Colour bars/Display: Difference between revisions

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Revision as of 12:32, 6 November 2013

The task is to display a series of vertical color bars across the width of the display. The color bars should either use the system palette, or the sequence of colors: Black, Red, Green, Blue, Magenta, Cyan, Yellow, White.

AutoHotkey

Library: GDI+

(available at http://www.autohotkey.net/~tic/Gdip.ahk)

<lang AutoHotkey>#SingleInstance, Force

NoEnv

SetBatchLines, -1

Uncomment if Gdip.ahk is not in your standard library

Include, Gdip.ahk

Start gdi+

If !pToken := Gdip_Startup() {

  message =
  ( LTrim
     gdiplus error!, Gdiplus failed to start.
     Please ensure you have gdiplus on your system.
  )
  MsgBox, 48, %message%
  ExitApp

} OnExit, Exit

Set the width and height we want as our drawing area, to draw everything in.
This will be the dimensions of our bitmap

Width := A_ScreenWidth, Height := A_ScreenHeight

Create a layered window
(+E0x80000: must be used for UpdateLayeredWindow to work!)
that is always on top (+AlwaysOnTop), has no taskbar entry or caption

Gui, 1: -Caption +E0x80000 +LastFound +OwnDialogs +Owner +AlwaysOnTop

Show the window

Gui, 1: Show, NA

Get a handle to this window we have created in order to update it later

hwnd1 := WinExist()

Create a gdi bitmap with width and height of what we are going to
draw into it. This is the entire drawing area for everything

hbm := CreateDIBSection(Width, Height)

Get a device context compatible with the screen

hdc := CreateCompatibleDC()

Select the bitmap into the device context

obm := SelectObject(hdc, hbm)

Get a pointer to the graphics of the bitmap, for use with drawing functions

G := Gdip_GraphicsFromHDC(hdc)

ARGB = Transparency, Red, Green, Blue

Colors := "0xFF000000,0xFFFF0000,0xFF00FF00,0xFF0000FF" Colors .= ",0xFFFF00FF,0xFF00FFFF,0xFFFFFF00,0xFFFFFFFF"

This list ^ is Black, Red, Green, Blue, Magenta, Cyan, Yellow, White

StringSplit Colors, Colors, `, w := Width // Colors0 Loop % Colors0 {

  ; Create a brush to draw a rectangle
  pBrush := Gdip_BrushCreateSolid(Colors%A_Index%)

  ; Fill the graphics of the bitmap with a rectangle using the brush created
  Gdip_FillRectangle(G, pBrush, w*(A_Index-1), 0, w, height)

  ; Delete the brush as it is no longer needed and wastes memory
  Gdip_DeleteBrush(pBrush)

}

Update the specified window we have created (hwnd1) with a handle to our
bitmap (hdc), specifying the x,y,w,h we want it positioned on our screen
So this will position our gui at (0,0) with the Width and
Height specified earlier

UpdateLayeredWindow(hwnd1, hdc, 0, 0, Width, Height)

Select the object back into the hdc

SelectObject(hdc, obm)

Now the bitmap may be deleted

DeleteObject(hbm)

Also the device context related to the bitmap may be deleted

DeleteDC(hdc)

The graphics may now be deleted

Gdip_DeleteGraphics(G) Return

GuiEscape: Exit:

gdi+ may now be shutdown on exiting the program

Gdip_Shutdown(pToken) ExitApp Return</lang>

BBC BASIC

Works with: BBC BASIC for Windows

<lang bbcbasic> SW_MAXIMIZE = 3

     SYS "ShowWindow", @hwnd%, SW_MAXIMIZE
     VDU 26
     
     W% = @vdu%!208 / 4
     H% = @vdu%!212 * 2
     
     COLOUR 1,9
     COLOUR 2,10
     COLOUR 3,12
     COLOUR 4,13
     COLOUR 5,14
     COLOUR 6,11
     COLOUR 7,15
     
     FOR C% = 0 TO 7
       GCOL C%
       RECTANGLE FILL C%*W%, 0, W%, H%
     NEXT

</lang>

C

This task requires functionality which allows the code to communicate to the video device. This will vary from vendor to vendor. The following examples show two ways of doing this, in the text and graphics mode, using Borland's Turbo C.

Text Mode

The required functions and structures are in conio.h <lang C> /*Abhishek Ghosh, 6th November 2013, Rotterdam*/

include<conio.h>

define COLOURS 8

int main() { int colour=0,i,j,MAXROW,MAXCOL; struct text_info tInfo; gettextinfo(&tInfo); MAXROW = tInfo.screenheight; MAXCOL = tInfo.screenwidth; textbackground(BLACK); //8 colour constants are defined clrscr();

for(colour=0;colour<COLOURS;colour++) { getch(); //waits for a key hit gotoxy(1+colour*MAXCOL/COLOURS,1); textbackground(colour); for(j=0;j<MAXROW;j++){ for(i=0;i<MAXCOL/COLOURS;i++){ cprintf(" "); } gotoxy(1+colour*MAXCOL/COLOURS,1+j); } }

getch(); textbackground(BLACK);

return 0; } </lang>

Graphics Mode

The required functions and structures are in graphics.h, conio.h is included for getch(). <lang C> /*Abhishek Ghosh, 6th November 2013, Rotterdam*/

include<graphics.h>
include<conio.h>

int main() { int d=DETECT,m,maxX,maxY,maxColours,i; initgraph(&d,&m,"c:/turboc3/bgi"); maxX = getmaxx(); maxY = getmaxy(); maxColours = getmaxcolor();

for(i=0;i<maxColours;i++) { setfillstyle(SOLID_FILL,i); bar(i*maxX/maxColours,0,(i+1)*maxX/maxColours,maxY); }

getch(); closegraph();

return 0; } </lang>

C++

using Qt 4.6

file colorbars.h:

<lang cpp>#ifndef MYWIDGET_H

define MYWIDGET_H
include <QWidget>

class QPaintEvent ;

class MyWidget : public QWidget { public :

  MyWidget( ) ;

protected :

  void paintEvent( QPaintEvent * ) ;

private :

  int width ;
  int height ;
  const int colornumber ;

} ;

endif</lang>

file colorbars.cpp:

<lang cpp>#include <QtGui>

include "colorbars.h"

MyWidget::MyWidget( ) :

  width( 640 ) ,
  height( 240 ) ,
  colornumber( 8 ) {
     setGeometry( 0, 0 , width , height ) ;

}

void MyWidget::paintEvent ( QPaintEvent * ) {

  int rgbtriplets[ ] = { 0 , 0 , 0 , 255 , 0 , 0 , 0 , 255 , 0 , 
     0 , 0 , 255 , 255 , 0 , 255 , 0 , 255 , 255 , 255 , 255 , 0 ,
     255 , 255 , 255 } ; 
  QPainter myPaint( this ) ;
  int rectwidth = width / colornumber ; //width of one rectangle
  int xstart = 1 ; //x coordinate of the first rectangle
  int offset = -1  ; //to allow for ++offset to define the red value even in the first run of the loop below
  for ( int i = 0 ; i < colornumber ; i++ ) {
     QColor rectColor ;
     rectColor.setRed( rgbtriplets[ ++offset ] ) ;
     rectColor.setGreen( rgbtriplets[ ++offset ] ) ;
     rectColor.setBlue( rgbtriplets[ ++offset ] ) ;
     myPaint.fillRect( xstart , 0 , rectwidth , height - 1 , rectColor ) ;
     xstart += rectwidth + 1 ;
  }

}</lang>

file main.cpp:

<lang cpp>#include <QApplication>

include "colorbars.h"

int main( int argc, char * argv[ ] ) {

  QApplication app( argc , argv ) ;
  MyWidget window ;
  window.setWindowTitle( QApplication::translate( "colorslides" , "color slides demonstration" ) ) ;
  window.show( ) ;
  return app.exec( ) ;

}</lang>

COBOL

Works with: OpenCOBOL

<lang cobol> IDENTIFICATION DIVISION.

      PROGRAM-ID. terminal-colour-bars.

      DATA DIVISION.
      WORKING-STORAGE SECTION.
      01  width           PIC 9(3).
      01  height          PIC 9(3).

      01  interval        PIC 9(3).

      01  colours-area.
          03  colour-values.
              05  FILLER  PIC 9 VALUE 0. *> Black
              05  FILLER  PIC 9 VALUE 4. *> Red
              05  FILLER  PIC 9 VALUE 2. *> Green
              05  FILLER  PIC 9 VALUE 1. *> Blue
              05  FILLER  PIC 9 VALUE 5. *> Magneta
              05  FILLER  PIC 9 VALUE 3. *> Cyan
              05  FILLER  PIC 9 VALUE 6. *> Yellow
              05  FILLER  PIC 9 VALUE 7. *> White

          03  colour-table REDEFINES colour-values.
              05  colours PIC 9 OCCURS 8 TIMES INDEXED BY colour-index.

      01  i               PIC 9(3).
      01  j               PIC 9(3).

      PROCEDURE DIVISION.
          ACCEPT width FROM COLUMNS
          ACCEPT height FROM LINES
          DIVIDE width BY 8 GIVING interval

          PERFORM VARYING i FROM 1 BY 1 UNTIL height < i
              PERFORM VARYING j FROM 1 BY 1 UNTIL width < j
                 COMPUTE colour-index = (j / interval) + 1
                 
                 IF 8 < colour-index
                     SET colour-index TO 8
                 END-IF

                 *> Some colours come a bit darker than they
                 *> should, with the yellow being orange and the white
                 *> being light-grey.
                 DISPLAY SPACE AT LINE i COLUMN j
                     WITH BACKGROUND-COLOR colours (colour-index)
              END-PERFORM
          END-PERFORM

          ACCEPT i *> Prevent ncurses returning to console immediately.

          GOBACK
          .</lang>

Icon and Unicon

The procedure below is generalized to take a description of a test card and display it.

<lang Icon>link graphics,printf

procedure main() # generalized colour bars

  DrawTestCard(Simple_TestCard())
  WDone()

end

procedure DrawTestCard(TC)

  size := sprintf("size=%d,%d",TC.width,TC.height)
  &window := TC.window := open(TC.id,"g","bg=black",size) | 
              stop("Unable to open window")

  every R := TC.bands[r := 1 to *TC.bands -1] do
     every C := R.bars[c := 1 to *R.bars - 1] do {

Fg(R.bars[c].colour) FillRectangle( C.left, R.top, R.bars[c+1].left-C.left, TC.bands[r+1].top-R.top ) }

  return TC

end

record testcard(window,id,width,height,bands) record band(top,bars) record bar(left,colour)

procedure Simple_TestCard() #: return structure simple testcard

  return testcard(,"Simple Test Card",width := 800,height := 600,

[ band( 1, [ bar( 1, "black"), bar(114, "red"), bar(228, "green"), bar(342, "blue"),

                                 bar(456, "magenta"),
                                 bar(570, "cyan"),
                                 bar(684, "yellow"),
                                 bar(width) ] ),

band(height) ]) end</lang>

The following example is a wee tiny bit more interesting.

<lang Icon>procedure SMPTE_TestCard() #: return structure with 480i(ish) testcard

  return testcard(,"SMPTE TV Test Card",width := 672,height := 504,

[ band( 1, [ bar( 1, "#c0c0c0"), bar( 95, "#c0c000"),

  	    		           bar(191, "#00c0c0"),

bar(288, "#00c000"), bar(383, "#c000c0"), bar(480, "#c00000"), bar(575, "#0000c0"), bar(width) ] ), band(335, [ bar( 1, "#0000c0"), bar( 95, "#131313"), bar(191, "#c000c0"), bar(288, "#131313"), bar(383, "#00c0c0"), bar(480, "#131313"), bar(575, "#c0c0c0"), bar(width) ] ), band(378, [ bar( 1, "#00214c"), bar(120, "#ffffff"), bar(240, "#32006a"), bar(360, "#131313"), bar(480, "#090909"), bar(512, "#131313"), bar(544, "#1d1d1d"), bar(576, "#131313"), bar(width) ] ), band(height) ]) end</lang>

Library: Icon Programming Library

graphics.icn provides graphics printf.icn provides sprintf

J

<lang j> load 'viewmat'

  size=: 2{.".wd'qm' NB. J6
  size=: getscreenwh_jgtk_  NB. J7
  'rgb'viewmat (|.size){. (>.&.(%&160)|.size)$ 20# 256#.255*#:i.8</lang>

Note: You need to pick an implementation of size based on the version of J you are using.

Java

<lang java> import java.awt.Color; import java.awt.Graphics;

import javax.swing.JFrame;

public class ColorFrame extends JFrame { public ColorFrame(int width, int height) { this.setDefaultCloseOperation(EXIT_ON_CLOSE); this.setSize(width, height); this.setVisible(true); }

@Override public void paint(Graphics g) { Color[] colors = { Color.black, Color.red, Color.green, Color.blue, Color.pink, Color.CYAN, Color.yellow, Color.white };

for (int i = 0; i < colors.length; i++) { g.setColor(colors[i]); g.fillRect(this.getWidth() / colors.length * i, 0, this.getWidth() / colors.length, this.getHeight()); } }

public static void main(String args[]) { new ColorFrame(200, 200); } } </lang>

Liberty BASIC

<lang lb>nomainwin colors$="black red green blue pink cyan yellow white" WindowWidth=DisplayWidth:WindowHeight=DisplayHeight UpperLeftX=1:UpperLeftY=1 barWidth=DisplayWidth/8 graphicbox #main.g, 0,0,DisplayWidth,DisplayHeight open "" for window_popup as #main

main "trapclose [quit]"
main.g "down; setfocus; when characterInput [quit]"
main.g "when leftButtonUp [quit]"
main.g "size ";barWidth

for x = barWidth/2 to DisplayWidth step barWidth

   i=i+1
   if i>8 then i=1
   col$=word$(colors$,i)
   #main.g "color ";col$;"; line ";x;" 0 ";x;" ";DisplayHeight

next wait [quit] close #main:end

</lang>

Locomotive Basic

Show the default MODE 0 palette (includes two blinking colors at the end):

<lang locobasic>10 MODE 0:BORDER 23 20 FOR x=0 TO 15 30 ORIGIN x*40,0 40 GRAPHICS PEN x 50 FOR z=0 TO 39 STEP 4:MOVE z,0:DRAW z,400:NEXT 60 NEXT 70 CALL &bb06 ' wait for key press</lang>

Mathematica

<lang mathematica>ArrayPlot[

ConstantArray[{Black, Red, Green, Blue, Magenta, Cyan, Yellow, 
  White}, 5]]</lang>

OCaml

<lang ocaml>open Graphics

let round x =

 int_of_float (floor (x +. 0.5))

let () =

 open_graph "";
 let cols = size_x () in
 let rows = size_y () in
 let colors = [| black; red; green; blue; magenta; cyan; yellow; white |] in
 let n = Array.length colors in
 let bar_width = (float cols) /. (float n) in
 Array.iteri (fun i color ->
   let x1 = bar_width *. (float i) in
   let x2 = bar_width *. (float (succ i)) in
   set_color color;
   fill_rect (round x1) 0 (round x2) rows;
 ) colors;
 ignore (read_key ());

</lang>

execute with:

$ ocaml graphics.cma display_colour_bars.ml

Perl

<lang Perl>#!/usr/bin/perl -w use strict ; use GD ;

my %colors = ( white => [ 255 , 255 , 255 ] , red => [255 , 0 , 0 ] ,

     green => [ 0 , 255 , 0 ] , blue => [ 0 , 0 , 255 ] , 
     magenta => [ 255 , 0 , 255 ] , yellow => [ 255 , 255 , 0 ] ,
     cyan => [ 0 , 255 , 255 ] , black => [ 0 , 0 , 0 ] ) ;

my $barwidth = 160 / 8 ; my $image = new GD::Image( 160 , 100 ) ; my $start = 0 ; foreach my $rgb ( values %colors ) {

  my $paintcolor = $image->colorAllocate( @$rgb ) ; 
  $image->filledRectangle( $start * $barwidth , 0 , $start * $barwidth +

$barwidth - 1 , 99 , $paintcolor ) ;

  $start++ ;

} open ( DISPLAY , ">" , "testprogram.png" ) || die ; binmode DISPLAY ; print DISPLAY $image->png ; close DISPLAY ;#to be watched with <image viewer> testprogram.png</lang>

Perl 6

<lang perl6>my $HOR = 1280; my $VERT = 720;

my @colors = map -> $r, $g, $b { Buf.new: ($r, $g, $b) xx $HOR div 8 },

                 0,  0,  0,
               255,  0,  0,
                 0,255,  0,
                 0,  0,255,
               255,  0,255,
                 0,255,255,
               255,255,  0,
               255,255,255;

my $PPM = open "colorbars.ppm", :w, :bin or die "Can't create colorbars.ppm: $!";

$PPM.print: qq:to/EOH/;

   P6
   # colorbars.ppm
   $HOR $VERT
   255
   EOH

for ^$VERT -> $v {

   for ^@colors -> $h {
       $PPM.write: @colors[$h];
   }

}

$PPM.close;</lang>

PicoLisp

Translation of: UNIX Shell

<lang PicoLisp>(call 'clear)

(let Width (in '(tput cols) (read))

  (do (in '(tput lines) (read))
     (for B (range 0 7)
        (call 'tput 'setab B)
        (space (/ Width 8)) )
     (prinl) ) )

(call 'tput 'sgr0) # reset</lang>

PHP

Translation of: Perl

Will output result directly to the browser. Use it as CGI/BIN script. <lang PHP><?php $colors = array(array(255, 255, 255), // white

               array(255,   0,   0),   // red
               array(  0, 255,   0),   // green
               array(  0,   0, 255),   // blue
               array(255,   0, 255),   // magenta
               array(255, 255,   0),   // yellow
               array(  0, 255, 255),   // cyan
               array(  0,   0,   0));  // black

define('BARWIDTH', 640 / count($colors)); define('HEIGHT', 480);

$image = imagecreate(BARWIDTH * count($colors), HEIGHT);

foreach ($colors as $position => $color) {

   $color = imagecolorallocate($image, $color[0], $color[1], $color[2]);
   imagefilledrectangle($image, $position * BARWIDTH, 0,
                        $position * BARWIDTH + BARWIDTH - 1,
                        HEIGHT - 1, $color);

}

header('Content-type:image/png'); imagepng($image); imagedestroy($image);</lang>

PureBasic

Press Enter or Escape to exit the program. <lang PureBasic>Dim color(7) color(0) = RGB($00, $00, $00) ;black color(1) = RGB($FF, $00, $00) ;red color(2) = RGB($00, $FF, $00) ;green color(3) = RGB($00, $00, $FF) ;blue color(4) = RGB($FF, $00, $FF) ;magenta color(5) = RGB($00, $FF, $FF) ;cyan color(6) = RGB($FF, $FF, $00) ;yellow color(7) = RGB($FF, $FF, $FF) ;white

If Not InitKeyboard(): End: EndIf ;can't init keyboard If Not InitSprite(): End: EndIf ;can't init sprite/screen library If Not ExamineDesktops(): End: EndIf ;can't retrieve information about desktop

height = DesktopHeight(0) width = DesktopWidth(0) depth = DesktopDepth(0) If OpenScreen(width, height, depth, "Press ENTER to exit")

 StartDrawing(ScreenOutput())
   For c = 0 To 7
     Box((width * c) / 8, 0, width / 8, height, color(c))
   Next
 StopDrawing()
 FlipBuffers()

 Repeat
   Delay(10)
   ExamineKeyboard()
 Until KeyboardPushed(#PB_Key_Escape) Or KeyboardPushed(#PB_Key_Return)
 CloseScreen()

EndIf</lang>

Alternate method using console

<lang PureBasic>DataSection

 ;Black, Red, Green, Blue, Magenta, Cyan, Yellow, White
 Data.i  0, 12, 10, 9, 13, 11, 14, 15

EndDataSection

Dim colors(7) For c = 0 To 7

 Read.i colors(c)

 ;The console display is 80 columns wide by 25 rows
 For r = 0 To 24
   For c = 0 To 7 
     ConsoleColor(colors(c), colors(c))
     Print(Space(80 / 8))
   Next
 Next
 EnableGraphicalConsole(1)
 ConsoleLocate(0, 0)
 
 ConsoleTitle("Press ENTER to exit"): Input()
 CloseConsole()

EndIf</lang>

Python

!/usr/bin/env python
vertical coloured stripes in window in Python 2.7.1

from livewires import *

horiz=640; vert=480 begin_graphics(width=horiz,height=vert,title="v_stripes",background=Colour.black) NameColors=["black","red","green","dark_blue","purple","blue","yellow","white"] stepik=horiz/len(NameColors)

for index,each in enumerate(NameColors): ExcStrng="set_colour(Colour."+each+")" exec ExcStrng box(index*stepik,0,(index+1)*stepik,vert,filled=1)

while keys_pressed() != ['x']: # press x key to terminate program pass

end_graphics() </lang>

R

Create the color palette, set margins to zero so the image will fill the display, and use image to create the graphic:

Racket

lang racket/gui

(define-values [W H] (get-display-size #t))

(define colors

 '("Black" "Red" "Green" "Blue" "Magenta" "Cyan" "Yellow" "White"))

(define (paint-pinstripe canvas dc)

 (send dc set-pen "black" 0 'transparent)
 (for ([x (in-range 0 W (/ W (length colors)))] [c colors])
   (send* dc (set-brush c 'solid) (draw-rectangle x 0 W H))))

(define full-frame%

 (class frame%
   (define/override (on-subwindow-char r e)
     (when (eq? 'escape (send e get-key-code))
       (send this show #f)))
   (super-new
    [label "Color bars"] [width W] [height H]
    [style '(no-caption no-resize-border hide-menu-bar no-system-menu)])
   (define c (new canvas% [parent this] [paint-callback paint-pinstripe]))
   (send this show #t)))

(void (new full-frame%)) </lang>

Run BASIC

<lang runbasic>colors$ = "black,red,green,blue,magenta,cyan,yellow,white"

html "

" for i = 1 to 8 html "<td width=20 bgcolor='";word$(colors$,i,",");"'" next i html "

"</lang>

Output

Scala

<lang scala>import java.awt.Color import scala.swing._

class ColorBars extends Component {

 override def paintComponent(g:Graphics2D)={
   val colors=List(Color.BLACK, Color.RED, Color.GREEN, Color.BLUE, Color.MAGENTA, Color.CYAN, Color.YELLOW, Color.WHITE)
   val colCount=colors.size
   val deltaX=size.width.toDouble/colCount
   for(x <- 0 until colCount){
     val startX=(deltaX*x).toInt
     val endX=(deltaX*(x+1)).toInt
     g.setColor(colors(x))
     g.fillRect(startX, 0, endX-startX, size.height)
   }
 }

}</lang> Open window:

<lang scala>new MainFrame(){

 title="Color bars"
 visible=true
 preferredSize=new Dimension(640, 320)
 contents=new ColorBars()

}</lang>

Tcl

Library: Tk

<lang tcl>package require Tcl 8.5 package require Tk 8.5

wm attributes . -fullscreen 1 pack [canvas .c -highlightthick 0] -fill both -expand 1 set colors {black red green blue magenta cyan yellow white}

for {set x 0} {$x < [winfo screenwidth .c]} {incr x 8} {

   .c create rectangle $x 0 [expr {$x+7}] [winfo screenheight .c] \
           -fill [lindex $colors 0] -outline {}
   set colors [list {*}[lrange $colors 1 end] [lindex $colors 0]]

}</lang>

UNIX Shell

<lang sh>#!/bin/sh clear WIDTH=`tput cols` HEIGHT=`tput lines` NUMBARS=8 BARWIDTH=`expr $WIDTH / $NUMBARS`

l="1" # Set the line counter to 1 while [ "$l" -lt $HEIGHT ]; do

 b="0"    # Bar counter
 while [ "$b" -lt $NUMBARS ]; do
   tput setab $b
   s="0"
   while [ "$s" -lt $BARWIDTH ]; do
     echo -n " "
     s=`expr $s + 1`
   done
   b=`expr $b + 1`
 done
 echo    # newline
 l=`expr $l + 1`

done

tput sgr0 # reset</lang>

XPL0

<lang XPL0>include c:\cxpl\codes; \intrinsic code declarations int W, X0, X1, Y, C; [SetVid($13); \320x200x8 graphics W:= 320/8; \width of color bar (pixels) for C:= 0 to 8-1 do

       [X0:= W*C; X1:= X0+W-1;
       for Y:= 0 to 200-1 do
               [Move(X0, Y); Line(X1, Y, C)];
       ];

C:= ChIn(1); \wait for keystroke SetVid(3); \restore normal text mode ]</lang>

ZX Spectrum Basic

<lang zxbasic>10 REM The ZX Spectrum display is 32 columns wide, so we have 8 columns of 4 spaces 20 FOR r=0 TO 20: REM There are 21 rows 30 FOR c=0 TO 7: REM We use the native colour sequence here 40 PAPER c: REM set the background colour for the spaces to be printed 50 PRINT " ";: REM four spaces, the semicolon prevents newline 60 NEXT c 70 REM at this point the cursor has wrapped, so we don't need a newline 80 NEXT r</lang>