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Make suggested changes in #19.

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This commit is contained in:
Steven Edwards 2015-09-09 07:19:54 -04:00
parent ff2b91c280
commit 134884e1a5
2 changed files with 73 additions and 43 deletions
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114
truetype/truetype.go
View file

@ -27,28 +27,28 @@ import (
type Index uint16
// A NameID represents the Name Identifiers in the name table.
type NameID uint16
type NameIDCode 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
NameIDCodeCopyright NameIDCode = 0
NameIDCodeFontFamily = 1
NameIDCodeFontSubfamily = 2
NameIDCodeUniqueSubfamilyID = 3
NameIDCodeFontFullName = 4
NameIDCodeNameTableVersion = 5
NameIDCodePostscriptName = 6
NameIDCodeTrademarkNotice = 7
NameIDCodeManufacturerName = 8
NameIDCodeDesignerName = 9
NameIDCodeFontDescription = 10
NameIDCodeFontVendorURL = 11
NameIDCodeFontDesignerURL = 12
NameIDCodeFontLicense = 13
NameIDCodeFontLicenseURL = 14
NameIDCodePreferredFamily = 16
NameIDCodePreferredSubfamily = 17
NameIDCodeCompatibleName = 18
NameIDCodeSampleText = 19
)
const (
@ -116,7 +116,7 @@ func readTable(ttf []byte, offsetLength []byte) ([]byte, error) {
// 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.
if utf16 { // Equivalent to tt_name_entry_ascii_from_utf16.
j := len(b)
if j&1 == 1 {
return ""
@ -132,7 +132,7 @@ func nameEntryInASCII(b []byte, utf16 bool) string {
buf = append(buf, byte(el))
}
}
} else { // Equivalent to tt_name_ascii_from_other.
} else { // Equivalent to tt_name_entry_ascii_from_other.
for _, el := range b {
if el == 0 {
continue
@ -158,42 +158,41 @@ func continueIf(b []byte, offsets, values []int) bool {
return true
}
type SubtableValidPredFunc func(b []byte) bool
// parseSubtables wraps the commonality in Name and parseCmap.
func parseSubtables(b []byte, name string, firstSubtableOffset, subtableSize, valueOffset, valueLengthOffset int, offsets, values []int, isU16Offset bool) (int, int, int, error) {
func parseSubtables(b []byte, name string, subtableOffset, subtableSize int, tableCheck SubtableValidPredFunc) (int, int, error) {
if len(b) < 4 {
return 0, 0, 0, FormatError(name + " too short")
return 0, 0, FormatError(name + " too short")
}
nsubtab := int(u16(b, 2))
if len(b) < subtableSize*nsubtab+firstSubtableOffset {
return 0, 0, 0, FormatError(name + " too short")
if len(b) < subtableSize*nsubtab+subtableOffset {
return 0, 0, FormatError(name + " too short")
}
offset, length, pid, x := uint32(0), uint16(0), uint16(0), firstSubtableOffset
offset, pid, x := 0, 0, subtableOffset
for i := 0; i < nsubtab; i++ {
if continueIf(b[x:], offsets, values) {
if tableCheck == nil || tableCheck(b[x:]) { // When tableCheck is nil, examine the table.
// We read the 16-bit Platform ID and 16-bit Platform Specific ID as a single uint32.
// All values are big-endian.
pidPsid := u32(b, x)
// We prefer the Unicode cmap encoding. Failing to find that, we fall
// back onto the Microsoft cmap encoding.
if pidPsid == unicodeEncoding {
offset, length, pid = u32(b, x+valueOffset), u16(b, x+valueLengthOffset), uint16(pidPsid>>16)
offset, pid = x, int(pidPsid>>16)
break
} else if pidPsid == microsoftSymbolEncoding ||
pidPsid == microsoftUCS2Encoding ||
pidPsid == microsoftUCS4Encoding {
offset, length, pid = u32(b, x+valueOffset), u16(b, x+valueLengthOffset), uint16(pidPsid>>16)
offset, pid = x, int(pidPsid>>16)
// We don't break out of the for loop, so that Unicode can override Microsoft.
}
}
x += subtableSize
}
if isU16Offset {
offset >>= 16
}
return int(offset), int(length), int(pid), nil
return offset, pid, nil
}
const (
@ -232,7 +231,8 @@ func (f *Font) parseCmap() error {
languageIndependent = 0
)
offset, _, _, err := parseSubtables(f.cmap, "cmap", 4, 8, 4, 0, []int{}, []int{}, false)
x, _, err := parseSubtables(f.cmap, "cmap", 4, 8, nil)
offset := int(u32(f.cmap, x+4))
if err != nil {
return err
}
@ -429,18 +429,48 @@ func (f *Font) Index(x rune) Index {
return 0
}
// Name returns the NameID value of a Font.
// Name returns the NameIDCode value of a Font.
// Returns "" on error or not found.
func (f *Font) Name(id NameID) string {
valueOffset, valueLength, pid, _ := parseSubtables(f.name, "name", 6, 12, 10, 8, []int{6}, []int{int(id)}, true)
if valueOffset == 0 {
func (f *Font) Name(id NameIDCode) string {
x, platformID, err := parseSubtables(f.name, "name", 6, 12,
func(b []byte) bool {
return NameIDCode(u16(b, 6)) == id
})
if err != nil {
return ""
}
stringOffset := int(u16(f.name, 4))
offset, length := u16(f.name, x+10), u16(f.name, x+8)
offset += u16(f.name, 4)
// 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)
// 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

2
truetype/truetype_test.go
View file

@ -228,7 +228,7 @@ func TestName(t *testing.T) {
}
continue
}
if got := f.Name(NameIDFontFamily); got != want {
if got := f.Name(NameIDCodeFontFamily); got != want {
t.Errorf("%s: got %q, want %q", name, got, want)
}
}