MDI: Semitransparent Child Windows?

Visual Studio259
Hi everybody

How can I implement an MDI application with the child windows semitransparent



Ok, Iâ??m going to explain myself better..

I have implement an MDI application under MFC

Briefly I have to make my application to do what you can see at



digilander.libero.it/griva/Index.htm



There you can find a screen shot of my application. How you can observe there are two child windows (in this example, but in general there could be more) displaying each one a bitmap. For each child window the user can set a transparency value (an alpha value) so that, putting that window on another he can compare the two images (medical interest). Obviously what you see in the screen shot is a fake example (otherwise I would not be here:-): in this example the â??sunsetâ?? bitmap has a 70% of opacity and the â??bmwâ?? bitmap has 100% o opacity; as you can see the â??sunsetâ?? window is focused and lays above the â??bmwâ?? window. I made this fake example first sizing and positioning the two windows, then I minimized them and I restore the â??bmwâ?? window first and then the â??sunsetâ?? window. But, if I move the windows they not repaint themselves properly. In fact I had subclassed the OnEraseBkgnd and the OnPaint of my child windows and then I had used the AlphaBlend method to paint the bitmap (Iâ??ll have to subclass also the OnMove when a child window hasnâ??t 100% opacity value). The problem is that on moving, sizing and so on, before repainting with the AlphaBlend method I need to repaint what lays under the focused child windows that is moving, sizing and so on. This means that I had to repaint the parent window (the MDI container) and eventually the sibling windows (the other MDI children) in the moving child client area..

But I donâ??t know how to do this



Is there anybody able to help me

Thank You in advance for all Your answers



Gianpiero Riv


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