mirror of
https://github.com/QB64-Phoenix-Edition/QB64pe.git
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6e01fc8dce
Added new _STRCMP and _STRICMP commands for quick string comparisons. Cleaned up QB64 to finish removing the QUI (quick user insert) code and folders. Altered UCASE and LCASE routines to be faster in some situations for us.
48 lines
2 KiB
Plaintext
48 lines
2 KiB
Plaintext
The [[_ALPHA32]] function returns the alpha transparency level of a 32 bit color value only.
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{{PageSyntax}}
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:{{Parameter|alpha&}} = '''_ALPHA32({{Parameter|colour32~&}})'''
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{{Parameters}}
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* {{Parameter|colour32&}} is the [[_UNSIGNED]] [[LONG]] 32 bit color value used to retrieve the alpha level.
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** Color values that are set as a [[_CLEARCOLOR]] always have an alpha level of 0 (transparent).
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** [[_SETALPHA]] can set any alpha level from 0 or fully transparent to 255 or opaque.
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** Normal color values that are set by [[_RGB]] or [[_RGB32]] always have an alpha level of 255(opaque).
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''Usage:''
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* In 4(16 color) or 8(256 color) bit palette screens the function will return 0.
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* [[_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.
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* '''NOTE: 32 bit [[_NEWIMAGE]] screen page backgrounds are transparent black or [[_ALPHA]] 0. Use [[_DONTBLEND]] or [[CLS]] for opaque!'''
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''Example:'' Finding the alpha transparency level in a 32 bit screen using an [[_RGBA]] [[_UNSIGNED]] [[LONG]] color value.
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{{CodeStart}} '' ''
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{{Cl|SCREEN}} {{Cl|_NEWIMAGE}}(640, 480, 32)
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clr~& = {{Cl|_RGBA}}(255, 0, 255, 192)
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{{Cl|PRINT}} "Color:"; clr~&
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{{Cl|COLOR}} clr~&
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{{Cl|PRINT}} "Alpha32:"; {{Cl|_ALPHA32}}(clr~&)
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{{Cl|END}} '' ''
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{{CodeEnd}}
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{{OutputStart}}{{text|Color: 3237937407|#FFFFFF}}
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{{text|Alpha32: 192|#FF00FF}}
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{{OutputEnd}}
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: ''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}}
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* [[_ALPHA]], [[_SETALPHA]]
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* [[_RGBA]], [[_RGBA32]] {{text|(set color with alpha)}}
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* [[_RED]], [[_GREEN]], [[_BLUE]]
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* [[_RED32]], [[_GREEN32]]. [[_BLUE32]]
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* [[_CLEARCOLOR]], [[_CLEARCOLOR (function)]]
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* [[Images]]
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{{PageNavigation}} |