skia2/include/private/SkImageInfoPriv.h

/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkImageInfoPriv_DEFINED
#define SkImageInfoPriv_DEFINED

#include "include/core/SkColor.h"
#include "include/core/SkImageInfo.h"

static inline uint32_t SkColorTypeChannelFlags(SkColorType ct) {
    switch (ct) {
        case kUnknown_SkColorType:            return 0;
        case kAlpha_8_SkColorType:            return kAlpha_SkColorChannelFlag;
        case kRGB_565_SkColorType:            return kRGB_SkColorChannelFlags;
        case kARGB_4444_SkColorType:          return kRGBA_SkColorChannelFlags;
        case kRGBA_8888_SkColorType:          return kRGBA_SkColorChannelFlags;
        case kRGB_888x_SkColorType:           return kRGB_SkColorChannelFlags;
        case kBGRA_8888_SkColorType:          return kRGBA_SkColorChannelFlags;
        case kRGBA_1010102_SkColorType:       return kRGBA_SkColorChannelFlags;
        case kRGB_101010x_SkColorType:        return kRGB_SkColorChannelFlags;
        case kBGRA_1010102_SkColorType:       return kRGBA_SkColorChannelFlags;
        case kBGR_101010x_SkColorType:        return kRGB_SkColorChannelFlags;
        case kGray_8_SkColorType:             return kGray_SkColorChannelFlag;
        case kRGBA_F16Norm_SkColorType:       return kRGBA_SkColorChannelFlags;
        case kRGBA_F16_SkColorType:           return kRGBA_SkColorChannelFlags;
        case kRGBA_F32_SkColorType:           return kRGBA_SkColorChannelFlags;
        case kR8G8_unorm_SkColorType:         return kRG_SkColorChannelFlags;
        case kA16_unorm_SkColorType:          return kAlpha_SkColorChannelFlag;
        case kR16G16_unorm_SkColorType:       return kRG_SkColorChannelFlags;
        case kA16_float_SkColorType:          return kAlpha_SkColorChannelFlag;
        case kR16G16_float_SkColorType:       return kRG_SkColorChannelFlags;
        case kR16G16B16A16_unorm_SkColorType: return kRGBA_SkColorChannelFlags;
        case kSRGBA_8888_SkColorType:         return kRGBA_SkColorChannelFlags;
    }
    SkUNREACHABLE;
}

static inline bool SkColorTypeIsAlphaOnly(SkColorType ct) {
    return SkColorTypeChannelFlags(ct) == kAlpha_SkColorChannelFlag;
}

static inline bool SkAlphaTypeIsValid(unsigned value) {
    return value <= kLastEnum_SkAlphaType;
}

static int SkColorTypeShiftPerPixel(SkColorType ct) {
    switch (ct) {
        case kUnknown_SkColorType:            return 0;
        case kAlpha_8_SkColorType:            return 0;
        case kRGB_565_SkColorType:            return 1;
        case kARGB_4444_SkColorType:          return 1;
        case kRGBA_8888_SkColorType:          return 2;
        case kRGB_888x_SkColorType:           return 2;
        case kBGRA_8888_SkColorType:          return 2;
        case kRGBA_1010102_SkColorType:       return 2;
        case kRGB_101010x_SkColorType:        return 2;
        case kBGRA_1010102_SkColorType:       return 2;
        case kBGR_101010x_SkColorType:        return 2;
        case kGray_8_SkColorType:             return 0;
        case kRGBA_F16Norm_SkColorType:       return 3;
        case kRGBA_F16_SkColorType:           return 3;
        case kRGBA_F32_SkColorType:           return 4;
        case kR8G8_unorm_SkColorType:         return 1;
        case kA16_unorm_SkColorType:          return 1;
        case kR16G16_unorm_SkColorType:       return 2;
        case kA16_float_SkColorType:          return 1;
        case kR16G16_float_SkColorType:       return 2;
        case kR16G16B16A16_unorm_SkColorType: return 3;
        case kSRGBA_8888_SkColorType:         return 2;
    }
    SkUNREACHABLE;
}

static inline size_t SkColorTypeMinRowBytes(SkColorType ct, int width) {
    return (size_t)(width * SkColorTypeBytesPerPixel(ct));
}

static inline bool SkColorTypeIsValid(unsigned value) {
    return value <= kLastEnum_SkColorType;
}

static inline size_t SkColorTypeComputeOffset(SkColorType ct, int x, int y, size_t rowBytes) {
    if (kUnknown_SkColorType == ct) {
        return 0;
    }
    return (size_t)y * rowBytes + ((size_t)x << SkColorTypeShiftPerPixel(ct));
}

static inline bool SkColorTypeIsNormalized(SkColorType ct) {
    switch (ct) {
        case kUnknown_SkColorType:
        case kAlpha_8_SkColorType:
        case kRGB_565_SkColorType:
        case kARGB_4444_SkColorType:
        case kRGBA_8888_SkColorType:
        case kRGB_888x_SkColorType:
        case kBGRA_8888_SkColorType:
        case kRGBA_1010102_SkColorType:
        case kRGB_101010x_SkColorType:
        case kBGRA_1010102_SkColorType:
        case kBGR_101010x_SkColorType:
        case kGray_8_SkColorType:
        case kRGBA_F16Norm_SkColorType:
        case kR8G8_unorm_SkColorType:
        case kA16_unorm_SkColorType:
        case kA16_float_SkColorType:          /*subtle... alpha is always [0,1]*/
        case kR16G16_unorm_SkColorType:
        case kR16G16B16A16_unorm_SkColorType:
        case kSRGBA_8888_SkColorType: return true;

        case kRGBA_F16_SkColorType:
        case kRGBA_F32_SkColorType:
        case kR16G16_float_SkColorType:       return false;
    }
    SkUNREACHABLE;
}

static inline int SkColorTypeMaxBitsPerChannel(SkColorType ct) {
    switch (ct) {
        case kUnknown_SkColorType:
            return 0;

        case kARGB_4444_SkColorType:
            return 4;

        case kRGB_565_SkColorType:
            return 6;

        case kAlpha_8_SkColorType:
        case kRGBA_8888_SkColorType:
        case kRGB_888x_SkColorType:
        case kBGRA_8888_SkColorType:
        case kGray_8_SkColorType:
        case kR8G8_unorm_SkColorType:
        case kSRGBA_8888_SkColorType:
            return 8;

        case kRGBA_1010102_SkColorType:
        case kRGB_101010x_SkColorType:
        case kBGRA_1010102_SkColorType:
        case kBGR_101010x_SkColorType:
            return 10;

        case kRGBA_F16Norm_SkColorType:
        case kA16_unorm_SkColorType:
        case kA16_float_SkColorType:
        case kR16G16_unorm_SkColorType:
        case kR16G16B16A16_unorm_SkColorType:
        case kRGBA_F16_SkColorType:
        case kR16G16_float_SkColorType:
            return 16;

        case kRGBA_F32_SkColorType:
            return 32;
    }
    SkUNREACHABLE;
}

/**
 *  Returns true if |info| contains a valid colorType and alphaType.
 */
static inline bool SkColorInfoIsValid(const SkColorInfo& info) {
    return info.colorType() != kUnknown_SkColorType && info.alphaType() != kUnknown_SkAlphaType;
}

/**
 *  Returns true if |info| contains a valid combination of width, height and colorInfo.
 */
static inline bool SkImageInfoIsValid(const SkImageInfo& info) {
    if (info.width() <= 0 || info.height() <= 0) {
        return false;
    }

    const int kMaxDimension = SK_MaxS32 >> 2;
    if (info.width() > kMaxDimension || info.height() > kMaxDimension) {
        return false;
    }

    return SkColorInfoIsValid(info.colorInfo());
}

/**
 *  Returns true if Skia has defined a pixel conversion from the |src| to the |dst|.
 *  Returns false otherwise.
 */
static inline bool SkImageInfoValidConversion(const SkImageInfo& dst, const SkImageInfo& src) {
    return SkImageInfoIsValid(dst) && SkImageInfoIsValid(src);
}
#endif  // SkImageInfoPriv_DEFINED