feat(编辑能力): 新增擦除工具，优化字体裁剪与资源清理

ofdgo_editor_erase.go

@@ -0,0 +1,136 @@
+// 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 (
+	"fmt"
+	"math"
+	"reflect"
+	"slices"
+)
+
+// EraseObjects 擦除同页对象与矩形区域重叠的可见部分，一次撤销恢复全部。
+// 全部覆盖时删除对象；局部覆盖使用OFD路径裁剪，保留原文字和资源，不用于敏感信息脱敏。
+// 不改变未相交对象，无法保真编辑时返回错误且不提交修改。
+// 入参: page 页面索引, ids 对象标识, box 页面毫米坐标中的擦除范围
+// 返回: error 错误信息
+func (e *Editor) EraseObjects(page int, ids []string, box Box) error {
+	if _, err := creationBox(editorBoxString(box)); err != nil {
+		return err
+	}
+	objects, indexes, err := e.selectedObjects(page, ids)
+	if err != nil || len(objects) == 0 {
+		return err
+	}
+	boxes, err := e.objectBounds(page, objects)
+	if err != nil {
+		return err
+	}
+	layers := copyEditorPage(e.pages[page]).Content.Layer
+	removed := make(map[string]bool)
+	changed := false
+	for i, object := range objects {
+		bounds := boxes[i]
+		x, y := math.Max(box.X, bounds.X), math.Max(box.Y, bounds.Y)
+		right, bottom := math.Min(box.X+box.W, bounds.X+bounds.W), math.Min(box.Y+box.H, bounds.Y+bounds.H)
+		if right <= x || bottom <= y {
+			continue
+		}
+		if x == bounds.X && y == bounds.Y && right == bounds.X+bounds.W && bottom == bounds.Y+bounds.H {
+			removed[ids[i]] = true
+			changed = true
+			continue
+		}
+		object, err := cloneEditorObject(object)
+		if err != nil {
+			return err
+		}
+		boundary, ctm := editorGeometry(object)
+		frame, _ := ParseBox(boundary)
+		outer := unionTextBox(bounds, frame)
+		outer.X, outer.Y, outer.W, outer.H = outer.X-1, outer.Y-1, outer.W+2, outer.H+2
+		x, y = math.Max(box.X, outer.X), math.Max(box.Y, outer.Y)
+		right, bottom = math.Min(box.X+box.W, outer.X+outer.W), math.Min(box.Y+box.H, outer.Y+outer.H)
+		clips := editorObjectClips(&object)
+		if *clips == nil {
+			*clips = &Clips{}
+		}
+		matrix := IdentityMatrix
+		if (*clips).TransFlag == nil || *(*clips).TransFlag {
+			if object.Type == "ImageObject" && ctm == "" {
+				ctm = Matrix{a: frame.W, d: frame.H}.String()
+			}
+			var ok bool
+			matrix, ok = NewMatrix(ctm).Invert()
+			if !ok {
+				return fmt.Errorf("object %q transform is not invertible", ids[i])
+			}
+		}
+		clip := Clip{}
+		for _, area := range []Box{
+			{X: outer.X, Y: outer.Y, W: outer.W, H: y - outer.Y},
+			{X: outer.X, Y: bottom, W: outer.W, H: outer.Y + outer.H - bottom},
+			{X: outer.X, Y: y, W: x - outer.X, H: bottom - y},
+			{X: right, Y: y, W: outer.X + outer.W - right, H: bottom - y},
+		} {
+			if area.W <= 0 || area.H <= 0 {
+				continue
+			}
+			area.X, area.Y = area.X-frame.X, area.Y-frame.Y
+			path, err := NewShape(ShapeRectangle, area)
+			if err != nil {
+				return err
+			}
+			fill, stroke := true, false
+			path.Fill, path.Stroke = &fill, &stroke
+			clip.Area = append(clip.Area, ClipArea{CTM: matrix.String(), Path: []PathObject{path}})
+		}
+		if slices.ContainsFunc((*clips).Clip, func(previous Clip) bool { return reflect.DeepEqual(previous, clip) }) {
+			continue
+		}
+		(*clips).Clip = append((*clips).Clip, clip)
+		changed = true
+		position := indexes[i]
+		layers[position.layer].Objects[position.index] = object
+	}
+	if changed {
+		for i := range layers {
+			objects := layers[i].Objects[:0]
+			for _, object := range layers[i].Objects {
+				if !removed[editorObjectID(object)] {
+					objects = append(objects, object)
+				}
+			}
+			layers[i].Objects = objects
+		}
+		e.replaceLayers(page, layers)
+	}
+	return nil
+}
+
+// editorObjectClips 获取基本对象的裁剪字段。
+// 入参: object 文字、路径或图片对象
+// 返回: **Clips 裁剪字段地址，不支持的对象返回nil
+func editorObjectClips(object *GraphicObject) **Clips {
+	switch object.Type {
+	case "TextObject":
+		return &object.TextObject.Clips
+	case "PathObject":
+		return &object.PathObject.Clips
+	case "ImageObject":
+		return &object.ImageObject.Clips
+	}
+	return nil
+}