Drawing in C++ using Visual Studio 2005

Question

Hello

I have a problem with drawing in C++ using Visual Studio 2005. After event handling on MouseMove the results of using DrawLine function appear in PictureBox but if some window overlap the part of PictureBox all pixels in this place dissapear after moving the window. How can I solve this problem?

Answer 1

In your MouseMove handler, you just want to store the points where you will draw the lines (but don't draw anything at that time). At the end of that handler, call InvalidateRect to tell Windows that your window needs re-painting. Windows will (eventually) respond to that with a WM_PAINT message. When you receive the WM_PAINT message, retrieve the points and do the actual drawing.

If you're doing anything other than bare Win32 programming, chances are that whatever framework you're using will handle a few bits and pieces of that for you, but the general structure normally remains roughly the same.