CLS

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgCls
• Last revised: 2021-06-22

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Clears the screen in both text modes and graphics modes

Syntax

` declare sub Cls ( byval mode as long = 1 )

`

Usage

` Cls mode

`

Parameters

mode

A optional numeric variable with a value from 0 to 2. If omitted, it defaults to 1.

Description

An optional mode parameter may be given,

If omitted, CLS clears either the text or graphics viewport. If a graphics viewport has been defined using the View (Graphics) statement, the graphics viewport is cleared. Otherwise, the text viewport, defined by View Print, is cleared. (If there is no explicit text viewport defined, the entire screen is cleared.)

If 0, clears the entire screen

If 1, clears the graphics viewport if defined. Otherwise, clears the text viewport

If 2, clears the text viewport

Examples

start GeSHi

'' set the color to light grey text on a blue background
Color 7, 1

'' clear the screen to the background color
Cls

'' print text in the center of the screen
Locate 12, 33
Print "Hello Universe!"

end GeSHi

In graphics modes, if you want to clear the entire screen to color 0, it can be faster using Clear to write zeroes to the screen memory than calling CLS.

start GeSHi

Dim scrbuf As Byte Ptr, scrsize As Integer
Dim As Long scrhei, scrpitch
Dim As Integer r = 0, dr = 1

ScreenRes 640, 480, 8

scrbuf = ScreenPtr: Assert( scrbuf <> 0 )
ScreenInfo( , scrhei, , , scrpitch )
scrsize = scrpitch * scrhei

Do
   
    '' lock the screen (must do this while working directly on screenbuffer)
    ScreenLock
       
        '' clear the screen (could use Cls here):
        Clear *scrbuf, 0, scrsize
       
        '' draw circle
        Circle (320, 240), r
       
    ScreenUnlock
   
    '' grow/shrink circle radius
    r += dr
    If r `<= 0 Then dr = 1 Else If r >`= 100 Then dr = -1
   
    '' short pause in each frame (prevents hogging the CPU)
    Sleep 1, 1
   
    '' run loop until user presses a key
Loop Until Len(Inkey) > 0

end GeSHi

Differences from QB

• None

See also

• Color
• Locate
• Print
• ?
• View (Graphics)

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