首页 > 代码库 > 第46课 查找对话框的功能实现
第46课 查找对话框的功能实现
1. 文本查找功能的核心思想
（1）获取当前光标的位置并作为起始点
（2）向后（前）查找目标第一次出现的位置
（3）通过目标位置以及目标长度在文本框中进行标记
2. QString类中提供的子串查找相关函数
（1）indexOf：从指定位置向后（即字符串末尾位置）查找目标子串的下标位置
（2）lastIndexOf:从指定位置向前（即字符串开始位置）查找目标子串的下标位置
（3）QString类中查找函数所使用的下标位置
QString text = "abcdefcdg"; QString target = "cd"; text.indexOf(target, 1);//从1位置开始向后查找，返回2 text.indexOf(target,-2);//从-2位置向前开始查找，返回6
3. Qt中的光标信息类QTextCursor
（1）文本框中的光标是一个QTextCursor对象
（2）所有与光标相关的信息都通过QTextCursor描述（如光标位置、文本选择等）
QTextCursor c = mainEditor.textCursor(); //获取当前光标 c.setPosition(1); //定位到下标1的位置 c.setPosition(4, QTextCursor::KeepAnchor);//文本选择范围[1,4] mainEditor.setTextCursor(c); //设置光标信息到文本框
4. 查找算法流程图
5. MainWindow与FindDialog之间的关系
【编程实验】查找功能的实现
//main.cpp
#include "MainWindow.h" #include <QApplication> int main(int argc, char *argv[]) { QApplication a(argc, argv); MainWindow* w = MainWindow::NewInstance(); int ret = -1; if(w != NULL) { w->show(); ret = a.exec(); } return ret; }
//FindDialog.h
#ifndef _FINDDIALOG_H_ #define _FINDDIALOG_H_ #include <QDialog> #include <QGridLayout> #include <QHBoxLayout> #include <QLabel> #include <QLineEdit> #include <QPushButton> #include <QRadioButton> #include <QCheckBox> #include <QGroupBox> #include <QPlainTextEdit> #include <QPointer> class FindDialog : public QDialog { Q_OBJECT protected: QGroupBox m_radioGrpBx; QGridLayout m_layout; QHBoxLayout m_hbLayout; QLabel m_findLbl; QLineEdit m_findEdit; QPushButton m_findBtn; QPushButton m_closeBtn; QCheckBox m_matchChkBx; QRadioButton m_forwardBtn; QRadioButton m_backwardBtn; //QPointer的特点： //(1)当QPointer对象本身被销毁时，不会自动销毁智能指针所指的对象。 //(2)当m_pText所指的Qt对象被销毁时，m_pText会被自动设置为NULL， //从而不会造成多次释放内存的错误。 //这两个特点很适合用来设计对象间的松耦合 //注意：m_pText //(1)m_pText本身是一个对象，会在作用域结束会被自动释放。 //(2)其内部重载了delete操作符，使delete m_pText删除的是其所指的对象。 QPointer<QPlainTextEdit> m_pText; void initControl(); void connectSlot(); protected slots: void onFindClicked(); void onCloseClicked(); public: FindDialog(QWidget* parent = 0, QPlainTextEdit* pText = 0); void setPlainTextEdit(QPlainTextEdit* pText); QPlainTextEdit* getPlainTextEdit(); bool event(QEvent* evt); }; #endif // _FINDDIALOG_H_
//FindDialog.cpp
#include "FindDialog.h" #include <QEvent> #include <QMessageBox> #include <QTextCursor> FindDialog::FindDialog(QWidget* parent,QPlainTextEdit* pText):QDialog(parent, Qt::WindowCloseButtonHint | Qt::Drawer) { initControl(); connectSlot(); setWindowTitle("Find"); setPlainTextEdit(pText); } void FindDialog::initControl() { m_findLbl.setText("Find What:"); m_findBtn.setText("Find Next"); m_closeBtn.setText("Close"); m_matchChkBx.setText("Match Case"); m_backwardBtn.setText("Backward"); m_backwardBtn.setChecked(true); m_forwardBtn.setText("Forward"); m_radioGrpBx.setTitle("Direction"); m_hbLayout.addWidget(&m_forwardBtn); m_hbLayout.addWidget(&m_backwardBtn); m_radioGrpBx.setLayout(&m_hbLayout); m_layout.setSpacing(10); m_layout.addWidget(&m_findLbl, 0, 0); m_layout.addWidget(&m_findEdit, 0, 1); m_layout.addWidget(&m_findBtn, 0, 2); m_layout.addWidget(&m_matchChkBx, 1, 0); m_layout.addWidget(&m_radioGrpBx, 1, 1); m_layout.addWidget(&m_closeBtn, 1, 2); setLayout(&m_layout); } void FindDialog::connectSlot() { connect(&m_findBtn, SIGNAL(clicked()), this, SLOT(onFindClicked())); connect(&m_closeBtn, SIGNAL(clicked()), this, SLOT(onCloseClicked())); } void FindDialog::setPlainTextEdit(QPlainTextEdit* pText) { //m_pText是个智能指针，使用上可以当成一般的指针来使用。 m_pText = pText; } QPlainTextEdit* FindDialog::getPlainTextEdit() { return m_pText; } //附加需求，当点击“关闭”后隐藏起来 bool FindDialog::event(QEvent *evt) { if(evt->type() == QEvent::Close) { hide(); return true; } return QDialog::event(evt); } void FindDialog::onFindClicked() { QString target = m_findEdit.text(); if ((m_pText == NULL) || (target == "")) return ; QString text = m_pText->toPlainText();//编辑框中的文本 QTextCursor c = m_pText->textCursor();//光标对象 int index = -1; //向后（即字符串末尾）查找 if(m_backwardBtn.isChecked()) { index = text.indexOf(target, c.position(), m_matchChkBx.isChecked() ? Qt::CaseSensitive : Qt::CaseInsensitive); if(index >=0) { c.setPosition(index); c.setPosition(index + target.length(), QTextCursor::KeepAnchor);//KeepAnchor光标位置不改变，起到选择范围的作用 m_pText->setTextCursor(c); } } else //向前（向字符串起始处方向）查找 { index = text.lastIndexOf(target, c.position() - text.length() - 1, m_matchChkBx.isChecked() ? Qt::CaseSensitive : Qt::CaseInsensitive); if(index >= 0) { c.setPosition(index + target.length()); c.setPosition(index, QTextCursor::KeepAnchor);//KeepAnchor光标位置不改变，起到选择范围的作用 m_pText->setTextCursor(c); } } if(index < 0) { QMessageBox msg(this); msg.setWindowTitle("Find"); msg.setText("Can not find \"" + target + "\" any more..."); msg.setStandardButtons(QMessageBox::Ok); msg.exec(); } } void FindDialog::onCloseClicked() { close(); }
//MainWindow.h
#ifndef MAINWINDOW_H #define MAINWINDOW_H #include <QMainWindow> #include <QMenuBar> //#include <QKeySequence> //#include <QAction> #include <QPlainTextEdit> #include <QLabel> #include <QFileDialog> #include <QSharedPointer> #include "FindDialog.h" class MainWindow : public QMainWindow { Q_OBJECT private: QPlainTextEdit mainEditor; QLabel statusLbl; QString m_filePath;//当前操作的文件路径 bool m_isTextChanged; //标识编辑框中的内容是否改变 QSharedPointer<FindDialog> m_pFindDlg;//组合关系，利用智能指针来管理其生命周期 //将构造函数、复制构造、赋值函数等私有化 MainWindow(QWidget *parent = 0); MainWindow(const MainWindow&); MainWindow& operator= (const MainWindow&); bool construct(); //二阶构造模式 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();//初始化文本编辑组件 //菜单设置 bool initFileMenu(QMenuBar* mb); //“文件”菜单 bool initEditMenu(QMenuBar* mb); //“编辑”菜单 bool initFormatMenu(QMenuBar* mb); //“格式”菜单 bool initViewMenu(QMenuBar* mb); //“查看”菜单 bool initHelpMenu(QMenuBar* mb); //“帮助”菜单 //工具栏设置 bool initFileToolItem(QToolBar* tb); bool initEditToolItem(QToolBar* tb); bool initFormatToolItem(QToolBar* tb); bool initViewToolItem(QToolBar* tb); //生成菜单项 bool makeAction(QAction*& action, QWidget* parent, QString text, int key); //生成工具栏中的各按钮 bool makeAction(QAction*& action, QWidget* parent, QString tip, QString icon); QString showFileDialog(QFileDialog::AcceptMode mode, QString title);//显示打开和保存对话框 void showErrorMessage(QString message);//显示“错误对话框”(QMessagBox) int showQueryMessage(QString message); //显示“询问对话框” QString saveCurrentData(QString path = "", QString title = "Save"); //保存编辑框中的内容 void preEditorChanged(); //判断文本框是否被更改，并决定是否弹出“保存对话框” void openFileToEditor(QString path); QAction* findMenuBarAction(QString text); QAction* findToolBarAction(QString text); protected: void closeEvent(QCloseEvent *e); //重写窗体的关闭事件 void dragEnterEvent(QDragEnterEvent* e); void dropEvent(QDropEvent * e); private slots: void onFileNew(); void onFileOpen(); void onFileSave(); void onFileSaveAs(); void onFilePrint(); void onFileExit(); void onTextChanged();//文本框内容发生改变里，会收到textChanged信号，这里是接收该信号的槽函数 void onCopyAvailable(bool available); void onRedoAvailable(bool available); void onUndoAvailable(bool available); void onCursorPositionChanged(); void onEditDelete(); void onEditFind(); public: static MainWindow* NewInstance(); ~MainWindow(); }; #endif // MAINWINDOW_H
//MainWindowUI.cpp
#include "MainWindow.h" #include <QMenu> #include <QToolBar> #include <QStatusBar> #include <QLabel> MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent),m_pFindDlg(new FindDialog(this,&mainEditor)) { setWindowTitle("NotePad - [ New ]"); mainEditor.setAcceptDrops(false);//默认下，QPlainTextEdit是接收拖放事件的 //其父对象会收不到“拖放”事件，这里设为false setAcceptDrops(true); //由MainWindow来接管拖放事件 m_filePath = ""; m_isTextChanged = false; } //二阶构造中的第2阶构造 bool MainWindow::construct() { bool ret = true; ret = ret && initMenuBar(); ret = ret && initToolBar(); ret = ret && initStatusBar(); ret = ret && initMainEditor(); return ret; } MainWindow* MainWindow::NewInstance() { MainWindow* ret = new MainWindow(); if((ret == NULL) || !ret->construct()) { delete ret; ret = NULL; } return ret; } //初始化菜单栏 bool MainWindow::initMenuBar() { bool ret = true; QMenuBar* mb = menuBar(); //menuBar为QMainWindow的成员变量 ret = ret && initFileMenu(mb); ret = ret && initEditMenu(mb); ret = ret && initFormatMenu(mb); ret = ret && initViewMenu(mb); ret = ret && initHelpMenu(mb); return ret; } //初始化工具栏 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(); ret = ret && initFormatToolItem(tb); tb->addSeparator(); ret = ret && initViewToolItem(tb); return ret; } //初始化状态栏 bool MainWindow::initStatusBar() { bool ret = true; QStatusBar* sb = statusBar(); QLabel* label = new QLabel("D.T.Software"); 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()); //添加分隔线 sb->addPermanentWidget(&statusLbl); sb->addPermanentWidget(label); } else { ret = false; } return ret; } //初始化主文本编辑组件 bool MainWindow::initMainEditor() { bool ret = true; mainEditor.setParent(this); connect(&mainEditor, SIGNAL(textChanged()), this, SLOT(onTextChanged())); connect(&mainEditor, SIGNAL(copyAvailable(bool)),this,SLOT(onCopyAvailable(bool))); connect(&mainEditor, SIGNAL(redoAvailable(bool)),this,SLOT(onRedoAvailable(bool))); connect(&mainEditor, SIGNAL(undoAvailable(bool)),this,SLOT(onUndoAvailable(bool))); connect(&mainEditor, SIGNAL(cursorPositionChanged()), this, SLOT(onCursorPositionChanged())); setCentralWidget(&mainEditor); return ret; } //文件(下拉)菜单 bool MainWindow::initFileMenu(QMenuBar* mb) { QMenu* menu = new QMenu("File(&F)", mb);//指定parent为mb bool ret = (menu != NULL); if ( ret ) { QAction* action = NULL; //"新建"菜单项 ret = ret && makeAction(action, mb, "New(&N)", Qt::CTRL + Qt::Key_N); if(ret) { connect(action, SIGNAL(triggered()), this, SLOT(onFileNew())); menu->addAction(action); //add Action to Menu Item } //"打开"菜单项 ret = ret && makeAction(action, mb, "Open(&O)...", Qt::CTRL + Qt::Key_O); if(ret) { connect(action, SIGNAL(triggered()), this, SLOT(onFileOpen())); menu->addAction(action); //add Action to Menu Item } //"保存"菜单项 ret = ret && makeAction(action, mb, "Save(&S)", Qt::CTRL + Qt::Key_S); if(ret) { connect(action, SIGNAL(triggered()), this, SLOT(onFileSave())); menu->addAction(action); //add Action to Menu Item } //"另存为"菜单项 ret = ret && makeAction(action, mb, "Save As(&A)...", 0); if(ret) { connect(action, SIGNAL(triggered()), this, SLOT(onFileSaveAs())); menu->addAction(action); //add Action to Menu Item } //水平分隔线 menu->addSeparator(); //"打印"菜单项 ret = ret && makeAction(action, mb, "Print(&P)...", Qt::CTRL + Qt::Key_P); if(ret) { connect(action, SIGNAL(triggered()),this, SLOT(onFilePrint())); menu->addAction(action); //add Action to Menu Item } menu->addSeparator(); //"退出"菜单项 ret = ret && makeAction(action, mb, "Exit(&X)", Qt::CTRL + Qt::Key_Q); if(ret) { connect(action, SIGNAL(triggered()), this, SLOT(onFileExit())); menu->addAction(action); //add Action Item to Menu } } if ( ret ) { mb->addMenu(menu); //add Menu to Menu Bar } else { delete menu; } return ret; } //“编辑”菜单 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, mb, "Undo(&U)", Qt::CTRL + Qt::Key_Z); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(undo())); action->setEnabled(false); menu->addAction(action); } ret = ret && makeAction(action, mb, "Redo(&R)...", Qt::CTRL + Qt::Key_Y); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(redo())); action->setEnabled(false); menu->addAction(action); } menu->addSeparator(); ret = ret && makeAction(action, mb, "Cut(&T)", Qt::CTRL + Qt::Key_X); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(cut())); action->setEnabled(false); menu->addAction(action); } ret = ret && makeAction(action, mb, "Copy(&C)", Qt::CTRL + Qt::Key_C); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(copy())); action->setEnabled(false); menu->addAction(action); } ret = ret && makeAction(action, mb, "Paste(&P)", Qt::CTRL + Qt::Key_V); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(paste())); menu->addAction(action); } ret = ret && makeAction(action, mb, "Delete(&L)", Qt::Key_Delete); if ( ret ) { connect(action, SIGNAL(triggered()), this, SLOT(onEditDelete())); menu->addAction(action); } menu->addSeparator(); ret = ret && makeAction(action, mb, "Find(&F)...", Qt::CTRL + Qt::Key_F); if ( ret ) { connect(action, SIGNAL(triggered()), this, SLOT(onEditFind())); menu->addAction(action); } ret = ret && makeAction(action, mb, "Replace(&R)...", Qt::CTRL + Qt::Key_H); if ( ret ) { menu->addAction(action); } ret = ret && makeAction(action, mb, "Goto(&G)...", Qt::CTRL + Qt::Key_G); if ( ret ) { menu->addAction(action); } menu->addSeparator(); ret = ret && makeAction(action, mb, "Select All(&A)...", Qt::CTRL + Qt::Key_A); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(selectAll())); menu->addAction(action); } } if ( ret ) { mb->addMenu(menu); } else { delete menu; } return ret; } //“格式”菜单 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, mb, "Auto Wrap(&W)", 0); if ( ret ) { menu ->addAction(action); } ret = ret && makeAction(action, mb, "Font(&F)...", 0); if ( ret ) { menu ->addAction(action); } } if ( ret ) { mb->addMenu(menu); } else { delete menu; } return ret; } //“查看”菜单 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, mb, "Tool Bar(&T)", 0); if ( ret ) { menu ->addAction(action); } ret = ret && makeAction(action, mb, "Status Bar(&S)", 0); if ( ret ) { menu ->addAction(action); } } if ( ret ) { mb->addMenu(menu); } else { delete menu; } return ret; } //“帮助”菜单 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, mb, "User Manual", 0); if ( ret ) { menu ->addAction(action); } ret = ret && makeAction(action, mb, "About NotePad...", 0); if ( ret ) { menu ->addAction(action); } } if ( ret ) { mb->addMenu(menu); } else { delete menu; } return ret; } //工具栏设置 bool MainWindow::initFileToolItem(QToolBar* tb) { bool ret = true; QAction* action = NULL; ret = ret && makeAction(action, tb, "New", ":/Res/pic/new.png"); if ( ret ) { connect(action, SIGNAL(triggered()), this, SLOT(onFileNew())); tb->addAction(action); } ret = ret && makeAction(action, tb, "Open", ":/Res/pic/open.png"); if ( ret ) { connect(action, SIGNAL(triggered()), this, SLOT(onFileOpen())); tb->addAction(action); } ret = ret && makeAction(action, tb, "Save", ":/Res/pic/save.png"); if ( ret ) { connect(action, SIGNAL(triggered()), this, SLOT(onFileSave())); tb->addAction(action); } ret = ret && makeAction(action, tb, "Save As", ":/Res/pic/saveas.png"); if ( ret ) { connect(action, SIGNAL(triggered()), this, SLOT(onFileSaveAs())); tb->addAction(action); } ret = ret && makeAction(action, tb, "Print", ":/Res/pic/print.png"); if ( ret ) { connect(action, SIGNAL(triggered()),this, SLOT(onFilePrint())); tb->addAction(action); } return ret; } bool MainWindow::initEditToolItem(QToolBar* tb) { bool ret = true; QAction* action = NULL; ret = ret && makeAction(action, tb, "Undo", ":/Res/pic/undo.png"); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(undo())); action->setEnabled(false); tb->addAction(action); } ret = ret && makeAction(action, tb, "Redo", ":/Res/pic/redo.png"); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(redo())); action->setEnabled(false); tb->addAction(action); } ret = ret && makeAction(action, tb, "Cut", ":/Res/pic/cut.png"); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(cut())); action->setEnabled(false); tb->addAction(action); } ret = ret && makeAction(action, tb, "Copy", ":/Res/pic/copy.png"); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(copy())); action->setEnabled(false); tb->addAction(action); } ret = ret && makeAction(action, tb, "Paste", ":/Res/pic/paste.png"); if ( ret ) { connect(action, SIGNAL(triggered()), &mainEditor, SLOT(paste())); tb->addAction(action); } ret = ret && makeAction(action, tb, "Find", ":/Res/pic/find.png"); if ( ret ) { tb->addAction(action); } ret = ret && makeAction(action, tb, "Replace", ":/Res/pic/replace.png"); if ( ret ) { tb->addAction(action); } ret = ret && makeAction(action, tb, "Goto", ":/Res/pic/goto.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", ":/Res/pic/wrap.png"); if ( ret ) { tb->addAction(action); } ret = ret && makeAction(action, tb, "Font", ":/Res/pic/font.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", ":/Res/pic/tool.png"); if ( ret ) { tb->addAction(action); } ret = ret && makeAction(action, tb, "Status Bar", ":/Res/pic/status.png"); if ( ret ) { tb->addAction(action); } return ret; } //生成菜单项（第1个参数是菜单项对象，第2个参数为父组件，第3个参数为显示文本，第4个参数为快捷键） bool MainWindow::makeAction(QAction*& action, QWidget* parent, QString text, int key) { bool ret = true; action = new QAction(text, parent); //设置parent if(action != NULL) { action->setShortcut(QKeySequence(key)); //设置快捷键 } else { ret = false; } return ret; } //生成工具栏中的各按钮 bool MainWindow::makeAction(QAction*& action, QWidget* parent, QString tip, QString icon) { bool ret = true; action = new QAction("", parent); if( action != NULL ) { action ->setToolTip(tip); action->setIcon(QIcon(icon)); } else { ret = false; } return ret; } MainWindow::~MainWindow() { }
//MainWindowSlots.cpp
//该文件MainWindowSlots.cpp与MainWindowUI.cpp的分离 //体现了界面和功能代码分离的思想 #include "MainWindow.h" #include <QMessageBox> #include <QFile> #include <QTextStream> #include <QMap> #include <QCloseEvent> #include <QDragEnterEvent> #include <QDropEvent> #include <QMimeData> #include <QToolBar> #include <QPrintDialog> //QT += printsupport #include <QApplication> #include <QDebug> void MainWindow::showErrorMessage(QString message) { QMessageBox msg(this); msg.setWindowTitle("Erro"); 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(); } QString MainWindow::showFileDialog(QFileDialog::AcceptMode mode, QString title) { QString ret = ""; QFileDialog fd(this); QStringList filters; QMap<QString, QString> map; const char* filterArray[][2] = { {"Text(*.txt)", ".txt"}, {"All Files(*.*)", "*" }, {NULL, NULL} }; for (int i=0; filterArray[i][0] != NULL; i++) { filters.append(filterArray[i][0]); map.insert(filterArray[i][0], filterArray[i][1]); } fd.setWindowTitle(title); fd.setAcceptMode(mode); //QFileDialog::AcceptOpen或AcceptSave fd.setNameFilters(filters); if(mode == QFileDialog::AcceptOpen) { fd.setFileMode(QFileDialog::ExistingFile); //打开文件必须存在！ } if(fd.exec() == QFileDialog::Accepted) { ret = fd.selectedFiles()[0]; //Qt5中ret返回的是完整的路径名，含后缀。因此，后面的if块可省略，但Qt4可能 //会返回不带后缀的文件名，当保存文件时，须手动加上去。 if(mode == QFileDialog::AcceptSave) { QString postfix = map[fd.selectedNameFilter()]; if((postfix != "*") && !ret.endsWith(postfix)) { ret = ret + postfix; } } } return ret; } void MainWindow::preEditorChanged() { if (m_isTextChanged) { int r = showQueryMessage("Do you want to save the changes to file?"); switch(r) { case QMessageBox::Yes: saveCurrentData(m_filePath); break; case QMessageBox::No: m_isTextChanged = false; break; case QMessageBox::Cancel: break; } } } void MainWindow::onFileNew() { preEditorChanged(); if(!m_isTextChanged) { mainEditor.clear(); setWindowTitle("NotePad - [ New ]"); m_filePath = ""; m_isTextChanged = false; } } void MainWindow::openFileToEditor(QString path) { if( path != "") { QFile file(path); if (file.open(QIODevice::ReadOnly | QIODevice::Text)) { mainEditor.setPlainText(QString(file.readAll())); file.close(); m_filePath = path; //记录当前打开的文件路径和文件名 m_isTextChanged = false; setWindowTitle("NotePad - [" + m_filePath + "]"); } else { showErrorMessage(QString("Open file Error!\n\n") + "\"" + path + "\""); } } } void MainWindow::onFileOpen() { preEditorChanged(); if( !m_isTextChanged) { QString path = showFileDialog(QFileDialog::AcceptOpen, "Open"); openFileToEditor(path); } } QString MainWindow::saveCurrentData(QString path, QString title) { QString ret = path; if (ret =="") { //执行下面语句时，用户可以点击“取消”，此时ret返回"" ret = showFileDialog(QFileDialog::AcceptSave, title); } if (ret != "") { QFile file(ret); if (file.open(QIODevice::WriteOnly | QIODevice::Text)) { QTextStream out(&file); out << mainEditor.toPlainText(); file.close(); setWindowTitle("NotePad - [" + ret + "]"); m_isTextChanged = false; //己保存 } else { showErrorMessage(QString("Save file Error!\n\n") + "\"" + m_filePath + "\""); ret =""; //保存失败时 } } return ret; } void MainWindow::onFileSave() { QString path = saveCurrentData(m_filePath, "Save"); if( path != "" ) { m_filePath = path; } } void MainWindow::onFileSaveAs() { QString path = saveCurrentData(m_filePath, "Save As"); if( path != "" ) { m_filePath = path; } } void MainWindow::onTextChanged() { if( !m_isTextChanged ) { setWindowTitle("*" + windowTitle()); } m_isTextChanged = true; //qDebug()<< "onTextChanged()"; } void MainWindow::closeEvent(QCloseEvent* e) { preEditorChanged(); if(!m_isTextChanged) { QMainWindow::closeEvent(e); } else { //当用户按下“取消” e->ignore();//忽略关闭事件 } } void MainWindow::dragEnterEvent(QDragEnterEvent *e) { if(e->mimeData()->hasUrls()) { e->acceptProposedAction(); } else { e->ignore(); } } void MainWindow::dropEvent(QDropEvent *e) { qDebug() << "dropEvent"; if(e->mimeData()->hasUrls()) { QList<QUrl> list = e->mimeData()->urls(); QString path = list[0].toLocalFile(); QFileInfo fi(path); if(fi.isFile()) { preEditorChanged(); if(!m_isTextChanged) { openFileToEditor(path); } } else { showErrorMessage("Can‘t open a folder!"); } } else { e->ignore(); } } void MainWindow::onCopyAvailable(bool available) { QAction* action = findMenuBarAction("Copy"); if (action != NULL) action->setEnabled(available); action = findMenuBarAction("Cut"); if (action != NULL) action->setEnabled(available); action = findToolBarAction("Copy"); if (action != NULL) action->setEnabled(available); action = findToolBarAction("Cut"); if (action != NULL) action->setEnabled(available); } void MainWindow::onRedoAvailable(bool available) { QAction* action = findMenuBarAction("Redo"); if (action != NULL) action->setEnabled(available); action = findToolBarAction("Redo"); if (action != NULL) action->setEnabled(available); } void MainWindow::onUndoAvailable(bool available) { QAction* action = findMenuBarAction("Undo"); if (action != NULL) action->setEnabled(available); action = findToolBarAction("Undo"); if (action != NULL) action->setEnabled(available); } QAction* MainWindow::findMenuBarAction(QString text) { QAction* ret = NULL; const QObjectList& list = menuBar()->children(); for( int i=0; i<list.count(); i++) { //各菜单（如文件、编辑、查看等） QMenu* menu = dynamic_cast<QMenu*>(list[i]); if(menu != NULL) { QList<QAction*> actions = menu->actions(); for(int j=0; j<actions.count(); j++) { if(actions[j]->text().startsWith(text)) { ret = actions[j]; break; } } } } return ret; } QAction* MainWindow::findToolBarAction(QString text) { QAction* ret = NULL; const QObjectList& list = children(); for( int i=0; i<list.count(); i++) { QToolBar* toolBar = dynamic_cast<QToolBar*>(list[i]); if(toolBar != NULL) { QList<QAction*> actions = toolBar->actions(); for(int j=0; j<actions.count(); j++) { if(actions[j]->toolTip().startsWith(text)) { ret = actions[j]; break; } } } } return ret; } void MainWindow::onFilePrint() { QPrintDialog dlg(this); dlg.setWindowTitle("Print"); if(dlg.exec() == QPrintDialog::Accepted) { QPrinter* p = dlg.printer(); mainEditor.document()->print(reinterpret_cast<QPagedPaintDevice*>(p)); } } void MainWindow::onCursorPositionChanged() { int pos = mainEditor.textCursor().position(); QString text = mainEditor.toPlainText(); int col = 0;//列数 int ln = 0; //行数 int flag = -1; //用于记录光标之前最后一个‘\n‘所在索引位置 //从头到光标所在位置 for(int i=0; i<pos; i++) { if( text[i] == ‘\n‘) { ln++; flag = i; } } col = pos -(flag + 1); statusLbl.setText("Ln: " + QString::number(ln+1) + " Col: " + QString::number(col+1)); } void MainWindow::onEditDelete() { QKeyEvent keyPress(QEvent::KeyPress, Qt::Key_Delete, Qt::NoModifier); QKeyEvent keyRelease(QEvent::KeyRelease, Qt::Key_Delete, Qt::NoModifier); QApplication::sendEvent(&mainEditor, &keyPress); QApplication::sendEvent(&mainEditor, &keyRelease); } void MainWindow::onEditFind() { m_pFindDlg->show(); } void MainWindow::onFileExit() { close(); }
6. 小结
（1）QString中提供了不同的子串查找方式
（2）QTextCursor对象保存了文本框中光标的相关信息
（3）QString对象和QTextCursor对象协作实现查找功能
（4）查找对话框与文本框的弱耦合关系满足了可复用的需求
第46课 查找对话框的功能实现
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