Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!killer!ames!lll-lcc!well!ewhac
From: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Newsgroups: comp.sys.amiga.tech
Subject: Re: bitmaps with intuition...
Message-ID: <6313@well.UUCP>
Date: 18 Jun 88 06:14:39 GMT
References: <4370@gryphon.CTS.COM> <3170@charon.unm.edu> <56215@sun.uucp> <6261@well.UUCP> <56628@sun.uucp>
Reply-To: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Organization: Speak Before You Think Enterprises
Lines: 37

In article <56628@sun.uucp> cmcmanis@sun.UUCP (Chuck McManis) writes:
>In article <6261@well.UUCP> (Leo 'Bols Ewhac' Schwab) writes:
>->In article <56215@sun.uucp> cmcmanis@sun.UUCP (Chuck McManis) writes:
>->>[ Chuck McManis attempts to help. ]
>->
>->	Hans specifically said 'window'.  Chuck's dissertation is correct
>->for screens and BitMap structures.  However, a window is a superset of a
>->layer, and layers can be anywhere on the screen.  Layers can also be
>->obscured.  There is severe voodoo involved in figuring out what the status
>->of a window's position and visibility is.  For an example of what you're
>->looking at, check out 'DropShadow'.
>
>Well clearly the workaround is to call WindowToFront, wait for it, then
>     ^^^^^^^
>LockIBase and play with the bitmap pointers :-). 
>
	Clear as mud :-).

	The BitMap pointer in the Window's Layer structure points to the
master bitmap on which the layers exist, namely, the screen's bitmap.  You
can perform various kinds of r*pe with this pointer if you go to the
layers.library directly, but Intuition does the Natural Thing when dealing
with layers.

	Thus, when you access the bitmap pointed to by the Window's BitMap
pointer, you'll start hitting the screen directly.  Unless the window is
right at the upper left corner of the screen, you won't get what you want.
Hans wants to get at the "virtual bitmap" the window represents.  Short of
using a SUPERBITMAP window, there's no way you can do this easily.  It's
much less painful to go through the graphics.library, as Dale will tell you
:-).

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Leo L. Schwab -- The Guy in The Cape  ihnp4!pacbell -\
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