From 500caaeda74dd9c660279036293f4b2997cf0b03 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Sat, 9 Sep 2017 09:42:37 +0200 Subject: Add vendor --- .../golang/freetype/truetype/truetype.go | 653 +++++++++++++++++++++ 1 file changed, 653 insertions(+) create mode 100644 vendor/github.com/golang/freetype/truetype/truetype.go (limited to 'vendor/github.com/golang/freetype/truetype/truetype.go') diff --git a/vendor/github.com/golang/freetype/truetype/truetype.go b/vendor/github.com/golang/freetype/truetype/truetype.go new file mode 100644 index 0000000..7270bbf --- /dev/null +++ b/vendor/github.com/golang/freetype/truetype/truetype.go @@ -0,0 +1,653 @@ +// Copyright 2010 The Freetype-Go Authors. All rights reserved. +// Use of this source code is governed by your choice of either the +// FreeType License or the GNU General Public License version 2 (or +// any later version), both of which can be found in the LICENSE file. + +// Package truetype provides a parser for the TTF and TTC file formats. +// Those formats are documented at http://developer.apple.com/fonts/TTRefMan/ +// and http://www.microsoft.com/typography/otspec/ +// +// Some of a font's methods provide lengths or co-ordinates, e.g. bounds, font +// metrics and control points. All these methods take a scale parameter, which +// is the number of pixels in 1 em, expressed as a 26.6 fixed point value. For +// example, if 1 em is 10 pixels then scale is fixed.I(10), which is equal to +// fixed.Int26_6(10 << 6). +// +// To measure a TrueType font in ideal FUnit space, use scale equal to +// font.FUnitsPerEm(). +package truetype // import "github.com/golang/freetype/truetype" + +import ( + "fmt" + + "golang.org/x/image/math/fixed" +) + +// An Index is a Font's index of a rune. +type Index uint16 + +// A NameID identifies a name table entry. +// +// See https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6name.html +type NameID uint16 + +const ( + NameIDCopyright NameID = 0 + NameIDFontFamily = 1 + NameIDFontSubfamily = 2 + NameIDUniqueSubfamilyID = 3 + NameIDFontFullName = 4 + NameIDNameTableVersion = 5 + NameIDPostscriptName = 6 + NameIDTrademarkNotice = 7 + NameIDManufacturerName = 8 + NameIDDesignerName = 9 + NameIDFontDescription = 10 + NameIDFontVendorURL = 11 + NameIDFontDesignerURL = 12 + NameIDFontLicense = 13 + NameIDFontLicenseURL = 14 + NameIDPreferredFamily = 16 + NameIDPreferredSubfamily = 17 + NameIDCompatibleName = 18 + NameIDSampleText = 19 +) + +const ( + // A 32-bit encoding consists of a most-significant 16-bit Platform ID and a + // least-significant 16-bit Platform Specific ID. The magic numbers are + // specified at https://www.microsoft.com/typography/otspec/name.htm + unicodeEncodingBMPOnly = 0x00000003 // PID = 0 (Unicode), PSID = 3 (Unicode 2.0 BMP Only) + unicodeEncodingFull = 0x00000004 // PID = 0 (Unicode), PSID = 4 (Unicode 2.0 Full Repertoire) + microsoftSymbolEncoding = 0x00030000 // PID = 3 (Microsoft), PSID = 0 (Symbol) + microsoftUCS2Encoding = 0x00030001 // PID = 3 (Microsoft), PSID = 1 (UCS-2) + microsoftUCS4Encoding = 0x0003000a // PID = 3 (Microsoft), PSID = 10 (UCS-4) +) + +// An HMetric holds the horizontal metrics of a single glyph. +type HMetric struct { + AdvanceWidth, LeftSideBearing fixed.Int26_6 +} + +// A VMetric holds the vertical metrics of a single glyph. +type VMetric struct { + AdvanceHeight, TopSideBearing fixed.Int26_6 +} + +// A FormatError reports that the input is not a valid TrueType font. +type FormatError string + +func (e FormatError) Error() string { + return "freetype: invalid TrueType format: " + string(e) +} + +// An UnsupportedError reports that the input uses a valid but unimplemented +// TrueType feature. +type UnsupportedError string + +func (e UnsupportedError) Error() string { + return "freetype: unsupported TrueType feature: " + string(e) +} + +// u32 returns the big-endian uint32 at b[i:]. +func u32(b []byte, i int) uint32 { + return uint32(b[i])<<24 | uint32(b[i+1])<<16 | uint32(b[i+2])<<8 | uint32(b[i+3]) +} + +// u16 returns the big-endian uint16 at b[i:]. +func u16(b []byte, i int) uint16 { + return uint16(b[i])<<8 | uint16(b[i+1]) +} + +// readTable returns a slice of the TTF data given by a table's directory entry. +func readTable(ttf []byte, offsetLength []byte) ([]byte, error) { + offset := int(u32(offsetLength, 0)) + if offset < 0 { + return nil, FormatError(fmt.Sprintf("offset too large: %d", uint32(offset))) + } + length := int(u32(offsetLength, 4)) + if length < 0 { + return nil, FormatError(fmt.Sprintf("length too large: %d", uint32(length))) + } + end := offset + length + if end < 0 || end > len(ttf) { + return nil, FormatError(fmt.Sprintf("offset + length too large: %d", uint32(offset)+uint32(length))) + } + return ttf[offset:end], nil +} + +// parseSubtables returns the offset and platformID of the best subtable in +// table, where best favors a Unicode cmap encoding, and failing that, a +// Microsoft cmap encoding. offset is the offset of the first subtable in +// table, and size is the size of each subtable. +// +// If pred is non-nil, then only subtables that satisfy that predicate will be +// considered. +func parseSubtables(table []byte, name string, offset, size int, pred func([]byte) bool) ( + bestOffset int, bestPID uint32, retErr error) { + + if len(table) < 4 { + return 0, 0, FormatError(name + " too short") + } + nSubtables := int(u16(table, 2)) + if len(table) < size*nSubtables+offset { + return 0, 0, FormatError(name + " too short") + } + ok := false + for i := 0; i < nSubtables; i, offset = i+1, offset+size { + if pred != nil && !pred(table[offset:]) { + continue + } + // We read the 16-bit Platform ID and 16-bit Platform Specific ID as a single uint32. + // All values are big-endian. + pidPsid := u32(table, offset) + // We prefer the Unicode cmap encoding. Failing to find that, we fall + // back onto the Microsoft cmap encoding. + if pidPsid == unicodeEncodingBMPOnly || pidPsid == unicodeEncodingFull { + bestOffset, bestPID, ok = offset, pidPsid>>16, true + break + + } else if pidPsid == microsoftSymbolEncoding || + pidPsid == microsoftUCS2Encoding || + pidPsid == microsoftUCS4Encoding { + + bestOffset, bestPID, ok = offset, pidPsid>>16, true + // We don't break out of the for loop, so that Unicode can override Microsoft. + } + } + if !ok { + return 0, 0, UnsupportedError(name + " encoding") + } + return bestOffset, bestPID, nil +} + +const ( + locaOffsetFormatUnknown int = iota + locaOffsetFormatShort + locaOffsetFormatLong +) + +// A cm holds a parsed cmap entry. +type cm struct { + start, end, delta, offset uint32 +} + +// A Font represents a Truetype font. +type Font struct { + // Tables sliced from the TTF data. The different tables are documented + // at http://developer.apple.com/fonts/TTRefMan/RM06/Chap6.html + cmap, cvt, fpgm, glyf, hdmx, head, hhea, hmtx, kern, loca, maxp, name, os2, prep, vmtx []byte + + cmapIndexes []byte + + // Cached values derived from the raw ttf data. + cm []cm + locaOffsetFormat int + nGlyph, nHMetric, nKern int + fUnitsPerEm int32 + ascent int32 // In FUnits. + descent int32 // In FUnits; typically negative. + bounds fixed.Rectangle26_6 // In FUnits. + // Values from the maxp section. + maxTwilightPoints, maxStorage, maxFunctionDefs, maxStackElements uint16 +} + +func (f *Font) parseCmap() error { + const ( + cmapFormat4 = 4 + cmapFormat12 = 12 + languageIndependent = 0 + ) + + offset, _, err := parseSubtables(f.cmap, "cmap", 4, 8, nil) + if err != nil { + return err + } + offset = int(u32(f.cmap, offset+4)) + if offset <= 0 || offset > len(f.cmap) { + return FormatError("bad cmap offset") + } + + cmapFormat := u16(f.cmap, offset) + switch cmapFormat { + case cmapFormat4: + language := u16(f.cmap, offset+4) + if language != languageIndependent { + return UnsupportedError(fmt.Sprintf("language: %d", language)) + } + segCountX2 := int(u16(f.cmap, offset+6)) + if segCountX2%2 == 1 { + return FormatError(fmt.Sprintf("bad segCountX2: %d", segCountX2)) + } + segCount := segCountX2 / 2 + offset += 14 + f.cm = make([]cm, segCount) + for i := 0; i < segCount; i++ { + f.cm[i].end = uint32(u16(f.cmap, offset)) + offset += 2 + } + offset += 2 + for i := 0; i < segCount; i++ { + f.cm[i].start = uint32(u16(f.cmap, offset)) + offset += 2 + } + for i := 0; i < segCount; i++ { + f.cm[i].delta = uint32(u16(f.cmap, offset)) + offset += 2 + } + for i := 0; i < segCount; i++ { + f.cm[i].offset = uint32(u16(f.cmap, offset)) + offset += 2 + } + f.cmapIndexes = f.cmap[offset:] + return nil + + case cmapFormat12: + if u16(f.cmap, offset+2) != 0 { + return FormatError(fmt.Sprintf("cmap format: % x", f.cmap[offset:offset+4])) + } + length := u32(f.cmap, offset+4) + language := u32(f.cmap, offset+8) + if language != languageIndependent { + return UnsupportedError(fmt.Sprintf("language: %d", language)) + } + nGroups := u32(f.cmap, offset+12) + if length != 12*nGroups+16 { + return FormatError("inconsistent cmap length") + } + offset += 16 + f.cm = make([]cm, nGroups) + for i := uint32(0); i < nGroups; i++ { + f.cm[i].start = u32(f.cmap, offset+0) + f.cm[i].end = u32(f.cmap, offset+4) + f.cm[i].delta = u32(f.cmap, offset+8) - f.cm[i].start + offset += 12 + } + return nil + } + return UnsupportedError(fmt.Sprintf("cmap format: %d", cmapFormat)) +} + +func (f *Font) parseHead() error { + if len(f.head) != 54 { + return FormatError(fmt.Sprintf("bad head length: %d", len(f.head))) + } + f.fUnitsPerEm = int32(u16(f.head, 18)) + f.bounds.Min.X = fixed.Int26_6(int16(u16(f.head, 36))) + f.bounds.Min.Y = fixed.Int26_6(int16(u16(f.head, 38))) + f.bounds.Max.X = fixed.Int26_6(int16(u16(f.head, 40))) + f.bounds.Max.Y = fixed.Int26_6(int16(u16(f.head, 42))) + switch i := u16(f.head, 50); i { + case 0: + f.locaOffsetFormat = locaOffsetFormatShort + case 1: + f.locaOffsetFormat = locaOffsetFormatLong + default: + return FormatError(fmt.Sprintf("bad indexToLocFormat: %d", i)) + } + return nil +} + +func (f *Font) parseHhea() error { + if len(f.hhea) != 36 { + return FormatError(fmt.Sprintf("bad hhea length: %d", len(f.hhea))) + } + f.ascent = int32(int16(u16(f.hhea, 4))) + f.descent = int32(int16(u16(f.hhea, 6))) + f.nHMetric = int(u16(f.hhea, 34)) + if 4*f.nHMetric+2*(f.nGlyph-f.nHMetric) != len(f.hmtx) { + return FormatError(fmt.Sprintf("bad hmtx length: %d", len(f.hmtx))) + } + return nil +} + +func (f *Font) parseKern() error { + // Apple's TrueType documentation (http://developer.apple.com/fonts/TTRefMan/RM06/Chap6kern.html) says: + // "Previous versions of the 'kern' table defined both the version and nTables fields in the header + // as UInt16 values and not UInt32 values. Use of the older format on the Mac OS is discouraged + // (although AAT can sense an old kerning table and still make correct use of it). Microsoft + // Windows still uses the older format for the 'kern' table and will not recognize the newer one. + // Fonts targeted for the Mac OS only should use the new format; fonts targeted for both the Mac OS + // and Windows should use the old format." + // Since we expect that almost all fonts aim to be Windows-compatible, we only parse the "older" format, + // just like the C Freetype implementation. + if len(f.kern) == 0 { + if f.nKern != 0 { + return FormatError("bad kern table length") + } + return nil + } + if len(f.kern) < 18 { + return FormatError("kern data too short") + } + version, offset := u16(f.kern, 0), 2 + if version != 0 { + return UnsupportedError(fmt.Sprintf("kern version: %d", version)) + } + + n, offset := u16(f.kern, offset), offset+2 + if n == 0 { + return UnsupportedError("kern nTables: 0") + } + // TODO: support multiple subtables. In practice, almost all .ttf files + // have only one subtable, if they have a kern table at all. But it's not + // impossible. Xolonium Regular (https://fontlibrary.org/en/font/xolonium) + // has 3 subtables. Those subtables appear to be disjoint, rather than + // being the same kerning pairs encoded in three different ways. + // + // For now, we'll use only the first subtable. + + offset += 2 // Skip the version. + length, offset := int(u16(f.kern, offset)), offset+2 + coverage, offset := u16(f.kern, offset), offset+2 + if coverage != 0x0001 { + // We only support horizontal kerning. + return UnsupportedError(fmt.Sprintf("kern coverage: 0x%04x", coverage)) + } + f.nKern, offset = int(u16(f.kern, offset)), offset+2 + if 6*f.nKern != length-14 { + return FormatError("bad kern table length") + } + return nil +} + +func (f *Font) parseMaxp() error { + if len(f.maxp) != 32 { + return FormatError(fmt.Sprintf("bad maxp length: %d", len(f.maxp))) + } + f.nGlyph = int(u16(f.maxp, 4)) + f.maxTwilightPoints = u16(f.maxp, 16) + f.maxStorage = u16(f.maxp, 18) + f.maxFunctionDefs = u16(f.maxp, 20) + f.maxStackElements = u16(f.maxp, 24) + return nil +} + +// scale returns x divided by f.fUnitsPerEm, rounded to the nearest integer. +func (f *Font) scale(x fixed.Int26_6) fixed.Int26_6 { + if x >= 0 { + x += fixed.Int26_6(f.fUnitsPerEm) / 2 + } else { + x -= fixed.Int26_6(f.fUnitsPerEm) / 2 + } + return x / fixed.Int26_6(f.fUnitsPerEm) +} + +// Bounds returns the union of a Font's glyphs' bounds. +func (f *Font) Bounds(scale fixed.Int26_6) fixed.Rectangle26_6 { + b := f.bounds + b.Min.X = f.scale(scale * b.Min.X) + b.Min.Y = f.scale(scale * b.Min.Y) + b.Max.X = f.scale(scale * b.Max.X) + b.Max.Y = f.scale(scale * b.Max.Y) + return b +} + +// FUnitsPerEm returns the number of FUnits in a Font's em-square's side. +func (f *Font) FUnitsPerEm() int32 { + return f.fUnitsPerEm +} + +// Index returns a Font's index for the given rune. +func (f *Font) Index(x rune) Index { + c := uint32(x) + for i, j := 0, len(f.cm); i < j; { + h := i + (j-i)/2 + cm := &f.cm[h] + if c < cm.start { + j = h + } else if cm.end < c { + i = h + 1 + } else if cm.offset == 0 { + return Index(c + cm.delta) + } else { + offset := int(cm.offset) + 2*(h-len(f.cm)+int(c-cm.start)) + return Index(u16(f.cmapIndexes, offset)) + } + } + return 0 +} + +// Name returns the Font's name value for the given NameID. It returns "" if +// there was an error, or if that name was not found. +func (f *Font) Name(id NameID) string { + x, platformID, err := parseSubtables(f.name, "name", 6, 12, func(b []byte) bool { + return NameID(u16(b, 6)) == id + }) + if err != nil { + return "" + } + offset, length := u16(f.name, 4)+u16(f.name, x+10), u16(f.name, x+8) + // Return the ASCII value of the encoded string. + // The string is encoded as UTF-16 on non-Apple platformIDs; Apple is platformID 1. + src := f.name[offset : offset+length] + var dst []byte + if platformID != 1 { // UTF-16. + if len(src)&1 != 0 { + return "" + } + dst = make([]byte, len(src)/2) + for i := range dst { + dst[i] = printable(u16(src, 2*i)) + } + } else { // ASCII. + dst = make([]byte, len(src)) + for i, c := range src { + dst[i] = printable(uint16(c)) + } + } + return string(dst) +} + +func printable(r uint16) byte { + if 0x20 <= r && r < 0x7f { + return byte(r) + } + return '?' +} + +// unscaledHMetric returns the unscaled horizontal metrics for the glyph with +// the given index. +func (f *Font) unscaledHMetric(i Index) (h HMetric) { + j := int(i) + if j < 0 || f.nGlyph <= j { + return HMetric{} + } + if j >= f.nHMetric { + p := 4 * (f.nHMetric - 1) + return HMetric{ + AdvanceWidth: fixed.Int26_6(u16(f.hmtx, p)), + LeftSideBearing: fixed.Int26_6(int16(u16(f.hmtx, p+2*(j-f.nHMetric)+4))), + } + } + return HMetric{ + AdvanceWidth: fixed.Int26_6(u16(f.hmtx, 4*j)), + LeftSideBearing: fixed.Int26_6(int16(u16(f.hmtx, 4*j+2))), + } +} + +// HMetric returns the horizontal metrics for the glyph with the given index. +func (f *Font) HMetric(scale fixed.Int26_6, i Index) HMetric { + h := f.unscaledHMetric(i) + h.AdvanceWidth = f.scale(scale * h.AdvanceWidth) + h.LeftSideBearing = f.scale(scale * h.LeftSideBearing) + return h +} + +// unscaledVMetric returns the unscaled vertical metrics for the glyph with +// the given index. yMax is the top of the glyph's bounding box. +func (f *Font) unscaledVMetric(i Index, yMax fixed.Int26_6) (v VMetric) { + j := int(i) + if j < 0 || f.nGlyph <= j { + return VMetric{} + } + if 4*j+4 <= len(f.vmtx) { + return VMetric{ + AdvanceHeight: fixed.Int26_6(u16(f.vmtx, 4*j)), + TopSideBearing: fixed.Int26_6(int16(u16(f.vmtx, 4*j+2))), + } + } + // The OS/2 table has grown over time. + // https://developer.apple.com/fonts/TTRefMan/RM06/Chap6OS2.html + // says that it was originally 68 bytes. Optional fields, including + // the ascender and descender, are described at + // http://www.microsoft.com/typography/otspec/os2.htm + if len(f.os2) >= 72 { + sTypoAscender := fixed.Int26_6(int16(u16(f.os2, 68))) + sTypoDescender := fixed.Int26_6(int16(u16(f.os2, 70))) + return VMetric{ + AdvanceHeight: sTypoAscender - sTypoDescender, + TopSideBearing: sTypoAscender - yMax, + } + } + return VMetric{ + AdvanceHeight: fixed.Int26_6(f.fUnitsPerEm), + TopSideBearing: 0, + } +} + +// VMetric returns the vertical metrics for the glyph with the given index. +func (f *Font) VMetric(scale fixed.Int26_6, i Index) VMetric { + // TODO: should 0 be bounds.YMax? + v := f.unscaledVMetric(i, 0) + v.AdvanceHeight = f.scale(scale * v.AdvanceHeight) + v.TopSideBearing = f.scale(scale * v.TopSideBearing) + return v +} + +// Kern returns the horizontal adjustment for the given glyph pair. A positive +// kern means to move the glyphs further apart. +func (f *Font) Kern(scale fixed.Int26_6, i0, i1 Index) fixed.Int26_6 { + if f.nKern == 0 { + return 0 + } + g := uint32(i0)<<16 | uint32(i1) + lo, hi := 0, f.nKern + for lo < hi { + i := (lo + hi) / 2 + ig := u32(f.kern, 18+6*i) + if ig < g { + lo = i + 1 + } else if ig > g { + hi = i + } else { + return f.scale(scale * fixed.Int26_6(int16(u16(f.kern, 22+6*i)))) + } + } + return 0 +} + +// Parse returns a new Font for the given TTF or TTC data. +// +// For TrueType Collections, the first font in the collection is parsed. +func Parse(ttf []byte) (font *Font, err error) { + return parse(ttf, 0) +} + +func parse(ttf []byte, offset int) (font *Font, err error) { + if len(ttf)-offset < 12 { + err = FormatError("TTF data is too short") + return + } + originalOffset := offset + magic, offset := u32(ttf, offset), offset+4 + switch magic { + case 0x00010000: + // No-op. + case 0x74746366: // "ttcf" as a big-endian uint32. + if originalOffset != 0 { + err = FormatError("recursive TTC") + return + } + ttcVersion, offset := u32(ttf, offset), offset+4 + if ttcVersion != 0x00010000 && ttcVersion != 0x00020000 { + err = FormatError("bad TTC version") + return + } + numFonts, offset := int(u32(ttf, offset)), offset+4 + if numFonts <= 0 { + err = FormatError("bad number of TTC fonts") + return + } + if len(ttf[offset:])/4 < numFonts { + err = FormatError("TTC offset table is too short") + return + } + // TODO: provide an API to select which font in a TrueType collection to return, + // not just the first one. This may require an API to parse a TTC's name tables, + // so users of this package can select the font in a TTC by name. + offset = int(u32(ttf, offset)) + if offset <= 0 || offset > len(ttf) { + err = FormatError("bad TTC offset") + return + } + return parse(ttf, offset) + default: + err = FormatError("bad TTF version") + return + } + n, offset := int(u16(ttf, offset)), offset+2 + offset += 6 // Skip the searchRange, entrySelector and rangeShift. + if len(ttf) < 16*n+offset { + err = FormatError("TTF data is too short") + return + } + f := new(Font) + // Assign the table slices. + for i := 0; i < n; i++ { + x := 16*i + offset + switch string(ttf[x : x+4]) { + case "cmap": + f.cmap, err = readTable(ttf, ttf[x+8:x+16]) + case "cvt ": + f.cvt, err = readTable(ttf, ttf[x+8:x+16]) + case "fpgm": + f.fpgm, err = readTable(ttf, ttf[x+8:x+16]) + case "glyf": + f.glyf, err = readTable(ttf, ttf[x+8:x+16]) + case "hdmx": + f.hdmx, err = readTable(ttf, ttf[x+8:x+16]) + case "head": + f.head, err = readTable(ttf, ttf[x+8:x+16]) + case "hhea": + f.hhea, err = readTable(ttf, ttf[x+8:x+16]) + case "hmtx": + f.hmtx, err = readTable(ttf, ttf[x+8:x+16]) + case "kern": + f.kern, err = readTable(ttf, ttf[x+8:x+16]) + case "loca": + f.loca, err = readTable(ttf, ttf[x+8:x+16]) + case "maxp": + f.maxp, err = readTable(ttf, ttf[x+8:x+16]) + case "name": + f.name, err = readTable(ttf, ttf[x+8:x+16]) + case "OS/2": + f.os2, err = readTable(ttf, ttf[x+8:x+16]) + case "prep": + f.prep, err = readTable(ttf, ttf[x+8:x+16]) + case "vmtx": + f.vmtx, err = readTable(ttf, ttf[x+8:x+16]) + } + if err != nil { + return + } + } + // Parse and sanity-check the TTF data. + if err = f.parseHead(); err != nil { + return + } + if err = f.parseMaxp(); err != nil { + return + } + if err = f.parseCmap(); err != nil { + return + } + if err = f.parseKern(); err != nil { + return + } + if err = f.parseHhea(); err != nil { + return + } + font = f + return +} -- cgit v1.2.3