| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "src/pdf/SkPDFMakeToUnicodeCmap.h" |
| |
| #include "include/private/SkTo.h" |
| #include "src/pdf/SkPDFUtils.h" |
| #include "src/utils/SkUTF.h" |
| |
| static void append_tounicode_header(SkDynamicMemoryWStream* cmap, |
| bool multibyte) { |
| // 12 dict begin: 12 is an Adobe-suggested value. Shall not change. |
| // It's there to prevent old version Adobe Readers from malfunctioning. |
| const char* kHeader = |
| "/CIDInit /ProcSet findresource begin\n" |
| "12 dict begin\n" |
| "begincmap\n"; |
| cmap->writeText(kHeader); |
| |
| // The /CIDSystemInfo must be consistent to the one in |
| // SkPDFFont::populateCIDFont(). |
| // We can not pass over the system info object here because the format is |
| // different. This is not a reference object. |
| const char* kSysInfo = |
| "/CIDSystemInfo\n" |
| "<< /Registry (Adobe)\n" |
| "/Ordering (UCS)\n" |
| "/Supplement 0\n" |
| ">> def\n"; |
| cmap->writeText(kSysInfo); |
| |
| // The CMapName must be consistent to /CIDSystemInfo above. |
| // /CMapType 2 means ToUnicode. |
| // Codespace range just tells the PDF processor the valid range. |
| const char* kTypeInfoHeader = |
| "/CMapName /Adobe-Identity-UCS def\n" |
| "/CMapType 2 def\n" |
| "1 begincodespacerange\n"; |
| cmap->writeText(kTypeInfoHeader); |
| if (multibyte) { |
| cmap->writeText("<0000> <FFFF>\n"); |
| } else { |
| cmap->writeText("<00> <FF>\n"); |
| } |
| cmap->writeText("endcodespacerange\n"); |
| } |
| |
| static void append_cmap_footer(SkDynamicMemoryWStream* cmap) { |
| const char kFooter[] = |
| "endcmap\n" |
| "CMapName currentdict /CMap defineresource pop\n" |
| "end\n" |
| "end"; |
| cmap->writeText(kFooter); |
| } |
| |
| namespace { |
| struct BFChar { |
| SkGlyphID fGlyphId; |
| SkUnichar fUnicode; |
| }; |
| |
| struct BFRange { |
| SkGlyphID fStart; |
| SkGlyphID fEnd; |
| SkUnichar fUnicode; |
| }; |
| } // namespace |
| |
| static void write_glyph(SkDynamicMemoryWStream* cmap, |
| bool multiByte, |
| SkGlyphID gid) { |
| if (multiByte) { |
| SkPDFUtils::WriteUInt16BE(cmap, gid); |
| } else { |
| SkPDFUtils::WriteUInt8(cmap, SkToU8(gid)); |
| } |
| } |
| |
| static void append_bfchar_section(const std::vector<BFChar>& bfchar, |
| bool multiByte, |
| SkDynamicMemoryWStream* cmap) { |
| // PDF spec defines that every bf* list can have at most 100 entries. |
| for (size_t i = 0; i < bfchar.size(); i += 100) { |
| int count = SkToInt(bfchar.size() - i); |
| count = std::min(count, 100); |
| cmap->writeDecAsText(count); |
| cmap->writeText(" beginbfchar\n"); |
| for (int j = 0; j < count; ++j) { |
| cmap->writeText("<"); |
| write_glyph(cmap, multiByte, bfchar[i + j].fGlyphId); |
| cmap->writeText("> <"); |
| SkPDFUtils::WriteUTF16beHex(cmap, bfchar[i + j].fUnicode); |
| cmap->writeText(">\n"); |
| } |
| cmap->writeText("endbfchar\n"); |
| } |
| } |
| |
| static void append_bfrange_section(const std::vector<BFRange>& bfrange, |
| bool multiByte, |
| SkDynamicMemoryWStream* cmap) { |
| // PDF spec defines that every bf* list can have at most 100 entries. |
| for (size_t i = 0; i < bfrange.size(); i += 100) { |
| int count = SkToInt(bfrange.size() - i); |
| count = std::min(count, 100); |
| cmap->writeDecAsText(count); |
| cmap->writeText(" beginbfrange\n"); |
| for (int j = 0; j < count; ++j) { |
| cmap->writeText("<"); |
| write_glyph(cmap, multiByte, bfrange[i + j].fStart); |
| cmap->writeText("> <"); |
| write_glyph(cmap, multiByte, bfrange[i + j].fEnd); |
| cmap->writeText("> <"); |
| SkPDFUtils::WriteUTF16beHex(cmap, bfrange[i + j].fUnicode); |
| cmap->writeText(">\n"); |
| } |
| cmap->writeText("endbfrange\n"); |
| } |
| } |
| |
| // Generate <bfchar> and <bfrange> table according to PDF spec 1.4 and Adobe |
| // Technote 5014. |
| // The function is not static so we can test it in unit tests. |
| // |
| // Current implementation guarantees bfchar and bfrange entries do not overlap. |
| // |
| // Current implementation does not attempt aggressive optimizations against |
| // following case because the specification is not clear. |
| // |
| // 4 beginbfchar 1 beginbfchar |
| // <0003> <0013> <0020> <0014> |
| // <0005> <0015> to endbfchar |
| // <0007> <0017> 1 beginbfrange |
| // <0020> <0014> <0003> <0007> <0013> |
| // endbfchar endbfrange |
| // |
| // Adobe Technote 5014 said: "Code mappings (unlike codespace ranges) may |
| // overlap, but succeeding maps supersede preceding maps." |
| // |
| // In case of searching text in PDF, bfrange will have higher precedence so |
| // typing char id 0x0014 in search box will get glyph id 0x0004 first. However, |
| // the spec does not mention how will this kind of conflict being resolved. |
| // |
| // For the worst case (having 65536 continuous unicode and we use every other |
| // one of them), the possible savings by aggressive optimization is 416KB |
| // pre-compressed and does not provide enough motivation for implementation. |
| void SkPDFAppendCmapSections(const SkUnichar* glyphToUnicode, |
| const SkPDFGlyphUse* subset, |
| SkDynamicMemoryWStream* cmap, |
| bool multiByteGlyphs, |
| SkGlyphID firstGlyphID, |
| SkGlyphID lastGlyphID) { |
| int glyphOffset = 0; |
| if (!multiByteGlyphs) { |
| glyphOffset = firstGlyphID - 1; |
| } |
| |
| std::vector<BFChar> bfcharEntries; |
| std::vector<BFRange> bfrangeEntries; |
| |
| BFRange currentRangeEntry = {0, 0, 0}; |
| bool rangeEmpty = true; |
| const int limit = (int)lastGlyphID + 1 - glyphOffset; |
| |
| for (int i = firstGlyphID - glyphOffset; i < limit + 1; ++i) { |
| SkGlyphID gid = i + glyphOffset; |
| bool inSubset = i < limit && (subset == nullptr || subset->has(gid)); |
| if (!rangeEmpty) { |
| // PDF spec requires bfrange not changing the higher byte, |
| // e.g. <1035> <10FF> <2222> is ok, but |
| // <1035> <1100> <2222> is no good |
| bool inRange = |
| i == currentRangeEntry.fEnd + 1 && |
| i >> 8 == currentRangeEntry.fStart >> 8 && |
| i < limit && |
| glyphToUnicode[gid] == |
| currentRangeEntry.fUnicode + i - currentRangeEntry.fStart; |
| if (!inSubset || !inRange) { |
| if (currentRangeEntry.fEnd > currentRangeEntry.fStart) { |
| bfrangeEntries.push_back(currentRangeEntry); |
| } else { |
| bfcharEntries.push_back({currentRangeEntry.fStart, currentRangeEntry.fUnicode}); |
| } |
| rangeEmpty = true; |
| } |
| } |
| if (inSubset) { |
| currentRangeEntry.fEnd = i; |
| if (rangeEmpty) { |
| currentRangeEntry.fStart = i; |
| currentRangeEntry.fUnicode = glyphToUnicode[gid]; |
| rangeEmpty = false; |
| } |
| } |
| } |
| |
| // The spec requires all bfchar entries for a font must come before bfrange |
| // entries. |
| append_bfchar_section(bfcharEntries, multiByteGlyphs, cmap); |
| append_bfrange_section(bfrangeEntries, multiByteGlyphs, cmap); |
| } |
| |
| std::unique_ptr<SkStreamAsset> SkPDFMakeToUnicodeCmap( |
| const SkUnichar* glyphToUnicode, |
| const SkPDFGlyphUse* subset, |
| bool multiByteGlyphs, |
| SkGlyphID firstGlyphID, |
| SkGlyphID lastGlyphID) { |
| SkDynamicMemoryWStream cmap; |
| append_tounicode_header(&cmap, multiByteGlyphs); |
| SkPDFAppendCmapSections(glyphToUnicode, subset, &cmap, multiByteGlyphs, |
| firstGlyphID, lastGlyphID); |
| append_cmap_footer(&cmap); |
| return cmap.detachAsStream(); |
| } |
