feat(电子公文): 支持标引解析与原文定位

ofdgo_structure_target.go

@@ -0,0 +1,105 @@
+// 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 "context"
+
+// structureVisitor 按引用收集图元及复合图元成员的原文和页面范围
+type structureVisitor struct {
+	ctx      context.Context
+	renderer *Renderer
+	targets  map[string]*StructureTarget
+	stack    []*StructureTarget
+}
+
+// BeginObject 记录当前图元的标引目标，使复合图元引用覆盖其成员
+// 入参: object 页面图元
+// 返回: bool 是否需要配对结束通知
+func (v *structureVisitor) BeginObject(object *GraphicObject) bool {
+	target := v.targets[editorResourceID(editorObjectID(*object))]
+	if target != nil {
+		target.Error = ""
+	}
+	v.stack = append(v.stack, target)
+	return true
+}
+
+// EndObject 结束当前图元的标引收集
+func (v *structureVisitor) EndObject() {
+	v.stack = v.stack[:len(v.stack)-1]
+}
+
+// BeginAnnotation 不为注解容器建立额外标引层级
+// 入参: id 注解标识
+// 返回: bool 始终为false
+func (v *structureVisitor) BeginAnnotation(id string) bool { return false }
+
+// SkipObjects 不使用渲染对象序号，隐藏成员不占用额外状态
+// 入参: count 跳过的图元数
+func (v *structureVisitor) SkipObjects(count int) {}
+
+// IncludeHidden 保留隐藏图元的结构语义，但不为其生成可见范围
+// 返回: bool 始终为true
+func (v *structureVisitor) IncludeHidden() bool { return true }
+
+// SkipClips 保留裁剪语义，以可见范围定位图元
+// 返回: bool 始终为false
+func (v *structureVisitor) SkipClips() bool { return false }
+
+// DrawObject 按继承变换和裁剪度量被引用的图元，不解码图片像素
+// 入参: object 页面图元, state 继承状态
+// 返回: error 度量或取消错误
+func (v *structureVisitor) DrawObject(object *GraphicObject, state RenderState) error {
+	if err := v.ctx.Err(); err != nil {
+		return err
+	}
+	wanted := false
+	for _, target := range v.stack {
+		wanted = wanted || target != nil
+	}
+	if !wanted {
+		return nil
+	}
+	var box Box
+	if !state.Hidden {
+		result, err := v.renderer.MeasureObject(*object, MeasureOptions{Defaults: state.Defaults, Parent: state.Parent, BoundaryInCTM: state.BoundaryInCTM, Clip: state.Clip})
+		if err != nil {
+			return err
+		}
+		box = result.Bounds
+	}
+	var text string
+	if object.Type == "TextObject" {
+		text = object.TextObject.Text()
+	}
+	for _, target := range v.stack {
+		if target == nil {
+			continue
+		}
+		target.Bounds = unionTextBox(target.Bounds, box)
+		if text != "" {
+			if target.Text != "" {
+				target.Text += "\n"
+			}
+			target.Text += text
+		}
+	}
+	return nil
+}
+
+// DrawStamp 不将签章外观混入正文标引
+// 入参: stamp 签章外观
+// 返回: error 取消错误
+func (v *structureVisitor) DrawStamp(stamp Stamp) error { return v.ctx.Err() }