Qt——文本编辑器中的功能交互

sycmancia2026-04-28 11:22

1.QPlainTextEdit能够触发与编辑操作相关的信号

  • void textChanged() 文本内容发生改变时触发
  • void copyAvailable(bool) 自动控制菜单栏里的 复制按钮 变灰 / 可用
  • void cursorPositionChanged() 光标换位置了，你可以更新状态栏行列号了
  • void redoAvailable(bool) 控制菜单 重做能否点击
  • void undoAvailable(bool) 控制菜单 撤销能否点击

2.判断编辑器是否有未保存的文本？

  1. 定义槽函数void onTextChanged()
  2. 映射textChanged()到槽函数
  3. 定义成员变量bool m_isTextChanged = false;
  4. 文本框中的字符发生变化时：m_isTextChanged = true;
  5. 当m_isTextChanged为真时，则存在未保存的数据

完善这一系列函数后

MainWindow.h

复制代码 
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QKeySequence> //快捷键
#include <QMenuBar> //菜单栏
#include <QAction> //菜单动作
#include <QToolBar>
#include <QPlainTextEdit>
#include <QLabel>
#include <QFileDialog>

class MainWindow : public QMainWindow
{
    Q_OBJECT

private:
    QPlainTextEdit mainEditor;
    QLabel statusLbl;
    QString m_filePath;
    bool m_isTextChanged;

    MainWindow();
    MainWindow(const MainWindow&); //拷贝构造函数
    MainWindow& operator= (const MainWindow&);

    bool construct(); // 总初始化函数

    bool initMenuBar(); //初始化菜单栏
    bool initToolBar(); //初始化工具栏
    bool initStatusBar(); //初始化状态栏
    bool initMainEditor(); //初始化文本编辑区

    bool initFileMenu(QMenuBar* mb); //初始化文件菜单
    bool initEditMenu(QMenuBar* mb); //初始化编辑菜单
    bool initFormatMenu(QMenuBar* mb);
    bool initViewMenu(QMenuBar* mb);
    bool initHelpMenu(QMenuBar* mb);

    bool initFileToolItem(QToolBar* tb);
    bool initEditToolItem(QToolBar* tb);
    bool initFormatToolItem(QToolBar* tb);
    bool initViewToolItem(QToolBar* tb);

    bool makeAction(QAction*& action, QWidget* parent, QString text, int key); //创建菜单栏菜单项
    bool makeAction(QAction*& action, QWidget* parent, QString tip, QString icon); //创建工具栏菜单项

    QString showFileDialog(QFileDialog::AcceptMode mode, QString title);
    void showErorrMessage(QString message);
    int showQueryMessage(QString message); //询问对话框
    QString saveCurrentData(QString path = ""); //保存函数
    void preEditorChange(); //文本编辑框中的内容发生改变

public slots:
    void onFileNew(); //新建文件槽函数
    void onFileOpen(); //打开文件槽函数
    void onFileSave(); //保存文件槽函数
    void onFileSaveAs(); //另存为槽函数

    void onTextChanged(); //判断文本是否有改变
public:
    static MainWindow* NewInstance(); //唯一创建窗口的接口
    ~MainWindow();
};

#endif // MAINWINDOW_H

MainWindowSlots.cpp

复制代码 
#include "MainWindow.h"
#include <QFileDialog>
#include <QDebug>
#include <QFile>
#include <QMessageBox>
#include <QTextStream>

void MainWindow::showErorrMessage(QString message){
    QMessageBox msg(this);

    msg.setWindowTitle("Error");
    msg.setText(message);
    msg.setIcon(QMessageBox::Critical);
    msg.setStandardButtons(QMessageBox::Ok);
    msg.exec();
}

int MainWindow::showQueryMessage(QString message)
{
    QMessageBox msg(this);

    msg.setWindowTitle("Query");
    msg.setText(message);
    msg.setIcon(QMessageBox::Question);
    msg.setStandardButtons(QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel);
    return msg.exec();
}

// 参数1：模式（打开/保存） 参数2：对话框标题
QString MainWindow::showFileDialog(QFileDialog::AcceptMode mode, QString title)
{
    QString ret = ""; // 存储最终返回的文件路径，默认空

    QFileDialog fd(this); //创建一个文件对话框对象
    QStringList filters; //创建一个字符串列表 filters，用来存储文件过滤器

    filters.append("Text Files (*.txt)");
    filters.append("All Files (*)");

    fd.setWindowTitle(title); //设置文件对话框的标题
    fd.setAcceptMode(QFileDialog::AcceptOpen); //设置对话框模式为打开文件
    fd.setNameFilters(filters);

    if( mode == QFileDialog::AcceptOpen )
    {
        fd.setFileMode(QFileDialog::ExistingFile); //设置文件选择模式：只能选择已存在的单个文件
    }

    if( fd.exec() == QFileDialog::Accepted ) //如果用户点击了对话框的 "打开" 按钮
    {
        ret = fd.selectedFiles()[0];
    }
    return ret;
}
void MainWindow::preEditorChange()
{
    if(m_isTextChanged)
    {
        int r = showQueryMessage("你是否想要保存数据到文件中？");
        switch(r)
        {
        case QMessageBox::Yes:
            saveCurrentData(m_filePath);
            break;
        case QMessageBox::No:
            m_isTextChanged = false;
            break;
        case QMessageBox::Cancel:
            break;
        }
    }
}
void MainWindow::onFileNew()
{
    preEditorChange();
    if( !m_isTextChanged )
    {
        mainEditor.clear();
        setWindowTitle("NotePad - [ New ]");
        m_filePath = "";
        m_isTextChanged = false;
    }
}
void MainWindow::onFileOpen()
{
    preEditorChange();

    if( !m_isTextChanged )
    {
        QString path = showFileDialog(QFileDialog::AcceptOpen, "Open");
        if( path != "" ) // 如果用户选择了文件（路径不为空）
        {
            QFile file(path); //绑定用户选中的第一个文件路径
            if( file.open(QIODevice::ReadOnly | QIODevice::Text))
            {
                //把读取到的文件内容显示到编辑器中
                mainEditor.setPlainText(QString(file.readAll()));
                file.close();
                m_filePath = path;
                m_isTextChanged = false;
                setWindowTitle("NotePad - [ " + m_filePath + " ]");
            }
            else{
                showErorrMessage(QString("open file error! \n\n") + "\"" + path + "\"");
            }
        }
    }
}
QString MainWindow::saveCurrentData(QString path)
{
    QString ret = path;
    if( ret == "" )
    {
        // 弹出【保存对话框】，让用户选择保存路径
        ret = showFileDialog(QFileDialog::AcceptSave, "Save");
    }
    if( ret != "" ) // 如果用户指定了保存路径
    {
        QFile file(ret); // 创建文件对象
        if( file.open(QIODevice::WriteOnly | QIODevice::Text) )
        {
            QTextStream out(&file);
            out << mainEditor.toPlainText(); // 把编辑器内容写入文件
            file.close();
            setWindowTitle("NotePad - [ " + ret + " ]");
            m_isTextChanged = false;
        }
        else{
            showErorrMessage(QString("Save file error! \n\n") + "\"" + ret + "\"");
            ret = "";
        }
    }
    return ret;
}
void MainWindow::onFileSave()
{
    QString path = saveCurrentData(m_filePath);
    if(path != "")
    {
        m_filePath = path;
    }
}
void MainWindow::onFileSaveAs()
{
    QString path = saveCurrentData(m_filePath);
    if( path != "" )
    {
        m_filePath = path;
    }
}

void MainWindow::onTextChanged()
{
    if( !m_isTextChanged)
    {
        setWindowTitle("*" + windowTitle());
    }
    m_isTextChanged = true;

}

MainWindowUI.cpp

复制代码 
#include "MainWindow.h"
#include <QMenu>
#include <QDebug>
#include <QIcon>
#include <QSize>
#include <QStatusBar>
#include <QLabel>

MainWindow::MainWindow()
{
    setWindowTitle("NotePad - [ New ]");
    m_filePath = "";
    m_isTextChanged = true;
}
MainWindow* MainWindow::NewInstance()
{
    MainWindow* ret = new MainWindow(); //创建对象
    if( (ret == NULL) || !ret->construct() )
    {
        delete ret;
        ret = NULL;
    }
    return ret;
}

bool MainWindow::construct() //初始化
{
    bool ret = true;
    ret = ret && initMenuBar();  // 初始化菜单栏
    ret = ret && initToolBar();
    ret = ret && initStatusBar();
    ret = ret && initMainEditor();
    return ret;
}
bool MainWindow::initMenuBar()
{
    bool ret = true;
    QMenuBar* mb = menuBar(); //获取Qt自带的菜单栏
    ret = ret && initFileMenu(mb); //初始化文件菜单
    ret = ret && initEditMenu(mb);
    ret = ret && initFormatMenu(mb);
    ret = ret && initViewMenu(mb);
    ret = ret && initHelpMenu(mb);
    return ret;
}

bool MainWindow::initToolBar()
{
    bool ret = true;
    QToolBar* tb = addToolBar("Tool Bar");

    tb->setIconSize(QSize(16, 16));
    ret = ret && initFileToolItem(tb);

    tb->addSeparator();
    ret = ret && initEditToolItem(tb);

    tb->addSeparator(); // 创建分隔符
    ret = ret && initFormatToolItem(tb);

    tb->addSeparator();
    ret = ret && initViewToolItem(tb);

    return ret;
}

bool MainWindow::initStatusBar()
{
    bool ret = true;
    QStatusBar* sb = statusBar();
    QLabel* label = new QLabel("hello world");

    if(label != NULL)
    {
        statusLbl.setMinimumWidth(200);
        statusLbl.setAlignment(Qt::AlignCenter);
        statusLbl.setText("Ln: 1    Col: 1");

        label->setMinimumWidth(200);
        label->setAlignment(Qt::AlignCenter);

        sb->addPermanentWidget(new QLabel());
        sb->addPermanentWidget(&statusLbl);
        sb->addPermanentWidget(label);
    }
    else
    {
        ret = false;
    }
    return ret;
}
bool MainWindow::initMainEditor()
{
    bool ret = true;
    mainEditor.setParent(this);
    connect(&mainEditor, SIGNAL(textChanged()), this, SLOT(onTextChanged()));
    setCentralWidget(&mainEditor);
    return ret;
}

bool MainWindow::initFileMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("File(&F)", mb); //创建菜单File(F)，&F表示使用快捷键Alt+F快速打开菜单
    bool ret = (menu != NULL);

    if(ret)
    {
        QAction* action = NULL;
        ret = ret && makeAction(action, menu, "New(&N)", Qt::CTRL + Qt::Key_N); //创建菜单项New,用快捷键Ctrl+N打开New
        if( ret )
        {
            connect(action, SIGNAL(triggered()), this, SLOT(onFileNew()));
            menu->addAction(action); // 把菜单项New放进File菜单中
        }
        ret = ret && makeAction(action, menu, "Open(&O)...", Qt::CTRL + Qt::Key_O);
        if( ret )
        {
            connect(action, SIGNAL(triggered()), this, SLOT(onFileOpen()));
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Save(&S)", Qt::CTRL + Qt::Key_S);
        if( ret )
        {
            connect(action, SIGNAL(triggered()), this, SLOT(onFileSave()));
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Save As(&A)...", 0);
        if( ret )
        {
            connect(action, SIGNAL(triggered()), this, SLOT(onFileSaveAs()));
            menu->addAction(action);
        }
        menu->addSeparator(); //分隔符
        ret = ret && makeAction(action, menu, "Print(&P)...", Qt::CTRL + Qt::Key_P);
        if( ret )
        {
            menu->addAction(action);
        }
        menu->addSeparator(); //分隔符
        ret = ret && makeAction(action, menu, "Exit(X)", Qt::CTRL + Qt::Key_X);
        if( ret )
        {
            menu->addAction(action);
        }
        menu->addSeparator(); //分隔符
    }
    if( ret )
    {
        mb->addMenu(menu); //把File菜单加到菜单栏
        qDebug() << menu->parent();
    }
    else
    {
        delete menu;
    }
    return ret;
}
bool MainWindow::initEditMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("Edit(&E)", mb);
    bool ret = (menu != NULL);

    if(ret)
    {
        QAction* action = NULL;
        ret = ret && makeAction(action, menu, "Undo(U)", Qt::CTRL + Qt::Key_U);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Redo(R)", Qt::CTRL + Qt::Key_R);
        if( ret )
        {
            menu->addAction(action);
        }
        menu->addSeparator();
        ret = ret && makeAction(action, menu, "Cut(T)", Qt::CTRL + Qt::Key_T);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Copy(C)", Qt::CTRL + Qt::Key_C);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Paste(P)", Qt::CTRL + Qt::Key_P);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Delete(L)", Qt::CTRL + Qt::Key_L);
        if( ret )
        {
            menu->addAction(action);
        }
        menu->addSeparator();
        ret = ret && makeAction(action, menu, "Find(F)", Qt::CTRL + Qt::Key_F);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Replace(R)", Qt::CTRL + Qt::Key_R);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Goto(G)", Qt::CTRL + Qt::Key_G);
        if( ret )
        {
            menu->addAction(action);
        }
        menu->addSeparator();
        ret = ret && makeAction(action, menu, "Select All(A)", Qt::CTRL + Qt::Key_A);
        if( ret )
        {
            menu->addAction(action);
        }
    }
    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }
    return ret;
}
bool MainWindow::initFormatMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("Format(&O)", mb);
    bool ret = (menu != NULL);

    if(ret)
    {
        QAction* action = NULL;
        ret = ret && makeAction(action, menu, "Auto Wrap(W)", Qt::CTRL + Qt::Key_W);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Font(F)", Qt::CTRL + Qt::Key_F);
        if( ret )
        {
            menu->addAction(action);
        }
    }
    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }
    return ret;
}
bool MainWindow::initViewMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("View(&V)", mb);
    bool ret = (menu != NULL);

    if(ret)
    {
        QAction* action = NULL;
        ret = ret && makeAction(action, menu, "Tool Bar(T)", Qt::CTRL + Qt::Key_T);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "Status Bar(S)", Qt::CTRL + Qt::Key_S);
        if( ret )
        {
            menu->addAction(action);
        }
    }
    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }
    return ret;
}
bool MainWindow::initHelpMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("Help(&H)", mb);
    bool ret = (menu != NULL);

    if(ret)
    {
        QAction* action = NULL;
        ret = ret && makeAction(action, menu, "User Manual", 0);
        if( ret )
        {
            menu->addAction(action);
        }
        ret = ret && makeAction(action, menu, "About NotePad", 0);
        if( ret )
        {
            menu->addAction(action);
        }
    }
    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }
    return ret;
}
bool MainWindow::initFileToolItem(QToolBar* tb)
{
    bool ret = true;
    QAction* action = NULL;
    ret = ret && makeAction(action, tb, "New", ":Bes/1.png");
    if(ret)
    {
        connect(action, SIGNAL(triggered()), this, SLOT(onFileNew()));
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Open", ":Bes/1.png");
    if(ret)
    {
        connect(action, SIGNAL(triggered()), this, SLOT(onFileOpen()));
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Save", ":Bes/1.png");
    if(ret)
    {
        connect(action, SIGNAL(triggered()), this, SLOT(onFileSave()));
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Save As", ":Bes/1.png");
    if(ret)
    {
        connect(action, SIGNAL(triggered()), this, SLOT(onFileSaveAs()));
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Print", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    return ret;
}

bool MainWindow::initEditToolItem(QToolBar* tb)
{
    bool ret = true;
    QAction* action = NULL;

    ret = ret && makeAction(action, tb, "Undo", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Redo", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Cut", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Copy", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Paste", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Find", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Replace", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Goto", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    return ret;
}
bool MainWindow::initFormatToolItem(QToolBar* tb)
{
    bool ret = true;
    QAction* action = NULL;

    ret = ret && makeAction(action, tb, "Auto Wrap", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    ret = ret && makeAction(action, tb, "Font", ":Bes/1.png");
    if(ret)
    {
        tb->addAction(action);
    }

    return ret;
}
bool MainWindow::initViewToolItem(QToolBar* tb)
{
    bool ret = true;
    QAction* action = NULL;

    ret = ret && makeAction(action, tb, "Tool Bar", ":Bes/1.png");
    if( ret )
    {
        tb->addAction(action);
    }
    ret = ret && makeAction(action, tb, "Status Bar", ":Bes/1.png");
    if( ret )
    {
        tb->addAction(action);
    }

    return ret;
}

bool MainWindow::makeAction(QAction*& action, QWidget* parent, QString text, int key)
{
    bool ret = true;
    action = new QAction(text, parent);
    if( action != NULL )
    {
        action->setShortcut(QKeySequence(key)); //设置快捷键
    }
    else{
        ret = false;
    }
    return ret;
}

bool MainWindow::makeAction(QAction*& action, QWidget* parent, QString tip, QString icon) //创建工具栏菜单项
{
    bool ret = true;
    action = new QAction("", parent);
    if( action != NULL )
    {
        action->setToolTip(tip);
        action->setIcon(QIcon(icon));
    }
    else{
        ret = false;
    }
    return ret;
}
MainWindow::~MainWindow()
{

}
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