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- /*
- * 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 "include/core/SkICC.h"
- #include "include/private/SkFixed.h"
- #include "src/core/SkAutoMalloc.h"
- #include "src/core/SkColorSpacePriv.h"
- #include "src/core/SkEndian.h"
- #include "src/core/SkICCPriv.h"
- #include "src/core/SkMD5.h"
- #include "src/core/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 skcms_Matrix3x3& toXYZD50, int col) {
- ptr[0] = SkEndian_SwapBE32(kXYZ_PCSSpace);
- ptr[1] = 0;
- ptr[2] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[0][col]));
- ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[1][col]));
- ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[2][col]));
- }
- static void write_trc_tag(uint32_t* ptr, const skcms_TransferFunction& 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.g));
- ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(fn.a));
- ptr[5] = SkEndian_SwapBE32(float_round_to_fixed(fn.b));
- ptr[6] = SkEndian_SwapBE32(float_round_to_fixed(fn.c));
- ptr[7] = SkEndian_SwapBE32(float_round_to_fixed(fn.d));
- ptr[8] = SkEndian_SwapBE32(float_round_to_fixed(fn.e));
- ptr[9] = SkEndian_SwapBE32(float_round_to_fixed(fn.f));
- }
- 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 skcms_TransferFunction& u,
- const skcms_TransferFunction& v) {
- return nearly_equal(u.g, v.g)
- && nearly_equal(u.a, v.a)
- && nearly_equal(u.b, v.b)
- && nearly_equal(u.c, v.c)
- && nearly_equal(u.d, v.d)
- && nearly_equal(u.e, v.e)
- && nearly_equal(u.f, v.f);
- }
- static bool nearly_equal(const skcms_Matrix3x3& u, const skcms_Matrix3x3& v) {
- for (int r = 0; r < 3; r++) {
- for (int c = 0; c < 3; c++) {
- if (!nearly_equal(u.vals[r][c], v.vals[r][c])) {
- return false;
- }
- }
- }
- return true;
- }
- // Return nullptr if the color profile doen't have a special name.
- const char* get_color_profile_description(const skcms_TransferFunction& fn,
- const skcms_Matrix3x3& toXYZD50) {
- bool srgb_xfer = nearly_equal(fn, SkNamedTransferFn::kSRGB);
- bool srgb_gamut = nearly_equal(toXYZD50, SkNamedGamut::kSRGB);
- if (srgb_xfer && srgb_gamut) {
- return "sRGB";
- }
- bool line_xfer = nearly_equal(fn, SkNamedTransferFn::kLinear);
- if (line_xfer && srgb_gamut) {
- return "Linear Transfer with sRGB Gamut";
- }
- bool twoDotTwo = nearly_equal(fn, SkNamedTransferFn::k2Dot2);
- if (twoDotTwo && srgb_gamut) {
- return "2.2 Transfer with sRGB Gamut";
- }
- if (twoDotTwo && nearly_equal(toXYZD50, SkNamedGamut::kAdobeRGB)) {
- return "AdobeRGB";
- }
- bool dcip3_gamut = nearly_equal(toXYZD50, SkNamedGamut::kDCIP3);
- 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, SkNamedGamut::kRec2020);
- if (srgb_xfer && rec2020) {
- return "sRGB Transfer with Rec-BT-2020 Gamut";
- }
- if (line_xfer && rec2020) {
- return "Linear Transfer with Rec-BT-2020 Gamut";
- }
- }
- return nullptr;
- }
- static void get_color_profile_tag(char dst[kICCDescriptionTagSize],
- const skcms_TransferFunction& fn,
- const skcms_Matrix3x3& toXYZD50) {
- 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, sizeof(toXYZD50));
- static_assert(sizeof(fn) == sizeof(float) * 7, "packed");
- md5.write(&fn, sizeof(fn));
- SkMD5::Digest digest = md5.finish();
- 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<SkData> SkWriteICCProfile(const skcms_TransferFunction& fn,
- const skcms_Matrix3x3& toXYZD50) {
- 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);
- }
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