Event when a window gets maximized/un-maximized

Question

Is there an event that is fired when you maximize a Form or un-maximize it?

Before you say Resize or SizeChanged: Those get only fired if the Size actually changes. If your window happens to be equal in size to the maximized window, they do not fire. Location looks like the next best bet, but that again feels like gambling on a coincidence.

Answer 1

Suprising that no one mentioned the inbuilt .NET method.

This way you don't need to override the Window Message Processing handler.

It even captures maximize/restore events caused by double-clicking the window titlebar, which the WndProc method does not.

Copy this in and link it to the "Resize" event handler on the form.

    FormWindowState LastWindowState = FormWindowState.Minimized;     private void Form1_Resize(object sender, EventArgs e) {          // When window state changes         if (WindowState != LastWindowState) {             LastWindowState = WindowState;               if (WindowState == FormWindowState.Maximized) {                  // Maximized!             }             if (WindowState == FormWindowState.Normal) {                  // Restored!             }         }      } 

Answer 2

You can do this by overriding WndProc:

protected override void WndProc( ref Message m ) {     if( m.Msg == 0x0112 ) // WM_SYSCOMMAND     {         // Check your window state here         if (m.WParam == new IntPtr( 0xF030 ) ) // Maximize event - SC_MAXIMIZE from Winuser.h         {               // THe window is being maximized         }     }     base.WndProc(ref m); } 

This should handle the event on any window. SC_RESTORE is 0xF120, and SC_MINIMIZE is 0XF020, if you need those constants, too.