Class: TranslucentColor

• Inheritance
• Description
• Class protocol
  • instance creation
• Instance protocol
  • accessing
  • color operations
  • comparing
  • conversion
  • inspecting
  • printing & storing
  • queries

Inheritance:

   Object
   |
   +--Color
      |
      +--TranslucentColor

Package:

stx:libview

Category:

Graphics-Support

Version:

rev: 1.16 date: 2023/05/20 02:11:29

user: cg

file: TranslucentColor.st directory: libview

module: stx stc-classLibrary: libview

Description:

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)

copyright
COPYRIGHT (c) 1999 by Claus Gittinger / eXept Software AG
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Class protocol:

 red: r green: g blue: b alpha: alpha

 scaledRed: r scaledGreen: g scaledBlue: b alpha: alpha

TranslucentColor scaledRed:0 scaledGreen:0 scaledBlue:0
TranslucentColor scaledRed:0 scaledGreen:0 scaledBlue:0 alpha:1
TranslucentColor scaledRed:0 scaledGreen:0 scaledBlue:0 alpha:0.5
(TranslucentColor scaledRed:0 scaledGreen:0 scaledBlue:0 alpha:0.5) lightened

Instance protocol:

 alpha

return the alpha value (0..1),
where 0 is completely transparent and 1 is completely opaque

 alpha: alphaFraction

return a (possibly) new color with the same color, but different alpha as the receiver.
The alpha argument's range is 0..1 (0=completely transparent; 1=completely opaque)

 alphaByte

return the alpha value as byte 0..255,
where 0 is completely transparent and 255 is completely opaque

 privateAlpha

return the internal alpha value (0..255),
where 0 is completely transparent and 255 is completely opaque

 scaledAlpha

return the alpha value (0..16rFFFF),
where 0 is completely transparent and 16rFFFF is completely opaque

 setAlpha: alphaFraction

set the alpha value (0..1),
where 0 is completely transparent and 1 is completely opaque

 setAlphaByte: aByteValuedInteger

set the alpha value (0..255),
where 0 is completely transparent and 255 is completely opaque

 setScaledRed: r scaledGreen: g scaledBlue: b

r,g,b must be 0..MAXVALUE

 setScaledRed: r scaledGreen: g scaledBlue: b alpha: alphaFraction

alphaFraction must be 0..1;
r,g,b must be 0..MAXVALUE

 setScaledRed: r scaledGreen: g scaledBlue: b alphaByte: a

a must be 0..255;
r,g,b must be 0..MAXVALUE

 mixed: amount with: aColor

create a new color from mixing amount of the receiver
with the argument, aColor.
Mixing is done by adding components (i.e. additive mixing)
(which is different from mixing colors on paper, which is subtractive).
With an amount of 1, this is the same as blendWith.

 = aColor

(comment from inherited method)
two colors are considered equal, if the color components are;
independent of the device, the color is on

 almostSameAs: aColor

return true, if aColor looks almost the same as the receiver
(i.e. the components differ by a small, invisible amount).
We assume, that the human eye can distinguish roughly 100 grey levels
(which is optimistic ;-);
therefore, allow a 1 percent difference in each component for the colors
to compare as looking the same.

 asOpaqueColor

 inspectorValueStringInListFor: anInspector

returns a string to be shown in the inspector's list

 storeOn: aStream

append a string representing an expression to reconstruct the receiver
to the argument, aStream

Usage example(s):

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

 isOpaque

return true, if I represent an opaque color

 isTranslucent

return true, if I represent a translucent color;
that is: not completely opaque

 isTranslucentColor

return true, if I represent a translucent color;
This means: self isTranslucent, but isTransparent not

 isTransparent

return true, if I represent a completely transparent color