WM_GETMINMAXINFO

This message is sent to a window whenever Windows needs to know the maximized size of the window, the minimum or maximum tracking size of the window, or the maximized position of the window. The maximized size of a window is the size of a window when its borders are fully extended. The maximum tracking size of a window is the largest window size that can be achieved by using the borders to size the window. The minimum tracking size of a window is the smallest window size that can be achieved by using the borders to size the window.

Parameter

Description

wParam	Is not used.
lParam	Points to an array of five points that contains the following information:
Parameter	Description

	Point	Description
	rgpt[0]	Used internally by Windows.
	rgpt[1]	The maximized size, which is the screen size by default. The width is (SM_CXSCREEN + (2 ´ SM_CXFRAME)). The height is (SM_CYSCREEN + (2 ´ SM_CYFRAME)).
	rgpt[2]	The maximized position of the upper-left corner of the window (in screen coordinates). The default x value is SM_CXFRAME. The default y value is SM_CYFRAME.
	rgpt[3]	The minimum tracking size, which is the iconic size by default. The width is SM_CXMINTRACK. The height is SM_CYMINTRACK.
	rgpt[4]	The maximum tracking size, which is less than the screen size by default. The width is (SM_CXSCREEN + (2 ´ SM_CXFRAME)). The height is (SM_CYSCREEN + (2 ´ SM_CYFRAME)).

Comments

The array contains default values for each point before Windows sends the WM_GETMINMAXINFO message. This message gives the application the opportunity to alter the default values.