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Crtdemo Pas

The document describes a program that demonstrates the use of routines from the Crt unit in Turbo Pascal. The program initializes the screen, creates random windows, and allows the user to insert, delete lines and move the cursor using keyboard commands.

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brahim yahmadi
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54 views3 pages

Crtdemo Pas

The document describes a program that demonstrates the use of routines from the Crt unit in Turbo Pascal. The program initializes the screen, creates random windows, and allows the user to insert, delete lines and move the cursor using keyboard commands.

Uploaded by

brahim yahmadi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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{************************************************}

{ }
{ CRT Unit Demo }
{ Copyright (c) 1985,90 by Borland International }
{ }
{************************************************}

program CrtDemo;
{ Example program that uses the Crt unit. Uses the following routines
from the Crt unit:

ClrScr
DelLine
GoToXY
InsLine
KeyPressed
ReadKey
TextBackground
TextColor
TextMode
WhereX
WhereY
Window
Write
WriteLn;

Also uses LastMode and WindMax variables from Crt unit.

1. Init routine:
- Save original video mode. On an EGA or VGA, use the 8x8 font
(43 lines on an EGA, 50 on VGA).
- Setup LastRow to preserve last line on screen for messages
(preserves last 2 lines in 40-column mode). Setup LastCol.
- Initialize the random number generator.
2. MakeWindow routine:
- Puts up random-sized, random-colored windows on screen.
3. Program body:
- Call Init
- Loop until Contrl-C is typed:
- Echo keystrokes (Turbo Pascal windows automatically wrap
and scroll).
- Support special keys:
<Ins> inserts a line at the cursor
<Del> deletes a line at the cursor
<Up>,
<Dn>,
<Right>,
<Left> position the cursor in the window
<Alt-R> generate random text until a key is pressed
<Alt-W> creates another random window
<ESC> exits the program
}

uses Crt;

var
OrigMode,LastCol,LastRow: Word;
Ch: Char;
Done: Boolean;

procedure Initialize;
{ Initialize the video mode, LastCol, LastRow, and the random number }
{ generator. Paint the help line. }
begin
CheckBreak:=False; { turn off Contrl-C checking }
OrigMode:=LastMode; { Remember original video mode }
TextMode(Lo(LastMode)+Font8x8); { use 43 or 50 lines on EGA/VGA
}
LastCol:=Lo(WindMax)+1; { get last column, row }
LastRow:=Hi(WindMax)+1;
GoToXY(1,LastRow); { put message line on screen }
TextBackground(Black);
TextColor(White);
Write(' Ins-InsLine ',
'Del-DelLine ',
#27#24#25#26'-Cursor ',
'Alt-W-Window ',
'Alt-R-Random ',
'Esc-Exit');
Dec(LastRow,80 div LastCol); { don't write on message line }
Randomize; { init random number generator }
end; { Init }

procedure MakeWindow;
{ Make a random window, with random background and foreground colors }
var
X,Y,Width,Height: Word;
begin
Width:=Random(LastCol-2)+2; { random window size }
Height:=Random(LastRow-2)+2;
X:=Random(LastCol-Width)+1; { random position on screen }
Y:=Random(LastRow-Height)+1;
Window(X,Y,X+Width,Y+Height);
if OrigMode = Mono then
begin
TextBackground(White);
TextColor(Black);
ClrScr;
Window(X+1,Y+1,X+Width-1,Y+Height-1);
TextBackground(Black);
TextColor(White);
ClrScr;
end
else
begin
TextBackground(Random(8));
TextColor(Random(7)+9);
end;
ClrScr;
end; { MakeWindow }

procedure RandomText;
{ Generate random text until a key is pressed. Filter out }
{ control characters. }
begin
repeat
Write(Chr(Random(256-32)+32));
until KeyPressed;
end; { RandomText }

begin { program body }


Initialize;
MakeWindow;
Done:=False;
repeat
Ch:=ReadKey;
case Ch of
#0: { Function keys }
begin
Ch:=ReadKey;
case Ch of
#17: MakeWindow; { Alt-W }
#19: RandomText; { Alt-R }
#45: Done:=True; { Alt-X }
#72: GotoXY(WhereX,WhereY-1); { Up }
#75: GotoXY(WhereX-1,WhereY); { Left }
#77: GotoXY(WhereX+1,WhereY); { Right }
#80: GotoXY(WhereX,WhereY+1); { Down }
#82: InsLine; { Ins }
#83: DelLine; { Del }
end;
end;
#3: Done:=True; { Ctrl-C }
#13: WriteLn; { Enter }
#27: Done:=True; { Esc }
else
Write(Ch);
end;
until Done;
TextMode(OrigMode);
end.

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