Advanced MFC Programming

Chapter 6. Dialog Box
Figure 6-5. All controls have transparent background, but their text doesn’t
We can call function CDC::SetBkMode(…) and use TRANSPARENT flag to set transparent background
drawing mode for text, otherwise it will be drawn with the default background color.
The background of a 3-D looking pushdown button can not be changed this way. Also, if we include
drop down or drop list combo box, the background color of its list box will not be customized by this
method because it is not created as the child window of the dialog box. To modify it, we need to derive new
class from CComboBox and override its OnCtlColor(…) member function.
6.6 Resizing the Form View
Form view is very similar to a dialog box. Usually we create form view from a dialog box template,
which can contain all the standard common controls. While they are similar, a form view is usually created
with a document/view structure, and has some properties that a standard dialog box lacks. For example, a
form view will be automatically implemented with scroll bars. If the window size becomes smaller than the
size of the dialog template, scroll bars will automatically be activated. They can be scrolled to allow the
user to see the hidden part of the dialog.
Since a form view is usually resizable, we sometimes need to move and resize the common controls
contained in the form view to make its appearance well balanced. For example, if we have an edit box
embedded in the form view, instead of fixing its size, we may want to adjust it dynamically according to
the dimension of the form view. This is usually a desired feature of form view because it will make the
controls and the window well balanced.
Coordinates Conversion
Every window can be moved and resized by calling function CWnd::MoveWindow(…) or CWnd::
SetWindowPos(…). Also, a window’s size and position can be retrieved by calling function CWnd::
GetClientRect(…) and CWnd::GetWindowRect(…). The points retrieved using the former function are
measured in the client window’s coordinate system, and the points retrieved from the latter function are
measured in the screen (desktop) coordinate system. To convert coordinates from one system to another,
we can call function CWnd::MapWindowPoints(…) or CWnd::ScreenToClient(…).
For example, if there are two windows: window A and window B, which are attached two CWnd type
variables wndA and wndB. If we want to know the size and position of window A measured in window B’s
coordinate system, we can first obtain the size and position of window A in its local coordinate system, and
then convert them to window B system as follows:
wndA.GetClientRect(rect);
wndA.MapWindowPoints(&wndB, rect);
Or we can find the position and size of window A in the screen coordinate system, and call CWnd::
ScreenToClient(…) to convert them to window B’s coordinate system:
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