src/pdf/SkPDFType1Font.cpp - skia - Git at Google

 // Copyright 2019 Google LLC.
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

 #include "src/pdf/SkPDFType1Font.h"

 #include "include/private/base/SkTemplates.h"
 #include "include/private/base/SkTo.h"
 #include "src/core/SkStrike.h"
 #include "src/core/SkStrikeSpec.h"

 #include <ctype.h>

 using namespace skia_private;

 /*
   "A standard Type 1 font program, as described in the Adobe Type 1
   Font Format specification, consists of three parts: a clear-text
   portion (written using PostScript syntax), an encrypted portion, and
   a fixed-content portion.  The fixed-content portion contains 512
   ASCII zeros followed by a cleartomark operator, and perhaps followed
   by additional data. Although the encrypted portion of a standard
   Type 1 font may be in binary or ASCII hexadecimal format, PDF
   supports only the binary format."
 */
 static bool parsePFBSection(const uint8_t** src, size_t* len, int sectionType,
                             size_t* size) {
     // PFB sections have a two or six bytes header. 0x80 and a one byte
     // section type followed by a four byte section length.  Type one is
     // an ASCII section (includes a length), type two is a binary section
     // (includes a length) and type three is an EOF marker with no length.
     const uint8_t* buf = *src;
     if (*len < 2 || buf[0] != 0x80 || buf[1] != sectionType) {
         return false;
     } else if (buf[1] == 3) {
         return true;
     } else if (*len < 6) {
         return false;
     }

     *size = (size_t)buf[2] | ((size_t)buf[3] << 8) | ((size_t)buf[4] << 16) |
             ((size_t)buf[5] << 24);
     size_t consumed = *size + 6;
     if (consumed > *len) {
         return false;
     }
     *src = *src + consumed;
     *len = *len - consumed;
     return true;
 }

 static bool parsePFB(const uint8_t* src, size_t size, size_t* headerLen,
                      size_t* dataLen, size_t* trailerLen) {
     const uint8_t* srcPtr = src;
     size_t remaining = size;

     return parsePFBSection(&srcPtr, &remaining, 1, headerLen) &&
            parsePFBSection(&srcPtr, &remaining, 2, dataLen) &&
            parsePFBSection(&srcPtr, &remaining, 1, trailerLen) &&
            parsePFBSection(&srcPtr, &remaining, 3, nullptr);
 }

 /* The sections of a PFA file are implicitly defined.  The body starts
  * after the line containing "eexec," and the trailer starts with 512
  * literal 0's followed by "cleartomark" (plus arbitrary white space).
  *
  * This function assumes that src is NUL terminated, but the NUL
  * termination is not included in size.
  *
  */
 static bool parsePFA(const char* src, size_t size, size_t* headerLen,
                      size_t* hexDataLen, size_t* dataLen, size_t* trailerLen) {
     const char* end = src + size;

     const char* dataPos = strstr(src, "eexec");
     if (!dataPos) {
         return false;
     }
     dataPos += strlen("eexec");
     while ((*dataPos == '\n' || *dataPos == '\r' || *dataPos == ' ') &&
             dataPos < end) {
         dataPos++;
     }
     *headerLen = dataPos - src;

     const char* trailerPos = strstr(dataPos, "cleartomark");
     if (!trailerPos) {
         return false;
     }
     int zeroCount = 0;
     for (trailerPos--; trailerPos > dataPos && zeroCount < 512; trailerPos--) {
         if (*trailerPos == '\n' || *trailerPos == '\r' || *trailerPos == ' ') {
             continue;
         } else if (*trailerPos == '0') {
             zeroCount++;
         } else {
             return false;
         }
     }
     if (zeroCount != 512) {
         return false;
     }

     *hexDataLen = trailerPos - src - *headerLen;
     *trailerLen = size - *headerLen - *hexDataLen;

     // Verify that the data section is hex encoded and count the bytes.
     int nibbles = 0;
     for (; dataPos < trailerPos; dataPos++) {
         if (isspace(*dataPos)) {
             continue;
         }
         // isxdigit() is locale-sensitive https://bugs.skia.org/8285
         if (nullptr == strchr("0123456789abcdefABCDEF", *dataPos)) {
             return false;
         }
         nibbles++;
     }
     *dataLen = (nibbles + 1) / 2;

     return true;
 }

 static int8_t hexToBin(uint8_t c) {
     if (!isxdigit(c)) {
         return -1;
     } else if (c <= '9') {
         return c - '0';
     } else if (c <= 'F') {
         return c - 'A' + 10;
     } else if (c <= 'f') {
         return c - 'a' + 10;
     }
     return -1;
 }

 static sk_sp<SkData> convert_type1_font_stream(std::unique_ptr<SkStreamAsset> srcStream,
                                                size_t* headerLen,
                                                size_t* dataLen,
                                                size_t* trailerLen) {
     size_t srcLen = srcStream ? srcStream->getLength() : 0;
     SkASSERT(srcLen);
     if (!srcLen) {
         return nullptr;
     }
     // Flatten and Nul-terminate the source stream so that we can use
     // strstr() to search it.
     AutoTMalloc<uint8_t> sourceBuffer(SkToInt(srcLen + 1));
     (void)srcStream->read(sourceBuffer.get(), srcLen);
     sourceBuffer[SkToInt(srcLen)] = 0;
     const uint8_t* src = sourceBuffer.get();

     if (parsePFB(src, srcLen, headerLen, dataLen, trailerLen)) {
         static const int kPFBSectionHeaderLength = 6;
         const size_t length = *headerLen + *dataLen + *trailerLen;
         SkASSERT(length > 0);
         SkASSERT(length + (2 * kPFBSectionHeaderLength) <= srcLen);

         sk_sp<SkData> data(SkData::MakeUninitialized(length));

         const uint8_t* const srcHeader = src + kPFBSectionHeaderLength;
         // There is a six-byte section header before header and data
         // (but not trailer) that we're not going to copy.
         const uint8_t* const srcData = srcHeader + *headerLen + kPFBSectionHeaderLength;
         const uint8_t* const srcTrailer = srcData + *headerLen;

         uint8_t* const resultHeader = (uint8_t*)data->writable_data();
         uint8_t* const resultData = resultHeader + *headerLen;
         uint8_t* const resultTrailer = resultData + *dataLen;

         SkASSERT(resultTrailer + *trailerLen == resultHeader + length);

         memcpy(resultHeader,  srcHeader,  *headerLen);
         memcpy(resultData,    srcData,    *dataLen);
         memcpy(resultTrailer, srcTrailer, *trailerLen);

         return data;
     }

     // A PFA has to be converted for PDF.
     size_t hexDataLen;
     if (!parsePFA((const char*)src, srcLen, headerLen, &hexDataLen, dataLen,
                  trailerLen)) {
         return nullptr;
     }
     const size_t length = *headerLen + *dataLen + *trailerLen;
     SkASSERT(length > 0);
     auto data = SkData::MakeUninitialized(length);
     uint8_t* buffer = (uint8_t*)data->writable_data();

     memcpy(buffer, src, *headerLen);
     uint8_t* const resultData = &(buffer[*headerLen]);

     const uint8_t* hexData = src + *headerLen;
     const uint8_t* trailer = hexData + hexDataLen;
     size_t outputOffset = 0;
     uint8_t dataByte = 0;  // To hush compiler.
     bool highNibble = true;
     for (; hexData < trailer; hexData++) {
         int8_t curNibble = hexToBin(*hexData);
         if (curNibble < 0) {
             continue;
         }
         if (highNibble) {
             dataByte = curNibble << 4;
             highNibble = false;
         } else {
             dataByte |= curNibble;
             highNibble = true;
             resultData[outputOffset++] = dataByte;
         }
     }
     if (!highNibble) {
         resultData[outputOffset++] = dataByte;
     }
     SkASSERT(outputOffset == *dataLen);

     uint8_t* const resultTrailer = &(buffer[SkToInt(*headerLen + outputOffset)]);
     memcpy(resultTrailer, src + *headerLen + hexDataLen, *trailerLen);
     return data;
 }

 inline static bool can_embed(const SkAdvancedTypefaceMetrics& metrics) {
     return !SkToBool(metrics.fFlags & SkAdvancedTypefaceMetrics::kNotEmbeddable_FontFlag);
 }

 inline static SkScalar from_font_units(SkScalar scaled, uint16_t emSize) {
     return emSize == 1000 ? scaled : scaled * 1000 / emSize;
 }

 static SkPDFIndirectReference make_type1_font_descriptor(SkPDFDocument* doc,
                                                          const SkTypeface* typeface,
                                                          const SkAdvancedTypefaceMetrics* info) {
     SkPDFDict descriptor("FontDescriptor");
     uint16_t emSize = SkToU16(typeface->getUnitsPerEm());
     if (info) {
         SkPDFFont::PopulateCommonFontDescriptor(&descriptor, *info, emSize, 0);
         if (can_embed(*info)) {
             int ttcIndex;
             size_t header SK_INIT_TO_AVOID_WARNING;
             size_t data SK_INIT_TO_AVOID_WARNING;
             size_t trailer SK_INIT_TO_AVOID_WARNING;
             std::unique_ptr<SkStreamAsset> rawFontData = typeface->openStream(&ttcIndex);
             sk_sp<SkData> fontData = convert_type1_font_stream(std::move(rawFontData),
                                                                &header, &data, &trailer);
             if (fontData) {
                 std::unique_ptr<SkPDFDict> dict = SkPDFMakeDict();
                 dict->insertInt("Length1", header);
                 dict->insertInt("Length2", data);
                 dict->insertInt("Length3", trailer);
                 auto fontStream = SkMemoryStream::Make(std::move(fontData));
                 descriptor.insertRef("FontFile",
                                      SkPDFStreamOut(std::move(dict), std::move(fontStream),
                                                     doc, SkPDFSteamCompressionEnabled::Yes));
             }
         }
     }
     return doc->emit(descriptor);
 }


 static const std::vector<SkString>& type_1_glyphnames(SkPDFDocument* canon,
                                                       const SkTypeface* typeface) {
     SkTypefaceID typefaceID = typeface->uniqueID();
     const std::vector<SkString>* glyphNames = canon->fType1GlyphNames.find(typefaceID);
     if (!glyphNames) {
         std::vector<SkString> names(typeface->countGlyphs());
         SkPDFFont::GetType1GlyphNames(*typeface, names.data());
         glyphNames = canon->fType1GlyphNames.set(typefaceID, std::move(names));
     }
     SkASSERT(glyphNames);
     return *glyphNames;
 }

 static SkPDFIndirectReference type1_font_descriptor(SkPDFDocument* doc,
                                                     const SkTypeface* typeface) {
     SkTypefaceID typefaceID = typeface->uniqueID();
     if (SkPDFIndirectReference* ptr = doc->fFontDescriptors.find(typefaceID)) {
         return *ptr;
     }
     const SkAdvancedTypefaceMetrics* info = SkPDFFont::GetMetrics(typeface, doc);
     auto fontDescriptor = make_type1_font_descriptor(doc, typeface, info);
     doc->fFontDescriptors.set(typefaceID, fontDescriptor);
     return fontDescriptor;
 }


 void SkPDFEmitType1Font(const SkPDFFont& pdfFont, SkPDFDocument* doc) {
     SkTypeface* typeface = pdfFont.typeface();
     const std::vector<SkString>& glyphNames = type_1_glyphnames(doc, typeface);
     SkGlyphID firstGlyphID = pdfFont.firstGlyphID();
     SkGlyphID lastGlyphID = pdfFont.lastGlyphID();

     SkPDFDict font("Font");
     font.insertRef("FontDescriptor", type1_font_descriptor(doc, typeface));
     font.insertName("Subtype", "Type1");
     if (const SkAdvancedTypefaceMetrics* info = SkPDFFont::GetMetrics(typeface, doc)) {
         font.insertName("BaseFont", info->fPostScriptName);
     }

     // glyphCount not including glyph 0
     unsigned glyphCount = 1 + lastGlyphID - firstGlyphID;
     SkASSERT(glyphCount > 0 && glyphCount <= 255);
     font.insertInt("FirstChar", (size_t)0);
     font.insertInt("LastChar", (size_t)glyphCount);
     {
         int emSize;
         auto widths = SkPDFMakeArray();

         int glyphRangeSize = lastGlyphID - firstGlyphID + 2;
         AutoTArray<SkGlyphID> glyphIDs{glyphRangeSize};
         glyphIDs[0] = 0;
         for (unsigned gId = firstGlyphID; gId <= lastGlyphID; gId++) {
             glyphIDs[gId - firstGlyphID + 1] = gId;
         }
         SkStrikeSpec strikeSpec = SkStrikeSpec::MakePDFVector(*typeface, &emSize);
         SkBulkGlyphMetrics metrics{strikeSpec};
         auto glyphs = metrics.glyphs(SkSpan(glyphIDs.get(), glyphRangeSize));
         for (int i = 0; i < glyphRangeSize; ++i) {
             widths->appendScalar(from_font_units(glyphs[i]->advanceX(), SkToU16(emSize)));
         }
         font.insertObject("Widths", std::move(widths));
     }
     auto encDiffs = SkPDFMakeArray();
     encDiffs->reserve(lastGlyphID - firstGlyphID + 3);
     encDiffs->appendInt(0);

     SkASSERT(glyphNames.size() > lastGlyphID);
     const SkString unknown("UNKNOWN");
     encDiffs->appendName(glyphNames[0].isEmpty() ? unknown : glyphNames[0]);
     for (int gID = firstGlyphID; gID <= lastGlyphID; gID++) {
         encDiffs->appendName(glyphNames[gID].isEmpty() ? unknown : glyphNames[gID]);
     }

     auto encoding = SkPDFMakeDict("Encoding");
     encoding->insertObject("Differences", std::move(encDiffs));
     font.insertObject("Encoding", std::move(encoding));

     doc->emit(font, pdfFont.indirectReference());
 }
	// Copyright 2019 Google LLC.
	// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

	#include "src/pdf/SkPDFType1Font.h"

	#include "include/private/base/SkTemplates.h"
	#include "include/private/base/SkTo.h"
	#include "src/core/SkStrike.h"
	#include "src/core/SkStrikeSpec.h"

	#include <ctype.h>

	using namespace skia_private;

	/*
	"A standard Type 1 font program, as described in the Adobe Type 1
	Font Format specification, consists of three parts: a clear-text
	portion (written using PostScript syntax), an encrypted portion, and
	a fixed-content portion. The fixed-content portion contains 512
	ASCII zeros followed by a cleartomark operator, and perhaps followed
	by additional data. Although the encrypted portion of a standard
	Type 1 font may be in binary or ASCII hexadecimal format, PDF
	supports only the binary format."
	*/
	static bool parsePFBSection(const uint8_t** src, size_t* len, int sectionType,
	size_t* size) {
	// PFB sections have a two or six bytes header. 0x80 and a one byte
	// section type followed by a four byte section length. Type one is
	// an ASCII section (includes a length), type two is a binary section
	// (includes a length) and type three is an EOF marker with no length.
	const uint8_t* buf = *src;
	if (*len < 2 \|\| buf[0] != 0x80 \|\| buf[1] != sectionType) {
	return false;
	} else if (buf[1] == 3) {
	return true;
	} else if (*len < 6) {
	return false;
	}

	*size = (size_t)buf[2] \| ((size_t)buf[3] << 8) \| ((size_t)buf[4] << 16) \|
	((size_t)buf[5] << 24);
	size_t consumed = *size + 6;
	if (consumed > *len) {
	return false;
	}
	src = src + consumed;
	len = len - consumed;
	return true;
	}

	static bool parsePFB(const uint8_t* src, size_t size, size_t* headerLen,
	size_t* dataLen, size_t* trailerLen) {
	const uint8_t* srcPtr = src;
	size_t remaining = size;

	return parsePFBSection(&srcPtr, &remaining, 1, headerLen) &&
	parsePFBSection(&srcPtr, &remaining, 2, dataLen) &&
	parsePFBSection(&srcPtr, &remaining, 1, trailerLen) &&
	parsePFBSection(&srcPtr, &remaining, 3, nullptr);
	}

	/* The sections of a PFA file are implicitly defined. The body starts
	* after the line containing "eexec," and the trailer starts with 512
	* literal 0's followed by "cleartomark" (plus arbitrary white space).
	*
	* This function assumes that src is NUL terminated, but the NUL
	* termination is not included in size.
	*
	*/
	static bool parsePFA(const char* src, size_t size, size_t* headerLen,
	size_t* hexDataLen, size_t* dataLen, size_t* trailerLen) {
	const char* end = src + size;

	const char* dataPos = strstr(src, "eexec");
	if (!dataPos) {
	return false;
	}
	dataPos += strlen("eexec");
	while ((dataPos == '\n' \|\| dataPos == '\r' \|\| *dataPos == ' ') &&
	dataPos < end) {
	dataPos++;
	}
	*headerLen = dataPos - src;

	const char* trailerPos = strstr(dataPos, "cleartomark");
	if (!trailerPos) {
	return false;
	}
	int zeroCount = 0;
	for (trailerPos--; trailerPos > dataPos && zeroCount < 512; trailerPos--) {
	if (trailerPos == '\n' \|\| trailerPos == '\r' \|\| *trailerPos == ' ') {
	continue;
	} else if (*trailerPos == '0') {
	zeroCount++;
	} else {
	return false;
	}
	}
	if (zeroCount != 512) {
	return false;
	}

	hexDataLen = trailerPos - src - headerLen;
	trailerLen = size - headerLen - *hexDataLen;

	// Verify that the data section is hex encoded and count the bytes.
	int nibbles = 0;
	for (; dataPos < trailerPos; dataPos++) {
	if (isspace(*dataPos)) {
	continue;
	}
	// isxdigit() is locale-sensitive https://bugs.skia.org/8285
	if (nullptr == strchr("0123456789abcdefABCDEF", *dataPos)) {
	return false;
	}
	nibbles++;
	}
	*dataLen = (nibbles + 1) / 2;

	return true;
	}

	static int8_t hexToBin(uint8_t c) {
	if (!isxdigit(c)) {
	return -1;
	} else if (c <= '9') {
	return c - '0';
	} else if (c <= 'F') {
	return c - 'A' + 10;
	} else if (c <= 'f') {
	return c - 'a' + 10;
	}
	return -1;
	}

	static sk_sp<SkData> convert_type1_font_stream(std::unique_ptr<SkStreamAsset> srcStream,
	size_t* headerLen,
	size_t* dataLen,
	size_t* trailerLen) {
	size_t srcLen = srcStream ? srcStream->getLength() : 0;
	SkASSERT(srcLen);
	if (!srcLen) {
	return nullptr;
	}
	// Flatten and Nul-terminate the source stream so that we can use
	// strstr() to search it.
	AutoTMalloc<uint8_t> sourceBuffer(SkToInt(srcLen + 1));
	(void)srcStream->read(sourceBuffer.get(), srcLen);
	sourceBuffer[SkToInt(srcLen)] = 0;
	const uint8_t* src = sourceBuffer.get();

	if (parsePFB(src, srcLen, headerLen, dataLen, trailerLen)) {
	static const int kPFBSectionHeaderLength = 6;
	const size_t length = headerLen + dataLen + *trailerLen;
	SkASSERT(length > 0);
	SkASSERT(length + (2 * kPFBSectionHeaderLength) <= srcLen);

	sk_sp<SkData> data(SkData::MakeUninitialized(length));

	const uint8_t* const srcHeader = src + kPFBSectionHeaderLength;
	// There is a six-byte section header before header and data
	// (but not trailer) that we're not going to copy.
	const uint8_t* const srcData = srcHeader + *headerLen + kPFBSectionHeaderLength;
	const uint8_t* const srcTrailer = srcData + *headerLen;

	uint8_t* const resultHeader = (uint8_t*)data->writable_data();
	uint8_t* const resultData = resultHeader + *headerLen;
	uint8_t* const resultTrailer = resultData + *dataLen;

	SkASSERT(resultTrailer + *trailerLen == resultHeader + length);

	memcpy(resultHeader, srcHeader, *headerLen);
	memcpy(resultData, srcData, *dataLen);
	memcpy(resultTrailer, srcTrailer, *trailerLen);

	return data;
	}

	// A PFA has to be converted for PDF.
	size_t hexDataLen;
	if (!parsePFA((const char*)src, srcLen, headerLen, &hexDataLen, dataLen,
	trailerLen)) {
	return nullptr;
	}
	const size_t length = headerLen + dataLen + *trailerLen;
	SkASSERT(length > 0);
	auto data = SkData::MakeUninitialized(length);
	uint8_t* buffer = (uint8_t*)data->writable_data();

	memcpy(buffer, src, *headerLen);
	uint8_t* const resultData = &(buffer[*headerLen]);

	const uint8_t* hexData = src + *headerLen;
	const uint8_t* trailer = hexData + hexDataLen;
	size_t outputOffset = 0;
	uint8_t dataByte = 0; // To hush compiler.
	bool highNibble = true;
	for (; hexData < trailer; hexData++) {
	int8_t curNibble = hexToBin(*hexData);
	if (curNibble < 0) {
	continue;
	}
	if (highNibble) {
	dataByte = curNibble << 4;
	highNibble = false;
	} else {
	dataByte \|= curNibble;
	highNibble = true;
	resultData[outputOffset++] = dataByte;
	}
	}
	if (!highNibble) {
	resultData[outputOffset++] = dataByte;
	}
	SkASSERT(outputOffset == *dataLen);

	uint8_t* const resultTrailer = &(buffer[SkToInt(*headerLen + outputOffset)]);
	memcpy(resultTrailer, src + headerLen + hexDataLen, trailerLen);
	return data;
	}

	inline static bool can_embed(const SkAdvancedTypefaceMetrics& metrics) {
	return !SkToBool(metrics.fFlags & SkAdvancedTypefaceMetrics::kNotEmbeddable_FontFlag);
	}

	inline static SkScalar from_font_units(SkScalar scaled, uint16_t emSize) {
	return emSize == 1000 ? scaled : scaled * 1000 / emSize;
	}

	static SkPDFIndirectReference make_type1_font_descriptor(SkPDFDocument* doc,
	const SkTypeface* typeface,
	const SkAdvancedTypefaceMetrics* info) {
	SkPDFDict descriptor("FontDescriptor");
	uint16_t emSize = SkToU16(typeface->getUnitsPerEm());
	if (info) {
	SkPDFFont::PopulateCommonFontDescriptor(&descriptor, *info, emSize, 0);
	if (can_embed(*info)) {
	int ttcIndex;
	size_t header SK_INIT_TO_AVOID_WARNING;
	size_t data SK_INIT_TO_AVOID_WARNING;
	size_t trailer SK_INIT_TO_AVOID_WARNING;
	std::unique_ptr<SkStreamAsset> rawFontData = typeface->openStream(&ttcIndex);
	sk_sp<SkData> fontData = convert_type1_font_stream(std::move(rawFontData),
	&header, &data, &trailer);
	if (fontData) {
	std::unique_ptr<SkPDFDict> dict = SkPDFMakeDict();
	dict->insertInt("Length1", header);
	dict->insertInt("Length2", data);
	dict->insertInt("Length3", trailer);
	auto fontStream = SkMemoryStream::Make(std::move(fontData));
	descriptor.insertRef("FontFile",
	SkPDFStreamOut(std::move(dict), std::move(fontStream),
	doc, SkPDFSteamCompressionEnabled::Yes));
	}
	}
	}
	return doc->emit(descriptor);
	}


	static const std::vector<SkString>& type_1_glyphnames(SkPDFDocument* canon,
	const SkTypeface* typeface) {
	SkTypefaceID typefaceID = typeface->uniqueID();
	const std::vector<SkString>* glyphNames = canon->fType1GlyphNames.find(typefaceID);
	if (!glyphNames) {
	std::vector<SkString> names(typeface->countGlyphs());
	SkPDFFont::GetType1GlyphNames(*typeface, names.data());
	glyphNames = canon->fType1GlyphNames.set(typefaceID, std::move(names));
	}
	SkASSERT(glyphNames);
	return *glyphNames;
	}

	static SkPDFIndirectReference type1_font_descriptor(SkPDFDocument* doc,
	const SkTypeface* typeface) {
	SkTypefaceID typefaceID = typeface->uniqueID();
	if (SkPDFIndirectReference* ptr = doc->fFontDescriptors.find(typefaceID)) {
	return *ptr;
	}
	const SkAdvancedTypefaceMetrics* info = SkPDFFont::GetMetrics(typeface, doc);
	auto fontDescriptor = make_type1_font_descriptor(doc, typeface, info);
	doc->fFontDescriptors.set(typefaceID, fontDescriptor);
	return fontDescriptor;
	}


	void SkPDFEmitType1Font(const SkPDFFont& pdfFont, SkPDFDocument* doc) {
	SkTypeface* typeface = pdfFont.typeface();
	const std::vector<SkString>& glyphNames = type_1_glyphnames(doc, typeface);
	SkGlyphID firstGlyphID = pdfFont.firstGlyphID();
	SkGlyphID lastGlyphID = pdfFont.lastGlyphID();

	SkPDFDict font("Font");
	font.insertRef("FontDescriptor", type1_font_descriptor(doc, typeface));
	font.insertName("Subtype", "Type1");
	if (const SkAdvancedTypefaceMetrics* info = SkPDFFont::GetMetrics(typeface, doc)) {
	font.insertName("BaseFont", info->fPostScriptName);
	}

	// glyphCount not including glyph 0
	unsigned glyphCount = 1 + lastGlyphID - firstGlyphID;
	SkASSERT(glyphCount > 0 && glyphCount <= 255);
	font.insertInt("FirstChar", (size_t)0);
	font.insertInt("LastChar", (size_t)glyphCount);
	{
	int emSize;
	auto widths = SkPDFMakeArray();

	int glyphRangeSize = lastGlyphID - firstGlyphID + 2;
	AutoTArray<SkGlyphID> glyphIDs{glyphRangeSize};
	glyphIDs[0] = 0;
	for (unsigned gId = firstGlyphID; gId <= lastGlyphID; gId++) {
	glyphIDs[gId - firstGlyphID + 1] = gId;
	}
	SkStrikeSpec strikeSpec = SkStrikeSpec::MakePDFVector(*typeface, &emSize);
	SkBulkGlyphMetrics metrics{strikeSpec};
	auto glyphs = metrics.glyphs(SkSpan(glyphIDs.get(), glyphRangeSize));
	for (int i = 0; i < glyphRangeSize; ++i) {
	widths->appendScalar(from_font_units(glyphs[i]->advanceX(), SkToU16(emSize)));
	}
	font.insertObject("Widths", std::move(widths));
	}
	auto encDiffs = SkPDFMakeArray();
	encDiffs->reserve(lastGlyphID - firstGlyphID + 3);
	encDiffs->appendInt(0);

	SkASSERT(glyphNames.size() > lastGlyphID);
	const SkString unknown("UNKNOWN");
	encDiffs->appendName(glyphNames[0].isEmpty() ? unknown : glyphNames[0]);
	for (int gID = firstGlyphID; gID <= lastGlyphID; gID++) {
	encDiffs->appendName(glyphNames[gID].isEmpty() ? unknown : glyphNames[gID]);
	}

	auto encoding = SkPDFMakeDict("Encoding");
	encoding->insertObject("Differences", std::move(encDiffs));
	font.insertObject("Encoding", std::move(encoding));

	doc->emit(font, pdfFont.indirectReference());
	}