/*
* Copyright 2016. SHENQINCI(沈钦赐)<946736079@qq.com>
*
* 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 ren.qinc.edit;
import android.support.annotation.NonNull;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.widget.EditText;
import java.util.Stack;
/**
* 撤销和恢复撤销
* Created by 沈钦赐 on 16/6/23.
*/
public class PerformEdit {
//操作序号(一次编辑可能对应多个操作，如替换文字，就是删除+插入)
int index;
//撤销栈
Stack<Action> history = new Stack<>();
//恢复栈
Stack<Action> historyBack = new Stack<>();
private Editable editable;
private EditText editText;
//自动操作标志，防止重复回调,导致无限撤销
private boolean flag = false;
public PerformEdit(@NonNull EditText editText) {
CheckNull(editText, "EditText不能为空");
this.editable = editText.getText();
this.editText = editText;
editText.addTextChangedListener(new Watcher());
}
protected void onEditableChanged(Editable s) {
}
protected void onTextChanged(Editable s) {
}
/**
* 清理记录
* Clear history.
*/
public final void clearHistory() {
history.clear();
historyBack.clear();
}
/**
* 撤销
* Undo.
*/
public final void undo() {
if (history.empty()) return;
//锁定操作
flag = true;
Action action = history.pop();
historyBack.push(action);
if (action.isAdd) {
//撤销添加
editable.delete(action.startCursor, action.startCursor + action.actionTarget.length());
editText.setSelection(action.startCursor, action.startCursor);
} else {
//插销删除
editable.insert(action.startCursor, action.actionTarget);
if (action.endCursor == action.startCursor) {
editText.setSelection(action.startCursor + action.actionTarget.length());
} else {
editText.setSelection(action.startCursor, action.endCursor);
}
}
//释放操作
flag = false;
//判断是否是下一个动作是否和本动作是同一个操作，直到不同为止
if (!history.empty() && history.peek().index == action.index) {
undo();
}
}
/**
* 恢复
* Redo.
*/
public final void redo() {
if (historyBack.empty()) return;
flag = true;
Action action = historyBack.pop();
history.push(action);
if (action.isAdd) {
//恢复添加
editable.insert(action.startCursor, action.actionTarget);
if (action.endCursor == action.startCursor) {
editText.setSelection(action.startCursor + action.actionTarget.length());
} else {
editText.setSelection(action.startCursor, action.endCursor);
}
} else {
//恢复删除
editable.delete(action.startCursor, action.startCursor + action.actionTarget.length());
editText.setSelection(action.startCursor, action.startCursor);
}
flag = false;
//判断是否是下一个动作是否和本动作是同一个操作
if (!historyBack.empty() && historyBack.peek().index == action.index)
redo();
}
/**
* 首次设置文本
* Set default text.
*/
public final void setDefaultText(CharSequence text) {
clearHistory();
flag = true;
editable.replace(0, editable.length(), text);
flag = false;
}
private class Watcher implements TextWatcher {
/**
* Before text changed.
*
* @param s the s
* @param start the start 起始光标
* @param count the endCursor 选择数量
* @param after the after 替换增加的文字数
*/
@Override
public final void beforeTextChanged(CharSequence s, int start, int count, int after) {
if (flag) return;
int end = start + count;
if (end > start && end <= s.length()) {
CharSequence charSequence = s.subSequence(start, end);
//删除了文字
if (charSequence.length() > 0) {
Action action = new Action(charSequence, start, false);
if (count > 1) {
//如果一次超过一个字符，说名用户选择了，然后替换或者删除操作
action.setSelectCount(count);
} else if (count == 1 && count == after) {
//一个字符替换
action.setSelectCount(count);
}
//还有一种情况:选择一个字符,然后删除(暂时没有考虑这种情况)
history.push(action);
historyBack.clear();
action.setIndex(++index);
}
}
}
/**
* On text changed.
*
* @param s the s
* @param start the start 起始光标
* @param before the before 选择数量
* @param count the endCursor 添加的数量
*/
@Override
public final void onTextChanged(CharSequence s, int start, int before, int count) {
if (flag) return;
int end = start + count;
if (end > start) {
CharSequence charSequence = s.subSequence(start, end);
//添加文字
if (charSequence.length() > 0) {
Action action = new Action(charSequence, start, true);
history.push(action);
historyBack.clear();
if (before > 0) {
//文字替换（先删除再增加），删除和增加是同一个操作，所以不需要增加序号
action.setIndex(index);
} else {
action.setIndex(++index);
}
}
}
}
@Override
public final void afterTextChanged(Editable s) {
if (flag) return;
if (s != editable) {
editable = s;
onEditableChanged(s);
}
PerformEdit.this.onTextChanged(s);
}
}
private class Action {
/** 改变字符. */
CharSequence actionTarget;
/** 光标位置. */
int startCursor;
int endCursor;
/** 标志增加操作. */
boolean isAdd;
/** 操作序号. */
int index;
public Action(CharSequence actionTag, int startCursor, boolean add) {
this.actionTarget = actionTag;
this.startCursor = startCursor;
this.endCursor = startCursor;
this.isAdd = add;
}
public void setSelectCount(int count) {
this.endCursor = endCursor + count;
}
public void setIndex(int index) {
this.index = index;
}
}
private static void CheckNull(Object o, String message) {
if (o == null) throw new IllegalStateException(message);
}
}