Digikam::DColorComposer Class Reference

#include <dcolorcomposer.h>

Inherited by Digikam::DColorComposerPorterDuffClear, Digikam::DColorComposerPorterDuffDstAtop, Digikam::DColorComposerPorterDuffDstIn, Digikam::DColorComposerPorterDuffDstOut, Digikam::DColorComposerPorterDuffDstOver, Digikam::DColorComposerPorterDuffNone, Digikam::DColorComposerPorterDuffSrc, Digikam::DColorComposerPorterDuffSrcAtop, Digikam::DColorComposerPorterDuffSrcIn, Digikam::DColorComposerPorterDuffSrcOut, Digikam::DColorComposerPorterDuffSrcOver, and Digikam::DColorComposerPorterDuffXor.

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

Static Public Member Functions
static DColorComposer *	getComposer (CompositingOperation rule)

Detailed Description

Definition at line 35 of file dcolorcomposer.h.

Member Enumeration Documentation

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

Definition at line 69 of file dcolorcomposer.h.

enum Digikam::DColorComposer::MultiplicationFlags

Enumerator
NoMultiplication
PremultiplySrc
PremultiplyDst
DemultiplyDst
MultiplicationFlagsDImg
MultiplicationFlagsPremultipliedColorOnDImg

Definition at line 85 of file dcolorcomposer.h.

Constructor & Destructor Documentation

virtual Digikam::DColorComposer::~DColorComposer ( )

inlinevirtual

Definition at line 128 of file dcolorcomposer.h.

Member Function Documentation

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.

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)

Definition at line 473 of file dcolorcomposer.cpp.

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.

Definition at line 493 of file dcolorcomposer.cpp.

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

• dcolorcomposer.h
• dcolorcomposer.cpp