183 lines
3.4 KiB
C++
183 lines
3.4 KiB
C++
/*
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* Halftone.h
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* Copyright 1999-2000 Y.Takagi. All Rights Reserved.
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*/
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#ifndef __HALFTONE_H
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#define __HALFTONE_H
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#include <GraphicsDefs.h>
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// definition for B_RGB32 (=B_RGB32_LITTLE) and B_RGBA32
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typedef struct {
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uchar blue;
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uchar green;
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uchar red;
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uchar alpha; // unused in B_RGB32
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} ColorRGB32Little;
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// definition for B_RGB32_BIG and B_RGBA32_BIG
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typedef struct {
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uchar alpha; // unused in B_RGB32_BIG
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uchar red;
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uchar green;
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uchar blue;
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} ColorRGB32Big;
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typedef union {
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ColorRGB32Little little;
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ColorRGB32Big big;
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} ColorRGB32;
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class Halftone;
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typedef void (Halftone::*PFN_dither)(uchar* destination, const uchar* source,
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int x, int y, int width);
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typedef uint (*PFN_gray)(ColorRGB32 c);
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class Halftone {
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public:
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enum DitherType {
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kType1,
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kType2,
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kType3,
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kTypeFloydSteinberg,
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};
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enum GrayFunction {
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kMixToGray,
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kRedChannel,
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kGreenChannel,
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kBlueChannel
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};
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enum Planes {
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kPlaneMonochrome1, // 1 bit depth (0 white, 1 black)
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kPlaneRGB1, // 3 planes, 1 bit depth (0 black, 7 white)
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};
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enum BlackValue {
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kHighValueMeansBlack,
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kLowValueMeansBlack,
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};
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Halftone(color_space colorSpace, double gamma = 1.4,
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double min = 0.0,
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DitherType dither_type = kTypeFloydSteinberg);
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~Halftone();
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void SetPlanes(Planes planes);
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void SetBlackValue(BlackValue blackValue);
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void Dither(uchar *destination, const uchar *source, int x,
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int y, int width);
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int GetPixelDepth() const;
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const uchar* GetPattern() const;
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void SetPattern(const uchar *pattern);
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protected:
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Halftone(const Halftone &);
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Halftone& operator=(const Halftone &);
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// PFN_gray: return value of 0 means low density (or black) and
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// value of 255 means high density (or white)
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PFN_gray GetGrayFunction() const;
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void SetGrayFunction(PFN_gray gray);
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void SetGrayFunction(GrayFunction grayFunction);
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void CreateGammaTable(double gamma, double min);
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void InitElements(int x, int y, uchar* elements);
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uint GetDensity(ColorRGB32 c) const;
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uchar ConvertUsingBlackValue(uchar byte) const;
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void DitherRGB32(uchar* destination, const uchar* source,
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int x, int y, int width);
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void InitFloydSteinberg();
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void DeleteErrorTables();
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void UninitFloydSteinberg();
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void SetupErrorBuffer(int x, int y, int width);
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void DitherFloydSteinberg(uchar* destination,
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const uchar* source, int x, int y, int width);
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private:
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enum {
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kGammaTableSize = 256,
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kMaxNumberOfPlanes = 3
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};
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PFN_dither fDither;
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PFN_gray fGray;
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int fPixelDepth;
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Planes fPlanes;
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BlackValue fBlackValue;
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const uchar* fPattern;
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uint fGammaTable[kGammaTableSize];
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int fNumberOfPlanes;
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int fCurrentPlane;
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// fields used for floyd-steinberg dithering
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int fX;
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int fY;
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int fWidth;
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int* fErrorTables[kMaxNumberOfPlanes];
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};
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inline int
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Halftone::GetPixelDepth() const
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{
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return fPixelDepth;
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}
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inline const uchar*
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Halftone::GetPattern() const
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{
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return fPattern;
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}
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inline void
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Halftone::SetPattern(const uchar* pattern)
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{
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fPattern = pattern;
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}
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inline PFN_gray
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Halftone::GetGrayFunction() const
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{
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return fGray;
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}
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inline void
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Halftone::SetGrayFunction(PFN_gray gray)
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{
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fGray = gray;
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}
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inline uint
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Halftone::GetDensity(ColorRGB32 c) const
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{
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return fGammaTable[fGray(c)];
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}
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inline uchar
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Halftone::ConvertUsingBlackValue(uchar byte) const
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{
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// bits with value = '1' in byte mean black
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if (fBlackValue == kHighValueMeansBlack)
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return byte;
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return ~byte;
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}
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#endif /* __HALFTONE_H */
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