ID Number: Q67166
3.00 3.10
WINDOWS
Summary:
Microsoft Windows sends a WM_GETMINMAXINFO message to a window to
determine the maximized size or position for the window, and the
maximum or minimum tracking size for the window. An application can
change these parameters by processing the WM_GETMINMAXINFO message.
Each window type has an absolute minimum size. If an application
changes any of the values associated with WM_GETMINMAXINFO to a value
smaller than the minimum, Windows will override the values specified
by the application and use the minimum size. This minimum window size
restriction has been removed from Windows version 3.1.
Note that Windows can send a WM_GETMINMAXINFO message to a window
prior to sending a WM_CREATE message. Therefore, any processing for
the WM_GETMINMAXINFO message must be independent of processing done
for the WM_CREATE message.
More Information:
An application can use the WM_GETMINMAXINFO message to constrain the
size of a window. For example, the application can prevent the user
from changing a window's width while allowing the user to affect its
height, or vice versa. The following code demonstrates fixing the
width:
int width;
LPPOINT lppt;
RECT rect;
case WM_GETMINMAXINFO:
lppt = (LPPOINT)lParam; // lParam points to array of POINTs
GetWindowRect(hWnd, &rect); // Get current window size
width = rect.right - rect.left + 1;
lppt[3].x = width // Set minimum width to current width
lppt[4].x = width // Set maximum width to current width
return DefWindowProc(hWnd, message, wParam, lParam);
The modifications required to fix the height are quite
straightforward.
For more information on the array of POINT structures that accompanies
the WM_GETMINMAXINFO message, please refer to the "Microsoft Windows
Software Development Kit Reference."
Additional reference words: 3.00 3.10 3.x