Screencopy

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ScreenCopy

Copies one graphics page onto another, by default the work page onto the shown one.

Syntax

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

Parameters

• from_page
• to_page

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.

Return Value

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

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.

See also

• PCopy
• Screen (Graphics)
• ScreenRes
• ScreenSet

Examples

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

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Category: Screen Functions
Kind: function

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.