digiKam
Public Types | Public Member Functions | Static Public Member Functions | List of all members
Digikam::DColorComposer Class Referenceabstract
+ Inheritance diagram for Digikam::DColorComposer:

Public Types

enum  CompositingOperation {
  PorterDuffNone , PorterDuffClear , PorterDuffSrc , PorterDuffSrcOver ,
  PorterDuffDstOver , PorterDuffSrcIn , PorterDuffDstIn , PorterDuffSrcOut ,
  PorterDuffDstOut , PorterDuffSrcAtop , PorterDuffDstAtop , PorterDuffXor
}
 
enum  MultiplicationFlags {
  NoMultiplication = 0x00 , PremultiplySrc = 0x01 , PremultiplyDst = 0x02 , DemultiplyDst = 0x04 ,
  MultiplicationFlagsDImg = PremultiplySrc | PremultiplyDst | DemultiplyDst , MultiplicationFlagsPremultipliedColorOnDImg = PremultiplyDst | DemultiplyDst
}
 

Public Member Functions

virtual void compose (DColor &dest, DColor &src)=0
 
virtual void compose (DColor &dest, DColor &src, MultiplicationFlags multiplicationFlags)
 
 DColorComposer ()=default
 
virtual ~DColorComposer ()=default
 

Static Public Member Functions

static DColorComposer * getComposer (CompositingOperation rule)
 

Member Enumeration Documentation

◆ CompositingOperation

enum Digikam::DColorComposer::CompositingOperation

The available rules to combine src and destination color.

For the Porter-Duff rules, the formula is component = (source * fs + destination * fd) where fs, fd according to the following table with sa = source alpha, da = destination alpha:

None fs: sa fd: 1.0-sa Clear fs: 0.0 fd: 0.0 Src fs: 1.0 fd: 0.0 Src Over fs: 1.0 fd: 1.0-sa Dst Over fs: 1.0-da fd: 1.0 Src In fs: da fd: 0.0 Dst In fs: 0.0 fd: sa Src Out fs: 1.0-da fd: 0.0 Dst Out fs: 0.0 fd: 1.0-sa

Src Atop fs: da fd: 1.0-sa Dst Atop fs: 1.0-da fd: sa Xor fs: 1.0-da fd: 1.0-sa

None is the default, classical blending mode, a "Src over" simplification: Blend non-premultiplied RGBA data "src over" a fully opaque background. Src is the painter's algorithm. All other operations require premultiplied colors. The documentation of java.awt.AlphaComposite (Java 1.5) provides a good introduction and documentation on Porter Duff.

Enumerator
PorterDuffNone 
PorterDuffClear 
PorterDuffSrc 
PorterDuffSrcOver 
PorterDuffDstOver 
PorterDuffSrcIn 
PorterDuffDstIn 
PorterDuffSrcOut 
PorterDuffDstOut 
PorterDuffSrcAtop 
PorterDuffDstAtop 
PorterDuffXor 

◆ MultiplicationFlags

enum Digikam::DColorComposer::MultiplicationFlags
Enumerator
NoMultiplication 
PremultiplySrc 
PremultiplyDst 
DemultiplyDst 
MultiplicationFlagsDImg 
MultiplicationFlagsPremultipliedColorOnDImg 

Constructor & Destructor Documentation

◆ DColorComposer()

Digikam::DColorComposer::DColorComposer ( )
default

◆ ~DColorComposer()

virtual Digikam::DColorComposer::~DColorComposer ( )
virtualdefault

Member Function Documentation

◆ compose() [1/2]

virtual void Digikam::DColorComposer::compose ( DColor &  dest,
DColor &  src 
)
pure virtual

Carry out the actual composition process. Src and Dest are composed and the result is written to dest. No pre-/demultiplication is done by this method, use the other overloaded methods, which call this method, if you need pre- or demultiplication (you need it if any of the colors are read from or written to a DImg).

If you just pass the object to a DImg method, you do not need to call this. Call this function if you want to compose two colors. Implement this function if you create a custom DColorComposer.

The bit depth of source and destination color must be identical.

Referenced by compose().

◆ compose() [2/2]

void Digikam::DColorComposer::compose ( DColor &  dest,
DColor &  src,
DColorComposer::MultiplicationFlags  multiplicationFlags 
)
virtual

Compose the two colors by calling compose(dest, src). Pre- and demultiplication operations are done as specified. For PorterDuff operations except PorterDuffNone, you need

  • PremultiplySrc if src is not premultiplied (read from a DImg)
  • PremultiplyDst if dst is not premultiplied (read from a DImg)
  • DemultiplyDst if dst will be written to non-premultiplied data (a DImg)

References compose(), Digikam::DColor::demultiply(), DemultiplyDst, Digikam::DColor::premultiply(), PremultiplyDst, and PremultiplySrc.

◆ getComposer()

DColorComposer * Digikam::DColorComposer::getComposer ( DColorComposer::CompositingOperation  rule)
static

Retrieve a DColorComposer object for one of the predefined rules. The object needs to be deleted by the caller.

References PorterDuffClear, PorterDuffDstAtop, PorterDuffDstIn, PorterDuffDstOut, PorterDuffDstOver, PorterDuffNone, PorterDuffSrc, PorterDuffSrcAtop, PorterDuffSrcIn, PorterDuffSrcOut, PorterDuffSrcOver, and PorterDuffXor.

Referenced by Digikam::DImg::bitBlendImageOnColor().

The documentation for this class was generated from the following files: