feat(印章渲染): 加强印章渲染兼容性

ofdgo_renderer.go

@@ -92,13 +92,22 @@ func (r *Renderer) GetPageBox(page *PageContent) (Box, error) {
 // 入参: ctx 画布上下文, page 页面内容
 // 返回: error 错误信息
 func (r *Renderer) RenderPageToContext(ctx *canvas.Context, page *PageContent) error {
+	return r.renderPageToContext(ctx, page, true)
+}
+
+// renderPageToContext 渲染页面到指定上下文
+// 入参: ctx 画布上下文, page 页面内容, drawBackground 是否绘制页面背景
+// 返回: error 错误信息
+func (r *Renderer) renderPageToContext(ctx *canvas.Context, page *PageContent, drawBackground bool) error {
 	box, err := r.GetPageBox(page)
 	if err != nil {
 		return err
 	}
 	pageH := box.H
+	if drawBackground {
 		ctx.SetFillColor(canvas.White)
 		ctx.DrawPath(0, 0, canvas.Rectangle(box.W, box.H))
+	}
 	if len(page.Template) > 0 && r.Reader.doc != nil {
 		for _, tplRef := range page.Template {
 			if tplRef.ZOrder != "Foreground" {
@@ -1058,7 +1067,7 @@ func (r *Renderer) renderStamp(ctx *canvas.Context, s Stamp, pageH float64) {
 					ctx.Push()
 					ctx.Translate(x, screenY)
 					ctx.Scale(w/sealBox.W, h/sealBox.H)
-					renderer.RenderPageToContext(ctx, content)
+					renderer.renderPageToContext(ctx, content, false)
 					ctx.Pop()
 				}
 				return

ofdgo_sign.go

@@ -19,7 +19,6 @@ import (
 	"encoding/asn1"
 	"encoding/binary"
 	"encoding/xml"
-	"path"
 	"strings"
 )
 
@@ -77,7 +76,7 @@ func (r *Reader) parseSignatures(doc *Document) error {
 	}
 	for _, sigRef := range signatures.List {
 		func(sigRef OFDSignature) {
-			sigPath := path.Join(path.Dir(doc.Signatures), sigRef.BaseLoc)
+			sigPath := resolveResourcePath(doc.Signatures, "", sigRef.BaseLoc)
 			sf, err := r.openFile(sigPath)
 			if err != nil {
 				return
@@ -90,17 +89,20 @@ func (r *Reader) parseSignatures(doc *Document) error {
 			var sealType string
 			var sealData []byte
 			if sigFile.SignedInfo.Seal.BaseLoc != "" {
-				sealPath := path.Join(path.Dir(sigPath), sigFile.SignedInfo.Seal.BaseLoc)
+				sealPath := resolveResourcePath(sigPath, "", sigFile.SignedInfo.Seal.BaseLoc)
 				if data, err := r.ResData(sealPath); err == nil {
 					sealType, sealData = extractSeal(data)
 				}
 			}
 			if len(sealData) == 0 && sigFile.SignedValue != "" {
-				signedValuePath := path.Join(path.Dir(sigPath), sigFile.SignedValue)
+				signedValuePath := resolveResourcePath(sigPath, "", sigFile.SignedValue)
 				if data, err := r.ResData(signedValuePath); err == nil {
 					sealType, sealData = extractSeal(data)
 				}
 			}
+			if len(sealData) == 0 {
+				return
+			}
 			for _, annot := range sigFile.SignedInfo.StampAnnot {
 				pageID := annot.PageRef
 				bbox, _ := ParseBox(annot.Boundary)
@@ -210,7 +212,9 @@ func extractImageData(data []byte) (string, []byte) {
 		}
 	}
 	if idx := bytes.Index(data, []byte("PK\x03\x04")); idx >= 0 {
-		return "ofd", data[idx:]
+		if end := zipDataEnd(data[idx:]); end > 0 {
+			return "ofd", data[idx : idx+end]
+		}
 	}
 	return "", nil
 }
@@ -237,6 +241,27 @@ func pngDataEnd(data []byte) int {
 	return 0
 }
 
+// zipDataEnd 获取ZIP数据结束位置
+// 入参: data ZIP数据
+// 返回: int 结束位置
+func zipDataEnd(data []byte) int {
+	if len(data) < 4 || !bytes.Equal(data[:4], []byte("PK\x03\x04")) {
+		return 0
+	}
+	sig := []byte("PK\x05\x06")
+	for i := len(data) - 22; i >= 0; i-- {
+		if i+22 > len(data) || !bytes.Equal(data[i:i+4], sig) {
+			continue
+		}
+		commentLen := int(binary.LittleEndian.Uint16(data[i+20 : i+22]))
+		end := i + 22 + commentLen
+		if end <= len(data) {
+			return end
+		}
+	}
+	return 0
+}
+
 // Stamp 印章信息结构
 type Stamp struct {
 	Box  Box