feat(强化兼容): 支持位图和优化字体渲染

ofdgo_font.go

@@ -20,6 +20,7 @@ import (
 
 // FixFontDataAggressive 激进修复字体数据
 // 尝试修复缺失表(OS/2, cmap等)的TrueType字体或包装CFF裸数据
+// 对显式字形映射补充私有字符cmap，便于按glyph id渲染
 // 入参: data 原始字体数据, fixCmap 是否修复cmap, fixName 是否修复name
 // 返回: bool 是否修复, []byte 修复后数据, map[rune]uint16 字符映射, bool 是否缺失cmap, error 错误信息
 func FixFontDataAggressive(data []byte, fixCmap, fixName bool) (bool, []byte, map[rune]uint16, bool, error) {

ofdgo_font_ttf.go

@@ -120,7 +120,7 @@ func fixTrueType(data []byte, fixCmap, fixName bool) (bool, []byte, map[rune]uin
 	if !missingPost && hasBadPostTable(existingTables["post"], numGlyphs, !isCFFSfnt) {
 		missingPost = true
 	}
-	if !missingHead && !missingMaxp && !missingHhea && !missingHmtx &&
+	if !fixCmap && !missingHead && !missingMaxp && !missingHhea && !missingHmtx &&
 		!missingOS2 && !missingCmap && !missingName && !missingPost && !malformedDirectory {
 		return false, data, nil, false, nil
 	}
@@ -166,16 +166,17 @@ func fixTrueType(data []byte, fixCmap, fixName bool) (bool, []byte, map[rune]uin
 		newTables["OS/2"] = buildOS2TableWithMetrics(ascender, descender)
 	}
 	var mapping map[rune]uint16
-	if missingCmap && fixCmap {
-		if isCFFSfnt {
+	if fixCmap {
+		if !missingCmap {
+			mapping = parseCmapMappings(newTables["cmap"])
+		}
+		if len(mapping) == 0 && isCFFSfnt {
 			mapping = getCmapFromCFF(newTables["CFF "], int(numGlyphs))
 		}
 		if len(mapping) == 0 {
 			mapping = make(map[rune]uint16)
-			for i := uint16(0); i < numGlyphs; i++ {
-				mapping[packedGlyphRune(i)] = i
-			}
 		}
+		addPackedGlyphMapping(mapping, numGlyphs)
 		newTables["cmap"] = buildCmapTable(numGlyphs, mapping)
 	}
 	if missingName && fixName {

ofdgo_font_util.go

@@ -76,6 +76,165 @@ func checkMissingCmap(data []byte) bool {
 	return true
 }
 
+// parseCmapMappings 解析 cmap 字符映射
+// 入参: data cmap表数据
+// 返回: map[rune]uint16 字符到字形映射
+func parseCmapMappings(data []byte) map[rune]uint16 {
+	if len(data) < 4 {
+		return nil
+	}
+	numTables := int(binary.BigEndian.Uint16(data[2:4]))
+	result := make(map[rune]uint16)
+	for i := 0; i < numTables; i++ {
+		pos := 4 + i*8
+		if pos+8 > len(data) {
+			break
+		}
+		platformID := binary.BigEndian.Uint16(data[pos : pos+2])
+		if platformID != 0 && platformID != 3 {
+			continue
+		}
+		offset := int(binary.BigEndian.Uint32(data[pos+4 : pos+8]))
+		if offset+2 > len(data) {
+			continue
+		}
+		switch binary.BigEndian.Uint16(data[offset : offset+2]) {
+		case 0:
+			parseCmapFormat0(data[offset:], result)
+		case 4:
+			parseCmapFormat4(data[offset:], result)
+		case 6:
+			parseCmapFormat6(data[offset:], result)
+		case 12:
+			parseCmapFormat12(data[offset:], result)
+		}
+	}
+	if len(result) == 0 {
+		return nil
+	}
+	return result
+}
+
+// parseCmapFormat0 解析 cmap format 0
+// 入参: data 子表数据, result 字符映射
+func parseCmapFormat0(data []byte, result map[rune]uint16) {
+	if len(data) < 262 {
+		return
+	}
+	for i := 0; i < 256; i++ {
+		gid := uint16(data[6+i])
+		if gid != 0 {
+			result[rune(i)] = gid
+		}
+	}
+}
+
+// parseCmapFormat4 解析 cmap format 4
+// 入参: data 子表数据, result 字符映射
+func parseCmapFormat4(data []byte, result map[rune]uint16) {
+	if len(data) < 16 {
+		return
+	}
+	length := int(binary.BigEndian.Uint16(data[2:4]))
+	if length > len(data) {
+		length = len(data)
+	}
+	segCount := int(binary.BigEndian.Uint16(data[6:8]) / 2)
+	endPos := 14
+	startPos := endPos + segCount*2 + 2
+	deltaPos := startPos + segCount*2
+	rangePos := deltaPos + segCount*2
+	if rangePos+segCount*2 > length {
+		return
+	}
+	for i := 0; i < segCount; i++ {
+		end := binary.BigEndian.Uint16(data[endPos+i*2:])
+		start := binary.BigEndian.Uint16(data[startPos+i*2:])
+		delta := int16(binary.BigEndian.Uint16(data[deltaPos+i*2:]))
+		rangeOffsetPos := rangePos + i*2
+		rangeOffset := binary.BigEndian.Uint16(data[rangeOffsetPos:])
+		if start == 0xFFFF && end == 0xFFFF {
+			continue
+		}
+		for c := start; c <= end; c++ {
+			var gid uint16
+			if rangeOffset == 0 {
+				gid = uint16(int(c) + int(delta))
+			} else {
+				gidPos := rangeOffsetPos + int(rangeOffset) + int(c-start)*2
+				if gidPos+2 > length {
+					continue
+				}
+				gid = binary.BigEndian.Uint16(data[gidPos:])
+				if gid != 0 {
+					gid = uint16(int(gid) + int(delta))
+				}
+			}
+			if gid != 0 {
+				result[rune(c)] = gid
+			}
+			if c == 0xFFFF {
+				break
+			}
+		}
+	}
+}
+
+// parseCmapFormat6 解析 cmap format 6
+// 入参: data 子表数据, result 字符映射
+func parseCmapFormat6(data []byte, result map[rune]uint16) {
+	if len(data) < 10 {
+		return
+	}
+	firstCode := int(binary.BigEndian.Uint16(data[6:8]))
+	entryCount := int(binary.BigEndian.Uint16(data[8:10]))
+	for i := 0; i < entryCount && 10+i*2+2 <= len(data); i++ {
+		gid := binary.BigEndian.Uint16(data[10+i*2:])
+		if gid != 0 {
+			result[rune(firstCode+i)] = gid
+		}
+	}
+}
+
+// parseCmapFormat12 解析 cmap format 12
+// 入参: data 子表数据, result 字符映射
+func parseCmapFormat12(data []byte, result map[rune]uint16) {
+	if len(data) < 16 {
+		return
+	}
+	length := int(binary.BigEndian.Uint32(data[4:8]))
+	if length > len(data) {
+		length = len(data)
+	}
+	nGroups := int(binary.BigEndian.Uint32(data[12:16]))
+	for i := 0; i < nGroups; i++ {
+		pos := 16 + i*12
+		if pos+12 > length {
+			break
+		}
+		startChar := binary.BigEndian.Uint32(data[pos:])
+		endChar := binary.BigEndian.Uint32(data[pos+4:])
+		startGID := binary.BigEndian.Uint32(data[pos+8:])
+		for c := startChar; c <= endChar; c++ {
+			gid := startGID + c - startChar
+			if gid != 0 && gid <= 0xFFFF {
+				result[rune(c)] = uint16(gid)
+			}
+			if c == endChar {
+				break
+			}
+		}
+	}
+}
+
+// addPackedGlyphMapping 添加字形ID私有映射
+// 入参: mapping 字符映射, numGlyphs 字形数量
+func addPackedGlyphMapping(mapping map[rune]uint16, numGlyphs uint16) {
+	for i := uint16(0); i < numGlyphs; i++ {
+		mapping[packedGlyphRune(i)] = i
+	}
+}
+
 // buildHeadTable 构建 head 表
 // 入参: unitsPerEm 每em单位数
 // 返回: []byte head表数据

ofdgo_image.go

@@ -0,0 +1,147 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"image"
+	"image/color"
+)
+
+// decodeImageData 解码图片数据
+// 入参: data 图片数据
+// 返回: image.Image 图片对象, string 图片格式, error 错误信息
+func decodeImageData(data []byte) (image.Image, string, error) {
+	img, format, err := image.Decode(bytes.NewReader(data))
+	if err == nil {
+		return img, normalizeSealType(format), nil
+	}
+	if img, err := decodeBMPImage(data); err == nil {
+		return img, "bmp", nil
+	}
+	return nil, "", err
+}
+
+// decodeImageConfigData 解码图片尺寸
+// 入参: data 图片数据
+// 返回: image.Config 图片尺寸, string 图片格式, error 错误信息
+func decodeImageConfigData(data []byte) (image.Config, string, error) {
+	cfg, format, err := image.DecodeConfig(bytes.NewReader(data))
+	if err == nil {
+		return cfg, normalizeSealType(format), nil
+	}
+	if cfg, err := decodeBMPConfig(data); err == nil {
+		return cfg, "bmp", nil
+	}
+	return image.Config{}, "", err
+}
+
+// decodeBMPConfig 解码 BMP 尺寸
+// 入参: data 图片数据
+// 返回: image.Config 图片尺寸, error 错误信息
+func decodeBMPConfig(data []byte) (image.Config, error) {
+	offset, width, height, bpp, compression, err := parseBMPHeader(data)
+	if err != nil {
+		return image.Config{}, err
+	}
+	if offset <= 0 || width <= 0 || height == 0 || compression != 0 {
+		return image.Config{}, fmt.Errorf("unsupported bmp")
+	}
+	if bpp != 16 && bpp != 24 && bpp != 32 {
+		return image.Config{}, fmt.Errorf("unsupported bmp")
+	}
+	if height < 0 {
+		height = -height
+	}
+	return image.Config{ColorModel: color.NRGBAModel, Width: width, Height: height}, nil
+}
+
+// decodeBMPImage 解码 BMP 图片
+// 入参: data 图片数据
+// 返回: image.Image 图片对象, error 错误信息
+func decodeBMPImage(data []byte) (image.Image, error) {
+	offset, width, height, bpp, compression, err := parseBMPHeader(data)
+	if err != nil {
+		return nil, err
+	}
+	if compression != 0 {
+		return nil, fmt.Errorf("unsupported bmp compression")
+	}
+	topDown := height < 0
+	if topDown {
+		height = -height
+	}
+	if width <= 0 || height <= 0 {
+		return nil, fmt.Errorf("invalid bmp size")
+	}
+	rowStride := ((width*int(bpp) + 31) / 32) * 4
+	if offset+rowStride*height > len(data) {
+		return nil, fmt.Errorf("truncated bmp")
+	}
+	img := image.NewNRGBA(image.Rect(0, 0, width, height))
+	for y := 0; y < height; y++ {
+		srcY := y
+		if !topDown {
+			srcY = height - 1 - y
+		}
+		row := data[offset+srcY*rowStride:]
+		for x := 0; x < width; x++ {
+			switch bpp {
+			case 16:
+				v := binary.LittleEndian.Uint16(row[x*2:])
+				img.SetNRGBA(x, y, color.NRGBA{
+					R: uint8(((v >> 10) & 0x1F) * 255 / 31),
+					G: uint8(((v >> 5) & 0x1F) * 255 / 31),
+					B: uint8((v & 0x1F) * 255 / 31),
+					A: 255,
+				})
+			case 24:
+				p := x * 3
+				img.SetNRGBA(x, y, color.NRGBA{R: row[p+2], G: row[p+1], B: row[p], A: 255})
+			case 32:
+				p := x * 4
+				img.SetNRGBA(x, y, color.NRGBA{R: row[p+2], G: row[p+1], B: row[p], A: 255})
+			default:
+				return nil, fmt.Errorf("unsupported bmp")
+			}
+		}
+	}
+	return img, nil
+}
+
+// parseBMPHeader 解析 BMP 文件头
+// 入参: data 图片数据
+// 返回: int 像素偏移, int 宽度, int 高度, uint16 位数, uint32 压缩方式, error 错误信息
+func parseBMPHeader(data []byte) (int, int, int, uint16, uint32, error) {
+	if len(data) < 54 || string(data[:2]) != "BM" {
+		return 0, 0, 0, 0, 0, fmt.Errorf("not bmp")
+	}
+	offset := int(binary.LittleEndian.Uint32(data[10:14]))
+	dibSize := binary.LittleEndian.Uint32(data[14:18])
+	if dibSize < 40 {
+		return 0, 0, 0, 0, 0, fmt.Errorf("unsupported bmp")
+	}
+	width := int(int32(binary.LittleEndian.Uint32(data[18:22])))
+	height := int(int32(binary.LittleEndian.Uint32(data[22:26])))
+	planes := binary.LittleEndian.Uint16(data[26:28])
+	bpp := binary.LittleEndian.Uint16(data[28:30])
+	compression := binary.LittleEndian.Uint32(data[30:34])
+	if planes != 1 {
+		return 0, 0, 0, 0, 0, fmt.Errorf("invalid bmp")
+	}
+	return offset, width, height, bpp, compression, nil
+}

ofdgo_renderer.go

@@ -32,6 +32,7 @@ import (
 	"github.com/tdewolff/canvas/renderers/pdf"
 	"github.com/tdewolff/canvas/renderers/rasterizer"
 	_ "github.com/xiaoqidun/jbig2"
+	_ "golang.org/x/image/bmp"
 )
 
 // Renderer 渲染器实现
@@ -501,7 +502,7 @@ func (r *Renderer) renderImage(ctx *canvas.Context, obj ImageObject, pageH float
 	if err != nil {
 		return
 	}
-	img, _, err := image.Decode(bytes.NewReader(imgData))
+	img, _, err := decodeImageData(imgData)
 	if err != nil {
 		return
 	}
@@ -1420,7 +1421,7 @@ func (r *Renderer) renderStamp(ctx *canvas.Context, s Stamp, pageH float64) {
 		}
 	}
 	if len(s.Data) > 0 {
-		img, _, err := image.Decode(bytes.NewReader(s.Data))
+		img, _, err := decodeImageData(s.Data)
 		if err == nil {
 			img = stampImageWithTransparentWhite(img)
 			ctx.Push()

ofdgo_sign.go

@@ -19,7 +19,6 @@ import (
 	"encoding/asn1"
 	"encoding/binary"
 	"encoding/xml"
-	"image"
 	"strings"
 )
 
@@ -220,6 +219,8 @@ func normalizeSealType(s string) string {
 	switch s {
 	case "jpg":
 		return "jpeg"
+	case "bmp":
+		return "bmp"
 	case "jb2", "gbig2":
 		return "jbig2"
 	default:
@@ -232,7 +233,7 @@ func normalizeSealType(s string) string {
 // 返回: bool 是否可渲染
 func isSealMediaType(s string) bool {
 	switch s {
-	case "png", "jpeg", "jbig2", "ofd":
+	case "png", "jpeg", "bmp", "jbig2", "ofd":
 		return true
 	default:
 		return false
@@ -286,7 +287,7 @@ func zipDataEnd(data []byte) int {
 // 入参: data 原始数据
 // 返回: string 媒体类型, []byte 图片数据
 func probeImageMedia(data []byte) (string, []byte) {
-	_, format, err := image.DecodeConfig(bytes.NewReader(data))
+	_, format, err := decodeImageConfigData(data)
 	if err != nil {
 		return "", nil
 	}