Switching to another application (previously active) on button click in .net - switch-statement

Question

Hi I want to do something like on screen keyboard. I want user to click a button on inactive application and then key press will be sent to active application while keeping active application active. I wrote the code for hover event of the button in inactive application and it is working. But what I want is to do it in click event. It is not working because inactive application becomes active. The code is below for hover event. Thank you.
private void button1_MouseHover(object sender, EventArgs e)
{
SendKeys.Send("{TAB}");
}

Answer 1

Finally I could figure out a way to do it.
Refer the code below.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Timers;
using tmr = System.Timers;
using System.Threading;
namespace KeyPressTest
{
public partial class Form1 : Form
{
[DllImport("user32.dll")]
static extern int GetForegroundWindow();
[DllImport("user32")]
private static extern UInt32 GetWindowThreadProcessId(Int32 hWnd, out Int32 lpdwProcessId);
[DllImport("user32.dll")]
static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern bool SetForegroundWindow(IntPtr hWnd);
tmr.Timer tm = new tmr.Timer();
Int32 hwnd = 0;
private Int32 GetWindowProcessID(Int32 hwnd)
{
Int32 pid = 1;
GetWindowThreadProcessId(hwnd, out pid);
return pid;
}
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
tm.Elapsed += Timer_Elapsed;
tm.Interval = 100;
tm.Start();
}
private void button1_Click(object sender, EventArgs e)
{
SetForegroundWindow((IntPtr)hwnd);
Thread.Sleep(40);
SendKeys.Send("{TAB}");
}
private void Timer_Elapsed(object sender, System.EventArgs args)
{
if (this.InvokeRequired)
{
this.Invoke(new MethodInvoker(delegate
{
if (this.Handle.ToInt32() != GetForegroundWindow())
{
hwnd = GetForegroundWindow();
}
}));
}
else
{
if (this.Handle.ToInt32() != GetForegroundWindow())
{
hwnd = GetForegroundWindow();
}
}
if (hwnd == 0)
{
return;
}
string appProcessName = "";
string appExePath = "";
string appExeName = "";
try
{
appProcessName = Process.GetProcessById(GetWindowProcessID(hwnd)).ProcessName;
appExePath = Process.GetProcessById(GetWindowProcessID(hwnd)).MainModule.FileName;
appExeName = appExePath.Substring(appExePath.LastIndexOf(#"\") + 1);
}
catch (Exception ex)
{
}
if (textBox1.InvokeRequired)
{
textBox1.Invoke(new MethodInvoker(delegate
{
textBox1.Text = appProcessName + " | " + appExePath + " | " + appExeName;
}));
}
else
{
textBox1.Text = appProcessName + " | " + appExePath + " | " + appExeName;
}
}
}
}

Answer 2

I have never done something similar, but here is what I found in this forum:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Diagnostics;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
[DllImport("user32.dll")]
static extern int GetForegroundWindow();
[DllImport("user32")]
private static extern UInt32 GetWindowThreadProcessId(Int32 hWnd, out Int32 lpdwProcessId);
private int teller = 0;
public Form1()
{
InitializeComponent();
}
private void timer1_Tick(object sender, EventArgs e)
{
if (teller == 1)
{
setTextje();
}
teller++;
}
private Int32 GetWindowProcessID(Int32 hwnd)
{
Int32 pid = 1;
GetWindowThreadProcessId(hwnd, out pid);
return pid;
}
private void setTextje()
{
Int32 hwnd = 0;
hwnd = GetForegroundWindow();
string appProcessName = Process.GetProcessById(GetWindowProcessID(hwnd)).ProcessName;
string appExePath = Process.GetProcessById(GetWindowProcessID(hwnd)).MainModule.FileName;
string appExeName = appExePath.Substring(appExePath.LastIndexOf(#"\") + 1);
textBox1.Text = appProcessName + " | " + appExePath + " | " + appExeName;
}
}
}
It doesn't answer exactly to your question but it will give you a hint. You need to DllImport "User32.dll". After that you can get the id of the foreground window and play with that.
There is also a very interesting article about application switch tracking written in C#