Transparent and non-rectangular windows

webionaire » Cursor Flicker

webionaire » Cursor Flicker — Tue, 15 May 2007 01:18:19 GMT

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re: Transparent and non-rectangular windows

rabidrobot — Tue, 09 May 2006 23:28:57 GMT

I'm sorry, I used "Tim" where I meant "Nick". My apologies.

re: Transparent and non-rectangular windows

rabidrobot — Tue, 09 May 2006 23:28:02 GMT

Tim said:
"We don’t currently support per-pixel alpha, if you try today you get black instead of transparent. We’re looking into this, right now it’s not clear which platforms we’ll be able to get it for."

Is this still the latest information, and could you be more specific as to what exactly you are referring to? We can make per-pixel alpha transparent (2D) images and place them in the HwndSource now. But I am seeing black where I expect transparency when I try to capture layered windows to a bitmap using CopyPixelOperation.CaptureBlt. Is it possible that fixes have been made in some areas but not all? CopyPixelOperation is .NET2.0, not Avalon, so... ?
(I am using WindowsXP, if that is a concern)

Tim also said:
"HRGNs work completely"

Is there any more information on how to use these available? Can the region path be defined by a XAML path? Or will it require creating a bitmap, then rectangulating the bitmap to get a region path? Any pointers in this area would be very welcome.

re: Transparent and non-rectangular windows

Nick Kramer [MSFT] — Thu, 04 May 2006 21:25:21 GMT

(I was referring to merging the layered windows, but the pop-up approaches also viable -- I keep meeting to write about that but I still haven't finished the complete sample)

re: Transparent and non-rectangular windows

Nick Kramer [MSFT] — Thu, 04 May 2006 21:24:37 GMT

Hmm, neat trick, that could work!

re: Transparent and non-rectangular windows

Alex Cohn — Thu, 04 May 2006 16:12:08 GMT

I have found (but not tested yet) another approach: using POPUP child windows for the layered window: cf. http://web.mac.com/seattleamadio/iWeb/OoeyGUI/Blog/8834809A-FC89-4534-8B7F-55306752131B.html

re: Transparent and non-rectangular windows

Alex Cohn — Thu, 04 May 2006 10:43:34 GMT

Yes, I thought about this. The trick is, at least in my case, while the window is being moved, it does not change - therefore, I can capture the opaque "region" window using PrintWindow(), hide it, and extend the layered one to the "full size".

re: Transparent and non-rectangular windows

Nick Kramer [MSFT] — Wed, 03 May 2006 04:37:10 GMT

That can work, and for many people in scenarios it's worth pursuing. The one complication you may run into is moving the two windows together -- traditionally in Win32, it's difficult to move two adjacent hwnds simultaneously in a way that doesn't have some kind of flashing at the boundary between them. (eg, the system repaints after the first hwnd is moved to before the second one...)

re: per-pixel alpha

Alex Cohn — Tue, 02 May 2006 18:53:55 GMT

Hi, have you ever seen an attempt to put side-by side a region window with an per-pixel aplha window? My idea was to make the latter (a thin stripe on the right-bottom) adjacent to the fully oblique region window to provide a 3D shadow effect.

The hwnd interop white paper

Nick Kramer on Avalon — Mon, 18 Jul 2005 23:02:55 GMT

So that&nbsp;concludes my series about hwnd interop, which is really a draft of the hwnd interop white...