/*
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* Copyright 2016 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "SkAutoMalloc.h"
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#include "SkColorSpacePriv.h"
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#include "SkEndian.h"
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#include "SkFixed.h"
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#include "SkICC.h"
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#include "SkICCPriv.h"
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#include "SkMD5.h"
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#include "SkUtils.h"
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static constexpr char kDescriptionTagBodyPrefix[12] =
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{ 'G', 'o', 'o', 'g', 'l', 'e', '/', 'S', 'k', 'i', 'a' , '/'};
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static constexpr size_t kICCDescriptionTagSize = 44;
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static_assert(kICCDescriptionTagSize ==
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sizeof(kDescriptionTagBodyPrefix) + 2 * sizeof(SkMD5::Digest), "");
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static constexpr size_t kDescriptionTagBodySize = kICCDescriptionTagSize * 2; // ascii->utf16be
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static_assert(SkIsAlign4(kDescriptionTagBodySize), "Description must be aligned to 4-bytes.");
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static constexpr uint32_t kDescriptionTagHeader[7] {
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SkEndian_SwapBE32(kTAG_TextType), // Type signature
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0, // Reserved
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SkEndian_SwapBE32(1), // Number of records
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SkEndian_SwapBE32(12), // Record size (must be 12)
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SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA
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SkEndian_SwapBE32(kDescriptionTagBodySize), // Length of string
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SkEndian_SwapBE32(28), // Offset of string
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};
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static constexpr uint32_t kWhitePointTag[5] {
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SkEndian_SwapBE32(kXYZ_PCSSpace),
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0,
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SkEndian_SwapBE32(0x0000f6d6), // X = 0.96420 (D50)
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SkEndian_SwapBE32(0x00010000), // Y = 1.00000 (D50)
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SkEndian_SwapBE32(0x0000d32d), // Z = 0.82491 (D50)
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};
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// Google Inc. 2016 (UTF-16)
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static constexpr uint8_t kCopyrightTagBody[] = {
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0x00, 0x47, 0x00, 0x6f,
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0x00, 0x6f, 0x00, 0x67,
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0x00, 0x6c, 0x00, 0x65,
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0x00, 0x20, 0x00, 0x49,
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0x00, 0x6e, 0x00, 0x63,
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0x00, 0x2e, 0x00, 0x20,
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0x00, 0x32, 0x00, 0x30,
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0x00, 0x31, 0x00, 0x36,
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};
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static_assert(SkIsAlign4(sizeof(kCopyrightTagBody)), "Copyright must be aligned to 4-bytes.");
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static constexpr uint32_t kCopyrightTagHeader[7] {
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SkEndian_SwapBE32(kTAG_TextType), // Type signature
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0, // Reserved
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SkEndian_SwapBE32(1), // Number of records
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SkEndian_SwapBE32(12), // Record size (must be 12)
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SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA
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SkEndian_SwapBE32(sizeof(kCopyrightTagBody)), // Length of string
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SkEndian_SwapBE32(28), // Offset of string
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};
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// We will write a profile with the minimum nine required tags.
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static constexpr uint32_t kICCNumEntries = 9;
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static constexpr uint32_t kTAG_desc = SkSetFourByteTag('d', 'e', 's', 'c');
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static constexpr uint32_t kTAG_desc_Bytes = sizeof(kDescriptionTagHeader) +
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kDescriptionTagBodySize;
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static constexpr uint32_t kTAG_desc_Offset = kICCHeaderSize +
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kICCNumEntries * kICCTagTableEntrySize;
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static constexpr uint32_t kTAG_XYZ_Bytes = 20;
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static constexpr uint32_t kTAG_rXYZ_Offset = kTAG_desc_Offset + kTAG_desc_Bytes;
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static constexpr uint32_t kTAG_gXYZ_Offset = kTAG_rXYZ_Offset + kTAG_XYZ_Bytes;
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static constexpr uint32_t kTAG_bXYZ_Offset = kTAG_gXYZ_Offset + kTAG_XYZ_Bytes;
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static constexpr uint32_t kTAG_TRC_Bytes = 40;
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static constexpr uint32_t kTAG_rTRC_Offset = kTAG_bXYZ_Offset + kTAG_XYZ_Bytes;
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static constexpr uint32_t kTAG_gTRC_Offset = kTAG_rTRC_Offset;
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static constexpr uint32_t kTAG_bTRC_Offset = kTAG_rTRC_Offset;
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static constexpr uint32_t kTAG_wtpt = SkSetFourByteTag('w', 't', 'p', 't');
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static constexpr uint32_t kTAG_wtpt_Offset = kTAG_bTRC_Offset + kTAG_TRC_Bytes;
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static constexpr uint32_t kTAG_cprt = SkSetFourByteTag('c', 'p', 'r', 't');
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static constexpr uint32_t kTAG_cprt_Bytes = sizeof(kCopyrightTagHeader) +
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sizeof(kCopyrightTagBody);
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static constexpr uint32_t kTAG_cprt_Offset = kTAG_wtpt_Offset + kTAG_XYZ_Bytes;
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static constexpr uint32_t kICCProfileSize = kTAG_cprt_Offset + kTAG_cprt_Bytes;
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static constexpr uint32_t kICCHeader[kICCHeaderSize / 4] {
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SkEndian_SwapBE32(kICCProfileSize), // Size of the profile
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0, // Preferred CMM type (ignored)
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SkEndian_SwapBE32(0x02100000), // Version 2.1
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SkEndian_SwapBE32(kDisplay_Profile), // Display device profile
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SkEndian_SwapBE32(kRGB_ColorSpace), // RGB input color space
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SkEndian_SwapBE32(kXYZ_PCSSpace), // XYZ profile connection space
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0, 0, 0, // Date and time (ignored)
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SkEndian_SwapBE32(kACSP_Signature), // Profile signature
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0, // Platform target (ignored)
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0x00000000, // Flags: not embedded, can be used independently
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0, // Device manufacturer (ignored)
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0, // Device model (ignored)
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0, 0, // Device attributes (ignored)
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SkEndian_SwapBE32(1), // Relative colorimetric rendering intent
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SkEndian_SwapBE32(0x0000f6d6), // D50 standard illuminant (X)
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SkEndian_SwapBE32(0x00010000), // D50 standard illuminant (Y)
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SkEndian_SwapBE32(0x0000d32d), // D50 standard illuminant (Z)
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0, // Profile creator (ignored)
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0, 0, 0, 0, // Profile id checksum (ignored)
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0, 0, 0, 0, 0, 0, 0, // Reserved (ignored)
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SkEndian_SwapBE32(kICCNumEntries), // Number of tags
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};
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static constexpr uint32_t kICCTagTable[3 * kICCNumEntries] {
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// Profile description
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SkEndian_SwapBE32(kTAG_desc),
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SkEndian_SwapBE32(kTAG_desc_Offset),
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SkEndian_SwapBE32(kTAG_desc_Bytes),
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// rXYZ
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SkEndian_SwapBE32(kTAG_rXYZ),
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SkEndian_SwapBE32(kTAG_rXYZ_Offset),
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SkEndian_SwapBE32(kTAG_XYZ_Bytes),
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// gXYZ
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SkEndian_SwapBE32(kTAG_gXYZ),
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SkEndian_SwapBE32(kTAG_gXYZ_Offset),
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SkEndian_SwapBE32(kTAG_XYZ_Bytes),
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// bXYZ
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SkEndian_SwapBE32(kTAG_bXYZ),
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SkEndian_SwapBE32(kTAG_bXYZ_Offset),
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SkEndian_SwapBE32(kTAG_XYZ_Bytes),
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// rTRC
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SkEndian_SwapBE32(kTAG_rTRC),
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SkEndian_SwapBE32(kTAG_rTRC_Offset),
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SkEndian_SwapBE32(kTAG_TRC_Bytes),
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// gTRC
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SkEndian_SwapBE32(kTAG_gTRC),
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SkEndian_SwapBE32(kTAG_gTRC_Offset),
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SkEndian_SwapBE32(kTAG_TRC_Bytes),
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// bTRC
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SkEndian_SwapBE32(kTAG_bTRC),
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SkEndian_SwapBE32(kTAG_bTRC_Offset),
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SkEndian_SwapBE32(kTAG_TRC_Bytes),
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// White point
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SkEndian_SwapBE32(kTAG_wtpt),
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SkEndian_SwapBE32(kTAG_wtpt_Offset),
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SkEndian_SwapBE32(kTAG_XYZ_Bytes),
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// Copyright
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SkEndian_SwapBE32(kTAG_cprt),
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SkEndian_SwapBE32(kTAG_cprt_Offset),
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SkEndian_SwapBE32(kTAG_cprt_Bytes),
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};
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// This is like SkFloatToFixed, but rounds to nearest, preserving as much accuracy as possible
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// when going float -> fixed -> float (it has the same accuracy when going fixed -> float -> fixed).
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// The use of double is necessary to accomodate the full potential 32-bit mantissa of the 16.16
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// SkFixed value, and so avoiding rounding problems with float. Also, see the comment in SkFixed.h.
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static SkFixed float_round_to_fixed(float x) {
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return sk_float_saturate2int((float)floor((double)x * SK_Fixed1 + 0.5));
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}
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static void write_xyz_tag(uint32_t* ptr, const skcms_Matrix3x3& toXYZD50, int col) {
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ptr[0] = SkEndian_SwapBE32(kXYZ_PCSSpace);
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ptr[1] = 0;
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ptr[2] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[0][col]));
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ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[1][col]));
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ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[2][col]));
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}
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static void write_trc_tag(uint32_t* ptr, const skcms_TransferFunction& fn) {
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ptr[0] = SkEndian_SwapBE32(kTAG_ParaCurveType);
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ptr[1] = 0;
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ptr[2] = (uint32_t) (SkEndian_SwapBE16(kGABCDEF_ParaCurveType));
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ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(fn.g));
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ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(fn.a));
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ptr[5] = SkEndian_SwapBE32(float_round_to_fixed(fn.b));
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ptr[6] = SkEndian_SwapBE32(float_round_to_fixed(fn.c));
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ptr[7] = SkEndian_SwapBE32(float_round_to_fixed(fn.d));
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ptr[8] = SkEndian_SwapBE32(float_round_to_fixed(fn.e));
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ptr[9] = SkEndian_SwapBE32(float_round_to_fixed(fn.f));
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}
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static bool nearly_equal(float x, float y) {
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// A note on why I chose this tolerance: transfer_fn_almost_equal() uses a
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// tolerance of 0.001f, which doesn't seem to be enough to distinguish
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// between similar transfer functions, for example: gamma2.2 and sRGB.
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//
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// If the tolerance is 0.0f, then this we can't distinguish between two
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// different encodings of what is clearly the same colorspace. Some
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// experimentation with example files lead to this number:
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static constexpr float kTolerance = 1.0f / (1 << 11);
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return ::fabsf(x - y) <= kTolerance;
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}
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static bool nearly_equal(const skcms_TransferFunction& u,
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const skcms_TransferFunction& v) {
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return nearly_equal(u.g, v.g)
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&& nearly_equal(u.a, v.a)
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&& nearly_equal(u.b, v.b)
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&& nearly_equal(u.c, v.c)
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&& nearly_equal(u.d, v.d)
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&& nearly_equal(u.e, v.e)
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&& nearly_equal(u.f, v.f);
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}
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static bool nearly_equal(const skcms_Matrix3x3& u, const skcms_Matrix3x3& v) {
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for (int r = 0; r < 3; r++) {
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for (int c = 0; c < 3; c++) {
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if (!nearly_equal(u.vals[r][c], v.vals[r][c])) {
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return false;
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}
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}
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}
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return true;
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}
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// Return nullptr if the color profile doen't have a special name.
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const char* get_color_profile_description(const skcms_TransferFunction& fn,
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const skcms_Matrix3x3& toXYZD50) {
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bool srgb_xfer = nearly_equal(fn, SkNamedTransferFn::kSRGB);
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bool srgb_gamut = nearly_equal(toXYZD50, SkNamedGamut::kSRGB);
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if (srgb_xfer && srgb_gamut) {
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return "sRGB";
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}
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bool line_xfer = nearly_equal(fn, SkNamedTransferFn::kLinear);
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if (line_xfer && srgb_gamut) {
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return "Linear Transfer with sRGB Gamut";
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}
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bool twoDotTwo = nearly_equal(fn, SkNamedTransferFn::k2Dot2);
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if (twoDotTwo && srgb_gamut) {
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return "2.2 Transfer with sRGB Gamut";
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}
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if (twoDotTwo && nearly_equal(toXYZD50, SkNamedGamut::kAdobeRGB)) {
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return "AdobeRGB";
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}
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bool dcip3_gamut = nearly_equal(toXYZD50, SkNamedGamut::kDCIP3);
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if (srgb_xfer || line_xfer) {
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if (srgb_xfer && dcip3_gamut) {
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return "sRGB Transfer with DCI-P3 Gamut";
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}
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if (line_xfer && dcip3_gamut) {
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return "Linear Transfer with DCI-P3 Gamut";
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}
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bool rec2020 = nearly_equal(toXYZD50, SkNamedGamut::kRec2020);
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if (srgb_xfer && rec2020) {
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return "sRGB Transfer with Rec-BT-2020 Gamut";
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}
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if (line_xfer && rec2020) {
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return "Linear Transfer with Rec-BT-2020 Gamut";
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}
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}
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return nullptr;
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}
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static void get_color_profile_tag(char dst[kICCDescriptionTagSize],
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const skcms_TransferFunction& fn,
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const skcms_Matrix3x3& toXYZD50) {
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SkASSERT(dst);
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if (const char* description = get_color_profile_description(fn, toXYZD50)) {
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SkASSERT(strlen(description) < kICCDescriptionTagSize);
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strncpy(dst, description, kICCDescriptionTagSize);
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// "If the length of src is less than n, strncpy() writes additional
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// null bytes to dest to ensure that a total of n bytes are written."
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} else {
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strncpy(dst, kDescriptionTagBodyPrefix, sizeof(kDescriptionTagBodyPrefix));
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SkMD5 md5;
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md5.write(&toXYZD50, sizeof(toXYZD50));
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static_assert(sizeof(fn) == sizeof(float) * 7, "packed");
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md5.write(&fn, sizeof(fn));
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SkMD5::Digest digest;
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md5.finish(digest);
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char* ptr = dst + sizeof(kDescriptionTagBodyPrefix);
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for (unsigned i = 0; i < sizeof(SkMD5::Digest); ++i) {
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uint8_t byte = digest.data[i];
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*ptr++ = SkHexadecimalDigits::gUpper[byte >> 4];
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*ptr++ = SkHexadecimalDigits::gUpper[byte & 0xF];
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}
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SkASSERT(ptr == dst + kICCDescriptionTagSize);
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}
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}
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sk_sp<SkData> SkWriteICCProfile(const skcms_TransferFunction& fn,
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const skcms_Matrix3x3& toXYZD50) {
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if (!is_valid_transfer_fn(fn)) {
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return nullptr;
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}
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SkAutoMalloc profile(kICCProfileSize);
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uint8_t* ptr = (uint8_t*) profile.get();
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// Write profile header
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memcpy(ptr, kICCHeader, sizeof(kICCHeader));
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ptr += sizeof(kICCHeader);
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// Write tag table
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memcpy(ptr, kICCTagTable, sizeof(kICCTagTable));
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ptr += sizeof(kICCTagTable);
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// Write profile description tag
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memcpy(ptr, kDescriptionTagHeader, sizeof(kDescriptionTagHeader));
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ptr += sizeof(kDescriptionTagHeader);
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{
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char colorProfileTag[kICCDescriptionTagSize];
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get_color_profile_tag(colorProfileTag, fn, toXYZD50);
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// ASCII --> big-endian UTF-16.
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for (size_t i = 0; i < kICCDescriptionTagSize; i++) {
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*ptr++ = 0;
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*ptr++ = colorProfileTag[i];
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}
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}
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// Write XYZ tags
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write_xyz_tag((uint32_t*) ptr, toXYZD50, 0);
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ptr += kTAG_XYZ_Bytes;
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write_xyz_tag((uint32_t*) ptr, toXYZD50, 1);
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ptr += kTAG_XYZ_Bytes;
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write_xyz_tag((uint32_t*) ptr, toXYZD50, 2);
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ptr += kTAG_XYZ_Bytes;
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// Write TRC tag
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write_trc_tag((uint32_t*) ptr, fn);
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ptr += kTAG_TRC_Bytes;
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// Write white point tag (must be D50)
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memcpy(ptr, kWhitePointTag, sizeof(kWhitePointTag));
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ptr += sizeof(kWhitePointTag);
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// Write copyright tag
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memcpy(ptr, kCopyrightTagHeader, sizeof(kCopyrightTagHeader));
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ptr += sizeof(kCopyrightTagHeader);
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memcpy(ptr, kCopyrightTagBody, sizeof(kCopyrightTagBody));
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ptr += sizeof(kCopyrightTagBody);
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SkASSERT(kICCProfileSize == ptr - (uint8_t*) profile.get());
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return SkData::MakeFromMalloc(profile.release(), kICCProfileSize);
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}
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