Contributor: SWAG SUPPORT TEAM
SECTION 18 - Turbo Vision
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This document contains information that is most often provided
to users of this section. There is a listing (when available)
of common Technical Information Documents and example files that
can be downloaded from the libraries, and a listing of the most
frequently asked questions and their answers.
TECHNICAL INFORMATION DOCUMENTS AND EXAMPLE FILES
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TI1721 Determining input focus on Turbo Vision
TI1725 Local Menus in Turbo Vision
TI1729 Simultaneous Dialogs in Turbo Vision
TI1779 Adding and Removing items from a Turbo Vision Listbox
TI469 Turbo Vision program to go into 132 column mode
TI991 Multiple variations of TInputLine for Turbo Vision
TI993 Use different color combinations in Turbo Vision
TVG110.ZIP Graphics Mode Version of Turbo Vision
FREQUENTLY ASKED QUESTIONS AND ANSWERS
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Q: "Can Turbo Vision be run in graphics mode?"
A: Turbo Vision was not designed to support graphics. However,
there is a file in this library 1 (TVG110.ZIP), which gives
you a graphics-mode version of Turbo Vision. There may be
others uploaded periodically, it's best to search the
libraries.
Q: "Are there any books that cover Turbo Vision?"
A: Books that cover Turbo Vision are:
"A Programmer Guide to Turbo Vision"
by Freddy Etrl, Ralph Machholz and Andi Golgath
Addison-Wesley ISBN 0-201-62401-X
"Turbo Pascal 6.0 Techniques and Utilities"
by Neil J. Rubenking
Ziff Davis Press ISBN 1-56276-010-6
"Clean Coding in Turbo Pascal 6"
by Amrik Dhillon
M&T Books ISBN 1-55851-228-4
Q: "I don't seem to be getting all the memory used by
collections after disposing them. What could be going
wrong?"
A: If you don't seem to be getting back all your memory when
disposing of a collection, then there are several things you
may be doing wrong:
* You are allocating the collection with
MyColl := New(PMyColl, init(...))
but are only destroying it with
MyColl^.Done
instead of
Dispose(MyColl, Done).
* You have a memory leak in your TObject descendant that
you are placing in the collection (check your allocations
in the Init constructor and the deallocs in your Done
destructor).
* You are not putting TObject descendants in the
collection at all (this generally creates program
crashes.
* If you call the delete method, the delete method just
removes the object from the collection but does NOT
destroy the object, Free removes the object from the
collection and then destroys it by calling FreeItem
(which normally calls Dispose(Item, Done)).
Q: "What is the proper way to switch from TVision to graphics
and back?"
A: For an example you can ook at the DosShell code in APP.PAS
(or in TVDEMO, if you're using TP6). Follow the same steps,
but replace the Exec statement with your graphics stuff.
If you're using TP7/BP7, you may find that you need to
replace the DoneDosMem/InitDosMem with
DoneMemory/InitMemory.
Q: "How do you make change the default background of a TVision
application?"
A: The TBackground object is designed to use only 1 ascii
character. You could create a new type of background
object.
Type
PMyBackground = ^TMyBackground;
TMyBackground = Object(TView)
{ Variables go here to support your box or text or whatever }
Procedure Draw; virtual;
Function GetPalette: PPalette; virtual; { You override this }
{ Other methods here like Load and Store }
End;
Procedure TMyBackground.Draw;
Begin
{ Your drawing routine which draws over the whole view }
End;
Also, you will have to override TDesktop.
Type
PMyDesktop = TMyDesktop;
TMyDesktop = Object(TDesktop)
Procedure InitBackground; virtual;
End;
Procedure TMyDesktop.InitBackground;
Var
P: PView;
R: TRect;
Begin
GetExtent(R);
P := New(PMyBackground, Init(R));
If ValidView(P) Then
Insert(P);
End;
You must also override InitDesktop in your main TApplication.
Type
PMyApp = ^TMyApp;
TMyApp = Object(TApplication)
Procedure InitDesktop; virtual;
End;
Procedure TMyApp.InitDesktop;
Var
P: PView;
Begin
GetExtent(R);
Inc(R.A.Y);
Dec(R.B.Y);
P := New(PDesktop, Init(R));
If ValidView(P) Then
Insert(P);
End;