DataTip
This article was contributed by Simon Wilson.
This class shows how I went about implementing my own tooltip window when I
had trouble getting the standard Tooltips to provide the functionality I
wanted. The attached code readily demonstrates the concepts of defining your
own windows for use with MFC, installing keyboard hooks, and handling the
correct clean-up of the system on completion (note the static methods and
instance counting). The windows use the same colour scheme as Tooltips under
Win95/NT (COLOR_INFOBK + COLOR_INFOTEXT) but you can choose your own colours
should you wish (see the OnPaint method).
The class uses the standard two-stage MFC creation process. You use the
class by defining an instance of the class in your view/dialog/etc and then
calling the Create method passing it a pointer to the parent window
(normally in your OnInitialUpdate or OnInitDialog methods).
You then handle the OnMouseMove event and call the Set method passing it a
display point and display string. If the mouse remains static for the
pre-defined delay time (set via SetDelay) then a tip window will be
displayed at the appropiate point. Pressing a key, pressing a mouse button,
or moving the mouse outside of a pre-defined are will remove the tip window
from the display.
Example:
class CMyView : public CView
{
:
SIMDataTip m_datatip;
:
};
void CMyView::OnInitialUpdate()
{
CView::OnInitialUpdate();
// enable datatips for this window
m_datatip.Create(this);
:
:
}
void CMyView::OnMouseMove(UINT nFlags, CPoint point)
{
CView::OnMouseMove(nFlags, point);
// intialise the datatip for this point
m_datatip.Set(point, "message");
}
The tip window can be turned on and off by calling the On method. It's
current status is available via the IsOn method, and the display offset
position (from the passed cursor position in Set) can be set using the
overloaded SetOffset method.
The class maintains a pointer to the active tip window ensuring that a
single tip window is visible at a time.
Please bear in mind that it hasn't been designed for extending but does
readily demonstrate the concepts behind getting it to work. If you wanted to
change it so that you could use multi-line tips, then the Display and
OnPaint methods can be changed to change the window size and display the
text over the correct number of lines respectively. Please let me know if
you find this class useful. If there is sufficient interest then I may
update the class to enable it to be more easily extendable.
The class was developed and tested under Visual C++ v4.1 but should work
equally well under VC5. (Note that with a few minor changes the class will
work under VC1.5)
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