How can I set the minimum / maximum size?

How can I set the minimum / maximum size?

Applies To: C++Builder 1 or higher
Category: Knowledge Base

The default C++Builder form can be resized to almost any size. I need to limit this setting. Is it possible?

Start a new project using File | New Application.

Insert in the header file of your form, under public:

MESSAGE void __fastcall MinMax(TMessage &message);

BEGIN_MESSAGE_MAP

MESSAGE_HANDLER(WM_GETMINMAXINFO, TMessage, MinMax);

END_MESSAGE_MAP(TForm);

Edit your source code and insert:

MESSAGE void __fastcall TForm1::MinMax(TMessage &message)

{

MINMAXINFO *info;

// Get the size info from the message parameter

info = (MINMAXINFO *)message.LParam;

// Specify the minimum size

info->ptMinTrackSize.x = 300;

info->ptMinTrackSize.y = 300;

// Specify the maximum size

info->ptMaxTrackSize.x = 400;

info->ptMaxTrackSize.y = 400;

}

The WM_GETMINMAXINFO message is sent when a window is about to be resized. You can catch this message and edit its parameters in order to change the default maximum and minimum size.

Notes

· C++Builder 4 and greater allows you to change directly this option using the Constraints property.