| // Copyright 2016 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package sfnt |
| |
| // Compact Font Format (CFF) fonts are written in PostScript, a stack-based |
| // programming language. |
| // |
| // A fundamental concept is a DICT, or a key-value map, expressed in reverse |
| // Polish notation. For example, this sequence of operations: |
| // - push the number 379 |
| // - version operator |
| // - push the number 392 |
| // - Notice operator |
| // - etc |
| // - push the number 100 |
| // - push the number 0 |
| // - push the number 500 |
| // - push the number 800 |
| // - FontBBox operator |
| // - etc |
| // defines a DICT that maps "version" to the String ID (SID) 379, "Notice" to |
| // the SID 392, "FontBBox" to the four numbers [100, 0, 500, 800], etc. |
| // |
| // The first 391 String IDs (starting at 0) are predefined as per the CFF spec |
| // Appendix A, in 5176.CFF.pdf referenced below. For example, 379 means |
| // "001.000". String ID 392 is not predefined, and is mapped by a separate |
| // structure, the "String INDEX", inside the CFF data. (String ID 391 is also |
| // not predefined. Specifically for ../testdata/CFFTest.otf, 391 means |
| // "uni4E2D", as this font contains a glyph for U+4E2D). |
| // |
| // The actual glyph vectors are similarly encoded (in PostScript), in a format |
| // called Type 2 Charstrings. The wire encoding is similar to but not exactly |
| // the same as CFF's. For example, the byte 0x05 means FontBBox for CFF DICTs, |
| // but means rlineto (relative line-to) for Type 2 Charstrings. See |
| // 5176.CFF.pdf Appendix H and 5177.Type2.pdf Appendix A in the PDF files |
| // referenced below. |
| // |
| // CFF is a stand-alone format, but CFF as used in SFNT fonts have further |
| // restrictions. For example, a stand-alone CFF can contain multiple fonts, but |
| // https://www.microsoft.com/typography/OTSPEC/cff.htm says that "The Name |
| // INDEX in the CFF must contain only one entry; that is, there must be only |
| // one font in the CFF FontSet". |
| // |
| // The relevant specifications are: |
| // - http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/font/pdfs/5176.CFF.pdf |
| // - http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/font/pdfs/5177.Type2.pdf |
| |
| import ( |
| "fmt" |
| "math" |
| "strconv" |
| |
| "golang.org/x/image/math/fixed" |
| ) |
| |
| const ( |
| // psArgStackSize is the argument stack size for a PostScript interpreter. |
| // 5176.CFF.pdf section 4 "DICT Data" says that "An operator may be |
| // preceded by up to a maximum of 48 operands". 5177.Type2.pdf Appendix B |
| // "Type 2 Charstring Implementation Limits" says that "Argument stack 48". |
| psArgStackSize = 48 |
| ) |
| |
| func bigEndian(b []byte) uint32 { |
| switch len(b) { |
| case 1: |
| return uint32(b[0]) |
| case 2: |
| return uint32(b[0])<<8 | uint32(b[1]) |
| case 3: |
| return uint32(b[0])<<16 | uint32(b[1])<<8 | uint32(b[2]) |
| case 4: |
| return uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3]) |
| } |
| panic("unreachable") |
| } |
| |
| // cffParser parses the CFF table from an SFNT font. |
| type cffParser struct { |
| src *source |
| base int |
| offset int |
| end int |
| err error |
| |
| buf []byte |
| locBuf [2]uint32 |
| |
| psi psInterpreter |
| } |
| |
| func (p *cffParser) parse() (locations []uint32, err error) { |
| // Parse header. |
| { |
| if !p.read(4) { |
| return nil, p.err |
| } |
| if p.buf[0] != 1 || p.buf[1] != 0 || p.buf[2] != 4 { |
| return nil, errUnsupportedCFFVersion |
| } |
| } |
| |
| // Parse Name INDEX. |
| { |
| count, offSize, ok := p.parseIndexHeader() |
| if !ok { |
| return nil, p.err |
| } |
| // https://www.microsoft.com/typography/OTSPEC/cff.htm says that "The |
| // Name INDEX in the CFF must contain only one entry". |
| if count != 1 { |
| return nil, errInvalidCFFTable |
| } |
| if !p.parseIndexLocations(p.locBuf[:2], count, offSize) { |
| return nil, p.err |
| } |
| p.offset = int(p.locBuf[1]) |
| } |
| |
| // Parse Top DICT INDEX. |
| { |
| count, offSize, ok := p.parseIndexHeader() |
| if !ok { |
| return nil, p.err |
| } |
| // 5176.CFF.pdf section 8 "Top DICT INDEX" says that the count here |
| // should match the count of the Name INDEX, which is 1. |
| if count != 1 { |
| return nil, errInvalidCFFTable |
| } |
| if !p.parseIndexLocations(p.locBuf[:2], count, offSize) { |
| return nil, p.err |
| } |
| if !p.read(int(p.locBuf[1] - p.locBuf[0])) { |
| return nil, p.err |
| } |
| p.psi.topDict.initialize() |
| if p.err = p.psi.run(psContextTopDict, p.buf); p.err != nil { |
| return nil, p.err |
| } |
| } |
| |
| // Parse the CharStrings INDEX, whose location was found in the Top DICT. |
| if p.psi.topDict.charStrings <= 0 || int32(p.end-p.base) < p.psi.topDict.charStrings { |
| return nil, errInvalidCFFTable |
| } |
| p.offset = p.base + int(p.psi.topDict.charStrings) |
| count, offSize, ok := p.parseIndexHeader() |
| if !ok { |
| return nil, p.err |
| } |
| if count == 0 { |
| return nil, errInvalidCFFTable |
| } |
| locations = make([]uint32, count+1) |
| if !p.parseIndexLocations(locations, count, offSize) { |
| return nil, p.err |
| } |
| return locations, nil |
| } |
| |
| // read sets p.buf to view the n bytes from p.offset to p.offset+n. It also |
| // advances p.offset by n. |
| // |
| // As per the source.view method, the caller should not modify the contents of |
| // p.buf after read returns, other than by calling read again. |
| // |
| // The caller should also avoid modifying the pointer / length / capacity of |
| // the p.buf slice, not just avoid modifying the slice's contents, in order to |
| // maximize the opportunity to re-use p.buf's allocated memory when viewing the |
| // underlying source data for subsequent read calls. |
| func (p *cffParser) read(n int) (ok bool) { |
| if p.end-p.offset < n { |
| p.err = errInvalidCFFTable |
| return false |
| } |
| p.buf, p.err = p.src.view(p.buf, p.offset, n) |
| p.offset += n |
| return p.err == nil |
| } |
| |
| func (p *cffParser) parseIndexHeader() (count, offSize int32, ok bool) { |
| if !p.read(2) { |
| return 0, 0, false |
| } |
| count = int32(u16(p.buf[:2])) |
| // 5176.CFF.pdf section 5 "INDEX Data" says that "An empty INDEX is |
| // represented by a count field with a 0 value and no additional fields. |
| // Thus, the total size of an empty INDEX is 2 bytes". |
| if count == 0 { |
| return count, 0, true |
| } |
| if !p.read(1) { |
| return 0, 0, false |
| } |
| offSize = int32(p.buf[0]) |
| if offSize < 1 || 4 < offSize { |
| p.err = errInvalidCFFTable |
| return 0, 0, false |
| } |
| return count, offSize, true |
| } |
| |
| func (p *cffParser) parseIndexLocations(dst []uint32, count, offSize int32) (ok bool) { |
| if count == 0 { |
| return true |
| } |
| if len(dst) != int(count+1) { |
| panic("unreachable") |
| } |
| if !p.read(len(dst) * int(offSize)) { |
| return false |
| } |
| |
| buf, prev := p.buf, uint32(0) |
| for i := range dst { |
| loc := bigEndian(buf[:offSize]) |
| buf = buf[offSize:] |
| |
| // Locations are off by 1 byte. 5176.CFF.pdf section 5 "INDEX Data" |
| // says that "Offsets in the offset array are relative to the byte that |
| // precedes the object data... This ensures that every object has a |
| // corresponding offset which is always nonzero". |
| if loc == 0 { |
| p.err = errInvalidCFFTable |
| return false |
| } |
| loc-- |
| |
| // In the same paragraph, "Therefore the first element of the offset |
| // array is always 1" before correcting for the off-by-1. |
| if i == 0 { |
| if loc != 0 { |
| p.err = errInvalidCFFTable |
| break |
| } |
| } else if loc <= prev { // Check that locations are increasing. |
| p.err = errInvalidCFFTable |
| break |
| } |
| |
| // Check that locations are in bounds. |
| if uint32(p.end-p.offset) < loc { |
| p.err = errInvalidCFFTable |
| break |
| } |
| |
| dst[i] = uint32(p.offset) + loc |
| prev = loc |
| } |
| return p.err == nil |
| } |
| |
| type psContext uint32 |
| |
| const ( |
| psContextTopDict psContext = iota |
| psContextType2Charstring |
| ) |
| |
| // psTopDictData contains fields specific to the Top DICT context. |
| type psTopDictData struct { |
| charStrings int32 |
| } |
| |
| func (d *psTopDictData) initialize() { |
| *d = psTopDictData{} |
| } |
| |
| // psType2CharstringsData contains fields specific to the Type 2 Charstrings |
| // context. |
| type psType2CharstringsData struct { |
| segments []Segment |
| x, y int32 |
| hintBits int32 |
| seenWidth bool |
| } |
| |
| func (d *psType2CharstringsData) initialize(segments []Segment) { |
| *d = psType2CharstringsData{ |
| segments: segments, |
| } |
| } |
| |
| // psInterpreter is a PostScript interpreter. |
| type psInterpreter struct { |
| ctx psContext |
| instructions []byte |
| argStack struct { |
| a [psArgStackSize]int32 |
| top int32 |
| } |
| parseNumberBuf [maxRealNumberStrLen]byte |
| topDict psTopDictData |
| type2Charstrings psType2CharstringsData |
| } |
| |
| func (p *psInterpreter) run(ctx psContext, instructions []byte) error { |
| p.ctx = ctx |
| p.instructions = instructions |
| p.argStack.top = 0 |
| |
| loop: |
| for len(p.instructions) > 0 { |
| // Push a numeric operand on the stack, if applicable. |
| if hasResult, err := p.parseNumber(); hasResult { |
| if err != nil { |
| return err |
| } |
| continue |
| } |
| |
| // Otherwise, execute an operator. |
| b := p.instructions[0] |
| p.instructions = p.instructions[1:] |
| |
| for escaped, ops := false, psOperators[ctx][0]; ; { |
| if b == escapeByte && !escaped { |
| if len(p.instructions) <= 0 { |
| return errInvalidCFFTable |
| } |
| b = p.instructions[0] |
| p.instructions = p.instructions[1:] |
| escaped = true |
| ops = psOperators[ctx][1] |
| continue |
| } |
| |
| if int(b) < len(ops) { |
| if op := ops[b]; op.name != "" { |
| if p.argStack.top < op.numPop { |
| return errInvalidCFFTable |
| } |
| if op.run != nil { |
| if err := op.run(p); err != nil { |
| return err |
| } |
| } |
| if op.numPop < 0 { |
| p.argStack.top = 0 |
| } else { |
| p.argStack.top -= op.numPop |
| } |
| continue loop |
| } |
| } |
| |
| if escaped { |
| return fmt.Errorf("sfnt: unrecognized CFF 2-byte operator (12 %d)", b) |
| } else { |
| return fmt.Errorf("sfnt: unrecognized CFF 1-byte operator (%d)", b) |
| } |
| } |
| } |
| return nil |
| } |
| |
| // See 5176.CFF.pdf section 4 "DICT Data". |
| func (p *psInterpreter) parseNumber() (hasResult bool, err error) { |
| number := int32(0) |
| switch b := p.instructions[0]; { |
| case b == 28: |
| if len(p.instructions) < 3 { |
| return true, errInvalidCFFTable |
| } |
| number, hasResult = int32(int16(u16(p.instructions[1:]))), true |
| p.instructions = p.instructions[3:] |
| |
| case b == 29 && p.ctx == psContextTopDict: |
| if len(p.instructions) < 5 { |
| return true, errInvalidCFFTable |
| } |
| number, hasResult = int32(u32(p.instructions[1:])), true |
| p.instructions = p.instructions[5:] |
| |
| case b == 30 && p.ctx == psContextTopDict: |
| // Parse a real number. This isn't listed in 5176.CFF.pdf Table 3 |
| // "Operand Encoding" but that table lists integer encodings. Further |
| // down the page it says "A real number operand is provided in addition |
| // to integer operands. This operand begins with a byte value of 30 |
| // followed by a variable-length sequence of bytes." |
| |
| s := p.parseNumberBuf[:0] |
| p.instructions = p.instructions[1:] |
| loop: |
| for { |
| if len(p.instructions) == 0 { |
| return true, errInvalidCFFTable |
| } |
| b := p.instructions[0] |
| p.instructions = p.instructions[1:] |
| // Process b's two nibbles, high then low. |
| for i := 0; i < 2; i++ { |
| nib := b >> 4 |
| b = b << 4 |
| if nib == 0x0f { |
| f, err := strconv.ParseFloat(string(s), 32) |
| if err != nil { |
| return true, errInvalidCFFTable |
| } |
| number, hasResult = int32(math.Float32bits(float32(f))), true |
| break loop |
| } |
| if nib == 0x0d { |
| return true, errInvalidCFFTable |
| } |
| if len(s)+maxNibbleDefsLength > len(p.parseNumberBuf) { |
| return true, errUnsupportedRealNumberEncoding |
| } |
| s = append(s, nibbleDefs[nib]...) |
| } |
| } |
| |
| case b < 32: |
| // No-op. |
| |
| case b < 247: |
| p.instructions = p.instructions[1:] |
| number, hasResult = int32(b)-139, true |
| |
| case b < 251: |
| if len(p.instructions) < 2 { |
| return true, errInvalidCFFTable |
| } |
| b1 := p.instructions[1] |
| p.instructions = p.instructions[2:] |
| number, hasResult = +int32(b-247)*256+int32(b1)+108, true |
| |
| case b < 255: |
| if len(p.instructions) < 2 { |
| return true, errInvalidCFFTable |
| } |
| b1 := p.instructions[1] |
| p.instructions = p.instructions[2:] |
| number, hasResult = -int32(b-251)*256-int32(b1)-108, true |
| |
| case b == 255 && p.ctx == psContextType2Charstring: |
| if len(p.instructions) < 5 { |
| return true, errInvalidCFFTable |
| } |
| number, hasResult = int32(u32(p.instructions[1:])), true |
| p.instructions = p.instructions[5:] |
| } |
| |
| if hasResult { |
| if p.argStack.top == psArgStackSize { |
| return true, errInvalidCFFTable |
| } |
| p.argStack.a[p.argStack.top] = number |
| p.argStack.top++ |
| } |
| return hasResult, nil |
| } |
| |
| const maxNibbleDefsLength = len("E-") |
| |
| // nibbleDefs encodes 5176.CFF.pdf Table 5 "Nibble Definitions". |
| var nibbleDefs = [16]string{ |
| 0x00: "0", |
| 0x01: "1", |
| 0x02: "2", |
| 0x03: "3", |
| 0x04: "4", |
| 0x05: "5", |
| 0x06: "6", |
| 0x07: "7", |
| 0x08: "8", |
| 0x09: "9", |
| 0x0a: ".", |
| 0x0b: "E", |
| 0x0c: "E-", |
| 0x0d: "", |
| 0x0e: "-", |
| 0x0f: "", |
| } |
| |
| type psOperator struct { |
| // numPop is the number of stack values to pop. -1 means "array" and -2 |
| // means "delta" as per 5176.CFF.pdf Table 6 "Operand Types". |
| numPop int32 |
| // name is the operator name. An empty name (i.e. the zero value for the |
| // struct overall) means an unrecognized 1-byte operator. |
| name string |
| // run is the function that implements the operator. Nil means that we |
| // ignore the operator, other than popping its arguments off the stack. |
| run func(*psInterpreter) error |
| } |
| |
| // psOperators holds the 1-byte and 2-byte operators for PostScript interpreter |
| // contexts. |
| var psOperators = [...][2][]psOperator{ |
| // The Top DICT operators are defined by 5176.CFF.pdf Table 9 "Top DICT |
| // Operator Entries" and Table 10 "CIDFont Operator Extensions". |
| psContextTopDict: {{ |
| // 1-byte operators. |
| 0: {+1, "version", nil}, |
| 1: {+1, "Notice", nil}, |
| 2: {+1, "FullName", nil}, |
| 3: {+1, "FamilyName", nil}, |
| 4: {+1, "Weight", nil}, |
| 5: {-1, "FontBBox", nil}, |
| 13: {+1, "UniqueID", nil}, |
| 14: {-1, "XUID", nil}, |
| 15: {+1, "charset", nil}, |
| 16: {+1, "Encoding", nil}, |
| 17: {+1, "CharStrings", func(p *psInterpreter) error { |
| p.topDict.charStrings = p.argStack.a[p.argStack.top-1] |
| return nil |
| }}, |
| 18: {+2, "Private", nil}, |
| }, { |
| // 2-byte operators. The first byte is the escape byte. |
| 0: {+1, "Copyright", nil}, |
| 1: {+1, "isFixedPitch", nil}, |
| 2: {+1, "ItalicAngle", nil}, |
| 3: {+1, "UnderlinePosition", nil}, |
| 4: {+1, "UnderlineThickness", nil}, |
| 5: {+1, "PaintType", nil}, |
| 6: {+1, "CharstringType", nil}, |
| 7: {-1, "FontMatrix", nil}, |
| 8: {+1, "StrokeWidth", nil}, |
| 20: {+1, "SyntheticBase", nil}, |
| 21: {+1, "PostScript", nil}, |
| 22: {+1, "BaseFontName", nil}, |
| 23: {-2, "BaseFontBlend", nil}, |
| 30: {+3, "ROS", nil}, |
| 31: {+1, "CIDFontVersion", nil}, |
| 32: {+1, "CIDFontRevision", nil}, |
| 33: {+1, "CIDFontType", nil}, |
| 34: {+1, "CIDCount", nil}, |
| 35: {+1, "UIDBase", nil}, |
| 36: {+1, "FDArray", nil}, |
| 37: {+1, "FDSelect", nil}, |
| 38: {+1, "FontName", nil}, |
| }}, |
| |
| // The Type 2 Charstring operators are defined by 5177.Type2.pdf Appendix A |
| // "Type 2 Charstring Command Codes". |
| psContextType2Charstring: {{ |
| // 1-byte operators. |
| 0: {}, // Reserved. |
| 1: {-1, "hstem", t2CStem}, |
| 2: {}, // Reserved. |
| 3: {-1, "vstem", t2CStem}, |
| 4: {-1, "vmoveto", t2CVmoveto}, |
| 5: {-1, "rlineto", t2CRlineto}, |
| 6: {-1, "hlineto", t2CHlineto}, |
| 7: {-1, "vlineto", t2CVlineto}, |
| 8: {-1, "rrcurveto", t2CRrcurveto}, |
| 9: {}, // Reserved. |
| 10: {}, // callsubr. |
| 11: {}, // return. |
| 12: {}, // escape. |
| 13: {}, // Reserved. |
| 14: {-1, "endchar", t2CEndchar}, |
| 15: {}, // Reserved. |
| 16: {}, // Reserved. |
| 17: {}, // Reserved. |
| 18: {-1, "hstemhm", t2CStem}, |
| 19: {-1, "hintmask", t2CMask}, |
| 20: {-1, "cntrmask", t2CMask}, |
| 21: {-1, "rmoveto", t2CRmoveto}, |
| 22: {-1, "hmoveto", t2CHmoveto}, |
| 23: {-1, "vstemhm", t2CStem}, |
| 24: {-1, "rcurveline", t2CRcurveline}, |
| 25: {-1, "rlinecurve", t2CRlinecurve}, |
| 26: {-1, "vvcurveto", t2CVvcurveto}, |
| 27: {-1, "hhcurveto", t2CHhcurveto}, |
| 28: {}, // shortint. |
| 29: {}, // callgsubr. |
| 30: {-1, "vhcurveto", t2CVhcurveto}, |
| 31: {-1, "hvcurveto", t2CHvcurveto}, |
| }, { |
| // 2-byte operators. The first byte is the escape byte. |
| 0: {}, // Reserved. |
| // TODO: more operators. |
| }}, |
| } |
| |
| // 5176.CFF.pdf section 4 "DICT Data" says that "Two-byte operators have an |
| // initial escape byte of 12". |
| const escapeByte = 12 |
| |
| // t2CReadWidth reads the optional width adjustment. If present, it is on the |
| // bottom of the stack. |
| // |
| // 5177.Type2.pdf page 16 Note 4 says: "The first stack-clearing operator, |
| // which must be one of hstem, hstemhm, vstem, vstemhm, cntrmask, hintmask, |
| // hmoveto, vmoveto, rmoveto, or endchar, takes an additional argument — the |
| // width... which may be expressed as zero or one numeric argument." |
| func t2CReadWidth(p *psInterpreter, nArgs int32) { |
| if p.type2Charstrings.seenWidth { |
| return |
| } |
| p.type2Charstrings.seenWidth = true |
| switch nArgs { |
| case 0: |
| if p.argStack.top != 1 { |
| return |
| } |
| case 1: |
| if p.argStack.top <= 1 { |
| return |
| } |
| default: |
| if p.argStack.top%nArgs != 1 { |
| return |
| } |
| } |
| // When parsing a standalone CFF, we'd save the value of p.argStack.a[0] |
| // here as it defines the glyph's width (horizontal advance). Specifically, |
| // if present, it is a delta to the font-global nominalWidthX value found |
| // in the Private DICT. If absent, the glyph's width is the defaultWidthX |
| // value in that dict. See 5176.CFF.pdf section 15 "Private DICT Data". |
| // |
| // For a CFF embedded in an SFNT font (i.e. an OpenType font), glyph widths |
| // are already stored in the hmtx table, separate to the CFF table, and it |
| // is simpler to parse that table for all OpenType fonts (PostScript and |
| // TrueType). We therefore ignore the width value here, and just remove it |
| // from the bottom of the argStack. |
| copy(p.argStack.a[:p.argStack.top-1], p.argStack.a[1:p.argStack.top]) |
| p.argStack.top-- |
| } |
| |
| func t2CStem(p *psInterpreter) error { |
| t2CReadWidth(p, 2) |
| if p.argStack.top%2 != 0 { |
| return errInvalidCFFTable |
| } |
| // We update the number of hintBits need to parse hintmask and cntrmask |
| // instructions, but this Type 2 Charstring implementation otherwise |
| // ignores the stem hints. |
| p.type2Charstrings.hintBits += p.argStack.top / 2 |
| if p.type2Charstrings.hintBits > maxHintBits { |
| return errUnsupportedNumberOfHints |
| } |
| return nil |
| } |
| |
| func t2CMask(p *psInterpreter) error { |
| hintBytes := (p.type2Charstrings.hintBits + 7) / 8 |
| t2CReadWidth(p, hintBytes) |
| if len(p.instructions) < int(hintBytes) { |
| return errInvalidCFFTable |
| } |
| p.instructions = p.instructions[hintBytes:] |
| return nil |
| } |
| |
| func t2CAppendMoveto(p *psInterpreter) { |
| p.type2Charstrings.segments = append(p.type2Charstrings.segments, Segment{ |
| Op: SegmentOpMoveTo, |
| Args: [6]fixed.Int26_6{ |
| 0: fixed.Int26_6(p.type2Charstrings.x), |
| 1: fixed.Int26_6(p.type2Charstrings.y), |
| }, |
| }) |
| } |
| |
| func t2CAppendLineto(p *psInterpreter) { |
| p.type2Charstrings.segments = append(p.type2Charstrings.segments, Segment{ |
| Op: SegmentOpLineTo, |
| Args: [6]fixed.Int26_6{ |
| 0: fixed.Int26_6(p.type2Charstrings.x), |
| 1: fixed.Int26_6(p.type2Charstrings.y), |
| }, |
| }) |
| } |
| |
| func t2CAppendCubeto(p *psInterpreter, dxa, dya, dxb, dyb, dxc, dyc int32) { |
| p.type2Charstrings.x += dxa |
| p.type2Charstrings.y += dya |
| xa := p.type2Charstrings.x |
| ya := p.type2Charstrings.y |
| p.type2Charstrings.x += dxb |
| p.type2Charstrings.y += dyb |
| xb := p.type2Charstrings.x |
| yb := p.type2Charstrings.y |
| p.type2Charstrings.x += dxc |
| p.type2Charstrings.y += dyc |
| xc := p.type2Charstrings.x |
| yc := p.type2Charstrings.y |
| p.type2Charstrings.segments = append(p.type2Charstrings.segments, Segment{ |
| Op: SegmentOpCubeTo, |
| Args: [6]fixed.Int26_6{ |
| 0: fixed.Int26_6(xa), |
| 1: fixed.Int26_6(ya), |
| 2: fixed.Int26_6(xb), |
| 3: fixed.Int26_6(yb), |
| 4: fixed.Int26_6(xc), |
| 5: fixed.Int26_6(yc), |
| }, |
| }) |
| } |
| |
| func t2CHmoveto(p *psInterpreter) error { |
| t2CReadWidth(p, 1) |
| if p.argStack.top < 1 { |
| return errInvalidCFFTable |
| } |
| for i := int32(0); i < p.argStack.top; i++ { |
| p.type2Charstrings.x += p.argStack.a[i] |
| } |
| t2CAppendMoveto(p) |
| return nil |
| } |
| |
| func t2CVmoveto(p *psInterpreter) error { |
| t2CReadWidth(p, 1) |
| if p.argStack.top < 1 { |
| return errInvalidCFFTable |
| } |
| for i := int32(0); i < p.argStack.top; i++ { |
| p.type2Charstrings.y += p.argStack.a[i] |
| } |
| t2CAppendMoveto(p) |
| return nil |
| } |
| |
| func t2CRmoveto(p *psInterpreter) error { |
| t2CReadWidth(p, 2) |
| if p.argStack.top < 2 || p.argStack.top%2 != 0 { |
| return errInvalidCFFTable |
| } |
| for i := int32(0); i < p.argStack.top; i += 2 { |
| p.type2Charstrings.x += p.argStack.a[i+0] |
| p.type2Charstrings.y += p.argStack.a[i+1] |
| } |
| t2CAppendMoveto(p) |
| return nil |
| } |
| |
| func t2CHlineto(p *psInterpreter) error { return t2CLineto(p, false) } |
| func t2CVlineto(p *psInterpreter) error { return t2CLineto(p, true) } |
| |
| func t2CLineto(p *psInterpreter, vertical bool) error { |
| if !p.type2Charstrings.seenWidth || p.argStack.top < 1 { |
| return errInvalidCFFTable |
| } |
| for i := int32(0); i < p.argStack.top; i, vertical = i+1, !vertical { |
| if vertical { |
| p.type2Charstrings.y += p.argStack.a[i] |
| } else { |
| p.type2Charstrings.x += p.argStack.a[i] |
| } |
| t2CAppendLineto(p) |
| } |
| return nil |
| } |
| |
| func t2CRlineto(p *psInterpreter) error { |
| if !p.type2Charstrings.seenWidth || p.argStack.top < 2 || p.argStack.top%2 != 0 { |
| return errInvalidCFFTable |
| } |
| for i := int32(0); i < p.argStack.top; i += 2 { |
| p.type2Charstrings.x += p.argStack.a[i+0] |
| p.type2Charstrings.y += p.argStack.a[i+1] |
| t2CAppendLineto(p) |
| } |
| return nil |
| } |
| |
| // As per 5177.Type2.pdf section 4.1 "Path Construction Operators", |
| // |
| // rcurveline is: |
| // - {dxa dya dxb dyb dxc dyc}+ dxd dyd |
| // |
| // rlinecurve is: |
| // - {dxa dya}+ dxb dyb dxc dyc dxd dyd |
| |
| func t2CRcurveline(p *psInterpreter) error { |
| if !p.type2Charstrings.seenWidth || p.argStack.top < 8 || p.argStack.top%6 != 2 { |
| return errInvalidCFFTable |
| } |
| i := int32(0) |
| for iMax := p.argStack.top - 2; i < iMax; i += 6 { |
| t2CAppendCubeto(p, |
| p.argStack.a[i+0], |
| p.argStack.a[i+1], |
| p.argStack.a[i+2], |
| p.argStack.a[i+3], |
| p.argStack.a[i+4], |
| p.argStack.a[i+5], |
| ) |
| } |
| p.type2Charstrings.x += p.argStack.a[i+0] |
| p.type2Charstrings.y += p.argStack.a[i+1] |
| t2CAppendLineto(p) |
| return nil |
| } |
| |
| func t2CRlinecurve(p *psInterpreter) error { |
| if !p.type2Charstrings.seenWidth || p.argStack.top < 8 || p.argStack.top%2 != 0 { |
| return errInvalidCFFTable |
| } |
| i := int32(0) |
| for iMax := p.argStack.top - 6; i < iMax; i += 2 { |
| p.type2Charstrings.x += p.argStack.a[i+0] |
| p.type2Charstrings.y += p.argStack.a[i+1] |
| t2CAppendLineto(p) |
| } |
| t2CAppendCubeto(p, |
| p.argStack.a[i+0], |
| p.argStack.a[i+1], |
| p.argStack.a[i+2], |
| p.argStack.a[i+3], |
| p.argStack.a[i+4], |
| p.argStack.a[i+5], |
| ) |
| return nil |
| } |
| |
| // As per 5177.Type2.pdf section 4.1 "Path Construction Operators", |
| // |
| // hhcurveto is: |
| // - dy1 {dxa dxb dyb dxc}+ |
| // |
| // vvcurveto is: |
| // - dx1 {dya dxb dyb dyc}+ |
| // |
| // hvcurveto is one of: |
| // - dx1 dx2 dy2 dy3 {dya dxb dyb dxc dxd dxe dye dyf}* dxf? |
| // - {dxa dxb dyb dyc dyd dxe dye dxf}+ dyf? |
| // |
| // vhcurveto is one of: |
| // - dy1 dx2 dy2 dx3 {dxa dxb dyb dyc dyd dxe dye dxf}* dyf? |
| // - {dya dxb dyb dxc dxd dxe dye dyf}+ dxf? |
| |
| func t2CHhcurveto(p *psInterpreter) error { return t2CCurveto(p, false, false) } |
| func t2CVvcurveto(p *psInterpreter) error { return t2CCurveto(p, false, true) } |
| func t2CHvcurveto(p *psInterpreter) error { return t2CCurveto(p, true, false) } |
| func t2CVhcurveto(p *psInterpreter) error { return t2CCurveto(p, true, true) } |
| |
| // t2CCurveto implements the hh / vv / hv / vh xxcurveto operators. N relative |
| // cubic curve requires 6*N control points, but only 4*N+0 or 4*N+1 are used |
| // here: all (or all but one) of the piecewise cubic curve's tangents are |
| // implicitly horizontal or vertical. |
| // |
| // swap is whether that implicit horizontal / vertical constraint swaps as you |
| // move along the piecewise cubic curve. If swap is false, the constraints are |
| // either all horizontal or all vertical. If swap is true, it alternates. |
| // |
| // vertical is whether the first implicit constraint is vertical. |
| func t2CCurveto(p *psInterpreter, swap, vertical bool) error { |
| if !p.type2Charstrings.seenWidth || p.argStack.top < 4 { |
| return errInvalidCFFTable |
| } |
| |
| i := int32(0) |
| switch p.argStack.top & 3 { |
| case 0: |
| // No-op. |
| case 1: |
| if swap { |
| break |
| } |
| i = 1 |
| if vertical { |
| p.type2Charstrings.x += p.argStack.a[0] |
| } else { |
| p.type2Charstrings.y += p.argStack.a[0] |
| } |
| default: |
| return errInvalidCFFTable |
| } |
| |
| for i != p.argStack.top { |
| i = t2CCurveto4(p, swap, vertical, i) |
| if i < 0 { |
| return errInvalidCFFTable |
| } |
| if swap { |
| vertical = !vertical |
| } |
| } |
| return nil |
| } |
| |
| func t2CCurveto4(p *psInterpreter, swap bool, vertical bool, i int32) (j int32) { |
| if i+4 > p.argStack.top { |
| return -1 |
| } |
| dxa := p.argStack.a[i+0] |
| dya := int32(0) |
| dxb := p.argStack.a[i+1] |
| dyb := p.argStack.a[i+2] |
| dxc := p.argStack.a[i+3] |
| dyc := int32(0) |
| i += 4 |
| |
| if vertical { |
| dxa, dya = dya, dxa |
| } |
| |
| if swap { |
| if i+1 == p.argStack.top { |
| dyc = p.argStack.a[i] |
| i++ |
| } |
| } |
| |
| if swap != vertical { |
| dxc, dyc = dyc, dxc |
| } |
| |
| t2CAppendCubeto(p, dxa, dya, dxb, dyb, dxc, dyc) |
| return i |
| } |
| |
| func t2CRrcurveto(p *psInterpreter) error { |
| if !p.type2Charstrings.seenWidth || p.argStack.top < 6 || p.argStack.top%6 != 0 { |
| return errInvalidCFFTable |
| } |
| for i := int32(0); i != p.argStack.top; i += 6 { |
| t2CAppendCubeto(p, |
| p.argStack.a[i+0], |
| p.argStack.a[i+1], |
| p.argStack.a[i+2], |
| p.argStack.a[i+3], |
| p.argStack.a[i+4], |
| p.argStack.a[i+5], |
| ) |
| } |
| return nil |
| } |
| |
| func t2CEndchar(p *psInterpreter) error { |
| t2CReadWidth(p, 0) |
| if p.argStack.top != 0 || len(p.instructions) != 0 { |
| if p.argStack.top == 4 { |
| // TODO: process the implicit "seac" command as per 5177.Type2.pdf |
| // Appendix C "Compatibility and Deprecated Operators". |
| return errUnsupportedType2Charstring |
| } |
| return errInvalidCFFTable |
| } |
| return nil |
| } |
