refactor(重构提升): 优化转换渲染与资源压缩

ofdgo_pdf_clip_group.go

@@ -0,0 +1,138 @@
+// 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 (
+	"reflect"
+)
+
+// sharedClipObjects 将连续重复的大裁剪区提取为复合对象，保留页面坐标和绘制顺序
+// 入参: objects 本库生成且尚未分配标识的对象
+// 返回: []GraphicObject 提取后的对象, error 资源创建或取消错误
+func (p *pdfImporter) sharedClipObjects(objects []GraphicObject) ([]GraphicObject, error) {
+	var output []GraphicObject
+	for start := 0; start < len(objects); {
+		if err := p.ctx.Err(); err != nil {
+			return nil, err
+		}
+		clips := pdfPageClip(objects[start])
+		end := start + 1
+		if clips != nil {
+			for end < len(objects) && pdfMatchesPageClip(objects[end], clips) {
+				if err := p.ctx.Err(); err != nil {
+					return nil, err
+				}
+				end++
+			}
+		}
+		if end-start < 2 {
+			if output != nil {
+				output = append(output, objects[start])
+			}
+			start = end
+			continue
+		}
+		if output == nil {
+			output = append(make([]GraphicObject, 0, len(objects)), objects[:start]...)
+		}
+		members := objects[start:end:end]
+		for index := range members {
+			*editorObjectClips(&members[index]) = nil
+		}
+		id, err := p.editor.addOwnedVector(p.ctx, members, p.pageWidth, p.pageHeight)
+		if err != nil {
+			return nil, err
+		}
+		output = append(output, GraphicObject{Type: "CompositeObject", CompositeGraphicUnit: CompositeGraphicUnit{
+			Boundary: pdfBoundary(Box{W: p.pageWidth, H: p.pageHeight}), ResourceID: id, Clips: clips,
+		}})
+		start = end
+	}
+	if output == nil {
+		return objects, nil
+	}
+	return output, nil
+}
+
+// pdfPageClip 将导入裁剪区还原到页面坐标，仅提取包含大量重复路径数据的裁剪
+// 入参: object 导入对象
+// 返回: *Clips 页面坐标裁剪，不满足提取条件时为空
+func pdfPageClip(object GraphicObject) *Clips {
+	if object.Type != "TextObject" && object.Type != "PathObject" && object.Type != "ImageObject" {
+		return nil
+	}
+	clips := *editorObjectClips(&object)
+	if clips == nil || clips.TransFlag == nil || *clips.TransFlag || len(clips.Clip) == 0 {
+		return nil
+	}
+	boundary, _ := editorGeometry(object)
+	box, err := ParseBox(boundary)
+	if err != nil {
+		return nil
+	}
+	translation := ""
+	if box.X != 0 || box.Y != 0 {
+		translation = pdfNumbers(1, 0, 0, 1, -box.X, -box.Y)
+	}
+	bytes := 0
+	result := &Clips{TransFlag: clips.TransFlag, Clip: make([]Clip, len(clips.Clip))}
+	for index, clip := range clips.Clip {
+		if len(clip.Area) != 1 || clip.Area[0].CTM != translation {
+			return nil
+		}
+		area := clip.Area[0]
+		area.CTM = ""
+		result.Clip[index].Area = []ClipArea{area}
+		for _, path := range area.Path {
+			bytes += len(path.AbbreviatedData)
+		}
+	}
+	if bytes < 2048 {
+		return nil
+	}
+	return result
+}
+
+// pdfMatchesPageClip 比较页面坐标裁剪，不将相同外接矩形视为相同路径
+// 入参: object 导入对象, pageClip 已还原的裁剪区
+// 返回: bool 是否可共享裁剪区
+func pdfMatchesPageClip(object GraphicObject, pageClip *Clips) bool {
+	if object.Type != "TextObject" && object.Type != "PathObject" && object.Type != "ImageObject" {
+		return false
+	}
+	clips := *editorObjectClips(&object)
+	if clips == nil || clips.TransFlag == nil || *clips.TransFlag || len(clips.Clip) != len(pageClip.Clip) {
+		return false
+	}
+	boundary, _ := editorGeometry(object)
+	box, err := ParseBox(boundary)
+	if err != nil {
+		return false
+	}
+	translation := ""
+	if box.X != 0 || box.Y != 0 {
+		translation = pdfNumbers(1, 0, 0, 1, -box.X, -box.Y)
+	}
+	for index, clip := range clips.Clip {
+		if len(clip.Area) != 1 || clip.Area[0].CTM != translation {
+			return false
+		}
+		area, expected := clip.Area[0], pageClip.Clip[index].Area[0]
+		if area.DrawParam != expected.DrawParam || !reflect.DeepEqual(area.Path, expected.Path) || !reflect.DeepEqual(area.Text, expected.Text) {
+			return false
+		}
+	}
+	return true
+}