src/core/SkImageInfo.cpp

/*
 * Copyright 2010 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "include/core/SkImageInfo.h"

#include "include/core/SkColorSpace.h"
#include "src/base/SkSafeMath.h"
#include "src/core/SkImageInfoPriv.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkWriteBuffer.h"

int SkColorTypeBytesPerPixel(SkColorType ct) {
    switch (ct) {
        case kUnknown_SkColorType:            return 0;
        case kAlpha_8_SkColorType:            return 1;
        case kRGB_565_SkColorType:            return 2;
        case kARGB_4444_SkColorType:          return 2;
        case kRGBA_8888_SkColorType:          return 4;
        case kBGRA_8888_SkColorType:          return 4;
        case kRGB_888x_SkColorType:           return 4;
        case kRGBA_1010102_SkColorType:       return 4;
        case kRGB_101010x_SkColorType:        return 4;
        case kBGRA_1010102_SkColorType:       return 4;
        case kBGR_101010x_SkColorType:        return 4;
        case kGray_8_SkColorType:             return 1;
        case kRGBA_F16Norm_SkColorType:       return 8;
        case kRGBA_F16_SkColorType:           return 8;
        case kRGBA_F32_SkColorType:           return 16;
        case kR8G8_unorm_SkColorType:         return 2;
        case kA16_unorm_SkColorType:          return 2;
        case kR16G16_unorm_SkColorType:       return 4;
        case kA16_float_SkColorType:          return 2;
        case kR16G16_float_SkColorType:       return 4;
        case kR16G16B16A16_unorm_SkColorType: return 8;
        case kSRGBA_8888_SkColorType:         return 4;
        case kR8_unorm_SkColorType:           return 1;
    }
    SkUNREACHABLE;
}

bool SkColorTypeIsAlwaysOpaque(SkColorType ct) {
    return !(SkColorTypeChannelFlags(ct) & kAlpha_SkColorChannelFlag);
}

///////////////////////////////////////////////////////////////////////////////////////////////////

SkColorInfo::SkColorInfo() = default;
SkColorInfo::~SkColorInfo() = default;

SkColorInfo::SkColorInfo(SkColorType ct, SkAlphaType at, sk_sp<SkColorSpace> cs)
            : fColorSpace(std::move(cs)), fColorType(ct), fAlphaType(at) {}

SkColorInfo::SkColorInfo(const SkColorInfo&) = default;
SkColorInfo::SkColorInfo(SkColorInfo&&) = default;

SkColorInfo& SkColorInfo::operator=(const SkColorInfo&) = default;
SkColorInfo& SkColorInfo::operator=(SkColorInfo&&) = default;

SkColorSpace* SkColorInfo::colorSpace() const { return fColorSpace.get(); }
sk_sp<SkColorSpace> SkColorInfo::refColorSpace() const { return fColorSpace; }

bool SkColorInfo::operator==(const SkColorInfo& other) const {
    return fColorType == other.fColorType && fAlphaType == other.fAlphaType &&
           SkColorSpace::Equals(fColorSpace.get(), other.fColorSpace.get());
}

bool SkColorInfo::operator!=(const SkColorInfo& other) const { return !(*this == other); }

SkColorInfo SkColorInfo::makeAlphaType(SkAlphaType newAlphaType) const {
    return SkColorInfo(this->colorType(), newAlphaType, this->refColorSpace());
}

SkColorInfo SkColorInfo::makeColorType(SkColorType newColorType) const {
    return SkColorInfo(newColorType, this->alphaType(), this->refColorSpace());
}

SkColorInfo SkColorInfo::makeColorSpace(sk_sp<SkColorSpace> cs) const {
    return SkColorInfo(this->colorType(), this->alphaType(), std::move(cs));
}

int SkColorInfo::bytesPerPixel() const { return SkColorTypeBytesPerPixel(fColorType); }

bool SkColorInfo::gammaCloseToSRGB() const {
    return fColorSpace && fColorSpace->gammaCloseToSRGB();
}

int SkColorInfo::shiftPerPixel() const { return SkColorTypeShiftPerPixel(fColorType); }

///////////////////////////////////////////////////////////////////////////////////////////////////

size_t SkImageInfo::computeOffset(int x, int y, size_t rowBytes) const {
    SkASSERT((unsigned)x < (unsigned)this->width());
    SkASSERT((unsigned)y < (unsigned)this->height());
    return SkColorTypeComputeOffset(this->colorType(), x, y, rowBytes);
}

size_t SkImageInfo::computeByteSize(size_t rowBytes) const {
    if (0 == this->height()) {
        return 0;
    }
    SkSafeMath safe;
    size_t bytes = safe.add(safe.mul(safe.addInt(this->height(), -1), rowBytes),
                            safe.mul(this->width(), this->bytesPerPixel()));

    // The CPU backend implements some memory operations on images using instructions that take a
    // signed 32-bit offset from the base. If we ever make an image larger than that, overflow can
    // cause us to read/write memory that starts 2GB *before* the buffer. (crbug.com/1264705)
    constexpr size_t kMaxSigned32BitSize = SK_MaxS32;
    return (safe.ok() && (bytes <= kMaxSigned32BitSize)) ? bytes : SIZE_MAX;
}

SkColorSpace* SkImageInfo::colorSpace() const { return fColorInfo.colorSpace(); }

sk_sp<SkColorSpace> SkImageInfo::refColorSpace() const { return fColorInfo.refColorSpace(); }

SkImageInfo SkImageInfo::makeColorSpace(sk_sp<SkColorSpace> cs) const {
    return Make(fDimensions, fColorInfo.makeColorSpace(std::move(cs)));
}

SkImageInfo SkImageInfo::Make(int width, int height, SkColorType ct, SkAlphaType at) {
    return Make(width, height, ct, at, nullptr);
}

SkImageInfo SkImageInfo::Make(int width, int height, SkColorType ct, SkAlphaType at,
                              sk_sp<SkColorSpace> cs) {
    return SkImageInfo({width, height}, {ct, at, std::move(cs)});
}

SkImageInfo SkImageInfo::Make(SkISize dimensions, SkColorType ct, SkAlphaType at) {
    return Make(dimensions, ct, at, nullptr);
}

SkImageInfo SkImageInfo::Make(SkISize dimensions, SkColorType ct, SkAlphaType at,
                        sk_sp<SkColorSpace> cs) {
    return SkImageInfo(dimensions, {ct, at, std::move(cs)});
}

SkImageInfo SkImageInfo::MakeN32(int width, int height, SkAlphaType at) {
    return MakeN32(width, height, at, nullptr);
}

SkImageInfo SkImageInfo::MakeN32(int width, int height, SkAlphaType at, sk_sp<SkColorSpace> cs) {
    return Make({width, height}, kN32_SkColorType, at, std::move(cs));
}

SkImageInfo SkImageInfo::MakeS32(int width, int height, SkAlphaType at) {
    return SkImageInfo({width, height}, {kN32_SkColorType, at, SkColorSpace::MakeSRGB()});
}

SkImageInfo SkImageInfo::MakeN32Premul(int width, int height) {
    return MakeN32Premul(width, height, nullptr);
}

SkImageInfo SkImageInfo::MakeN32Premul(int width, int height, sk_sp<SkColorSpace> cs) {
    return Make({width, height}, kN32_SkColorType, kPremul_SkAlphaType, std::move(cs));
}

SkImageInfo SkImageInfo::MakeN32Premul(SkISize dimensions) {
    return MakeN32Premul(dimensions, nullptr);
}

SkImageInfo SkImageInfo::MakeN32Premul(SkISize dimensions, sk_sp<SkColorSpace> cs) {
    return Make(dimensions, kN32_SkColorType, kPremul_SkAlphaType, std::move(cs));
}

SkImageInfo SkImageInfo::MakeA8(int width, int height) {
    return Make({width, height}, kAlpha_8_SkColorType, kPremul_SkAlphaType, nullptr);
}

SkImageInfo SkImageInfo::MakeA8(SkISize dimensions) {
    return Make(dimensions, kAlpha_8_SkColorType, kPremul_SkAlphaType, nullptr);
}

SkImageInfo SkImageInfo::MakeUnknown(int width, int height) {
    return Make({width, height}, kUnknown_SkColorType, kUnknown_SkAlphaType, nullptr);
}

#ifdef SK_DEBUG
void SkImageInfo::validate() const {
    SkASSERT(fDimensions.width() >= 0);
    SkASSERT(fDimensions.height() >= 0);
    SkASSERT(SkColorTypeIsValid(this->colorType()));
    SkASSERT(SkAlphaTypeIsValid(this->alphaType()));
}
#endif

bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
                                  SkAlphaType* canonical) {
    switch (colorType) {
        case kUnknown_SkColorType:
            alphaType = kUnknown_SkAlphaType;
            break;
        case kAlpha_8_SkColorType:         // fall-through
        case kA16_unorm_SkColorType:       // fall-through
        case kA16_float_SkColorType:
            if (kUnpremul_SkAlphaType == alphaType) {
                alphaType = kPremul_SkAlphaType;
            }
            [[fallthrough]];
        case kARGB_4444_SkColorType:
        case kRGBA_8888_SkColorType:
        case kSRGBA_8888_SkColorType:
        case kBGRA_8888_SkColorType:
        case kRGBA_1010102_SkColorType:
        case kBGRA_1010102_SkColorType:
        case kRGBA_F16Norm_SkColorType:
        case kRGBA_F16_SkColorType:
        case kRGBA_F32_SkColorType:
        case kR16G16B16A16_unorm_SkColorType:
            if (kUnknown_SkAlphaType == alphaType) {
                return false;
            }
            break;
        case kGray_8_SkColorType:
        case kR8G8_unorm_SkColorType:
        case kR16G16_unorm_SkColorType:
        case kR16G16_float_SkColorType:
        case kRGB_565_SkColorType:
        case kRGB_888x_SkColorType:
        case kRGB_101010x_SkColorType:
        case kBGR_101010x_SkColorType:
        case kR8_unorm_SkColorType:
            alphaType = kOpaque_SkAlphaType;
            break;
    }
    if (canonical) {
        *canonical = alphaType;
    }
    return true;
}

///////////////////////////////////////////////////////////////////////////////////////////////////

#include "src/image/SkReadPixelsRec.h"

bool SkReadPixelsRec::trim(int srcWidth, int srcHeight) {
    if (nullptr == fPixels || fRowBytes < fInfo.minRowBytes()) {
        return false;
    }
    if (0 >= fInfo.width() || 0 >= fInfo.height()) {
        return false;
    }

    int x = fX;
    int y = fY;
    SkIRect srcR = SkIRect::MakeXYWH(x, y, fInfo.width(), fInfo.height());
    if (!srcR.intersect({0, 0, srcWidth, srcHeight})) {
        return false;
    }

    // if x or y are negative, then we have to adjust pixels
    if (x > 0) {
        x = 0;
    }
    if (y > 0) {
        y = 0;
    }
    // here x,y are either 0 or negative
    // we negate and add them so UBSAN (pointer-overflow) doesn't get confused.
    fPixels = ((char*)fPixels + -y*fRowBytes + -x*fInfo.bytesPerPixel());
    // the intersect may have shrunk info's logical size
    fInfo = fInfo.makeDimensions(srcR.size());
    fX = srcR.x();
    fY = srcR.y();

    return true;
}

///////////////////////////////////////////////////////////////////////////////////////////////////

#include "src/core/SkWritePixelsRec.h"

bool SkWritePixelsRec::trim(int dstWidth, int dstHeight) {
    if (nullptr == fPixels || fRowBytes < fInfo.minRowBytes()) {
        return false;
    }
    if (0 >= fInfo.width() || 0 >= fInfo.height()) {
        return false;
    }

    int x = fX;
    int y = fY;
    SkIRect dstR = SkIRect::MakeXYWH(x, y, fInfo.width(), fInfo.height());
    if (!dstR.intersect({0, 0, dstWidth, dstHeight})) {
        return false;
    }

    // if x or y are negative, then we have to adjust pixels
    if (x > 0) {
        x = 0;
    }
    if (y > 0) {
        y = 0;
    }
    // here x,y are either 0 or negative
    // we negate and add them so UBSAN (pointer-overflow) doesn't get confused.
    fPixels = ((const char*)fPixels + -y*fRowBytes + -x*fInfo.bytesPerPixel());
    // the intersect may have shrunk info's logical size
    fInfo = fInfo.makeDimensions(dstR.size());
    fX = dstR.x();
    fY = dstR.y();

    return true;
}