feat(创建编辑): WebUI新增OFD创建与可视化编辑功能

ofdgo_editor_history.go

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+// 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 "slices"
+
+// editorChange 页面或对象操作及其修订标识
+type editorChange struct {
+	undo   func(*Editor)
+	redo   func(*Editor)
+	before uint64
+	after  uint64
+}
+
+// SetHistoryLimit 设置撤销和重做记录的总上限，默认关闭，非正数关闭并释放记录
+// 缩减上限时优先保留最近的撤销记录，不影响当前文档及修订标识
+// 记录页面和对象操作，不包含Info的直接修改及字体、图片注册，资源继续共享
+// 入参: limit 最大记录数
+func (e *Editor) SetHistoryLimit(limit int) {
+	e.historyLimit = max(0, limit)
+	if e.historyLimit == 0 {
+		e.history = nil
+		e.historyIndex = 0
+		return
+	}
+	if len(e.history) > e.historyLimit {
+		start := max(0, e.historyIndex-e.historyLimit)
+		end := min(len(e.history), start+e.historyLimit)
+		e.history = slices.Clone(e.history[start:end])
+		e.historyIndex -= start
+	}
+}
+
+// CanUndo 判断是否有可撤销的操作
+// 返回: bool 是否可以撤销
+func (e *Editor) CanUndo() bool {
+	return e.historyIndex > 0
+}
+
+// CanRedo 判断是否有可重做的操作
+// 返回: bool 是否可以重做
+func (e *Editor) CanRedo() bool {
+	return e.historyIndex < len(e.history)
+}
+
+// Undo 撤销最近一次页面或对象操作，保留资源和已分配的标识
+// 返回: bool 是否执行了撤销
+func (e *Editor) Undo() bool {
+	if !e.CanUndo() {
+		return false
+	}
+	e.historyIndex--
+	change := e.history[e.historyIndex]
+	change.undo(e)
+	e.revision = change.before
+	return true
+}
+
+// Redo 重做最近一次撤销的操作，新的有效修改会清除重做记录
+// 返回: bool 是否执行了重做
+func (e *Editor) Redo() bool {
+	if !e.CanRedo() {
+		return false
+	}
+	change := e.history[e.historyIndex]
+	change.redo(e)
+	e.historyIndex++
+	e.revision = change.after
+	return true
+}
+
+// Revision 获取页面和对象的当前修订标识，撤销或重做时恢复对应标识
+// Info的直接修改和资源注册不计入修订，标识仅在当前Editor实例内有效
+// 返回: uint64 修订标识
+func (e *Editor) Revision() uint64 {
+	return e.revision
+}
+
+// recordChange 分配修订标识并为已完成的有效修改预留记录
+// 返回: *editorChange 记录，未启用历史时为nil
+func (e *Editor) recordChange() *editorChange {
+	e.serial++
+	change := editorChange{before: e.revision, after: e.serial}
+	e.revision = e.serial
+	if e.historyLimit == 0 {
+		return nil
+	}
+	clear(e.history[e.historyIndex:])
+	e.history = e.history[:e.historyIndex]
+	if len(e.history) == e.historyLimit {
+		copy(e.history, e.history[1:])
+		e.history = e.history[:len(e.history)-1]
+	}
+	e.history = append(e.history, change)
+	e.historyIndex = len(e.history)
+	return &e.history[e.historyIndex-1]
+}
+
+// recordPageAddition 记录新增或复制的页面
+// 入参: index 页面索引
+func (e *Editor) recordPageAddition(index int) {
+	if change := e.recordChange(); change != nil {
+		page := copyEditorPage(e.pages[index])
+		change.undo = func(e *Editor) { e.pages = slices.Delete(e.pages, index, index+1) }
+		change.redo = func(e *Editor) { e.pages = slices.Insert(e.pages, index, copyEditorPage(page)) }
+	}
+}
+
+// copyEditorPage 复制页面容器，共享经校验且按替换方式更新的对象数据
+// 入参: page 页面
+// 返回: PageContent 独立页面容器
+func copyEditorPage(page PageContent) PageContent {
+	page.Content.Layer = slices.Clone(page.Content.Layer)
+	for i := range page.Content.Layer {
+		page.Content.Layer[i].Objects = slices.Clone(page.Content.Layer[i].Objects)
+	}
+	return page
+}
+
+// moveEditorItem 按目标索引移动页面或对象
+// 入参: items 页面或对象序列, from 原索引, to 目标索引
+func moveEditorItem[T any](items []T, from, to int) {
+	item := items[from]
+	if from < to {
+		copy(items[from:to], items[from+1:to+1])
+	} else {
+		copy(items[to+1:from+1], items[to:from])
+	}
+	items[to] = item
+}