/* * Copyright 2016 Google Inc. * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #include "SkAutoMalloc.h" #include "SkColorSpacePriv.h" #include "SkEndian.h" #include "SkFixed.h" #include "SkICC.h" #include "SkICCPriv.h" #include "SkMD5.h" #include "SkUtils.h" static constexpr char kDescriptionTagBodyPrefix[12] = { 'G', 'o', 'o', 'g', 'l', 'e', '/', 'S', 'k', 'i', 'a' , '/'}; static constexpr size_t kICCDescriptionTagSize = 44; static_assert(kICCDescriptionTagSize == sizeof(kDescriptionTagBodyPrefix) + 2 * sizeof(SkMD5::Digest), ""); static constexpr size_t kDescriptionTagBodySize = kICCDescriptionTagSize * 2; // ascii->utf16be static_assert(SkIsAlign4(kDescriptionTagBodySize), "Description must be aligned to 4-bytes."); static constexpr uint32_t kDescriptionTagHeader[7] { SkEndian_SwapBE32(kTAG_TextType), // Type signature 0, // Reserved SkEndian_SwapBE32(1), // Number of records SkEndian_SwapBE32(12), // Record size (must be 12) SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA SkEndian_SwapBE32(kDescriptionTagBodySize), // Length of string SkEndian_SwapBE32(28), // Offset of string }; static constexpr uint32_t kWhitePointTag[5] { SkEndian_SwapBE32(kXYZ_PCSSpace), 0, SkEndian_SwapBE32(0x0000f6d6), // X = 0.96420 (D50) SkEndian_SwapBE32(0x00010000), // Y = 1.00000 (D50) SkEndian_SwapBE32(0x0000d32d), // Z = 0.82491 (D50) }; // Google Inc. 2016 (UTF-16) static constexpr uint8_t kCopyrightTagBody[] = { 0x00, 0x47, 0x00, 0x6f, 0x00, 0x6f, 0x00, 0x67, 0x00, 0x6c, 0x00, 0x65, 0x00, 0x20, 0x00, 0x49, 0x00, 0x6e, 0x00, 0x63, 0x00, 0x2e, 0x00, 0x20, 0x00, 0x32, 0x00, 0x30, 0x00, 0x31, 0x00, 0x36, }; static_assert(SkIsAlign4(sizeof(kCopyrightTagBody)), "Copyright must be aligned to 4-bytes."); static constexpr uint32_t kCopyrightTagHeader[7] { SkEndian_SwapBE32(kTAG_TextType), // Type signature 0, // Reserved SkEndian_SwapBE32(1), // Number of records SkEndian_SwapBE32(12), // Record size (must be 12) SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA SkEndian_SwapBE32(sizeof(kCopyrightTagBody)), // Length of string SkEndian_SwapBE32(28), // Offset of string }; // We will write a profile with the minimum nine required tags. static constexpr uint32_t kICCNumEntries = 9; static constexpr uint32_t kTAG_desc = SkSetFourByteTag('d', 'e', 's', 'c'); static constexpr uint32_t kTAG_desc_Bytes = sizeof(kDescriptionTagHeader) + kDescriptionTagBodySize; static constexpr uint32_t kTAG_desc_Offset = kICCHeaderSize + kICCNumEntries * kICCTagTableEntrySize; static constexpr uint32_t kTAG_XYZ_Bytes = 20; static constexpr uint32_t kTAG_rXYZ_Offset = kTAG_desc_Offset + kTAG_desc_Bytes; static constexpr uint32_t kTAG_gXYZ_Offset = kTAG_rXYZ_Offset + kTAG_XYZ_Bytes; static constexpr uint32_t kTAG_bXYZ_Offset = kTAG_gXYZ_Offset + kTAG_XYZ_Bytes; static constexpr uint32_t kTAG_TRC_Bytes = 40; static constexpr uint32_t kTAG_rTRC_Offset = kTAG_bXYZ_Offset + kTAG_XYZ_Bytes; static constexpr uint32_t kTAG_gTRC_Offset = kTAG_rTRC_Offset; static constexpr uint32_t kTAG_bTRC_Offset = kTAG_rTRC_Offset; static constexpr uint32_t kTAG_wtpt = SkSetFourByteTag('w', 't', 'p', 't'); static constexpr uint32_t kTAG_wtpt_Offset = kTAG_bTRC_Offset + kTAG_TRC_Bytes; static constexpr uint32_t kTAG_cprt = SkSetFourByteTag('c', 'p', 'r', 't'); static constexpr uint32_t kTAG_cprt_Bytes = sizeof(kCopyrightTagHeader) + sizeof(kCopyrightTagBody); static constexpr uint32_t kTAG_cprt_Offset = kTAG_wtpt_Offset + kTAG_XYZ_Bytes; static constexpr uint32_t kICCProfileSize = kTAG_cprt_Offset + kTAG_cprt_Bytes; static constexpr uint32_t kICCHeader[kICCHeaderSize / 4] { SkEndian_SwapBE32(kICCProfileSize), // Size of the profile 0, // Preferred CMM type (ignored) SkEndian_SwapBE32(0x02100000), // Version 2.1 SkEndian_SwapBE32(kDisplay_Profile), // Display device profile SkEndian_SwapBE32(kRGB_ColorSpace), // RGB input color space SkEndian_SwapBE32(kXYZ_PCSSpace), // XYZ profile connection space 0, 0, 0, // Date and time (ignored) SkEndian_SwapBE32(kACSP_Signature), // Profile signature 0, // Platform target (ignored) 0x00000000, // Flags: not embedded, can be used independently 0, // Device manufacturer (ignored) 0, // Device model (ignored) 0, 0, // Device attributes (ignored) SkEndian_SwapBE32(1), // Relative colorimetric rendering intent SkEndian_SwapBE32(0x0000f6d6), // D50 standard illuminant (X) SkEndian_SwapBE32(0x00010000), // D50 standard illuminant (Y) SkEndian_SwapBE32(0x0000d32d), // D50 standard illuminant (Z) 0, // Profile creator (ignored) 0, 0, 0, 0, // Profile id checksum (ignored) 0, 0, 0, 0, 0, 0, 0, // Reserved (ignored) SkEndian_SwapBE32(kICCNumEntries), // Number of tags }; static constexpr uint32_t kICCTagTable[3 * kICCNumEntries] { // Profile description SkEndian_SwapBE32(kTAG_desc), SkEndian_SwapBE32(kTAG_desc_Offset), SkEndian_SwapBE32(kTAG_desc_Bytes), // rXYZ SkEndian_SwapBE32(kTAG_rXYZ), SkEndian_SwapBE32(kTAG_rXYZ_Offset), SkEndian_SwapBE32(kTAG_XYZ_Bytes), // gXYZ SkEndian_SwapBE32(kTAG_gXYZ), SkEndian_SwapBE32(kTAG_gXYZ_Offset), SkEndian_SwapBE32(kTAG_XYZ_Bytes), // bXYZ SkEndian_SwapBE32(kTAG_bXYZ), SkEndian_SwapBE32(kTAG_bXYZ_Offset), SkEndian_SwapBE32(kTAG_XYZ_Bytes), // rTRC SkEndian_SwapBE32(kTAG_rTRC), SkEndian_SwapBE32(kTAG_rTRC_Offset), SkEndian_SwapBE32(kTAG_TRC_Bytes), // gTRC SkEndian_SwapBE32(kTAG_gTRC), SkEndian_SwapBE32(kTAG_gTRC_Offset), SkEndian_SwapBE32(kTAG_TRC_Bytes), // bTRC SkEndian_SwapBE32(kTAG_bTRC), SkEndian_SwapBE32(kTAG_bTRC_Offset), SkEndian_SwapBE32(kTAG_TRC_Bytes), // White point SkEndian_SwapBE32(kTAG_wtpt), SkEndian_SwapBE32(kTAG_wtpt_Offset), SkEndian_SwapBE32(kTAG_XYZ_Bytes), // Copyright SkEndian_SwapBE32(kTAG_cprt), SkEndian_SwapBE32(kTAG_cprt_Offset), SkEndian_SwapBE32(kTAG_cprt_Bytes), }; // This is like SkFloatToFixed, but rounds to nearest, preserving as much accuracy as possible // when going float -> fixed -> float (it has the same accuracy when going fixed -> float -> fixed). // The use of double is necessary to accomodate the full potential 32-bit mantissa of the 16.16 // SkFixed value, and so avoiding rounding problems with float. Also, see the comment in SkFixed.h. static SkFixed float_round_to_fixed(float x) { return sk_float_saturate2int((float)floor((double)x * SK_Fixed1 + 0.5)); } static void write_xyz_tag(uint32_t* ptr, const float toXYZD50[9], int col) { ptr[0] = SkEndian_SwapBE32(kXYZ_PCSSpace); ptr[1] = 0; ptr[2] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50[0*3 + col])); ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50[1*3 + col])); ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50[2*3 + col])); } static void write_trc_tag(uint32_t* ptr, const SkColorSpaceTransferFn& fn) { ptr[0] = SkEndian_SwapBE32(kTAG_ParaCurveType); ptr[1] = 0; ptr[2] = (uint32_t) (SkEndian_SwapBE16(kGABCDEF_ParaCurveType)); ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(fn.fG)); ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(fn.fA)); ptr[5] = SkEndian_SwapBE32(float_round_to_fixed(fn.fB)); ptr[6] = SkEndian_SwapBE32(float_round_to_fixed(fn.fC)); ptr[7] = SkEndian_SwapBE32(float_round_to_fixed(fn.fD)); ptr[8] = SkEndian_SwapBE32(float_round_to_fixed(fn.fE)); ptr[9] = SkEndian_SwapBE32(float_round_to_fixed(fn.fF)); } static bool nearly_equal(float x, float y) { // A note on why I chose this tolerance: transfer_fn_almost_equal() uses a // tolerance of 0.001f, which doesn't seem to be enough to distinguish // between similar transfer functions, for example: gamma2.2 and sRGB. // // If the tolerance is 0.0f, then this we can't distinguish between two // different encodings of what is clearly the same colorspace. Some // experimentation with example files lead to this number: static constexpr float kTolerance = 1.0f / (1 << 11); return ::fabsf(x - y) <= kTolerance; } static bool nearly_equal(const SkColorSpaceTransferFn& u, const SkColorSpaceTransferFn& v) { return nearly_equal(u.fG, v.fG) && nearly_equal(u.fA, v.fA) && nearly_equal(u.fB, v.fB) && nearly_equal(u.fC, v.fC) && nearly_equal(u.fD, v.fD) && nearly_equal(u.fE, v.fE) && nearly_equal(u.fF, v.fF); } static bool nearly_equal(const float u[9], const float v[9]) { for (int i = 0; i < 9; i++) { if (!nearly_equal(u[i], v[i])) { return false; } } return true; } // Return nullptr if the color profile doen't have a special name. const char* get_color_profile_description(const SkColorSpaceTransferFn& fn, const float toXYZD50[9]) { bool srgb_xfer = nearly_equal(fn, gSRGB_TransferFn); bool srgb_gamut = nearly_equal(toXYZD50, gSRGB_toXYZD50); if (srgb_xfer && srgb_gamut) { return "sRGB"; } bool line_xfer = nearly_equal(fn, gLinear_TransferFn); if (line_xfer && srgb_gamut) { return "Linear Transfer with sRGB Gamut"; } bool twoDotTwo = nearly_equal(fn, g2Dot2_TransferFn); if (twoDotTwo && srgb_gamut) { return "2.2 Transfer with sRGB Gamut"; } if (twoDotTwo && nearly_equal(toXYZD50, gAdobeRGB_toXYZD50)) { return "AdobeRGB"; } bool dcip3_gamut = nearly_equal(toXYZD50, gDCIP3_toXYZD50); if (srgb_xfer || line_xfer) { if (srgb_xfer && dcip3_gamut) { return "sRGB Transfer with DCI-P3 Gamut"; } if (line_xfer && dcip3_gamut) { return "Linear Transfer with DCI-P3 Gamut"; } bool rec2020 = nearly_equal(toXYZD50, gRec2020_toXYZD50); if (srgb_xfer && rec2020) { return "sRGB Transfer with Rec-BT-2020 Gamut"; } if (line_xfer && rec2020) { return "Linear Transfer with Rec-BT-2020 Gamut"; } } if (dcip3_gamut && nearly_equal(fn, gDCIP3_TransferFn)) { return "DCI-P3"; } return nullptr; } static void get_color_profile_tag(char dst[kICCDescriptionTagSize], const SkColorSpaceTransferFn& fn, const float toXYZD50[9]) { SkASSERT(dst); if (const char* description = get_color_profile_description(fn, toXYZD50)) { SkASSERT(strlen(description) < kICCDescriptionTagSize); strncpy(dst, description, kICCDescriptionTagSize); // "If the length of src is less than n, strncpy() writes additional // null bytes to dest to ensure that a total of n bytes are written." } else { strncpy(dst, kDescriptionTagBodyPrefix, sizeof(kDescriptionTagBodyPrefix)); SkMD5 md5; md5.write(toXYZD50, 9*sizeof(float)); static_assert(sizeof(fn) == sizeof(float) * 7, "packed"); md5.write(&fn, sizeof(fn)); SkMD5::Digest digest; md5.finish(digest); char* ptr = dst + sizeof(kDescriptionTagBodyPrefix); for (unsigned i = 0; i < sizeof(SkMD5::Digest); ++i) { uint8_t byte = digest.data[i]; *ptr++ = SkHexadecimalDigits::gUpper[byte >> 4]; *ptr++ = SkHexadecimalDigits::gUpper[byte & 0xF]; } SkASSERT(ptr == dst + kICCDescriptionTagSize); } } sk_sp SkWriteICCProfile(const SkColorSpaceTransferFn& fn, const float toXYZD50[9]) { if (!is_valid_transfer_fn(fn)) { return nullptr; } SkAutoMalloc profile(kICCProfileSize); uint8_t* ptr = (uint8_t*) profile.get(); // Write profile header memcpy(ptr, kICCHeader, sizeof(kICCHeader)); ptr += sizeof(kICCHeader); // Write tag table memcpy(ptr, kICCTagTable, sizeof(kICCTagTable)); ptr += sizeof(kICCTagTable); // Write profile description tag memcpy(ptr, kDescriptionTagHeader, sizeof(kDescriptionTagHeader)); ptr += sizeof(kDescriptionTagHeader); { char colorProfileTag[kICCDescriptionTagSize]; get_color_profile_tag(colorProfileTag, fn, toXYZD50); // ASCII --> big-endian UTF-16. for (size_t i = 0; i < kICCDescriptionTagSize; i++) { *ptr++ = 0; *ptr++ = colorProfileTag[i]; } } // Write XYZ tags write_xyz_tag((uint32_t*) ptr, toXYZD50, 0); ptr += kTAG_XYZ_Bytes; write_xyz_tag((uint32_t*) ptr, toXYZD50, 1); ptr += kTAG_XYZ_Bytes; write_xyz_tag((uint32_t*) ptr, toXYZD50, 2); ptr += kTAG_XYZ_Bytes; // Write TRC tag write_trc_tag((uint32_t*) ptr, fn); ptr += kTAG_TRC_Bytes; // Write white point tag (must be D50) memcpy(ptr, kWhitePointTag, sizeof(kWhitePointTag)); ptr += sizeof(kWhitePointTag); // Write copyright tag memcpy(ptr, kCopyrightTagHeader, sizeof(kCopyrightTagHeader)); ptr += sizeof(kCopyrightTagHeader); memcpy(ptr, kCopyrightTagBody, sizeof(kCopyrightTagBody)); ptr += sizeof(kCopyrightTagBody); SkASSERT(kICCProfileSize == ptr - (uint8_t*) profile.get()); return SkData::MakeFromMalloc(profile.release(), kICCProfileSize); }