"{ Package: 'stx:libview' }"

Color subclass:#TranslucentColor

	instanceVariableNames:'alpha'

	classVariableNames:''

	poolDictionaries:''

	category:'Graphics-Support'

!

!TranslucentColor class methodsFor:'documentation'!

documentation

"

    TranslucentColor represents colors with an alpha (transparency)

    channel.

    This is experimental and not yet used by the system.

    [Instance variables:]

      alpha           <Integer>       the internal alpha value (0..255)

"

! !

!TranslucentColor class methodsFor:'instance creation'!

red:r green:g blue:b alpha:alpha

    alpha = 1 ifTrue:[

	^ super red:r green:g blue:b

    ].

    ^ (super

	   scaledRed:(r * MaxValue // 100)

	   scaledGreen:(g * MaxValue // 100)

	   scaledBlue:(b * MaxValue // 100)) alpha:alpha

! !

!TranslucentColor methodsFor:'accessing'!

alpha

    "return the alpha value (0..1),

     where 0 is completely transparent and 1 is completely opaque"

    ^ alpha asFloat / 255.0

!

alpha:alphaFraction

    "set the alpha value (0..1),

     where 0 is completely transparent and 1 is completely opaque"

    alpha := (alphaFraction * 255) rounded

!

alphaByte

    "return the alpha value as byte 0..255,

     where 0 is completely transparent and 255 is completely opaque"

    ^ alpha

!

privateAlpha

    "return the internal alpha value (0..255),

     where 0 is completely transparent and 255 is completely opaque"

    ^ alpha

!

scaledAlpha

    "return the alpha value (0..16rFFFF),

     where 0 is completely transparent and 16rFFFF is completely opaque"

    ^ alpha * 16rFFFF // 255

!

setAlphaByte:aByteValuedInteger

    "set the alpha value (0..255),

     where 0 is completely transparent and 255 is completely opaque"

    alpha := aByteValuedInteger

! !

!TranslucentColor methodsFor:'printing & storing'!

storeOn:aStream

    "append a string representing an expression to reconstruct the receiver

     to the argument, aStream"

    |clsName|

    clsName := self class name.

    aStream nextPutAll:'(' , clsName , ' red:'.

    (self red) storeOn:aStream.

    aStream nextPutAll:' green:'.

    (self green) storeOn:aStream.

    aStream nextPutAll:' blue:'.

    (self blue) storeOn:aStream.

    aStream nextPutAll:' alpha:'.

    (self alpha) storeOn:aStream.

    aStream nextPut:$).

    "

     (self red:100 green:100 blue:0 alpha:1) storeOn:Transcript

    "

! !

!TranslucentColor methodsFor:'queries'!

isOpaque

    "return true, if I represent an opaque color"

    ^ alpha == 255

!

isTranslucent

    "return true, if I represent a translucent color;

     that is: not completely opaque"

    ^ alpha < 255

!

isTranslucentColor

    "return true, if I represent a translucent color;

     This means: self isTranslucent, but isTransparent not"

    ^ alpha > 0

!

isTransparent

    "return true, if I represent a completely transparent color"

    ^ alpha == 0

! !

!TranslucentColor class methodsFor:'documentation'!

version

    ^ '$Header: /cvs/stx/stx/libview/TranslucentColor.st,v 1.5 2014-03-22 09:26:53 cg Exp $'

! !