oecheruo@silver.ucs.indiana.edu (Chima Echeruo) (06/07/91)
Hi,
I have been working on an alternative GUI system for plain DOS,Turbo BGI and
TP 5-6. I would like to support most of the GIU section of WIN3/MAC without
the GDI and other bitlevel graphics work. I expect to use ONLY the borland
BGI that is standard along with some SVGA BGI drivers posted recently.
My problem involves the methodology and logic of repainting exposed and
destroyed regions of windows. Initially I began with saving a bitmap of the
underlying regions of popped-up windows. It seemed to work fine and gave me
the least problems. That was before I decided that I wanted random access
windows (not just stacked). Also, using TP 6.0, 384KB EMS and DOS 3.3 left
me with only about 150 KB or so for background bitmaps.
What I wanted to do was find the most efficient way of updating window regions
that are destroyed or exposed without having each window procedure to implement
it's own methods.
I have looked at several GUI packages: WNDX,MENUET,ZINC,and a shareware toolkit
posted to comp.binaries.ibm.pc. The three commercial packages were underspec.
They were LARGE and the windows were either inconsistent with WIN3/MAC or they
were slow and cumbersome. These packages required MetaWindows - a third party
GDI library. BGI does NOT allow virtual windows written to RAM and does only
but the basic functions that a GUI would need. I have to use it.
So, without using MS Windows 3.0 SDK. How can I get some pointers or code to
demonstrate the updating of hidden windows,exposed regions and destroyed
regions?
I enclose a post I made to comp.lang.pascal a while ago including some p-code
that I was thinking off. Also, how does WIN3 handle the updating of destroyed
and exposed window regions?
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I am still working on my simple user interface library for TP 5 & 6. I have
built most of the messaging system, window management and data structures -
bitmaps, ICONS etc.. In order to allow flexiblity for custom repainting of
exposed windows I have decided not to simply 'GetImage the underlying screen
background but to send messages to each window when its contents are over-
written. The window procedure then has the oppurtunity to 'GetImage the portion
of his window that is about to be overwritten. Later on, when the window
system discovers that a previously hidden region is about to be exposed, it
sends an EXPOSE message to the window with the region as the parameter. The
window can then 'PutImage the previously saved bitmap without having to get
the input focus (bring it's window to the top).
Since this procedure is very common for most windows, the base window class
will have defined procedures to handle the DESTROY/EXPOSE messages in case
the window or it's derivatives decide not to handle the messages. Right now,
I have a rough idea of the kind of data structures I am looking for:
RECT = Record
left,top,right,bottom :integer;
end;
RegPtr = ^REGION;
REGION = Record
rc :RECT;
next :RegPtr;
end;
I will need a function say, InvalidateRegion:
procedure InvalidateRegion(var rgn :REGION) {
wnd:=First(WindowList); {sorted by focus}
while (rgn is valid) and (wnd<>NIL) {
destroyed_reg:=intersection(rgn,wnd^.region);
if (destroyed_reg is valid) then
sendmessage(wnd,DESTROYED,0,0,addr(destroyed_reg));
rgn:=subtract_region(rgn,destroyed_reg);
wnd:=Next(wnd);
}
free(regions, etc..);
}
the way I have it, most of the destroyed background ends up being sent to
the background window which can then paint it (during EXPOSE) with whatever
color or pattern that a user selects (or even a bitmap). My problem is with
a suitable subtract,intersect etc.. routine that works efficiently and can
handle non-contigious RECTs and consolidate them to one if possible.
The RECT routines that I have seen only work with simple rectangles and cannot
create multiple non-contigious rects (Regions). Does anyone have some pointers
to some code? also, I know that Windows 3 exists but I cannot afford the SDK
nor do I need the power of a REAL GUI. I am looking at a SMALL GIU library that
can get my PC to look like a MAC without much work on the programmer's part.
thanks.
Chima Echeruo
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----- Chima Oke Echeruo -----
oecheruo@silver.ucs.indiana.edu ++++++ oecheruo@amber.ucs.indiana.edu
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