ScreenCopyfunction

Copies the contents of a graphical page into another graphical page

Syntax

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

Parameters

Name		Description
`from_page`		page to copy from
`to_page`		page to copy to

Return value

Returns zero (0) if successful, or a non-zero error code to indicate a failure.

Description

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 (Graphics).

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.

The error code returned by ScreenCopy can be checked using Err in the next line. The function version of ScreenCopy returns directly the error code as a 32 bit Long.

Remarks

Usage



ScreenCopy [ from_page ] [, to_page ]

Dialect Differences

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

Differences from QB

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

Example

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

Reference

Documented in KeyPgScreencopy.html