Declare Function ScreenCopy ( ByVal from_page As Long = -1, ByVal to_page As Long = -1 ) As Long

ScreenCopy [ from_page ] [, to_page ]

from_page
to_page

from_page is the page to copy from. If this argument is omitted, the current work page is assumed. to_page is the page to copy to. If this argument is omitted, the currently visible page is assumed. Page numbers range from 0 to num_pages - 1, where num_pages is the number of pages specified when setting the graphics mode with ScreenRes or Screen.

You can use this function to add a double buffer to your graphics. Any graphics screen mode with multiple pages supports this function.

ScreenCopy is inactive if the destination page is locked.

There are two other functions similar to this: Flip and PCopy. Flip is designed to work in OpenGL modes, while PCopy supports console pages on some platforms. Both do the same thing as ScreenCopy in normal graphics modes.

See also ScreenSet example.

'' 320x200x8, with 3 pages
Screen 13,,3

'' image for working page #1 (visible page #0)
ScreenSet 1, 0
Cls
Circle( 160, 100 ), 90, 1 ,,,, f
Circle( 160, 100 ), 90, 15
Print "Press 2 to copy page #2 to visible page"
Print "Press escape to exit"

'' image for working page #2 (visible page #0)
ScreenSet 2, 0
Cls
Line( 50, 50 )-( 270, 150 ), 2, bf
Line( 50, 50 )-( 270, 150 ), 15, b
Print "Press 1 to copy page #1 to visible page"
Print "Press escape to exit"

'' page #0 is the working page (visible page #0)
ScreenSet 0, 0
Cls
Print "Press 1 to copy page #1 to visible page"
Print "Press 2 to copy page #2 to visible page"
Print "Press escape to exit"

Dim k As String

Do
  k = Inkey
  Select Case k
  Case Chr(27)
    Exit Do
  Case "1"
    ScreenCopy 1, 0
  Case "2"
    ScreenCopy 2, 0
  End Select

  Sleep 25
Loop

• Not available in the -lang qb dialect unless referenced with the alias __Screencopy.
  
  

• New to FreeBASIC. It is a graphics-only version of PCopy - which works in both text and graphics modes.
  
  

• PCopy
  
• Screen (Graphics)
  
• ScreenRes
  
• ScreenSet