Qt_Demos

Qt Demos for book "Qt5.9 C++ Development Guide"

Some small demos I made during the Qt process are Qt5.9 C++ Development Guide.

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2-1_HelloWorld

Hello World.

• Label
• Push Button
• SIGNAL & SLOT

2-2_Widgets

Simple editor.

• Check Box
• Radio Button
• Layout
• Text Edit: set font italic, set font bold, set font underline, set palette(to set textedit font color)
• SIGNAL & SLOT
• QObject::connect: connect(const QObject *sender, const char *signal, const QObject *receiver, const char *method, Qt::ConnectionType type = Qt::AutoConnection)

2-4_TextEditor

Text editor.

• Design Mode: Code+visualization (code+ui)
• Set icon
• ToorBar
• statusBar
• SIGNAL & SLOT
• Action
• qDebug()
• ProgressBar
• SpinBox
• Text Edit: set font, set font italic, set font bold, set font underline, set font pointsize, clear...
• QDir
• QFileDialog
• QMessageBox
• QFile + QIODevice & QFile + QTextStream to read and write text file

4-3_SpinBox_Sample

Simple price caculator.

• SpinBox(prefix, suffix)
• Group Box
• lineEdit
• QString::number(), QString.setNum() ...

4-4_QSliderSample

Simple Color Mixer

• Slider
• Dial
• QColor: QColor color; color.setRgb(r, g, b, a);
• QPalette:

    QPalette p = ui->textEdit->palette();
    p.setColor(QPalette::Base, color);
    ui->textEdit->setPalette(p);
  

4-5_Time

Use of time Classes.

• QTime

   QTime t;
  t.start();
  //do something
  t.elapsed();//do something time in miliseconds.
  

• QDateTime

   QDateTime datetime = QDateTime::currentDateTime();
  QString time_str = datetime.toString("yyyy-MM-dd hh:mm:ss"));
  QDateTime datetime = QDateTime::fromString(time_str,"yyyy-MM-dd hh:mm:ss");
  

• QTimer

   QTimer* timer_1 = new QTimer(this);
  timer_1->stop();
  timer_1->setInterval(1000);
  connect(timer_1, SIGNAL(timeout()), this, SLOT(on_timer_1_timeout()));
  
  void on_on_timer_1_timeout()
  {
      //do something every timer interval
  }
  

• Date/Time Edit

4-7_ItemWidget

Use of item-based or model-view Widgets.

• Tool Box(Container)
• Tab Widget(Container)
• QListWidgetItem
• QListWidget(item based)
• QTableWidgetItem
• QTableWidget(item based), how to fill the table with items
• QStandardItemModel
• QTableView(Model-View), setModel
• QListWidget/QTableWidget: append, insert, delete(QTableWidget reverse traversal remove), clear, selectAll, selectNone, selectInvert, autoResize
• How to custom right-click Menu: How to customize the right-click menu
• Tool Button(How to bind action)
• Button setStyleSheet
• Read CSV(std ifstream, getline() split string)
• Container:QList, QStringList
• QDir:

   //get dir_path files.
  QDir dir;
  dir.setPath(path);
  return dir.entryList(QDir::Files);
  

5-1_QFileSystemModel

Use of QFileSystemModel to show the file-system.

• QFileSystemModel: setRootPath, index(QString path) , size(), type(), filePath
• QTreeView/QTableView/QListView: setModel,setRootIndex

   file_sys_model->setRootPath(path);
  qDebug()<<"file_sys_model root path:"<<file_sys_model->rootPath();
  ui->treeView->setRootIndex(file_sys_model->index(path));//设置treeView根节点为选定目录
  ui->tableView->setRootIndex(file_sys_model->index(path));
  ui->tableView->resizeColumnsToContents();
  ui->tableView->resizeRowsToContents();
  ui->listView->setRootIndex(file_sys_model->index(path));
  

• QDesktopServices: QDesktopServices::openUrl(QUrl(file_sys_model->filePath(index)));//listView item双击事件, 调用系统程序打开文件

5-2_QStringListModel

Use of QStringListModel + QListView to show a csv file.

• QStringListModel: setStringList, insertRow(), setData(), removeRow(), removeRows(), index(int ​​row)
• QModelIndex: QModelIndex.row()
• Bind the QStringListModel to QListView using QListView.setModel(), the QListView changes with the QStringListModel,
• QListView: currentIndex(), setCurrentIndex()

5-3_QStandardItemModel

• QStandardItemModel
• Bind QStandardItemModel to QTableView
• QTextStream: read csv file
• CountryPopulation class
• QDataStream:
  • export TableView data and read data to TableView using qt stream, override >> & << operator to read and write data from and to CountryPopulation objects.
  • export TableView data and read data to TableView using binary format.
• Append/Insert/Delete/Modify the table, set the index on focus

6-1_Dialog

• QFileDialog
• QMessageBox
• QFontDialog
• QColorDialog
• QInputDialog