Clssub

Clears the screen in both text modes and graphics modes

Syntax

Declare Sub Cls ( ByVal mode As Long = 1 )

Parameters

Name		Description
`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

Remarks

Usage



Cls mode

Differences from QB

None

Example

'' 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 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

Reference

Documented in KeyPgCls.html