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
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 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

- None

See also

- `Color`
- `Locate`
- `Print`
- `View (Graphics)`