SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS > Class Template Reference

#include <SkMaskGamma.h>

Inheritance diagram for SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >:

Public Types
typedef SkTMaskPreBlend< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >	PreBlend

Public Member Functions
	SkTMaskGamma ()
	SkTMaskGamma (SkScalar contrast, SkScalar deviceGamma)
PreBlend	preBlend (SkColor color) const
void	getGammaTableDimensions (int *tableWidth, int *numTables) const
const uint8_t *	getGammaTables () const
Public Member Functions inherited from SkRefCntBase
	SkRefCntBase ()
virtual	~SkRefCntBase ()
bool	unique () const
void	ref () const
void	unref () const

Static Public Member Functions
static SkColor	CanonicalColor (SkColor color)

Detailed Description

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>
class SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >

A regular mask contains linear alpha values. A gamma correcting mask contains non-linear alpha values in an attempt to create gamma correct blits in the presence of a gamma incorrect (linear) blend in the blitter.

SkMaskGamma creates and maintains tables which convert linear alpha values to gamma correcting alpha values.

Parameters

R	The number of luminance bits to use [1, 8] from the red channel.
G	The number of luminance bits to use [1, 8] from the green channel.
B	The number of luminance bits to use [1, 8] from the blue channel.

Definition at line 99 of file SkMaskGamma.h.

Member Typedef Documentation

PreBlend

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>

typedef SkTMaskPreBlend<R_LUM_BITS, G_LUM_BITS, B_LUM_BITS> SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >::PreBlend

The type of the mask pre-blend which will be returned from preBlend(SkColor).

Definition at line 132 of file SkMaskGamma.h.

Constructor & Destructor Documentation

SkTMaskGamma() [1/2]

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>

SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >::SkTMaskGamma ( )

inline

Creates a linear SkTMaskGamma.

Definition at line 104 of file SkMaskGamma.h.

: fIsLinear(true) { }

SkTMaskGamma() [2/2]

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>

SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >::SkTMaskGamma ( SkScalar  contrast, SkScalar  deviceGamma  )

inline

Creates tables to convert linear alpha values to gamma correcting alpha values.

Parameters

contrast	A value in the range [0.0, 1.0] which indicates the amount of artificial contrast to add.
device	The color space of the target device.

Definition at line 114 of file SkMaskGamma.h.

                                                          : fIsLinear(false) {
        const SkColorSpaceLuminance& deviceConvert = SkColorSpaceLuminance::Fetch(deviceGamma);
        for (U8CPU i = 0; i < (1 << MAX_LUM_BITS); ++i) {
            U8CPU lum = sk_t_scale255<MAX_LUM_BITS>(i);
            SkTMaskGamma_build_correcting_lut(fGammaTables[i], lum, contrast,
                                              deviceConvert, deviceGamma);
        }
    }

Member Function Documentation

CanonicalColor()

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>

static SkColor SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >::CanonicalColor ( SkColor  color )

inlinestatic

Given a color, returns the closest canonical color.

Definition at line 124 of file SkMaskGamma.h.

                                                 {
        return SkColorSetRGB(
                   sk_t_scale255<R_LUM_BITS>(SkColorGetR(color) >> (8 - R_LUM_BITS)),
                   sk_t_scale255<G_LUM_BITS>(SkColorGetG(color) >> (8 - G_LUM_BITS)),
                   sk_t_scale255<B_LUM_BITS>(SkColorGetB(color) >> (8 - B_LUM_BITS)));
    }

getGammaTableDimensions()

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>

void SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >::getGammaTableDimensions ( int *  tableWidth, int *  numTables  ) const

inline

Get dimensions for the full table set, so it can be allocated as a block.

Definition at line 144 of file SkMaskGamma.h.

                                                                        {
        *tableWidth = 256;
        *numTables = (1 << MAX_LUM_BITS);
    }

getGammaTables()

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>

const uint8_t * SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >::getGammaTables ( ) const

inline

Provides direct access to the full table set, so it can be uploaded into a texture or analyzed in other ways. Returns nullptr if fGammaTables hasn't been initialized.

Definition at line 154 of file SkMaskGamma.h.

                                          {
        return fIsLinear ? nullptr : (const uint8_t*) fGammaTables;
    }

preBlend()

template<int R_LUM_BITS, int G_LUM_BITS, int B_LUM_BITS>

SkTMaskPreBlend< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS > SkTMaskGamma< R_LUM_BITS, G_LUM_BITS, B_LUM_BITS >::preBlend

(

SkColor

color

)

const

Provides access to the tables appropriate for converting linear alpha values into gamma correcting alpha values when drawing the given color through the mask. The destination color will be approximated.

Definition at line 209 of file SkMaskGamma.h.

                                                                              {
    return fIsLinear ? SkTMaskPreBlend<R_LUM_BITS, G_LUM_BITS, B_LUM_BITS>()
                     : SkTMaskPreBlend<R_LUM_BITS, G_LUM_BITS, B_LUM_BITS>(sk_ref_sp(this),
                         fGammaTables[SkColorGetR(color) >> (8 - MAX_LUM_BITS)],
                         fGammaTables[SkColorGetG(color) >> (8 - MAX_LUM_BITS)],
                         fGammaTables[SkColorGetB(color) >> (8 - MAX_LUM_BITS)]);
}

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

• third_party/skia/src/core/SkMaskGamma.h