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Forums » Prof-UIS Tech Support » Please teach it about UpdateLayeredWindow Collapse All
Subject Author Date
tera t Jul 16, 2007 - 8:38 PM


If you like.
Please teach it about UpdateLayeredWindow.
By using this function.
Can I do some domains of application View transparently?

If there are sample programs, give me it.

Technical Support Jul 17, 2007 - 7:56 AM

All layered window have the WS_EX_LAYERED extended window style and are supported on Windows 2000 and later. There are two types of layered windows:

1) The layered windows which have equal transparency for each window pixel. You should simply apply WS_EX_LAYERED and invoke the SetLayeredWindowAttributes() API to make the window equally transparent for each of its pixels including all the child windows. This is a simple type of layered window and it works exactly like a regular non-transparent window. I.e. such a transparent window and all its child windows are receiving WM_PAINT for painting.

2) The layered windows which have per-pixel transparency. You should also simply apply the WS_EX_LAYERED extended window style first and then invoke the UpdateLayeredWindow() API to assign a 32-bit bitmap with alpha channel to the layered window. The window size should be exactly the same as the bitmap size. If you need to change the window, then you should re-invoke the UpdateLayeredWindow() API and specify a new bitmap with the correct size. The per-pixel transparent layered windows are very specific. You should think about such windows as they are not windows at all. They are per-pixel bitmaps which are displayed between other windows on the desktop. You should not create child windows inside such layered windows. So, these windows are typically used for implementing some popup markers during drag-and-drop or some small notification popup windows with a skinned look.

tera t Jul 18, 2007 - 7:50 PM


Thank you for advice.