The _BLEND statement turns on 32 bit alpha blending for an image or screen mode and is on by default.
Syntax
_BLEND [imageHandle&]
Parameters
- imageHandle& refers to an image in memory. If not specified, the current destination page (See _DEST) is affected.
Description
- Alpha blending is on by default when loading a .PNG image to a 32-bit surface.
- Normally it is used to turn blending on after a previous _DONTBLEND call.
- _BLEND can only be used on 32-bit surfaces, otherwise it will produce the error ERROR Codes.
- Note: _DONTBLEND is faster than the default _BLEND unless you really need to use it in 32 bit.
- 32 bit screen surface backgrounds (black) have zero _ALPHA so that they are transparent when placed over other surfaces.
Example(s)
SCREEN _NEWIMAGE(640, 480, 32)
'CLS , _RGB(128, 128, 128) 'change background color for other results
_DONTBLEND
bg& = POINT(0, 0)
PRINT _RED(bg&), _GREEN(bg&), _BLUE(bg&), _ALPHA(bg&)
LINE (100, 100)-(200, 200), _RGBA32(255, 128, 0, 128), BF
LINE (440, 100)-(540, 200), _RGBA32(0, 0, 255, 64), BF
K$ = INPUT$(1)
_BLEND
LINE (270, 300)-(370, 400), _RGBA32(255, 128, 0, 128), BF
m& = POINT(303, 302)
PRINT _RED(m&), _GREEN(m&), _BLUE(m&), _ALPHA(m&)
K$ = INPUT$(1)
LINE (270, 300)-(370, 400), _RGBA32(0, 0, 255, 64), BF
m& = POINT(303, 302)
PRINT _RED(m&), _GREEN(m&), _BLUE(m&), _ALPHA(m&)
_RGBA(255,128,0,128) onto _RGBA(0,0,255,64)
results in
_RGBA(95,48,64,128)