feat(转换服务): 完善PDF印章并提速
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xiaoqidun committed 2026-09-25 23:21:24 +08:00
1 parent 725ea0eceb
commit 7624d2dc91
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@@ -22,10 +22,223 @@ import (
"image/color"
"image/png"
"math"
"strconv"
"strings"
"time"
"github.com/xiaoqidun/pdfgo"
)
// stampAnnotation 将PDF印章外观转换为OFD注解
// 入参: ctx取消上下文, page PDF页面, annotation PDF印章
// 返回: error 外观或转换错误
func (p *pdfImporter) stampAnnotation(ctx context.Context, page *pdfgo.Page, annotation pdfgo.Annotation) error {
flags := int64(0)
if value := annotation.Dictionary["F"]; value != nil {
resolved, err := p.reader.Resolve(value)
if err != nil {
return err
}
number, ok := resolved.(pdfgo.Integer)
if !ok {
return fmt.Errorf("invalid PDF annotation flags")
}
flags = int64(number)
}
box := pdfBounds([]pdfgo.Point{
p.matrix.Apply(pdfgo.Point{X: annotation.Rect.XMin, Y: annotation.Rect.YMin}),
p.matrix.Apply(pdfgo.Point{X: annotation.Rect.XMax, Y: annotation.Rect.YMin}),
p.matrix.Apply(pdfgo.Point{X: annotation.Rect.XMax, Y: annotation.Rect.YMax}),
p.matrix.Apply(pdfgo.Point{X: annotation.Rect.XMin, Y: annotation.Rect.YMax}),
})
stamp := *p
stamp.matrix = (pdfgo.Matrix{1, 0, 0, 1, -box.X, -box.Y}).Mul(p.matrix)
stamp.objects = nil
stamp.pendingPath = nil
stamp.report = PDFImportReport{}
var darkenImages []pdfgo.ImageMark
visitor := pdfgo.Visitor{
Path: func(mark pdfgo.PathMark) error {
if mark.Style.BlendMode == "Darken" {
return &pdfgo.UnsupportedError{Feature: "darken stamp path"}
}
return stamp.path(mark)
},
Text: func(mark pdfgo.TextMark) error {
if mark.Style.BlendMode == "Darken" {
return &pdfgo.UnsupportedError{Feature: "darken stamp text"}
}
if err := stamp.text(mark); err != nil {
return fmt.Errorf("stamp text: %w", err)
}
return nil
},
Image: func(mark pdfgo.ImageMark) error {
if mark.Style.BlendMode == "Darken" {
darkenImages = append(darkenImages, mark)
return nil
}
return stamp.image(mark)
},
}
visitor.Group = func(group pdfgo.GroupMark, walk func(pdfgo.Visitor) error) error {
return stamp.group(group, walk, visitor)
}
if err := p.reader.WalkAnnotationAppearance(ctx, page, annotation, visitor); err != nil {
return err
}
if err := stamp.flushPath(); err != nil {
return err
}
if len(darkenImages) != 0 {
if len(darkenImages) != 1 || len(stamp.objects) != 0 {
return &pdfgo.UnsupportedError{Feature: "mixed darken stamp appearance"}
}
if err := p.darkenStampAppearance(page, box, darkenImages[0], &stamp); err != nil {
return err
}
p.report.Warnings = append(p.report.Warnings, pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF darken stamp appearance flattened over page content"})
}
converted := Annotation{Type: "Stamp", Appearance: Appearance{Boundary: pdfBoundary(box), Objects: stamp.objects}}
if flags&(1|2|32) != 0 {
visible := false
converted.Visible = &visible
}
converted.NoZoom = flags&8 != 0
converted.NoRotate = flags&16 != 0
if value := annotation.Dictionary["T"]; value != nil {
resolved, err := p.reader.Resolve(value)
if err != nil {
return err
}
creator, ok := resolved.(pdfgo.String)
if !ok {
return fmt.Errorf("invalid PDF stamp creator")
}
converted.Creator, err = pdfgo.DecodeTextString(creator)
if err != nil {
return err
}
}
if value := annotation.Dictionary["M"]; value != nil {
resolved, err := p.reader.Resolve(value)
if err != nil {
return err
}
encoded, ok := resolved.(pdfgo.String)
if !ok {
return fmt.Errorf("invalid PDF stamp modification date")
}
date, err := pdfgo.DecodeTextString(encoded)
if err != nil {
return err
}
date = strings.TrimPrefix(date, "D:")
if len(date) < 4 {
return fmt.Errorf("invalid PDF stamp modification date")
}
year, err := strconv.Atoi(date[:4])
if err != nil {
return fmt.Errorf("invalid PDF stamp modification date: %w", err)
}
month, day := 1, 1
if len(date) >= 6 {
month, err = strconv.Atoi(date[4:6])
if err != nil {
return fmt.Errorf("invalid PDF stamp modification month: %w", err)
}
}
if len(date) >= 8 {
day, err = strconv.Atoi(date[6:8])
if err != nil {
return fmt.Errorf("invalid PDF stamp modification day: %w", err)
}
}
parsed := time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.UTC)
if parsed.Year() != year || int(parsed.Month()) != month || parsed.Day() != day {
return fmt.Errorf("invalid PDF stamp modification date")
}
converted.LastModDate = parsed.Format("2006-01-02")
if len(date) > 8 {
p.report.Warnings = append(p.report.Warnings, pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF stamp modification time cannot fit OFD annotation date"})
}
}
if _, err := p.editor.AddAnnotation(p.page, converted); err != nil {
return fmt.Errorf("stamp annotation: %w", err)
}
p.report.TextObjects += stamp.report.TextObjects
p.report.PathObjects += stamp.report.PathObjects
p.report.ImageObjects += stamp.report.ImageObjects
if flags&64 != 0 {
p.report.Warnings = append(p.report.Warnings, pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF stamp read-only flag not transferred"})
}
return nil
}
// darkenStampAppearance 按PDF的Darken公式合成印章范围
// 入参: page PDF页面, box印章范围, mark图像, stamp局部转换器
// 返回: error 转换错误
func (p *pdfImporter) darkenStampAppearance(page *pdfgo.Page, box Box, mark pdfgo.ImageMark, stamp *pdfImporter) error {
if err := p.commitObjects(); err != nil {
return err
}
base, err := renderImportedPage(p.editor, p.page, false)
if err != nil {
return err
}
_, width, height := pdfPageMatrix(page)
appearance := NewEditor()
appearance.SetRenderBackends(p.editor.backends)
if _, err := appearance.AddPage(width, height); err != nil {
return err
}
imageImporter := pdfImporter{reader: p.reader, editor: appearance, matrix: p.matrix, pageBox: page.CropBox}
mark.Style.BlendMode = "Normal"
if err := imageImporter.image(mark); err != nil {
return err
}
if _, err := appearance.CopyObjects(0, imageImporter.objects, 0, 0); err != nil {
return err
}
overlay, err := renderImportedPage(appearance, 0, true)
if err != nil {
return err
}
if base.Bounds() != overlay.Bounds() {
return fmt.Errorf("stamp appearance page size mismatch")
}
const dpi = 300.0
pixelsPerMM := dpi / 25.4
region := image.Rect(int(math.Floor(box.X*pixelsPerMM)), int(math.Floor(box.Y*pixelsPerMM)), int(math.Ceil((box.X+box.W)*pixelsPerMM)), int(math.Ceil((box.Y+box.H)*pixelsPerMM))).Intersect(base.Bounds())
if region.Empty() {
return fmt.Errorf("stamp appearance outside page")
}
composite := image.NewRGBA(image.Rect(0, 0, region.Dx(), region.Dy()))
for y := region.Min.Y; y < region.Max.Y; y++ {
for x := region.Min.X; x < region.Max.X; x++ {
background := color.NRGBAModel.Convert(base.At(x, y)).(color.NRGBA)
foreground := color.NRGBAModel.Convert(overlay.At(x, y)).(color.NRGBA)
alpha := float64(foreground.A) / 255
blend := func(back, front uint8) uint8 {
return uint8(math.Round((1-alpha)*float64(back) + alpha*math.Min(float64(back), float64(front))))
}
composite.SetRGBA(x-region.Min.X, y-region.Min.Y, color.RGBA{R: blend(background.R, foreground.R), G: blend(background.G, foreground.G), B: blend(background.B, foreground.B), A: 255})
}
}
var encoded bytes.Buffer
if err := png.Encode(&encoded, composite); err != nil {
return err
}
id, err := p.editor.AddImage(encoded.Bytes())
if err != nil {
return err
}
regionBox := Box{X: float64(region.Min.X)/pixelsPerMM - box.X, Y: float64(region.Min.Y)/pixelsPerMM - box.Y, W: float64(region.Dx()) / pixelsPerMM, H: float64(region.Dy()) / pixelsPerMM}
stamp.objects = append(stamp.objects, GraphicObject{Type: "ImageObject", ImageObject: ImageObject{Boundary: pdfBoundary(regionBox), ResourceID: id}})
stamp.report.ImageObjects++
return nil
}
// signatureWidget 转换可见签名外观,不将PDF签名误写成OFD签名
// 入参: ctx 取消上下文, page PDF页面, annotation 签名控件
// 返回: error 外观或转换错误
@@ -90,7 +303,7 @@ func (p *pdfImporter) multiplySignatureAppearance(page *pdfgo.Page, annotation p
if err := p.commitObjects(); err != nil {
return err
}
base, err := renderImportedPage(p.editor, p.page)
base, err := renderImportedPage(p.editor, p.page, false)
if err != nil {
return err
}
@@ -108,7 +321,7 @@ func (p *pdfImporter) multiplySignatureAppearance(page *pdfgo.Page, annotation p
if _, err := appearance.CopyObjects(0, stamp.objects, 0, 0); err != nil {
return err
}
overlay, err := renderImportedPage(appearance, 0)
overlay, err := renderImportedPage(appearance, 0, false)
if err != nil {
return err
}
@@ -156,9 +369,9 @@ func (p *pdfImporter) multiplySignatureAppearance(page *pdfgo.Page, annotation p
}
// renderImportedPage 在固定印刷分辨率绘制待合成页面
// 入参: editor 编辑文档, page 页序号
// 入参: editor 编辑文档, page 页序号, transparent 是否保留透明背景
// 返回: image.Image 页面像素, error 渲染错误
func renderImportedPage(editor *Editor, page int) (image.Image, error) {
func renderImportedPage(editor *Editor, page int, transparent bool) (image.Image, error) {
reader, err := editor.Reader()
if err != nil {
return nil, err
@@ -168,5 +381,7 @@ func renderImportedPage(editor *Editor, page int) (image.Image, error) {
if err != nil {
return nil, err
}
return NewRenderer(reader, WithDPI(300), WithRenderBackends(editor.backends)).RenderToImage(content)
renderer := NewRenderer(reader, WithDPI(300), WithRenderBackends(editor.backends), WithAnnotations(!transparent))
renderer.TransparentBackground = transparent
return renderer.RenderToImage(content)
}