feat(后端架构): 完善后端解耦

ofdgo_renderer_stamp_canvas.go

@@ -0,0 +1,125 @@
+// 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"
+	"image"
+
+	"github.com/tdewolff/canvas"
+)
+
+// renderStamp 渲染印章
+// 入参: ctx 画布上下文, s 印章对象, pageH 页面高度
+func (r *Renderer) renderStamp(ctx *canvas.Context, s Stamp, pageH float64) {
+	if r.textOnly {
+		return
+	}
+	if s.Type == "ofd" && len(s.Data) > 0 {
+		if s.Clip != nil {
+			if img := r.renderOFDStampImage(s.Data); img != nil {
+				r.renderStampImage(ctx, stampImageWithTransparentWhite(img), s, pageH)
+			}
+			return
+		}
+		reader, err := NewReader(bytes.NewReader(s.Data), int64(len(s.Data)))
+		if err == nil {
+			defer reader.Close()
+			doc, err := reader.Doc()
+			if err == nil {
+				renderer := r.childRenderer(reader)
+				for _, pageRef := range doc.Pages.Page {
+					content, err := reader.PageContent(pageRef)
+					if err != nil {
+						continue
+					}
+					sealBox, err := renderer.GetPageBox(content)
+					if err != nil {
+						continue
+					}
+					ctx.Push()
+					ctx.Translate(s.Box.X, pageH-(s.Box.Y+s.Box.H))
+					ctx.Scale(s.Box.W/sealBox.W, s.Box.H/sealBox.H)
+					err = renderer.renderCanvasPageToContext(ctx, content, false)
+					ctx.Pop()
+					if err != nil {
+						r.renderError = err
+						return
+					}
+				}
+				return
+			}
+		}
+	}
+	if len(s.Data) > 0 {
+		img, _, err := decodeImageData(s.Data)
+		if err == nil {
+			if r.decodeImages {
+				img = imagePixelSource(img)
+			}
+			r.renderStampImage(ctx, stampImageWithTransparentWhite(img), s, pageH)
+			return
+		}
+	}
+}
+
+// renderOFDStampImage 渲染OFD印章图像
+// 入参: data OFD印章数据
+// 返回: image.Image 印章图像
+func (r *Renderer) renderOFDStampImage(data []byte) image.Image {
+	reader, err := NewReader(bytes.NewReader(data), int64(len(data)))
+	if err != nil {
+		return nil
+	}
+	defer reader.Close()
+	doc, err := reader.Doc()
+	if err != nil {
+		return nil
+	}
+	renderer := r.childRenderer(reader)
+	renderer.decodeImages = true
+	renderer.TransparentBackground = true
+	for _, pageRef := range doc.Pages.Page {
+		content, err := reader.PageContent(pageRef)
+		if err != nil {
+			continue
+		}
+		img, err := renderer.RenderToImage(content)
+		if err != nil {
+			r.renderError = err
+			return nil
+		}
+		return img
+	}
+	return nil
+}
+
+// renderStampImage 渲染印章图像
+// 入参: ctx 画布上下文, img 印章图像, s 印章对象, pageH 页面高度
+func (r *Renderer) renderStampImage(ctx *canvas.Context, img image.Image, s Stamp, pageH float64) {
+	box := s.Box
+	if s.Clip != nil {
+		img = clipStampImage(img, box, *s.Clip)
+		box.X += s.Clip.X
+		box.Y += s.Clip.Y
+		box.W = s.Clip.W
+		box.H = s.Clip.H
+	}
+	ctx.Push()
+	ctx.Translate(box.X, pageH-(box.Y+box.H))
+	ctx.Scale(box.W/float64(img.Bounds().Dx()), box.H/float64(img.Bounds().Dy()))
+	ctx.DrawImage(0, 0, img, canvas.DPMM(1.0))
+	ctx.Pop()
+}