(UnmanagedType.LPStr)] string lParam); // second message parameter

[DllImport("User32.dll")]
public static extern Int32 SendMessage(
    int hWnd,               // handle to destination window
    int Msg,                // message
    int wParam,             // first message parameter
    int lParam);            // second message parameter
}

Answer 1

嗯，对于字符串值，你可以这样做：

// receiver
protected override void WndProc(ref Message msg)
{
    if (msg.Msg == WM_COPYDATA)
    {
        if (msg.WParam == this.Handle)
        {
            CopyDataStruct copyStruct = (CopyDataStruct)Marshal.PtrToStructure(msg.LParam, typeof(CopyDataStruct));
            string messageText = Utf8PtrToString(copyStruct.lpData);
            MessageBox.Show(messageText);
        }                
    }
    base.WndProc(ref msg);
}

// sends text message to all other instances of itself
private void button1_Click(object sender, EventArgs e)
{
    Process[] myInstances = Process.GetProcessesByName(System.IO.Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetEntryAssembly().Location));

    if (myInstances.Length == 0) return;

    foreach (Process instance in myInstances)
    {
        IntPtr handle = instance.MainWindowHandle;
        if (handle != this.Handle) SendStr(handle, "echo.. echo.. echo..");
    }
}

private static string Utf8PtrToString(IntPtr utf8)
{
    int len = MultiByteToWideChar(65001, 0, utf8, -1, null, 0);
    if (len == 0) return null;
    StringBuilder sb = new StringBuilder(len);
    len = MultiByteToWideChar(65001, 0, utf8, -1, sb, len);
    return sb.ToString();
}

public void SendStr(IntPtr targetHandle, string msg)
{
    int cmdLength = Encoding.UTF8.GetByteCount(msg) + 1;
    byte[] utf8cmd = new byte[cmdLength];
    Encoding.UTF8.GetBytes(msg, 0, cmdLength - 1, utf8cmd, 0);

    CopyDataStruct copyStruct = new CopyDataStruct();
    copyStruct.dwData = IntPtr.Zero;
    copyStruct.cbData = cmdLength;
    copyStruct.lpData = Marshal.AllocHGlobal(cmdLength);
    Marshal.Copy(utf8cmd, 0, copyStruct.lpData, cmdLength);

    SendMessage(targetHandle, WM_COPYDATA, targetHandle, ref copyStruct);
}

public static uint WM_COPYDATA = 0x004A;

[DllImport("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, ref CopyDataStruct lParam);

[DllImport("user32.dll")]
static extern uint RegisterWindowMessage(string lpString);

[StructLayout(LayoutKind.Sequential)]
public struct CopyDataStruct
{
    public IntPtr dwData;
    public int cbData;
    public IntPtr lpData;
}

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern int MultiByteToWideChar(int codepage, int flags, IntPtr utf8, int utf8len, StringBuilder buffer, int buflen);

如何在另一个应用程序中获取元素的wParam和lParam值？

1 个答案: