ALPHA32: Difference between revisions
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''Example:'' Finding the alpha transparency level in a 32 bit screen using an [[_RGBA]] [[_UNSIGNED]] [[LONG]] color value. | ''Example:'' Finding the alpha transparency level in a 32 bit screen using an [[_RGBA]] [[_UNSIGNED]] [[LONG]] color value. | ||
{{CodeStart}} | {{CodeStart}} | ||
{{Cl|SCREEN}} {{Cl|_NEWIMAGE}}(640, 480, 32) | {{Cl|SCREEN}} {{Cl|_NEWIMAGE}}({{Text|640|#F580B1}}, {{Text|480|#F580B1}}, {{Text|32|#F580B1}}) | ||
clr~& = {{Cl|_RGBA}}(255, 0, 255, 192) | clr~& = {{Cl|_RGBA}}({{Text|255|#F580B1}}, {{Text|0|#F580B1}}, {{Text|255|#F580B1}}, {{Text|192|#F580B1}}) | ||
{{Cl|PRINT}} "Color:"; clr~& | {{Cl|PRINT}} {{Text|<nowiki>"Color:"</nowiki>|#FFB100}}; clr~& | ||
{{Cl|COLOR}} clr~& | {{Cl|COLOR}} clr~& | ||
{{Cl|PRINT}} "Alpha32:"; {{Cl|_ALPHA32}}(clr~&) | {{Cl|PRINT}} {{Text|<nowiki>"Alpha32:"</nowiki>|#FFB100}}; {{Cl|_ALPHA32}}(clr~&) | ||
{{Cl|END}} | {{Cl|END}} | ||
{{CodeEnd}} | {{CodeEnd}} | ||
{{OutputStart}}{{ | {{OutputStart}}{{Text|Color: 3237937407|#FFFFFF}} | ||
{{ | {{Text|Alpha32: 192|#FF00FF}} | ||
{{OutputEnd}} | {{OutputEnd}} | ||
: ''Notes:'' The color value is equivalent to [[&H|hexadecimal]] &HC0FF00FF where &HC0 equals 192. [[_RGB]] alphas are always &HFF(255). | : ''Notes:'' The color value is equivalent to [[&H|hexadecimal]] &HC0FF00FF where &HC0 equals 192. [[_RGB]] alphas are always &HFF(255). | ||
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{{PageSeeAlso}} | {{PageSeeAlso}} | ||
* [https://qb64phoenix.com/forum/showthread.php?tid=1060 Featured in our "Keyword of the Day" series] | |||
* [[_ALPHA]], [[_SETALPHA]] | * [[_ALPHA]], [[_SETALPHA]] | ||
* [[_RGBA]], [[_RGBA32]] {{ | * [[_RGBA]], [[_RGBA32]] {{Text|(set color with alpha)}} | ||
* [[_RED]], [[_GREEN]], [[_BLUE]] | * [[_RED]], [[_GREEN]], [[_BLUE]] | ||
* [[_RED32]], [[_GREEN32]]. [[_BLUE32]] | * [[_RED32]], [[_GREEN32]]. [[_BLUE32]] | ||
Latest revision as of 19:21, 24 May 2024
The _ALPHA32 function returns the alpha transparency level of a 32 bit color value.
Syntax
- alpha& = _ALPHA32(color32~&)
Parameters
- color32& is the _UNSIGNED LONG 32 bit color value used to retrieve the alpha level.
- Color values that are set as a _CLEARCOLOR always have an alpha level of 0 (transparent).
- _SETALPHA can set any alpha level from 0 (or fully transparent) to 255 (or opaque).
- Normal color values that are set by _RGB or _RGB32 always have an alpha level of 255 (opaque).
Description
- In 4-bit (16 colors) or 8-bit (256 colors) palette screens the function will return 0.
- _RED32, _GREEN32, _BLUE32 and _ALPHA32 are all equivalent to _RED, _GREEN, _BLUE and _ALPHA but they are highly optimized and only accept a 32-bit color (RGBA) value. Using these in your code (opposed to dividing then ANDing 32-bit color values) makes code easy to read.
- NOTE: 32 bit _NEWIMAGE screen page backgrounds are transparent black or _ALPHA 0. Use _DONTBLEND or CLS for opaque!
Examples
Example: Finding the alpha transparency level in a 32 bit screen using an _RGBA _UNSIGNED LONG color value.
SCREEN _NEWIMAGE(640, 480, 32) clr~& = _RGBA(255, 0, 255, 192) PRINT "Color:"; clr~& COLOR clr~& PRINT "Alpha32:"; _ALPHA32(clr~&) END |
Color: 3237937407 Alpha32: 192 |
- Notes: The color value is equivalent to hexadecimal &HC0FF00FF where &HC0 equals 192. _RGB alphas are always &HFF(255).
See also
- Featured in our "Keyword of the Day" series
- _ALPHA, _SETALPHA
- _RGBA, _RGBA32 (set color with alpha)
- _RED, _GREEN, _BLUE
- _RED32, _GREEN32. _BLUE32
- _CLEARCOLOR, _CLEARCOLOR (function)
- Images