Simple Full Screen Method (Hides Taskbar)

Introduction

This is an easy way to put Winforms in 100% Full Screen.

Background

I tried for hours to find a simple way to go full screen without using [DllImport("user32.dll")], etc. because the risk of the user closing the program with the taskbar still hidden was too great.

Using the Code

So after experimenting for a few hours, I discovered if I put FormWindowState.Normal before FormWindowState.Maximized, I could cover the taskbar every time.

This code uses KeyDown to look for Alt+Enter which toggles Form1 to full-screen. The Esc key will also cancel the full-screen.

Make sure you set Form1.KeyPreview = true for KeyDown to work.

You can ignore TopPanel. It's here to show you how to hide other controls when full-screen if needed.

Using TopMost is not necessary and is up to you.

Tested on Windows 7 Ultimate. If you use this on a later Windows version, please let us know how it works.

Size _size;
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Escape && this.FormBorderStyle == FormBorderStyle.None)
    {
        e.SuppressKeyPress = true;
        SendKeys.Send("%{ENTER}");    	// Alt+Enter again to cancel full screen
    }
    if (e.Alt && e.KeyCode == Keys.Enter)	// Full Screen
    {
        e.SuppressKeyPress = true;            		// the order is important
        isFullScreen = (FormBorderStyle == FormBorderStyle.None) ? true : false;
        LeftPanel.Visible = isFullScreen;
 
        if (!isFullScreen) _size = this.Size;
 
        this.Visible = false;
        this.FormBorderStyle = (isFullScreen) ? FormBorderStyle.Sizable : FormBorderStyle.None;
        this.WindowState = FormWindowState.Normal; // forces the taskbar to be covered
        this.WindowState = FormWindowState.Maximized;
 
        if (isFullScreen) this.Size = _size;
 
        this.Visible = true;
 
        if (isFullScreen) this.WindowState = FormWindowState.Normal;

        this.TopMost = !isFullScreen;
    }
}

Points of Interest

This executes quickly with no unwanted artifacts.

History

• 5^th January, 2015: Initial version