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Move parseName to Name, rewritten to be lazy.

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Move nameEntryInASCII into the global scope.
This commit is contained in:
Steven Edwards 2015-09-04 15:34:45 -04:00
parent c765a57301
commit b81666dccc
1 changed files with 75 additions and 144 deletions
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219
truetype/truetype.go
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@ -110,6 +110,40 @@ func readTable(ttf []byte, offsetLength []byte) ([]byte, error) {
return ttf[offset:end], nil
}
// nameEntryInASCII converts b, which may be UTF-16 encoded, into an ACSII string.
func nameEntryInASCII(b []byte, utf16 bool) string {
var buf []byte
if utf16 { // Equivalent to tt_name_ascii_from_utf16.
j := len(b)
if j&1 == 1 {
return ""
}
for i := 0; i < j; i += 2 {
el := u16(b, i)
if el == 0 {
continue
} else if el < 32 || el > 127 {
buf = append(buf, '?')
} else {
buf = append(buf, byte(el))
}
}
} else { // Equivalent to tt_name_ascii_from_other.
for _, el := range b {
if el == 0 {
continue
} else if el < 32 || el > 127 {
buf = append(buf, '?')
} else {
buf = append(buf, el)
}
}
}
return string(buf)
}
const (
locaOffsetFormatUnknown int = iota
locaOffsetFormatShort
@ -121,11 +155,6 @@ type cm struct {
start, end, delta, offset uint32
}
// nnameInfo holds a font's name and style.
type nameInfo struct {
values [20]string
}
// A Font represents a Truetype font.
type Font struct {
// Tables sliced from the TTF data. The different tables are documented
@ -142,8 +171,6 @@ type Font struct {
bounds fixed.Rectangle26_6
// Values from the maxp section.
maxTwilightPoints, maxStorage, maxFunctionDefs, maxStackElements uint16
// First value from head table.
nameRecord *nameInfo
}
func (f *Font) parseCmap() error {
@ -339,142 +366,6 @@ func (f *Font) parseMaxp() error {
return nil
}
func (f *Font) parseName() error {
if len(f.name) < 18 { // The name table is three uint16s + at least one Name Record. Name Records are six uint16s.
return FormatError("name table too short")
}
if u16(f.name, 0) != 0 { // The first uint16 in the name table should be set to 0, per the spec.
return FormatError(fmt.Sprintf("invalid format specifier: %d", u16(f.name, 0)))
}
numNames := int(u16(f.name, 2)) // The number of Name Records is the second uint16 in the name table.
stringOffset := u16(f.name, 4) // And the offset marking the beginning of the character data is the third int16.
if len(f.name) < int(stringOffset) {
return FormatError("string offset is larger than the name table")
}
const ( // The platform IDs in the name table.
PLATFORM_UNICODE = 0
PLATFORM_MACINTOSH = 1
PLATFORM_MICROSOFT = 3
)
const ( // Encoding IDs for the Microsoft platform.
MICROSOFT_SYMBOL_CS = 1
MICROSOFT_UNICODE_CS = 2
MICROSOFT_UCS_4 = 10
)
// Keep track of which records contain the name and style information.
var foundUnicode, foundAppleEnglish, foundAppleRoman, foundMicrosoft, foundApple [2]int
foundMicrosoftEnglish := false
// Name Records begin at the fourth uint16 and are six uint16s long.
// Loop through them and keep track of records of interest.
for offset, i := 6, 0; i < numNames; i, offset = i+1, offset+12 {
platformID, encodingID, languageID, nameID := u16(f.name, offset), u16(f.name, offset+2), u16(f.name, offset+4), NameID(u16(f.name, offset+6))
switch nameID {
case NameIDFontFamily, NameIDFontSubfamily:
if u16(f.name, offset+8) == 0 { // Offset + 8 is the location of the string length. If zero, skip it.
break
}
switch platformID {
case PLATFORM_UNICODE:
foundUnicode[nameID-1] = offset
case PLATFORM_MACINTOSH:
if languageID == 0 { // The language ID for English is zero.
foundAppleEnglish[nameID-1] = offset
} else if encodingID == 0 { // A zero encoding ID means Roman.
foundAppleRoman[nameID-1] = offset
}
case PLATFORM_MICROSOFT:
if foundMicrosoft[nameID-1] == 0 || languageID&0x3FF == 0x009 { // Prefer Microsoft fonts in English.
if encodingID == MICROSOFT_SYMBOL_CS || encodingID == MICROSOFT_UNICODE_CS || encodingID == MICROSOFT_UCS_4 {
foundMicrosoftEnglish = languageID&0x3FF == 9
foundMicrosoft[nameID-1] = offset
}
}
}
}
}
foundApple = foundAppleRoman
if foundAppleEnglish[0] > 0 {
foundApple = foundAppleEnglish
}
var nameOffset, nameLength, styleOffset, styleLength uint16
nameRecord := &nameInfo{}
// Retrieve ASCII version of the values.
switch {
case foundMicrosoft[0] > 0 && !(foundApple[0] > 0 && !foundMicrosoftEnglish):
nameOffset, styleOffset = u16(f.name, foundMicrosoft[0]+10)+stringOffset, u16(f.name, foundMicrosoft[1]+10)+stringOffset
nameLength, styleLength = u16(f.name, foundMicrosoft[0]+8), u16(f.name, foundMicrosoft[1]+8)
case foundApple[0] > 0:
nameOffset, styleOffset = u16(f.name, foundApple[0]+10)+stringOffset, u16(f.name, foundApple[1]+10)+stringOffset
nameLength, styleLength = u16(f.name, foundApple[0]+8), u16(f.name, foundApple[1]+8)
case foundUnicode[0] > 0:
nameOffset, styleOffset = u16(f.name, foundUnicode[0]+10)+stringOffset, u16(f.name, foundUnicode[1]+10)+stringOffset
nameLength, styleLength = u16(f.name, foundUnicode[0]+8), u16(f.name, foundUnicode[1]+8)
}
nameRecord.values[NameIDFontFamily] = f.nameEntryInASCII(f.name[nameOffset:nameOffset+nameLength], true)
nameRecord.values[NameIDFontSubfamily] = f.nameEntryInASCII(f.name[styleOffset:styleOffset+styleLength], true)
f.nameRecord = nameRecord
return nil
}
func (f *Font) nameEntryInASCII(b []byte, utf16 bool) string {
var buf []byte
if utf16 { // Equivalent to tt_name_ascii_from_utf16.
j := len(b)
if j&1 == 1 {
return ""
}
for i := 0; i < j; i += 2 {
el := u16(b, i)
if el == 0 {
continue
} else if el < 32 || el > 127 {
buf = append(buf, '?')
} else {
buf = append(buf, byte(el))
}
}
} else { // Equivalent to tt_name_ascii_from_other.
for _, el := range b {
if el == 0 {
continue
} else if el < 32 || el > 127 {
buf = append(buf, '?')
} else {
buf = append(buf, el)
}
}
}
return string(buf)
}
// Name returns the font's name.
func (f *Font) Name(id NameID) string {
if f.nameRecord == nil {
f.parseName()
}
// Return empty string if caller requests something larger than we support.
if id > NameIDSampleText {
return ""
}
return f.nameRecord.values[id]
}
// 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 {
@ -520,6 +411,47 @@ func (f *Font) Index(x rune) Index {
return 0
}
// Name returns the NameID value of a Font.
// Returns "" on error or not found.
func (f *Font) Name(id NameID) string {
if len(f.name) < 18 { // The name table is three uint16s + at least one Name Record. Name Records are six uint16s.
return ""
}
if u16(f.name, 0) != 0 { // The first uint16 in the name table should be set to 0, per the spec.
return ""
}
numNames := int(u16(f.name, 2)) // The number of Name Records is the second uint16 in the name table.
stringOffset := u16(f.name, 4) // And the offset marking the beginning of the character data is the third int16.
if len(f.name) < int(stringOffset) {
return ""
}
valueOffset, valueLength, pid := uint16(0), uint16(0), uint16(0)
// Name Records begin at the fourth uint16 and are six uint16s long.
for offset, i := 6, 0; i < numNames; i, offset = i+1, offset+12 {
if u16(f.name, offset+8) == 0 { // Offset + 8 is the location of the string length. If zero, skip it.
break
}
nameID := NameID(u16(f.name, offset+6))
// Find the first matching nameID, regardless of platform.
if nameID == id {
valueOffset, valueLength, pid = u16(f.name, offset+10), u16(f.name, offset+8), u16(f.name, offset)
break
}
}
if valueOffset == 0 {
return ""
}
// Return the ASCII value of the encoded string.
// The string is encoded as UTF-16 on non-Apple pids; Apple is pid 1.
return nameEntryInASCII(f.name[stringOffset+valueOffset:stringOffset+valueOffset+valueLength], pid != 1)
}
// unscaledHMetric returns the unscaled horizontal metrics for the glyph with
// the given index.
func (f *Font) unscaledHMetric(i Index) (h HMetric) {
@ -722,7 +654,6 @@ func parse(ttf []byte, offset int) (font *Font, err error) {
if err = f.parseHhea(); err != nil {
return
}
font = f
return
}