Resize Event

[Spilled]

How would I Catch a Resize event? Would I Use WM_SIZE? If so how would I determine if the form is resized because aint this used for catching Minimize and Maximize events?

[MyndFyre]

I knew this would come in handy for more than skinning one day!

Code Select Expand


                case WM.WM_SYSCOMMAND:
                    if (m.WParam == (IntPtr)SystemCommands.Maximize ||
                        m.WParam == (IntPtr)SystemCommands.MaximizeByFrame)
                    {
                        OnMaximized();
                    }
                    else if (m.WParam == (IntPtr)SystemCommands.Restore ||
                        m.WParam == (IntPtr)SystemCommands.RestoreByFrame)
                    {
                        OnRestored();
                    }
                    else if (m.WParam == (IntPtr)SystemCommands.Minimize)
                    {
                        OnMinimized();
                    }
                    DefWndProc(ref m);
                    break;
                    #endregion

m is the Msg struct (this is C# btw, so I wouldn't try to stick this into your code directly), but look up WM_SYSCOMMAND in MSDN to find out what the command constants are (I wouldn't be surprised if it was SC_MAXIMIZE/SC_MINIMIZE).

WM_SIZE does other resize events though.

[Spilled]

Thanks once again Myndfyre, appreciate it!

[Skywing]

I think looking at WM_SYSCOMMAND for that purpose is wrong and might not work properly for things programmatically minimizing or maximizing a window.

It would probably be better to use WM_WINDOWPOSCHANGED, or if you are passing that to DefWindowProc, WM_SIZE.

If you are using WM_WINDOWPOSCHANGED, you will have to figure out what operation is happening based on the old and new window positions.

If you are using WM_SIZE, wParam indicates what sort of operation just occured.
You should use GetClientRect in WM_SIZE to determine the new client area instead of relying on the truncated values provided in lParam.

[MyndFyre]

I think looking at WM_SYSCOMMAND for that purpose is wrong and might not work properly for things programmatically minimizing or maximizing a window.

It would probably be better to use WM_WINDOWPOSCHANGED, or if you are passing that to DefWindowProc, WM_SIZE.

If you are using WM_WINDOWPOSCHANGED, you will have to figure out what operation is happening based on the old and new window positions.

If you are using WM_SIZE, wParam indicates what sort of operation just occured.
You should use GetClientRect in WM_SIZE to determine the new client area instead of relying on the truncated values provided in lParam.

Ahh, so WM_SIZE does work?  I couldn't ever get this to function.  But -- C#. 

[Skywing]

Ahh, so WM_SIZE does work?  I couldn't ever get this to function.  But -- C#. 

I suspect that you (or something else) is handling WM_WINDOWPOSCHANGED and not passing it to DefWindowProc.

WM_SIZE/WM_MOVE are compatibility messages sent to programs that don't support figuring out their new positioning from the newer WM_WINDOWPOSCHANGED.  If the program handles WM_WINDOWPOSCHANGED internally, WM_SIZE/WM_MOVE would not be sent as they are generated by DefWindowProc in response to WM_WINDOWPOSCHANGED.

You can use them in new programs if you don't want to write code to determine your new positioning from WM_WINDOWPOSCHANGED, however.  This requires that you pass WM_WINDOWPOSCHANGED to DefWindowProc, though.