mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
402 lines
14 KiB
Go
402 lines
14 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ofdgo
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"image"
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"image/color"
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"image/png"
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"math"
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"strconv"
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"unicode/utf16"
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"unicode/utf8"
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"github.com/xiaoqidun/pdfgo"
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)
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// image 转换图像样本，不将整页或其他对象栅格化
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// 入参: mark PDF图像绘制信息
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// 返回: error 错误信息
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func (p *pdfImporter) image(mark pdfgo.ImageMark) error {
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if mark.Style.BlendMode == "Multiply" {
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return &pdfgo.UnsupportedError{Feature: "multiply image outside annotation appearance"}
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}
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if err := p.flushPath(); err != nil {
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return err
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}
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if mark.Image.ImageMask && (mark.Style.Fill.Axial != nil || mark.Style.Fill.Radial != nil) {
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return &pdfgo.UnsupportedError{Feature: "gradient stencil image"}
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}
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var err error
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mark.Style, err = p.maskStyle(mark.Style)
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if err != nil {
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return err
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}
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if mark.Style.FillOverprint {
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return &pdfgo.UnsupportedError{Feature: "image color separation overprint"}
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}
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source := mark.Image
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id := p.imageIDs[source.Stream]
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if source.ImageMask {
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id = ""
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}
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if id == "" {
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jbig2Original, err := source.JBIG2File()
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if err != nil {
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return err
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}
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filter, err := p.reader.Resolve(source.Stream.Dictionary["Filter"])
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if err != nil {
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return err
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}
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space, _ := source.ColorSpace.(pdfgo.Name)
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jpegOriginal := filter == pdfgo.Name("DCTDecode") && len(source.Decode) == 0 && !source.ImageMask && (space == "DeviceGray" || space == "DeviceRGB") && source.Mask == nil && source.SoftMask == nil
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var decoded image.Image
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if len(jbig2Original) == 0 {
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decoded, err = source.DecodeImage()
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if err != nil {
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return err
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}
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}
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if source.ImageMask {
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fill := mark.Style.Fill.RGB
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if mark.Style.Fill.CMYK != nil {
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if *mark.Style.Fill.CMYK != [4]float64{} {
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return &pdfgo.UnsupportedError{Feature: "CMYK stencil image"}
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}
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fill = [3]float64{1, 1, 1}
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}
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stencil := image.NewNRGBA64(image.Rect(0, 0, source.Width, source.Height))
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for y := 0; y < source.Height; y++ {
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for x := 0; x < source.Width; x++ {
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gray, _, _, _ := decoded.At(x, y).RGBA()
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stencil.SetNRGBA64(x, y, color.NRGBA64{
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R: uint16(math.Round(fill[0] * 65535)),
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G: uint16(math.Round(fill[1] * 65535)),
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B: uint16(math.Round(fill[2] * 65535)),
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A: uint16(65535 - gray),
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})
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}
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}
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decoded = stencil
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}
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var encoded bytes.Buffer
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if len(jbig2Original) != 0 {
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encoded.Write(jbig2Original)
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} else if jpegOriginal {
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encoded.Write(source.Stream.Data)
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} else {
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if err := png.Encode(&encoded, decoded); err != nil {
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return err
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}
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}
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id, err = p.editor.AddImage(encoded.Bytes())
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if err != nil {
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return err
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}
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if !source.ImageMask {
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if p.imageIDs == nil {
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p.imageIDs = map[*pdfgo.Stream]string{}
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}
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p.imageIDs[source.Stream] = id
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}
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}
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m := p.matrix.Mul(mark.Matrix).Mul(pdfgo.Matrix{1, 0, 0, -1, 0, 1})
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box := pdfBounds([]pdfgo.Point{m.Apply(pdfgo.Point{}), m.Apply(pdfgo.Point{X: 1}), m.Apply(pdfgo.Point{Y: 1}), m.Apply(pdfgo.Point{X: 1, Y: 1})})
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alpha := int(math.Round(mark.Style.Fill.Alpha * 255))
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object := ImageObject{Boundary: pdfBoundary(box), ResourceID: id, CTM: pdfNumbers(m[0], m[1], m[2], m[3], m[4]-box.X, m[5]-box.Y), Alpha: &alpha, Clips: p.clips(mark.Style.Clips, box)}
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p.objects = append(p.objects, GraphicObject{Type: "ImageObject", ImageObject: object})
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p.report.ImageObjects++
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return nil
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}
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// text 保留内嵌字形及逐字基线，外部字体保留名称引用
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// 入参: mark PDF文字绘制信息
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// 返回: error 错误信息
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func (p *pdfImporter) text(mark pdfgo.TextMark) error {
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if mark.Font.Subtype == pdfgo.Name("Type3") {
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if err := p.flushPath(); err != nil {
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return err
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}
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visitor := pdfgo.Visitor{Path: p.path, Image: p.image}
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visitor.Group = func(group pdfgo.GroupMark, walk func(pdfgo.Visitor) error) error {
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return p.group(group, walk, visitor)
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}
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for index := range mark.Glyphs {
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if err := p.reader.WalkType3Glyph(p.ctx, mark, index, visitor); err != nil {
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return err
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}
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}
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return p.flushPath()
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}
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if mark.Style.BlendMode == "Multiply" {
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return &pdfgo.UnsupportedError{Feature: "multiply text"}
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}
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if err := p.flushPath(); err != nil {
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return err
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}
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var err error
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mark.Style, err = p.maskStyle(mark.Style)
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if err != nil {
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return err
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}
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if (mark.Mode == 0 || mark.Mode == 2) && mark.Style.FillOverprint && pdfOverprintNeedsSeparation(mark.Style.Fill) || (mark.Mode == 1 || mark.Mode == 2) && mark.Style.StrokeOverprint && pdfOverprintNeedsSeparation(mark.Style.Stroke) {
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return &pdfgo.UnsupportedError{Feature: "text color separation overprint"}
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}
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font := mark.Font
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embedded := len(font.Program) != 0
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if embedded && font.ProgramType != "FontFile2" && font.ProgramType != "OpenType" && font.ProgramType != "Type1C" && font.ProgramType != "CIDFontType0C" {
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return &pdfgo.UnsupportedError{Feature: "font program " + string(font.ProgramType)}
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}
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id := p.fontIDs[font]
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if id == "" {
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var err error
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if embedded {
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var program []byte
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program, err = pdfFontProgram(font)
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if err != nil {
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return fmt.Errorf("PDF font %s program: %w", font.Name, err)
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}
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id, err = p.editor.AddFont(FontFile{Name: font.Name + ".ttf", Data: program}, 0)
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} else {
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id, err = p.editor.AddExternalFont(font.Name)
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}
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if err != nil {
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return fmt.Errorf("PDF font %s resource: %w", font.Name, err)
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}
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p.fontIDs[font] = id
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}
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var metrics FontMetrics
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var outline FontOutlines
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if embedded {
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metrics = p.fontMetrics[id]
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if metrics == nil {
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if p.editor.backends.Fonts == nil {
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return fmt.Errorf("PDF font backend unavailable")
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}
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metrics, err = p.editor.backends.Fonts.OpenFont(p.editor.fonts[id].Data)
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if err != nil {
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return fmt.Errorf("PDF font %s metrics: %w", font.Name, err)
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}
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p.fontMetrics[id] = metrics
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}
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var ok bool
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outline, ok = metrics.(FontOutlines)
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if !ok {
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return fmt.Errorf("PDF font backend does not provide glyph outlines")
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}
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}
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const unit = 25.4 / 72
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m := p.matrix.Mul(mark.Matrix).Mul(pdfgo.Matrix{1 / unit, 0, 0, -1 / unit, 0, 0})
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var points []pdfgo.Point
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object := TextObject{Font: id, Size: mark.Size * unit, HScale: mark.HorizontalScale}
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position := 0
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for n, glyph := range mark.Glyphs {
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gid := glyph.ID
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if glyph.Text == "" && glyph.HasID {
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character := getUnicodeFromName(glyph.Name)
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if character == 0 {
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character = packedGlyphRune(gid)
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}
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glyph.Text = string(character)
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}
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if embedded && !glyph.HasID {
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if utf8.RuneCountInString(glyph.Text) != 1 {
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return &pdfgo.UnsupportedError{Feature: "simple font glyph ligature mapping"}
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}
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char, _ := utf8.DecodeRuneInString(glyph.Text)
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gid = metrics.GlyphIndex(char)
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if gid == 0 && char != 0 {
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return fmt.Errorf("missing PDF glyph for %U", char)
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}
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}
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if embedded && gid >= metrics.NumGlyphs() {
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return fmt.Errorf("PDF glyph index %d outside embedded font %s (%d glyphs)", gid, font.Name, metrics.NumGlyphs())
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}
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if !embedded && glyph.Text == "" {
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return &pdfgo.UnsupportedError{Feature: "unmapped external font character"}
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}
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origin := mark.Positions[n]
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object.TextCode = append(object.TextCode, TextCode{X: pdfNumbers(origin.X * unit), Y: pdfNumbers(-origin.Y * unit), Value: glyph.Text})
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if embedded {
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count := utf8.RuneCountInString(glyph.Text)
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object.CGTransform = append(object.CGTransform, CGTransform{CodePosition: position, CodeCount: count, GlyphCount: 1, Glyphs: strconv.Itoa(int(gid))})
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position += count
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path, err := outline.GlyphOutline(gid, object.Size)
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if err != nil {
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return err
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}
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bounds, err := path.Bounds()
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if err != nil {
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return err
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}
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for _, point := range []pdfgo.Point{{X: bounds.X, Y: bounds.Y}, {X: bounds.X + bounds.W, Y: bounds.Y}, {X: bounds.X, Y: bounds.Y + bounds.H}, {X: bounds.X + bounds.W, Y: bounds.Y + bounds.H}} {
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points = append(points, m.Apply(pdfgo.Point{X: origin.X*unit + point.X*mark.HorizontalScale, Y: -origin.Y*unit + point.Y}))
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}
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} else {
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width := glyph.Width / 1000 * object.Size * mark.HorizontalScale
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for _, point := range []pdfgo.Point{{X: 0, Y: -object.Size}, {X: width, Y: -object.Size}, {X: 0, Y: object.Size / 4}, {X: width, Y: object.Size / 4}} {
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points = append(points, m.Apply(pdfgo.Point{X: origin.X*unit + point.X, Y: -origin.Y*unit + point.Y}))
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}
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}
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}
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box := pdfBounds(points)
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fill, stroke, visible := mark.Mode == 0 || mark.Mode == 2, mark.Mode == 1 || mark.Mode == 2, mark.Mode != 3
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if stroke {
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scale := math.Sqrt(math.Abs(m[0]*m[3] - m[1]*m[2]))
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if scale == 0 || math.IsNaN(scale) || math.IsInf(scale, 0) {
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return &pdfgo.UnsupportedError{Feature: "degenerate text stroke matrix"}
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}
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margin := mark.Style.LineWidth * unit / 2 * math.Max(1, mark.Style.MiterLimit)
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box = Box{box.X - margin, box.Y - margin, box.W + 2*margin, box.H + 2*margin}
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object.LineWidth = mark.Style.LineWidth * unit / scale
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object.LineWidthSet = object.LineWidth == 0
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object.Join = []string{"Miter", "Round", "Bevel"}[mark.Style.Join]
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object.MiterLimit = mark.Style.MiterLimit
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if len(mark.Style.Dash) > 0 {
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return &pdfgo.UnsupportedError{Feature: "dashed text stroke"}
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}
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}
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object.Boundary = pdfBoundary(box)
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if stroke {
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strokePaint, err := p.paintColor(mark.Style.Stroke, box)
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if err != nil {
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return err
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}
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color := StrokeColor(*strokePaint)
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object.StrokeColor = &color
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}
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if box.X >= p.pageWidth || box.Y >= p.pageHeight || box.X+box.W <= 0 || box.Y+box.H <= 0 {
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visible = false
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}
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object.CTM = pdfNumbers(m[0], m[1], m[2], m[3], m[4]-box.X, m[5]-box.Y)
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object.Fill = &fill
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object.Stroke = &stroke
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object.Visible = &visible
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object.FillColor, err = p.paintColor(mark.Style.Fill, box)
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if err != nil {
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return err
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}
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object.Clips = p.clips(mark.Style.Clips, box)
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p.objects = append(p.objects, GraphicObject{Type: "TextObject", TextObject: object})
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p.report.TextObjects++
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return nil
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}
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// pdfFontProgram 为PDF子集字体补齐封装表，保留字形轮廓和编号
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// 入参: source PDF字体
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// 返回: []byte 封装后的字体数据, error 错误信息
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func pdfFontProgram(source *pdfgo.Font) ([]byte, error) {
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program := source.Program
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bareCFF := len(program) >= 4 && program[0] == 1 && program[1] == 0 && program[2] >= 4 && program[3] >= 1 && program[3] <= 4
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if source.ProgramType == "Type1C" || source.ProgramType == "CIDFontType0C" || bareCFF {
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var err error
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program, _, err = wrapCFFToOTF(source.Program)
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if err != nil {
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return nil, err
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}
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}
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tables, err := fontFileTables(program, 0)
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if err != nil {
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return nil, err
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}
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if len(tables["head"]) < 54 || len(tables["maxp"]) < 6 || len(tables["hhea"]) < 36 || len(tables["hmtx"]) == 0 {
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return nil, fmt.Errorf("embedded PDF font lacks required metrics")
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}
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count := binary.BigEndian.Uint16(tables["maxp"][4:6])
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if count == 0 {
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return nil, fmt.Errorf("embedded PDF font has no glyphs")
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}
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changed := false
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metrics := int(binary.BigEndian.Uint16(tables["hhea"][34:36]))
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if metrics == 0 || metrics > int(count) {
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return nil, fmt.Errorf("invalid embedded PDF font metric count")
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}
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metricLength := 4*metrics + 2*(int(count)-metrics)
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if len(tables["hmtx"]) < metricLength {
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return nil, fmt.Errorf("incomplete embedded PDF font metrics")
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}
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if len(tables["hmtx"]) > metricLength {
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tables["hmtx"] = tables["hmtx"][:metricLength]
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changed = true
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}
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if len(tables["cmap"]) == 0 {
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mapping := map[rune]uint16{}
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for code := range source.Unicode {
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glyphs, err := source.Decode([]byte(code))
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if err != nil {
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return nil, err
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}
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if len(glyphs) != 1 || !glyphs[0].HasID {
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return nil, &pdfgo.UnsupportedError{Feature: "font without explicit glyph mapping"}
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}
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glyph := glyphs[0]
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if utf8.RuneCountInString(glyph.Text) == 1 {
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char, _ := utf8.DecodeRuneInString(glyph.Text)
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if _, exists := mapping[char]; !exists {
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mapping[char] = glyph.ID
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}
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}
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}
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addPackedGlyphMapping(mapping, count)
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tables["cmap"] = buildCmapTable(count, mapping)
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changed = true
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}
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if len(fontNamesFromTable(tables["name"])) == 0 {
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name := utf16.Encode([]rune(source.Name))
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if len(name) == 0 || len(name) > 32767 {
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return nil, fmt.Errorf("PDF font name missing or excessive")
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}
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data := make([]byte, 42+len(name)*2)
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binary.BigEndian.PutUint16(data[2:], 3)
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binary.BigEndian.PutUint16(data[4:], 42)
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for n, id := range []uint16{1, 4, 6} {
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record := data[6+n*12:]
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binary.BigEndian.PutUint16(record, 3)
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binary.BigEndian.PutUint16(record[2:], 1)
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binary.BigEndian.PutUint16(record[4:], 0x409)
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binary.BigEndian.PutUint16(record[6:], id)
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binary.BigEndian.PutUint16(record[8:], uint16(len(name)*2))
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}
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for n, v := range name {
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binary.BigEndian.PutUint16(data[42+n*2:], v)
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}
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tables["name"] = data
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changed = true
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}
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if len(tables["post"]) == 0 {
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tables["post"] = buildPostTable()
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changed = true
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}
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if len(tables["OS/2"]) == 0 {
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hhea := tables["hhea"]
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tables["OS/2"] = buildOS2TableWithMetrics(int16(binary.BigEndian.Uint16(hhea[4:6])), int16(binary.BigEndian.Uint16(hhea[6:8])))
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changed = true
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}
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for _, tag := range []string{"cvt ", "fpgm", "prep"} {
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if data, ok := tables[tag]; ok && len(data) == 0 {
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delete(tables, tag)
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changed = true
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}
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}
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if !changed && len(program)%4 == 0 {
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return program, nil
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}
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return serializeOTF(tables)
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}
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