For some idea I recently had I would need a window similar to what tokai did with his elephant, read transparency with alpha-blending and windows shaped to any given polygon.

Only thing I found sofar is "examples/intuition/transparency.c" which makes the window-border 100% invisible.

Another question is wether the shape of a window can be changed on the fly (read without the flicker of closing and reopening it).

Can't advise you but I'm just curious if you need such a feature for SteamDraw project :)

transparency.c was written when we didn't have Enhanced Display. Nowdays all you need to do is set a few WA_ attributes. See the intuition includes from the sdk update. I can patch up a quick example if needed later.

The 'shape' is determined by the alpha channel and obviously is what you paint it to be. No flicker involved.

[ Edited by jacadcaps on 2010/1/29 23:32 ]

@r-tea

Not directly for SteamDraw, but for a side-project for SteamDraw which may also be used in another context in which transparency might come in handy ..... Everything cleared up ?

@jacadcaps

Doh, and there is even a similar tag in mui_window.doc (which doesn't seem to show up in mui.h).

O.k. now what was that about shaped windows ? Has_Alpha is defined both in intuition and mui_window, but I'm not sure what it does ?

The window shouldn't just disappear on fully invisible areas, but clicking there should also be send to the next window underneath it.

A quick and dirty example might be helpfull.

[ Edited by Kronos on 2010/1/29 23:53 ]

O.k. MUIA_Window_HasAlpha fails when the window contains "Dtpic.mui" ("incompatible source and destination bitmaps..." in RAMDebug), using just 1 SimpleButton() as WindowContents does work, and I can doubleclick Ambient-icons through the largly invisible border of my test-app.

Seems I need to write my own alpha-enabled replacement for "Dtpic.mui", something that was planned anyways as I also need scaling

O.k. this is getting silly ....

Seems that DTPic is alpha-enabled, and it does work as it should. I've sofar failed to reproduce the above error-message....

Well... MUI generally isn't "alpha enabled". You shouldn't set MUIA_Window_HasAlpha on normal windows, but rather only on windows whose content you will paint yourself in 100%.

O.k. things are getting closer (and uglier ;) ).

Currently I use ScalePixelArray() with RECTFMT_RGBA, which does just a vanilla (scaled) copy, what I would need is a function that simply leaves the background unchanged in placed where the PixelArray has alpha.

Just asking before I start writing my own pixel_by_pixel routine.