SkTableMaskFilter Class Reference

#include <SkTableMaskFilter.h>

Public Member Functions
	SkTableMaskFilter ()=delete

Static Public Member Functions
static void	MakeGammaTable (uint8_t table[256], SkScalar gamma)
static void	MakeClipTable (uint8_t table[256], uint8_t min, uint8_t max)
static SkMaskFilter *	Create (const uint8_t table[256])
static SkMaskFilter *	CreateGamma (SkScalar gamma)
static SkMaskFilter *	CreateClip (uint8_t min, uint8_t max)

Detailed Description

Applies a table lookup on each of the alpha values in the mask. Helper methods create some common tables (e.g. gamma, clipping)

Definition at line 23 of file SkTableMaskFilter.h.

Constructor & Destructor Documentation

SkTableMaskFilter()

SkTableMaskFilter::SkTableMaskFilter ( )

delete

Member Function Documentation

Create()

SkMaskFilter * SkTableMaskFilter::Create ( const uint8_t  table[256] )

static

Definition at line 127 of file SkTableMaskFilter.cpp.

                                                                {
    return new SkTableMaskFilterImpl(table);
}

CreateClip()

SkMaskFilter * SkTableMaskFilter::CreateClip ( uint8_t  min, uint8_t  max  )

static

Definition at line 137 of file SkTableMaskFilter.cpp.

                                                                    {
    uint8_t table[256];
    MakeClipTable(table, min, max);
    return new SkTableMaskFilterImpl(table);
}

CreateGamma()

SkMaskFilter * SkTableMaskFilter::CreateGamma ( SkScalar  gamma )

static

Definition at line 131 of file SkTableMaskFilter.cpp.

                                                           {
    uint8_t table[256];
    MakeGammaTable(table, gamma);
    return new SkTableMaskFilterImpl(table);
}

MakeClipTable()

void SkTableMaskFilter::MakeClipTable ( uint8_t  table[256], uint8_t  min, uint8_t  max  )

static

Utility that creates a clipping table: clamps values below min to 0 and above max to 255, and rescales the remaining into 0..255

Definition at line 155 of file SkTableMaskFilter.cpp.

                                                   {
    if (0 == max) {
        max = 1;
    }
    if (min >= max) {
        min = max - 1;
    }
    SkASSERT(min < max);
 
    SkFixed scale = (1 << 16) * 255 / (max - min);
    memset(table, 0, min + 1);
    for (int i = min + 1; i < max; i++) {
        int value = SkFixedRoundToInt(scale * (i - min));
        SkASSERT(value <= 255);
        table[i] = value;
    }
    memset(table + max, 255, 256 - max);
 
#if 0
    int j;
    for (j = 0; j < 256; j++) {
        if (table[j]) {
            break;
        }
    }
    SkDebugf("%d %d start [%d]", min, max, j);
    for (; j < 256; j++) {
        SkDebugf(" %d", table[j]);
    }
    SkDebugf("\n\n");
#endif
}

MakeGammaTable()

void SkTableMaskFilter::MakeGammaTable ( uint8_t  table[256], SkScalar  gamma  )

static

Utility that sets the gamma table

Definition at line 143 of file SkTableMaskFilter.cpp.

                                                                         {
    const float dx = 1 / 255.0f;
    const float g = gamma;
 
    float x = 0;
    for (int i = 0; i < 256; i++) {
     // float ee = powf(x, g) * 255;
        table[i] = SkTPin(sk_float_round2int(powf(x, g) * 255), 0, 255);
        x += dx;
    }
}

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

• third_party/skia/include/effects/SkTableMaskFilter.h
• third_party/skia/src/effects/SkTableMaskFilter.cpp