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dropshadow
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1992-05-06
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------------- Slice here ----------
DropShadow (C) Copyright James Mackraz, 1987 (Mr. Intuition)
this version may be freely redistibuted
Version 2, Revision 0 April 7, 1987
----- ----------------------------------------- -----
Notes for Version 2, Revision 0 April 7, 1987
Added the following from the wish list:
-A slider gadget is implemented to adjust the 3-dimensional
distance between the planes of the windows.
-A slider gadget is implemented to adjust shadow darkness. If
desired, full independent control of the shadow colors is
possible.
I had some problems with the latter, so I now increase the
task priority while the darkness slider is selected. It
has not been tested thoroughly.
----- ----------------------------------------- -----
Notes for Version 1, Revision 1 March 12,1987
-When Windows are moved, created, sized, deleted, or depth-
arranged, Intuition calls layers.library. This program
intercepts those calls to determine that the shadow needs
to be recalculated. Before this version, this recalculating
and redrawing was done before Intuition got a chance to
redraw Window borders and Gadgets.
This version of DropShadow performs the work on its schedule,
and is only signaled by the code which intercepts the
layers calls. This makes for a smoother and less dangerous
implementation.
----- ----------------------------------------- -----
Notes for Version 1, Revision 0 March 1, 1987
-The program on this disk creates and maintains multi-level
transparent drop shadows of windows on the Workbench screen.
-The program creates its own window, and is terminated by closing
that window. The program, named DropShadow, may be run from
the CLI, or if associated with an icon, from the Workbench.
-The shadows are created by attaching an additional bitplane to
the Workbench's display bit map, but doing so in a way which
is transparent to the Workbench or its application programs.
-Unfortunately, this third bitplane brings the Workbench screen
to a point which causes processor cycles to be stolen by the
display generation hardware. Thus, this program is probably
best used only for demos and having fun, at least for users
without "Fast" RAM.
Enhancements which are planned include:
-The program detects that the shadow image needs to be
recalculated by monitoring the layers library. That section
of code should check that the layers activity is in fact in
the Workbench screen.
-A way to detect color changes in preferences would allow the
shadow colors to track user changes to the Workbench colors.
In the meantime, the program must be restarted to initialize the
shadow colors. Commodities Exchange can be used for this.
-A technique of unknown type is planned for user control of
the light source which casts shadows. Shadows cast according
to the position of the sun (time of day and season) are possible
but unlikely.
-This program is not yet a safe Library vector stealer. It should
refuse to exit if some other program has displaced its vectors,
lest that other program call DropShadow after it has exited.
Jim Mackraz
7101 Rainbow Drive #8
San Jose, CA 95129