1427 lines
38 KiB
Go
1427 lines
38 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package sfnt
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// Compact Font Format (CFF) fonts are written in PostScript, a stack-based
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// programming language.
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//
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// A fundamental concept is a DICT, or a key-value map, expressed in reverse
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// Polish notation. For example, this sequence of operations:
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// - push the number 379
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// - version operator
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// - push the number 392
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// - Notice operator
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// - etc
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// - push the number 100
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// - push the number 0
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// - push the number 500
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// - push the number 800
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// - FontBBox operator
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// - etc
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// defines a DICT that maps "version" to the String ID (SID) 379, "Notice" to
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// the SID 392, "FontBBox" to the four numbers [100, 0, 500, 800], etc.
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//
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// The first 391 String IDs (starting at 0) are predefined as per the CFF spec
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// Appendix A, in 5176.CFF.pdf referenced below. For example, 379 means
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// "001.000". String ID 392 is not predefined, and is mapped by a separate
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// structure, the "String INDEX", inside the CFF data. (String ID 391 is also
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// not predefined. Specifically for ../testdata/CFFTest.otf, 391 means
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// "uni4E2D", as this font contains a glyph for U+4E2D).
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//
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// The actual glyph vectors are similarly encoded (in PostScript), in a format
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// called Type 2 Charstrings. The wire encoding is similar to but not exactly
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// the same as CFF's. For example, the byte 0x05 means FontBBox for CFF DICTs,
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// but means rlineto (relative line-to) for Type 2 Charstrings. See
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// 5176.CFF.pdf Appendix H and 5177.Type2.pdf Appendix A in the PDF files
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// referenced below.
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//
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// CFF is a stand-alone format, but CFF as used in SFNT fonts have further
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// restrictions. For example, a stand-alone CFF can contain multiple fonts, but
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// https://www.microsoft.com/typography/OTSPEC/cff.htm says that "The Name
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// INDEX in the CFF must contain only one entry; that is, there must be only
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// one font in the CFF FontSet".
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//
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// The relevant specifications are:
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// - http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/font/pdfs/5176.CFF.pdf
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// - http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/font/pdfs/5177.Type2.pdf
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import (
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"fmt"
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"math"
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"strconv"
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"golang.org/x/image/math/fixed"
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)
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const (
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// psArgStackSize is the argument stack size for a PostScript interpreter.
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// 5176.CFF.pdf section 4 "DICT Data" says that "An operator may be
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// preceded by up to a maximum of 48 operands". 5177.Type2.pdf Appendix B
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// "Type 2 Charstring Implementation Limits" says that "Argument stack 48".
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psArgStackSize = 48
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// Similarly, Appendix B says "Subr nesting, stack limit 10".
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psCallStackSize = 10
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)
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func bigEndian(b []byte) uint32 {
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switch len(b) {
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case 1:
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return uint32(b[0])
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case 2:
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return uint32(b[0])<<8 | uint32(b[1])
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case 3:
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return uint32(b[0])<<16 | uint32(b[1])<<8 | uint32(b[2])
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case 4:
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return uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3])
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}
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panic("unreachable")
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}
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// fdSelect holds a CFF font's Font Dict Select data.
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type fdSelect struct {
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format uint8
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numRanges uint16
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offset int32
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}
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func (t *fdSelect) lookup(f *Font, b *Buffer, x GlyphIndex) (int, error) {
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switch t.format {
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case 0:
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buf, err := b.view(&f.src, int(t.offset)+int(x), 1)
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if err != nil {
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return 0, err
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}
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return int(buf[0]), nil
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case 3:
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lo, hi := 0, int(t.numRanges)
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for lo < hi {
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i := (lo + hi) / 2
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buf, err := b.view(&f.src, int(t.offset)+3*i, 3+2)
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if err != nil {
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return 0, err
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}
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// buf holds the range [xlo, xhi).
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if xlo := GlyphIndex(u16(buf[0:])); x < xlo {
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hi = i
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continue
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}
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if xhi := GlyphIndex(u16(buf[3:])); xhi <= x {
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lo = i + 1
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continue
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}
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return int(buf[2]), nil
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}
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}
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return 0, ErrNotFound
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}
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// cffParser parses the CFF table from an SFNT font.
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type cffParser struct {
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src *source
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base int
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offset int
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end int
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err error
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buf []byte
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locBuf [2]uint32
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psi psInterpreter
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}
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func (p *cffParser) parse(numGlyphs int32) (ret glyphData, err error) {
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// Parse the header.
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{
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if !p.read(4) {
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return glyphData{}, p.err
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}
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if p.buf[0] != 1 || p.buf[1] != 0 || p.buf[2] != 4 {
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return glyphData{}, errUnsupportedCFFVersion
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}
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}
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// Parse the Name INDEX.
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{
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count, offSize, ok := p.parseIndexHeader()
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if !ok {
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return glyphData{}, p.err
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}
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// https://www.microsoft.com/typography/OTSPEC/cff.htm says that "The
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// Name INDEX in the CFF must contain only one entry".
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if count != 1 {
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return glyphData{}, errInvalidCFFTable
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}
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if !p.parseIndexLocations(p.locBuf[:2], count, offSize) {
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return glyphData{}, p.err
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}
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p.offset = int(p.locBuf[1])
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}
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// Parse the Top DICT INDEX.
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p.psi.topDict.initialize()
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{
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count, offSize, ok := p.parseIndexHeader()
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if !ok {
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return glyphData{}, p.err
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}
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// 5176.CFF.pdf section 8 "Top DICT INDEX" says that the count here
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// should match the count of the Name INDEX, which is 1.
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if count != 1 {
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return glyphData{}, errInvalidCFFTable
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}
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if !p.parseIndexLocations(p.locBuf[:2], count, offSize) {
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return glyphData{}, p.err
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}
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if !p.read(int(p.locBuf[1] - p.locBuf[0])) {
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return glyphData{}, p.err
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}
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if p.err = p.psi.run(psContextTopDict, p.buf, 0, 0); p.err != nil {
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return glyphData{}, p.err
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}
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}
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// Skip the String INDEX.
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{
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count, offSize, ok := p.parseIndexHeader()
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if !ok {
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return glyphData{}, p.err
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}
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if count != 0 {
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// Read the last location. Locations are off by 1 byte. See the
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// comment in parseIndexLocations.
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if !p.skip(int(count * offSize)) {
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return glyphData{}, p.err
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}
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if !p.read(int(offSize)) {
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return glyphData{}, p.err
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}
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loc := bigEndian(p.buf) - 1
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// Check that locations are in bounds.
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if uint32(p.end-p.offset) < loc {
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return glyphData{}, errInvalidCFFTable
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}
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// Skip the index data.
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if !p.skip(int(loc)) {
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return glyphData{}, p.err
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}
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}
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}
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// Parse the Global Subrs [Subroutines] INDEX.
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{
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count, offSize, ok := p.parseIndexHeader()
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if !ok {
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return glyphData{}, p.err
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}
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if count != 0 {
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if count > maxNumSubroutines {
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return glyphData{}, errUnsupportedNumberOfSubroutines
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}
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ret.gsubrs = make([]uint32, count+1)
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if !p.parseIndexLocations(ret.gsubrs, count, offSize) {
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return glyphData{}, p.err
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}
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}
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}
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// Parse the CharStrings INDEX, whose location was found in the Top DICT.
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{
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if !p.seekFromBase(p.psi.topDict.charStringsOffset) {
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return glyphData{}, errInvalidCFFTable
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}
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count, offSize, ok := p.parseIndexHeader()
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if !ok {
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return glyphData{}, p.err
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}
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if count == 0 || int32(count) != numGlyphs {
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return glyphData{}, errInvalidCFFTable
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}
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ret.locations = make([]uint32, count+1)
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if !p.parseIndexLocations(ret.locations, count, offSize) {
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return glyphData{}, p.err
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}
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}
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if !p.psi.topDict.isCIDFont {
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// Parse the Private DICT, whose location was found in the Top DICT.
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ret.singleSubrs, err = p.parsePrivateDICT(
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p.psi.topDict.privateDictOffset,
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p.psi.topDict.privateDictLength,
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)
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if err != nil {
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return glyphData{}, err
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}
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} else {
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// Parse the Font Dict Select data, whose location was found in the Top
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// DICT.
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ret.fdSelect, err = p.parseFDSelect(p.psi.topDict.fdSelect, numGlyphs)
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if err != nil {
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return glyphData{}, err
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}
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// Parse the Font Dicts. Each one contains its own Private DICT.
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if !p.seekFromBase(p.psi.topDict.fdArray) {
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return glyphData{}, errInvalidCFFTable
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}
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count, offSize, ok := p.parseIndexHeader()
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if !ok {
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return glyphData{}, p.err
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}
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if count > maxNumFontDicts {
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return glyphData{}, errUnsupportedNumberOfFontDicts
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}
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fdLocations := make([]uint32, count+1)
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if !p.parseIndexLocations(fdLocations, count, offSize) {
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return glyphData{}, p.err
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}
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privateDicts := make([]struct {
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offset, length int32
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}, count)
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for i := range privateDicts {
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length := fdLocations[i+1] - fdLocations[i]
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if !p.read(int(length)) {
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return glyphData{}, errInvalidCFFTable
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}
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p.psi.topDict.initialize()
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if p.err = p.psi.run(psContextTopDict, p.buf, 0, 0); p.err != nil {
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return glyphData{}, p.err
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}
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privateDicts[i].offset = p.psi.topDict.privateDictOffset
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privateDicts[i].length = p.psi.topDict.privateDictLength
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}
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ret.multiSubrs = make([][]uint32, count)
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for i, pd := range privateDicts {
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ret.multiSubrs[i], err = p.parsePrivateDICT(pd.offset, pd.length)
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if err != nil {
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return glyphData{}, err
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}
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}
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}
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return ret, err
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}
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// parseFDSelect parses the Font Dict Select data as per 5176.CFF.pdf section
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// 19 "FDSelect".
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func (p *cffParser) parseFDSelect(offset int32, numGlyphs int32) (ret fdSelect, err error) {
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if !p.seekFromBase(p.psi.topDict.fdSelect) {
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return fdSelect{}, errInvalidCFFTable
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}
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if !p.read(1) {
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return fdSelect{}, p.err
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}
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ret.format = p.buf[0]
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switch ret.format {
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case 0:
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if p.end-p.offset < int(numGlyphs) {
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return fdSelect{}, errInvalidCFFTable
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}
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ret.offset = int32(p.offset)
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return ret, nil
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case 3:
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if !p.read(2) {
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return fdSelect{}, p.err
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}
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ret.numRanges = u16(p.buf)
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if p.end-p.offset < 3*int(ret.numRanges)+2 {
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return fdSelect{}, errInvalidCFFTable
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}
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ret.offset = int32(p.offset)
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return ret, nil
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}
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return fdSelect{}, errUnsupportedCFFFDSelectTable
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}
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func (p *cffParser) parsePrivateDICT(offset, length int32) (subrs []uint32, err error) {
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p.psi.privateDict.initialize()
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if length != 0 {
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fullLength := int32(p.end - p.base)
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if offset <= 0 || fullLength < offset || fullLength-offset < length || length < 0 {
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return nil, errInvalidCFFTable
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}
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p.offset = p.base + int(offset)
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if !p.read(int(length)) {
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return nil, p.err
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}
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if p.err = p.psi.run(psContextPrivateDict, p.buf, 0, 0); p.err != nil {
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return nil, p.err
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}
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}
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// Parse the Local Subrs [Subroutines] INDEX, whose location was found in
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// the Private DICT.
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if p.psi.privateDict.subrsOffset != 0 {
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if !p.seekFromBase(offset + p.psi.privateDict.subrsOffset) {
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return nil, errInvalidCFFTable
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}
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count, offSize, ok := p.parseIndexHeader()
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if !ok {
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return nil, p.err
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}
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if count != 0 {
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if count > maxNumSubroutines {
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return nil, errUnsupportedNumberOfSubroutines
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}
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subrs = make([]uint32, count+1)
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if !p.parseIndexLocations(subrs, count, offSize) {
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return nil, p.err
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}
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}
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}
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return subrs, err
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}
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// read sets p.buf to view the n bytes from p.offset to p.offset+n. It also
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// advances p.offset by n.
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//
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// As per the source.view method, the caller should not modify the contents of
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// p.buf after read returns, other than by calling read again.
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//
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// The caller should also avoid modifying the pointer / length / capacity of
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// the p.buf slice, not just avoid modifying the slice's contents, in order to
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// maximize the opportunity to re-use p.buf's allocated memory when viewing the
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// underlying source data for subsequent read calls.
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func (p *cffParser) read(n int) (ok bool) {
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if n < 0 || p.end-p.offset < n {
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p.err = errInvalidCFFTable
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return false
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}
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p.buf, p.err = p.src.view(p.buf, p.offset, n)
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// TODO: if p.err == io.EOF, change that to a different error??
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p.offset += n
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return p.err == nil
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}
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func (p *cffParser) skip(n int) (ok bool) {
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if p.end-p.offset < n {
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p.err = errInvalidCFFTable
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return false
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}
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p.offset += n
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return true
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}
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func (p *cffParser) seekFromBase(offset int32) (ok bool) {
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if offset < 0 || int32(p.end-p.base) < offset {
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return false
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}
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p.offset = p.base + int(offset)
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return true
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}
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func (p *cffParser) parseIndexHeader() (count, offSize int32, ok bool) {
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if !p.read(2) {
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return 0, 0, false
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}
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count = int32(u16(p.buf[:2]))
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// 5176.CFF.pdf section 5 "INDEX Data" says that "An empty INDEX is
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// represented by a count field with a 0 value and no additional fields.
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// Thus, the total size of an empty INDEX is 2 bytes".
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if count == 0 {
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return count, 0, true
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}
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if !p.read(1) {
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return 0, 0, false
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}
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offSize = int32(p.buf[0])
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if offSize < 1 || 4 < offSize {
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p.err = errInvalidCFFTable
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return 0, 0, false
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}
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return count, offSize, true
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}
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func (p *cffParser) parseIndexLocations(dst []uint32, count, offSize int32) (ok bool) {
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if count == 0 {
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return true
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}
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if len(dst) != int(count+1) {
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panic("unreachable")
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}
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if !p.read(len(dst) * int(offSize)) {
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return false
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}
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buf, prev := p.buf, uint32(0)
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for i := range dst {
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loc := bigEndian(buf[:offSize])
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buf = buf[offSize:]
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|
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// Locations are off by 1 byte. 5176.CFF.pdf section 5 "INDEX Data"
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// says that "Offsets in the offset array are relative to the byte that
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// precedes the object data... This ensures that every object has a
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// corresponding offset which is always nonzero".
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if loc == 0 {
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p.err = errInvalidCFFTable
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return false
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}
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loc--
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// In the same paragraph, "Therefore the first element of the offset
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// array is always 1" before correcting for the off-by-1.
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if i == 0 {
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if loc != 0 {
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p.err = errInvalidCFFTable
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break
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}
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} else if loc <= prev { // Check that locations are increasing.
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p.err = errInvalidCFFTable
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break
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}
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// Check that locations are in bounds.
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if uint32(p.end-p.offset) < loc {
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p.err = errInvalidCFFTable
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break
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}
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dst[i] = uint32(p.offset) + loc
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prev = loc
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}
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return p.err == nil
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}
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|
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type psCallStackEntry struct {
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offset, length uint32
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}
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|
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type psContext uint32
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|
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const (
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psContextTopDict psContext = iota
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psContextPrivateDict
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psContextType2Charstring
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)
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|
|
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// psTopDictData contains fields specific to the Top DICT context.
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type psTopDictData struct {
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charStringsOffset int32
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fdArray int32
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fdSelect int32
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isCIDFont bool
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privateDictOffset int32
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privateDictLength int32
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}
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|
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func (d *psTopDictData) initialize() {
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*d = psTopDictData{}
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}
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|
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// psPrivateDictData contains fields specific to the Private DICT context.
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type psPrivateDictData struct {
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subrsOffset int32
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}
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|
|
|
func (d *psPrivateDictData) initialize() {
|
|
*d = psPrivateDictData{}
|
|
}
|
|
|
|
// psType2CharstringsData contains fields specific to the Type 2 Charstrings
|
|
// context.
|
|
type psType2CharstringsData struct {
|
|
f *Font
|
|
b *Buffer
|
|
x int32
|
|
y int32
|
|
firstX int32
|
|
firstY int32
|
|
hintBits int32
|
|
seenWidth bool
|
|
ended bool
|
|
glyphIndex GlyphIndex
|
|
// fdSelectIndexPlusOne is the result of the Font Dict Select lookup, plus
|
|
// one. That plus one lets us use the zero value to denote either unused
|
|
// (for CFF fonts with a single Font Dict) or lazily evaluated.
|
|
fdSelectIndexPlusOne int32
|
|
}
|
|
|
|
func (d *psType2CharstringsData) initialize(f *Font, b *Buffer, glyphIndex GlyphIndex) {
|
|
*d = psType2CharstringsData{
|
|
f: f,
|
|
b: b,
|
|
glyphIndex: glyphIndex,
|
|
}
|
|
}
|
|
|
|
func (d *psType2CharstringsData) closePath() {
|
|
if d.x != d.firstX || d.y != d.firstY {
|
|
d.b.segments = append(d.b.segments, Segment{
|
|
Op: SegmentOpLineTo,
|
|
Args: [3]fixed.Point26_6{{
|
|
X: fixed.Int26_6(d.firstX),
|
|
Y: fixed.Int26_6(d.firstY),
|
|
}},
|
|
})
|
|
}
|
|
}
|
|
|
|
func (d *psType2CharstringsData) moveTo(dx, dy int32) {
|
|
d.closePath()
|
|
d.x += dx
|
|
d.y += dy
|
|
d.b.segments = append(d.b.segments, Segment{
|
|
Op: SegmentOpMoveTo,
|
|
Args: [3]fixed.Point26_6{{
|
|
X: fixed.Int26_6(d.x),
|
|
Y: fixed.Int26_6(d.y),
|
|
}},
|
|
})
|
|
d.firstX = d.x
|
|
d.firstY = d.y
|
|
}
|
|
|
|
func (d *psType2CharstringsData) lineTo(dx, dy int32) {
|
|
d.x += dx
|
|
d.y += dy
|
|
d.b.segments = append(d.b.segments, Segment{
|
|
Op: SegmentOpLineTo,
|
|
Args: [3]fixed.Point26_6{{
|
|
X: fixed.Int26_6(d.x),
|
|
Y: fixed.Int26_6(d.y),
|
|
}},
|
|
})
|
|
}
|
|
|
|
func (d *psType2CharstringsData) cubeTo(dxa, dya, dxb, dyb, dxc, dyc int32) {
|
|
d.x += dxa
|
|
d.y += dya
|
|
xa := fixed.Int26_6(d.x)
|
|
ya := fixed.Int26_6(d.y)
|
|
d.x += dxb
|
|
d.y += dyb
|
|
xb := fixed.Int26_6(d.x)
|
|
yb := fixed.Int26_6(d.y)
|
|
d.x += dxc
|
|
d.y += dyc
|
|
xc := fixed.Int26_6(d.x)
|
|
yc := fixed.Int26_6(d.y)
|
|
d.b.segments = append(d.b.segments, Segment{
|
|
Op: SegmentOpCubeTo,
|
|
Args: [3]fixed.Point26_6{{X: xa, Y: ya}, {X: xb, Y: yb}, {X: xc, Y: yc}},
|
|
})
|
|
}
|
|
|
|
// psInterpreter is a PostScript interpreter.
|
|
type psInterpreter struct {
|
|
ctx psContext
|
|
instructions []byte
|
|
instrOffset uint32
|
|
instrLength uint32
|
|
argStack struct {
|
|
a [psArgStackSize]int32
|
|
top int32
|
|
}
|
|
callStack struct {
|
|
a [psCallStackSize]psCallStackEntry
|
|
top int32
|
|
}
|
|
parseNumberBuf [maxRealNumberStrLen]byte
|
|
|
|
topDict psTopDictData
|
|
privateDict psPrivateDictData
|
|
type2Charstrings psType2CharstringsData
|
|
}
|
|
|
|
func (p *psInterpreter) hasMoreInstructions() bool {
|
|
if len(p.instructions) != 0 {
|
|
return true
|
|
}
|
|
for i := int32(0); i < p.callStack.top; i++ {
|
|
if p.callStack.a[i].length != 0 {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// run runs the instructions in the given PostScript context. For the
|
|
// psContextType2Charstring context, offset and length give the location of the
|
|
// instructions in p.type2Charstrings.f.src.
|
|
func (p *psInterpreter) run(ctx psContext, instructions []byte, offset, length uint32) error {
|
|
p.ctx = ctx
|
|
p.instructions = instructions
|
|
p.instrOffset = offset
|
|
p.instrLength = length
|
|
p.argStack.top = 0
|
|
p.callStack.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 != psContextType2Charstring:
|
|
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 != psContextType2Charstring:
|
|
// 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:]
|
|
// 5177.Type2.pdf section 3.2 "Charstring Number Encoding" says "If the
|
|
// charstring byte contains the value 255... [this] number is
|
|
// interpreted as a Fixed; that is, a signed number with 16 bits of
|
|
// fraction".
|
|
//
|
|
// TODO: change the psType2CharstringsData.b.segments and
|
|
// psInterpreter.argStack data structures to optionally hold fixed
|
|
// point values, not just integer values. That's a substantial
|
|
// re-design, though. Until then, just round the 16.16 fixed point
|
|
// number to the closest integer value. This isn't just "number =
|
|
// ((number + 0x8000) >> 16)" because of potential overflow.
|
|
number = (number >> 16) + (1 & (number >> 15))
|
|
}
|
|
|
|
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.charStringsOffset = p.argStack.a[p.argStack.top-1]
|
|
return nil
|
|
}},
|
|
18: {+2, "Private", func(p *psInterpreter) error {
|
|
p.topDict.privateDictLength = p.argStack.a[p.argStack.top-2]
|
|
p.topDict.privateDictOffset = p.argStack.a[p.argStack.top-1]
|
|
return 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", func(p *psInterpreter) error {
|
|
p.topDict.isCIDFont = true
|
|
return nil
|
|
}},
|
|
31: {+1, "CIDFontVersion", nil},
|
|
32: {+1, "CIDFontRevision", nil},
|
|
33: {+1, "CIDFontType", nil},
|
|
34: {+1, "CIDCount", nil},
|
|
35: {+1, "UIDBase", nil},
|
|
36: {+1, "FDArray", func(p *psInterpreter) error {
|
|
p.topDict.fdArray = p.argStack.a[p.argStack.top-1]
|
|
return nil
|
|
}},
|
|
37: {+1, "FDSelect", func(p *psInterpreter) error {
|
|
p.topDict.fdSelect = p.argStack.a[p.argStack.top-1]
|
|
return nil
|
|
}},
|
|
38: {+1, "FontName", nil},
|
|
}},
|
|
|
|
// The Private DICT operators are defined by 5176.CFF.pdf Table 23 "Private
|
|
// DICT Operators".
|
|
psContextPrivateDict: {{
|
|
// 1-byte operators.
|
|
6: {-2, "BlueValues", nil},
|
|
7: {-2, "OtherBlues", nil},
|
|
8: {-2, "FamilyBlues", nil},
|
|
9: {-2, "FamilyOtherBlues", nil},
|
|
10: {+1, "StdHW", nil},
|
|
11: {+1, "StdVW", nil},
|
|
19: {+1, "Subrs", func(p *psInterpreter) error {
|
|
p.privateDict.subrsOffset = p.argStack.a[p.argStack.top-1]
|
|
return nil
|
|
}},
|
|
20: {+1, "defaultWidthX", nil},
|
|
21: {+1, "nominalWidthX", nil},
|
|
}, {
|
|
// 2-byte operators. The first byte is the escape byte.
|
|
9: {+1, "BlueScale", nil},
|
|
10: {+1, "BlueShift", nil},
|
|
11: {+1, "BlueFuzz", nil},
|
|
12: {-2, "StemSnapH", nil},
|
|
13: {-2, "StemSnapV", nil},
|
|
14: {+1, "ForceBold", nil},
|
|
17: {+1, "LanguageGroup", nil},
|
|
18: {+1, "ExpansionFactor", nil},
|
|
19: {+1, "initialRandomSeed", 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: {+1, "callsubr", t2CCallsubr},
|
|
11: {+0, "return", t2CReturn},
|
|
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: {+1, "callgsubr", t2CCallgsubr},
|
|
30: {-1, "vhcurveto", t2CVhcurveto},
|
|
31: {-1, "hvcurveto", t2CHvcurveto},
|
|
}, {
|
|
// 2-byte operators. The first byte is the escape byte.
|
|
34: {+7, "hflex", t2CHflex},
|
|
36: {+9, "hflex1", t2CHflex1},
|
|
// 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 arg stack. nArgs is the expected number of arguments on the
|
|
// stack. A negative nArgs means a multiple of 2.
|
|
//
|
|
// 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
|
|
if nArgs >= 0 {
|
|
if p.argStack.top != nArgs+1 {
|
|
return
|
|
}
|
|
} else if p.argStack.top&1 == 0 {
|
|
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, -1)
|
|
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 {
|
|
// 5176.CFF.pdf section 4.3 "Hint Operators" says that "If hstem and vstem
|
|
// hints are both declared at the beginning of a charstring, and this
|
|
// sequence is followed directly by the hintmask or cntrmask operators, the
|
|
// vstem hint operator need not be included."
|
|
//
|
|
// What we implement here is more permissive (but the same as what the
|
|
// FreeType implementation does, and simpler than tracking the previous
|
|
// operator and other hinting state): if a hintmask is given any arguments
|
|
// (i.e. the argStack is non-empty), we run an implicit vstem operator.
|
|
//
|
|
// Note that the vstem operator consumes from p.argStack, but the hintmask
|
|
// or cntrmask operators consume from p.instructions.
|
|
if p.argStack.top != 0 {
|
|
if err := t2CStem(p); err != nil {
|
|
return err
|
|
}
|
|
} else if !p.type2Charstrings.seenWidth {
|
|
p.type2Charstrings.seenWidth = true
|
|
}
|
|
|
|
hintBytes := (p.type2Charstrings.hintBits + 7) / 8
|
|
if len(p.instructions) < int(hintBytes) {
|
|
return errInvalidCFFTable
|
|
}
|
|
p.instructions = p.instructions[hintBytes:]
|
|
return nil
|
|
}
|
|
|
|
func t2CHmoveto(p *psInterpreter) error {
|
|
t2CReadWidth(p, 1)
|
|
if p.argStack.top != 1 {
|
|
return errInvalidCFFTable
|
|
}
|
|
p.type2Charstrings.moveTo(p.argStack.a[0], 0)
|
|
return nil
|
|
}
|
|
|
|
func t2CVmoveto(p *psInterpreter) error {
|
|
t2CReadWidth(p, 1)
|
|
if p.argStack.top != 1 {
|
|
return errInvalidCFFTable
|
|
}
|
|
p.type2Charstrings.moveTo(0, p.argStack.a[0])
|
|
return nil
|
|
}
|
|
|
|
func t2CRmoveto(p *psInterpreter) error {
|
|
t2CReadWidth(p, 2)
|
|
if p.argStack.top != 2 {
|
|
return errInvalidCFFTable
|
|
}
|
|
p.type2Charstrings.moveTo(p.argStack.a[0], p.argStack.a[1])
|
|
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 {
|
|
dx, dy := p.argStack.a[i], int32(0)
|
|
if vertical {
|
|
dx, dy = dy, dx
|
|
}
|
|
p.type2Charstrings.lineTo(dx, dy)
|
|
}
|
|
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.lineTo(p.argStack.a[i], p.argStack.a[i+1])
|
|
}
|
|
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 {
|
|
p.type2Charstrings.cubeTo(
|
|
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.lineTo(p.argStack.a[i], p.argStack.a[i+1])
|
|
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.lineTo(p.argStack.a[i], p.argStack.a[i+1])
|
|
}
|
|
p.type2Charstrings.cubeTo(
|
|
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
|
|
}
|
|
|
|
p.type2Charstrings.cubeTo(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 {
|
|
p.type2Charstrings.cubeTo(
|
|
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
|
|
}
|
|
|
|
// For the flex operators, we ignore the flex depth and always produce cubic
|
|
// segments, not linear segments. It's not obvious why the Type 2 Charstring
|
|
// format cares about switching behavior based on a metric in pixels, not in
|
|
// ideal font units. The Go vector rasterizer has no problems with almost
|
|
// linear cubic segments.
|
|
|
|
func t2CHflex(p *psInterpreter) error {
|
|
p.type2Charstrings.cubeTo(
|
|
p.argStack.a[0], 0,
|
|
p.argStack.a[1], +p.argStack.a[2],
|
|
p.argStack.a[3], 0,
|
|
)
|
|
p.type2Charstrings.cubeTo(
|
|
p.argStack.a[4], 0,
|
|
p.argStack.a[5], -p.argStack.a[2],
|
|
p.argStack.a[6], 0,
|
|
)
|
|
return nil
|
|
}
|
|
|
|
func t2CHflex1(p *psInterpreter) error {
|
|
dy1 := p.argStack.a[1]
|
|
dy2 := p.argStack.a[3]
|
|
dy5 := p.argStack.a[7]
|
|
dy6 := -dy1 - dy2 - dy5
|
|
p.type2Charstrings.cubeTo(
|
|
p.argStack.a[0], dy1,
|
|
p.argStack.a[2], dy2,
|
|
p.argStack.a[4], 0,
|
|
)
|
|
p.type2Charstrings.cubeTo(
|
|
p.argStack.a[5], 0,
|
|
p.argStack.a[6], dy5,
|
|
p.argStack.a[8], dy6,
|
|
)
|
|
return nil
|
|
}
|
|
|
|
// subrBias returns the subroutine index bias as per 5177.Type2.pdf section 4.7
|
|
// "Subroutine Operators".
|
|
func subrBias(numSubroutines int) int32 {
|
|
if numSubroutines < 1240 {
|
|
return 107
|
|
}
|
|
if numSubroutines < 33900 {
|
|
return 1131
|
|
}
|
|
return 32768
|
|
}
|
|
|
|
func t2CCallgsubr(p *psInterpreter) error {
|
|
return t2CCall(p, p.type2Charstrings.f.cached.glyphData.gsubrs)
|
|
}
|
|
|
|
func t2CCallsubr(p *psInterpreter) error {
|
|
t := &p.type2Charstrings
|
|
d := &t.f.cached.glyphData
|
|
subrs := d.singleSubrs
|
|
if d.multiSubrs != nil {
|
|
if t.fdSelectIndexPlusOne == 0 {
|
|
index, err := d.fdSelect.lookup(t.f, t.b, t.glyphIndex)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if index < 0 || len(d.multiSubrs) <= index {
|
|
return errInvalidCFFTable
|
|
}
|
|
t.fdSelectIndexPlusOne = int32(index + 1)
|
|
}
|
|
subrs = d.multiSubrs[t.fdSelectIndexPlusOne-1]
|
|
}
|
|
return t2CCall(p, subrs)
|
|
}
|
|
|
|
func t2CCall(p *psInterpreter, subrs []uint32) error {
|
|
if p.callStack.top == psCallStackSize || len(subrs) == 0 {
|
|
return errInvalidCFFTable
|
|
}
|
|
length := uint32(len(p.instructions))
|
|
p.callStack.a[p.callStack.top] = psCallStackEntry{
|
|
offset: p.instrOffset + p.instrLength - length,
|
|
length: length,
|
|
}
|
|
p.callStack.top++
|
|
|
|
subrIndex := p.argStack.a[p.argStack.top-1] + subrBias(len(subrs)-1)
|
|
if subrIndex < 0 || int32(len(subrs)-1) <= subrIndex {
|
|
return errInvalidCFFTable
|
|
}
|
|
i := subrs[subrIndex+0]
|
|
j := subrs[subrIndex+1]
|
|
if j < i {
|
|
return errInvalidCFFTable
|
|
}
|
|
if j-i > maxGlyphDataLength {
|
|
return errUnsupportedGlyphDataLength
|
|
}
|
|
buf, err := p.type2Charstrings.b.view(&p.type2Charstrings.f.src, int(i), int(j-i))
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
p.instructions = buf
|
|
p.instrOffset = i
|
|
p.instrLength = j - i
|
|
return nil
|
|
}
|
|
|
|
func t2CReturn(p *psInterpreter) error {
|
|
if p.callStack.top <= 0 {
|
|
return errInvalidCFFTable
|
|
}
|
|
p.callStack.top--
|
|
o := p.callStack.a[p.callStack.top].offset
|
|
n := p.callStack.a[p.callStack.top].length
|
|
buf, err := p.type2Charstrings.b.view(&p.type2Charstrings.f.src, int(o), int(n))
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
p.instructions = buf
|
|
p.instrOffset = o
|
|
p.instrLength = n
|
|
return nil
|
|
}
|
|
|
|
func t2CEndchar(p *psInterpreter) error {
|
|
t2CReadWidth(p, 0)
|
|
if p.argStack.top != 0 || p.hasMoreInstructions() {
|
|
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
|
|
}
|
|
p.type2Charstrings.closePath()
|
|
p.type2Charstrings.ended = true
|
|
return nil
|
|
}
|