Advanced MFC Programming

Chapter 13. Adding Special Features to Application
not be processed. The active state of the non-client area should always be painted after receiving message
WM_NCPAINT (instead of WM_NCACTIVE).
Since we only want to change the appearance of default caption bar, we will let the rest non-client area
be painted by default implementation. To do this, after receiving WM_NCPAINT and WM_NCACTIVATE
messages, we can first call the default message handlers (Which will cause the non-client area to be painted
by the default method), then paint the caption bar using our own implementation.
The default handlers of the above two messages are functions CWnd::OnNcPaint() and CWnd::
OnNcActivate(…). By default, they paint the caption bar, draw the icon and system buttons on the caption
bar, draw the frame and border.
The other two messages we must handle are WM_SETTEXT and WM_SYSCOMMAND. The first command
corresponds to the situation when the caption text is first set or when it is changed. The second message
corresponds to the situation when the application resumes from the iconic state to its original state. In the
above two cases, after message WM_NCPAINT is sent to the application, the text will be put directly to the
caption bar.
Caption Text Area
Figure 13-4 shows the composition of a caption bar: the outer frame, within which there is an icon
located at the left side, and three system buttons located at the right of the caption bar. The minimize button
and the maximize button are abut together, also, there is a space between them and the close button. By
default, the caption text is aligned to the left.
The position and size of a caption window can be obtained by calling function CWnd::
GetWindowRect(…). We need to exclude the frame, icon and buttons in order to calculate the area where we
can put the caption text.
So the actual caption text area can be calculated as follows:
left position =
(
left position of the caption window +
border width +
system button horizontal size +
frame width
)
Icon
Frame
Caption Text
Minimize Button
Maximize Button
Figure 13-4. Caption bar
Close Button
top position = top position of the caption window + frame height
right position =
(
right position of the caption window -
border width -
frame width -
3×(system button horizontal size)
)
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