diff options
Diffstat (limited to 'Godeps/_workspace/src/code.google.com/p/freetype-go/freetype/truetype/truetype.go')
| -rw-r--r-- | Godeps/_workspace/src/code.google.com/p/freetype-go/freetype/truetype/truetype.go | 554 |
1 files changed, 0 insertions, 554 deletions
diff --git a/Godeps/_workspace/src/code.google.com/p/freetype-go/freetype/truetype/truetype.go b/Godeps/_workspace/src/code.google.com/p/freetype-go/freetype/truetype/truetype.go deleted file mode 100644 index 96ceef547..000000000 --- a/Godeps/_workspace/src/code.google.com/p/freetype-go/freetype/truetype/truetype.go +++ /dev/null @@ -1,554 +0,0 @@ -// 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 device units in 1 em. For example, if 1 em is 10 pixels and -// 1 pixel is 64 units, then scale is 640. If the device space involves pixels, -// 64 units per pixel is recommended, since that is what the bytecode hinter -// uses when snapping point co-ordinates to the pixel grid. -// -// To measure a TrueType font in ideal FUnit space, use scale equal to -// font.FUnitsPerEm(). -package truetype - -import ( - "fmt" -) - -// An Index is a Font's index of a rune. -type Index uint16 - -// A Bounds holds the co-ordinate range of one or more glyphs. -// The endpoints are inclusive. -type Bounds struct { - XMin, YMin, XMax, YMax int32 -} - -// An HMetric holds the horizontal metrics of a single glyph. -type HMetric struct { - AdvanceWidth, LeftSideBearing int32 -} - -// A VMetric holds the vertical metrics of a single glyph. -type VMetric struct { - AdvanceHeight, TopSideBearing int32 -} - -// 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 -} - -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, os2, prep, vmtx []byte - - cmapIndexes []byte - - // Cached values derived from the raw ttf data. - cm []cm - locaOffsetFormat int - nGlyph, nHMetric, nKern int - fUnitsPerEm int32 - bounds Bounds - // Values from the maxp section. - maxTwilightPoints, maxStorage, maxFunctionDefs, maxStackElements uint16 -} - -func (f *Font) parseCmap() error { - const ( - cmapFormat4 = 4 - cmapFormat12 = 12 - languageIndependent = 0 - - // 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 - unicodeEncoding = 0x00000003 // PID = 0 (Unicode), PSID = 3 (Unicode 2.0) - 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) - ) - - if len(f.cmap) < 4 { - return FormatError("cmap too short") - } - nsubtab := int(u16(f.cmap, 2)) - if len(f.cmap) < 8*nsubtab+4 { - return FormatError("cmap too short") - } - offset, found, x := 0, false, 4 - for i := 0; i < nsubtab; i++ { - // We read the 16-bit Platform ID and 16-bit Platform Specific ID as a single uint32. - // All values are big-endian. - pidPsid, o := u32(f.cmap, x), u32(f.cmap, x+4) - x += 8 - // We prefer the Unicode cmap encoding. Failing to find that, we fall - // back onto the Microsoft cmap encoding. - if pidPsid == unicodeEncoding { - offset, found = int(o), true - break - - } else if pidPsid == microsoftSymbolEncoding || - pidPsid == microsoftUCS2Encoding || - pidPsid == microsoftUCS4Encoding { - - offset, found = int(o), true - // We don't break out of the for loop, so that Unicode can override Microsoft. - } - } - if !found { - return UnsupportedError("cmap encoding") - } - 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.XMin = int32(int16(u16(f.head, 36))) - f.bounds.YMin = int32(int16(u16(f.head, 38))) - f.bounds.XMax = int32(int16(u16(f.head, 40))) - f.bounds.YMax = int32(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.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 != 1 { - return UnsupportedError(fmt.Sprintf("kern nTables: %d", n)) - } - offset += 2 - 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 int32) int32 { - if x >= 0 { - x += f.fUnitsPerEm / 2 - } else { - x -= f.fUnitsPerEm / 2 - } - return x / f.fUnitsPerEm -} - -// Bounds returns the union of a Font's glyphs' bounds. -func (f *Font) Bounds(scale int32) Bounds { - b := f.bounds - b.XMin = f.scale(scale * b.XMin) - b.YMin = f.scale(scale * b.YMin) - b.XMax = f.scale(scale * b.XMax) - b.YMax = f.scale(scale * b.YMax) - 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 -} - -// 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: int32(u16(f.hmtx, p)), - LeftSideBearing: int32(int16(u16(f.hmtx, p+2*(j-f.nHMetric)+4))), - } - } - return HMetric{ - AdvanceWidth: int32(u16(f.hmtx, 4*j)), - LeftSideBearing: int32(int16(u16(f.hmtx, 4*j+2))), - } -} - -// HMetric returns the horizontal metrics for the glyph with the given index. -func (f *Font) HMetric(scale int32, 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 int32) (v VMetric) { - j := int(i) - if j < 0 || f.nGlyph <= j { - return VMetric{} - } - if 4*j+4 <= len(f.vmtx) { - return VMetric{ - AdvanceHeight: int32(u16(f.vmtx, 4*j)), - TopSideBearing: int32(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 := int32(int16(u16(f.os2, 68))) - sTypoDescender := int32(int16(u16(f.os2, 70))) - return VMetric{ - AdvanceHeight: sTypoAscender - sTypoDescender, - TopSideBearing: sTypoAscender - yMax, - } - } - return VMetric{ - AdvanceHeight: f.fUnitsPerEm, - TopSideBearing: 0, - } -} - -// VMetric returns the vertical metrics for the glyph with the given index. -func (f *Font) VMetric(scale int32, 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 -} - -// Kerning returns the kerning for the given glyph pair. -func (f *Font) Kerning(scale int32, i0, i1 Index) int32 { - 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 * int32(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 { - // TODO: support TTC version 2.0, once I have such a .ttc file to test with. - 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 - if len(ttf) < 16*n+12 { - err = FormatError("TTF data is too short") - return - } - f := new(Font) - // Assign the table slices. - for i := 0; i < n; i++ { - x := 16*i + 12 - 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 "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 -} |