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feat(字体解耦): 解耦字体依赖，完善字体处理
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xiaoqidun committed 2026-10-11 00:52:01 +08:00
1 parent 051fc3b65e
commit cf8dfd046b
21 files changed
+1071 -237
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ofdgo_font_resource_sfnt.go
+126 -43
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@@ -20,15 +20,13 @@ import (
"fmt"
"maps"
"slices"
"github.com/tdewolff/font"
)
// SFNTBackend 提供默认字体资源处理，不依赖Canvas绘图库
// SFNTBackend 提供独立的OpenType字体度量、轮廓和资源处理
type SFNTBackend struct{}
// sfntResourceMetrics 隔离资源解析器的度量实现
type sfntResourceMetrics struct{ *font.SFNT }
type sfntResourceMetrics struct{ *sfntFont }
// Name 返回资源后端标识
// 返回: string 后端标识
@@ -47,11 +45,11 @@ func (SFNTBackend) OpenFontResource(file FontFile, index int) (*FontResource, er
if err != nil {
return nil, err
}
sfnt, err := font.ParseSFNT(data, 0)
sfnt, err := parseSFNTFont(data)
if err != nil {
return nil, err
}
name := sfntFontName(sfnt, font.NamePostScript, font.NameFull, font.NameFontFamily)
name := sfntFontName(sfnt, 6, 4, 1)
if name == "" {
return nil, fmt.Errorf("font has no name")
}
@@ -61,7 +59,7 @@ func (SFNTBackend) OpenFontResource(file FontFile, index int) (*FontResource, er
}
return &FontResource{
FontMetrics: sfntResourceMetrics{sfnt}, Data: data, Extension: extension,
Font: Font{FontName: name, FamilyName: sfntFontName(sfnt, font.NamePreferredFamily, font.NameFontFamily), Charset: "unicode", Bold: sfnt.Head.MacStyle[0], Italic: sfnt.Head.MacStyle[1], FixedWidth: sfnt.Post.IsFixedPitch != 0},
Font: Font{FontName: name, FamilyName: sfntFontName(sfnt, 16, 1), Charset: "unicode", Bold: binary.BigEndian.Uint16(sfnt.Tables["head"][44:])&1 != 0, Italic: binary.BigEndian.Uint16(sfnt.Tables["head"][44:])&2 != 0, FixedWidth: len(sfnt.Tables["post"]) >= 16 && binary.BigEndian.Uint32(sfnt.Tables["post"][12:]) != 0},
CanSubset: sfntSubsettable(sfnt),
}, nil
}
@@ -90,12 +88,12 @@ func (SFNTBackend) SubsetSourceFont(data []byte, usage FontUsage) ([]byte, error
// Write 返回未改动元信息的字体数据
// 返回: []byte 字体数据
func (f sfntResourceMetrics) Write() []byte { return fontSFNTData(f.SFNT) }
func (f sfntResourceMetrics) Write() []byte { return f.sfntFont.Write() }
// sfntSubsettable 判断默认资源后端能否无损裁剪该字体
// 入参: sfnt 已解析字体
// 返回: bool 是否支持裁剪
func sfntSubsettable(sfnt *font.SFNT) bool {
func sfntSubsettable(sfnt *sfntFont) bool {
if fontEmbeddingFlags(sfnt)&0x0100 != 0 || slices.ContainsFunc([]string{"COLR", "CBDT", "sbix", "SVG "}, func(tag string) bool { return sfnt.Tables[tag] != nil }) {
return false
}
@@ -108,7 +106,7 @@ func sfntSubsettable(sfnt *font.SFNT) bool {
// fontEmbeddingFlags 读取OpenType的嵌入标志，未提供OS/2表时返回零
// 入参: sfnt 已解析字体
// 返回: uint16 嵌入标志
func fontEmbeddingFlags(sfnt *font.SFNT) uint16 {
func fontEmbeddingFlags(sfnt *sfntFont) uint16 {
if table := sfnt.Tables["OS/2"]; len(table) >= 10 {
return binary.BigEndian.Uint16(table[8:10])
}
@@ -119,7 +117,7 @@ func fontEmbeddingFlags(sfnt *font.SFNT) uint16 {
// 入参: data 独立OpenType字体
// 返回: error 字体解析或嵌入限制
func validateFontEmbedding(data []byte) error {
sfnt, err := font.ParseSFNT(data, 0)
sfnt, err := parseSFNTFont(data)
if err != nil {
return err
}
@@ -133,10 +131,14 @@ func validateFontEmbedding(data []byte) error {
// sfntFontName 获取字体中的名称
// 入参: sfnt 字体, names 名称类型，按顺序查找
// 返回: string 字体名称
func sfntFontName(sfnt *font.SFNT, names ...font.NameID) string {
func sfntFontName(sfnt *sfntFont, names ...uint16) string {
records, values := fontNameValues(sfnt.Tables["name"])
for _, name := range names {
for _, record := range sfnt.Name.Get(name) {
if value := record.String(); value != "" {
for _, record := range records {
if record.Name != name {
continue
}
if value := values[[4]uint16{record.Platform, record.Encoding, record.Language, name}]; value != "" {
return value
}
}
@@ -152,7 +154,7 @@ func subsetSFNTFont(data []byte, glyphs []uint16, mapped bool) ([]byte, error) {
if err != nil {
return nil, err
}
sfnt, err := font.ParseSFNT(bytes.Clone(data), 0)
sfnt, err := parseSFNTFont(data)
if err != nil {
return nil, err
}
@@ -169,7 +171,7 @@ func subsetSFNTFont(data []byte, glyphs []uint16, mapped bool) ([]byte, error) {
usage := newEditorFontUsage()
for _, id := range glyphs {
usage.glyphs[id] = true
for _, char := range sfnt.Cmap.ToUnicode(id) {
for _, char := range sfnt.glyphCharacters(id) {
usage.chars[char] = true
}
}
@@ -188,15 +190,7 @@ func subsetSFNTFont(data []byte, glyphs []uint16, mapped bool) ([]byte, error) {
}
return fixed, nil
}
subset, err := sfnt.Subset(glyphs, font.SubsetOptions{Tables: []string{
"cmap", "head", "hhea", "hmtx", "maxp", "OS/2", "post", "glyf", "loca", "cvt ", "fpgm", "prep", "gasp",
}})
if err != nil {
return nil, err
}
subset.Tables["name"] = sfnt.Tables["name"]
clear(subset.Tables["head"][8:12])
return serializeOTF(subset.Tables)
return subsetCompactSFNTFont(sfnt, glyphs)
}
// subsetSourceSFNTFont 裁剪静态TrueType原有字体，保留字形编号、复合依赖、度量及提示指令
@@ -207,7 +201,7 @@ func subsetSourceSFNTFont(data []byte, usage *editorFontUsage) []byte {
if usage.unsafe || len(usage.chars)+len(usage.glyphs) == 0 || bytes.HasPrefix(data, []byte("ttcf")) {
return nil
}
sfnt, err := font.ParseSFNT(data, 0)
sfnt, err := parseSFNTFont(data)
if err != nil || !sfnt.IsTrueType || fontEmbeddingFlags(sfnt)&0x0100 != 0 {
return nil
}
@@ -218,20 +212,13 @@ func subsetSourceSFNTFont(data []byte, usage *editorFontUsage) []byte {
return nil
}
}
var unicodeTables []uint16
subtables := make(map[uint32]uint16)
for i, record := range sfnt.Cmap.EncodingRecords {
if record.Format == 14 {
var unicodeTables []sfntCmap
for _, record := range sfnt.cmaps {
if record.format == 14 {
return nil
}
offset := binary.BigEndian.Uint32(sfnt.Tables["cmap"][8+8*i:])
index, ok := subtables[offset]
if !ok {
index = uint16(len(subtables))
subtables[offset] = index
}
if record.PlatformID == 0 || record.PlatformID == 3 && (record.EncodingID == 1 || record.EncodingID == 10) {
unicodeTables = append(unicodeTables, index)
if record.platform == 0 || record.platform == 3 && (record.encoding == 1 || record.encoding == 10) {
unicodeTables = append(unicodeTables, record)
}
}
if len(unicodeTables) == 0 {
@@ -242,8 +229,8 @@ func subsetSourceSFNTFont(data []byte, usage *editorFontUsage) []byte {
mapping := make(map[rune]uint16, len(usage.chars))
for char := range usage.chars {
id := sfnt.GlyphIndex(char)
for _, index := range unicodeTables {
if alternate, ok := sfnt.Cmap.Subtables[index].Get(char); ok && alternate != id {
for _, cmap := range unicodeTables {
if alternate, ok := cmap.mapping[char]; ok && alternate != id {
return nil
}
}
@@ -261,7 +248,7 @@ func subsetSourceSFNTFont(data []byte, usage *editorFontUsage) []byte {
if id >= sfnt.NumGlyphs() {
return nil
}
dependencies, err := sfnt.Glyf.Dependencies(id)
dependencies, err := sfnt.glyphDependencies(id)
if err != nil {
return nil
}
@@ -271,13 +258,14 @@ func subsetSourceSFNTFont(data []byte, usage *editorFontUsage) []byte {
}
var glyf, loca []byte
for id := 0; id <= int(sfnt.NumGlyphs()); id++ {
if sfnt.Head.IndexToLocFormat == 0 {
if binary.BigEndian.Uint16(sfnt.Tables["head"][50:]) == 0 {
loca = binary.BigEndian.AppendUint16(loca, uint16(len(glyf)/2))
} else {
loca = binary.BigEndian.AppendUint32(loca, uint32(len(glyf)))
}
if id < int(sfnt.NumGlyphs()) && glyphs[uint16(id)] {
glyf = append(glyf, sfnt.Glyf.Get(uint16(id))...)
data, _ := trueTypeGlyphData(sfnt.Tables, uint16(id))
glyf = append(glyf, data...)
if len(glyf)%2 != 0 {
glyf = append(glyf, 0)
}
@@ -295,3 +283,98 @@ func subsetSourceSFNTFont(data []byte, usage *editorFontUsage) []byte {
}
return result
}
// subsetCompactSFNTFont 重排新建静态字体的字形，同步复合引用、字符映射和度量
// 入参: sfnt 字体, glyphs 使用字形
// 返回: []byte 紧凑字体子集, error 字形数据错误
func subsetCompactSFNTFont(sfnt *sfntFont, glyphs []uint16) ([]byte, error) {
ids := []uint16{0}
remap := map[uint16]uint16{0: 0}
for _, id := range glyphs {
if id >= sfnt.NumGlyphs() {
return nil, fmt.Errorf("font glyph index out of range")
}
if _, ok := remap[id]; !ok {
remap[id] = uint16(len(ids))
ids = append(ids, id)
}
}
for index := 0; index < len(ids); index++ {
dependencies, err := sfnt.glyphDependencies(ids[index])
if err != nil {
return nil, err
}
for _, id := range dependencies {
if _, ok := remap[id]; !ok {
remap[id] = uint16(len(ids))
ids = append(ids, id)
}
}
}
table := make(map[string][]byte)
for _, tag := range []string{"head", "hhea", "maxp", "OS/2", "post", "name", "cvt ", "fpgm", "prep", "gasp", "vhea"} {
if data := sfnt.Tables[tag]; data != nil {
table[tag] = bytes.Clone(data)
}
}
var glyf, loca, hmtx, vmtx []byte
mapping := make(map[rune]uint16)
for _, id := range ids {
loca = binary.BigEndian.AppendUint32(loca, uint32(len(glyf)))
data, err := trueTypeGlyphData(sfnt.Tables, id)
if err != nil {
return nil, err
}
data = bytes.Clone(data)
if len(data) >= 10 && int16(binary.BigEndian.Uint16(data)) < 0 {
for pos := 10; ; {
flags := binary.BigEndian.Uint16(data[pos:])
child := binary.BigEndian.Uint16(data[pos+2:])
binary.BigEndian.PutUint16(data[pos+2:], remap[child])
pos += 6
if flags&1 != 0 {
pos += 2
}
switch flags & 0xc8 {
case 8:
pos += 2
case 0x40:
pos += 4
case 0x80:
pos += 8
}
if flags&0x20 == 0 {
break
}
}
}
glyf = append(glyf, data...)
for len(glyf)%4 != 0 {
glyf = append(glyf, 0)
}
hmtx = binary.BigEndian.AppendUint16(hmtx, sfnt.GlyphAdvance(id))
hmtx = binary.BigEndian.AppendUint16(hmtx, uint16(sfnt.sideBearing(id, false)))
if sfnt.vertical != 0 {
vmtx = binary.BigEndian.AppendUint16(vmtx, sfnt.GlyphVerticalAdvance(id))
vmtx = binary.BigEndian.AppendUint16(vmtx, uint16(sfnt.sideBearing(id, true)))
}
for _, char := range sfnt.glyphCharacters(id) {
mapping[char] = remap[id]
}
}
loca = binary.BigEndian.AppendUint32(loca, uint32(len(glyf)))
table["glyf"], table["loca"], table["hmtx"] = glyf, loca, hmtx
table["cmap"] = buildCmapTable(uint16(len(ids)), mapping)
binary.BigEndian.PutUint16(table["head"][50:], 1)
binary.BigEndian.PutUint16(table["hhea"][34:], uint16(len(ids)))
binary.BigEndian.PutUint16(table["maxp"][4:], uint16(len(ids)))
if len(table["post"]) >= 32 {
table["post"] = table["post"][:32]
binary.BigEndian.PutUint32(table["post"], 0x30000)
}
if sfnt.vertical != 0 {
table["vmtx"] = vmtx
binary.BigEndian.PutUint16(table["vhea"][34:], uint16(len(ids)))
}
return serializeOTF(table)
}