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_COPYIMAGE

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Cory Smith edited this page Sep 2, 2022 · 6 revisions

The _COPYIMAGE function creates an identical designated image in memory with a different negative LONG handle value.

Syntax

newhandle& = _COPYIMAGE[(imageHandle&[, mode%)]]

Parameter(s)

  • The LONG newhandle& value returned will be different than the source handle value supplied.
  • If imageHandle& parameter is omitted or zero is designated, the current software _DEST screen or image is copied.
  • If 1 is designated instead of an imageHandle&, it designates the last OpenGL hardware surface to copy.
  • Mode 32 can be used to convert 256 color images to 32 bit colors.
  • Mode 33 images are hardware accelerated in version 1.000 and up, and are created using _LOADIMAGE or _COPYIMAGE.

Description

  • The function copies any image or screen handle to a new and unique negative LONG handle value.
  • Valid copy handles are less than -1. Invalid handles return -1 or 0 if it was never created.
  • Every attribute of the passed image or program screen is copied to a new handle value in memory.
  • 32 bit screen surface backgrounds (black) have zero _ALPHA so that they are transparent when placed over other surfaces.

Use CLS or _DONTBLEND to make a new surface background _ALPHA 255 or opaque.

  • Images are not deallocated when the SUB or FUNCTION they are created in ends. Free them with _FREEIMAGE.
  • It is important to free discarded images with _FREEIMAGE to prevent PC memory allocation errors!
  • Do not try to free image handles currently being used as the active SCREEN. Change screen modes first.

Example(s)

Restoring a Legacy SCREEN using the _COPYIMAGE return value.

SCREEN 13
CIRCLE (160, 100), 100, 40
DO: SLEEP: LOOP UNTIL INKEY$ <> ""

'backup screen before changing SCREEN mode
oldmode& = _COPYIMAGE(0)  'the 0 value designates the current destination SCREEN

s& = _NEWIMAGE(800, 600, 32)
SCREEN s&
LINE (100, 100)-(500, 500), _RGB(0, 255, 255), BF
DO: SLEEP: LOOP UNTIL INKEY$ <> ""

SCREEN oldmode&        'restore original screen
IF s& < -1 THEN _FREEIMAGE s&
END

Note: Only free valid handle values with _FREEIMAGE AFTER a new SCREEN mode is being used by the program.

Program that copies desktop to a hardware image to form a 3D triangle:

SCREEN _NEWIMAGE(640, 480, 32)
my_hardware_handle = _COPYIMAGE(_SCREENIMAGE, 33) 'take a screenshot and use it as our texture
_MAPTRIANGLE (0, 0)-(500, 0)-(250, 500), my_hardware_handle TO_ 
(-1, 0, -1)-(1, 0, -1)-(0, 5, -10), , _SMOOTH
_DISPLAY
DO: _LIMIT 30: LOOP UNTIL INKEY$ <> ""

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