CLS


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:
'' 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!"


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.

Dim scrbuf As Byte Ptr, scrsize As Integer
Dim As Integer 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


Differences from QB:
See also:
Back to Console Functions
Back to Screen Functions Index
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