Qt Creator Lubuntu

QTreeView example 3: improved undo/redo and added drag/drop is an example to use a QTreeView.

Technical facts

Application type(s)

Desktop application

Operating system(s) or programming environment(s)

Lubuntu 15.04 (vivid)

IDE(s):

Qt Creator 3.1.1

Project type:

GUI application

C++ standard:

C++98

Compiler(s):

G++ 4.9.2

Libraries used:

Qt: version 5.4.1 (32 bit)
STL: GNU ISO C++ Library, version 4.9.2

Qt project file: ./CppQTreeViewExample3/CppQTreeViewExample3.pro


QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TEMPLATE = app



SOURCES += \

    qtdialog.cpp \

    qtmain.cpp \

    qtaddrowcommand.cpp \

    qtmytreeview.cpp \

    qtmyitem.cpp



HEADERS  += qtdialog.h \

    qtaddrowcommand.h \

    qtmytreeview.h \

    qtmyitem.h



FORMS    += qtdialog.ui

./CppQTreeViewExample3/qtaddrowcommand.h


#ifndef QTADDROWCOMMAND_H

#define QTADDROWCOMMAND_H



#include <QModelIndex>

#include <QUndoCommand>



struct QStandardItemModel;

struct QAbstractItemView;



struct QtAddRowCommand : public QUndoCommand

{

  QtAddRowCommand(

    QStandardItemModel * const model,

    QAbstractItemView * const view,

    const std::string& text = "");

  void redo();

  void undo();



  private:

  QStandardItemModel * const m_model;

  const QModelIndex m_prev_index;

  std::string m_text;

  QAbstractItemView  * const m_view;

};



#endif // QTADDROWCOMMAND_H

./CppQTreeViewExample3/qtaddrowcommand.cpp


#include "qtaddrowcommand.h"



#include <QAbstractItemModel>

#include <QAbstractItemView>

#include <QStandardItemModel>



#include "qtmyitem.h"



QtAddRowCommand::QtAddRowCommand(

  QStandardItemModel * const model,

  QAbstractItemView * const view,

  const std::string& text)

  : m_model(model),

    m_prev_index(view->currentIndex()),

    m_text(text),

    m_view(view)

{



}



void QtAddRowCommand::redo()

{

  QtMyItem * const item = new QtMyItem(m_text.c_str());

  item->setText(m_text.c_str());

  m_model->appendRow(item);

  m_view->setCurrentIndex(item->index());

  this->setText("Added row at index " + QString::number(item->index().row()));

}



void QtAddRowCommand::undo()

{

  const int n_rows = m_model->rowCount();

  QtMyItem * const item = dynamic_cast<QtMyItem *>(m_model->item(n_rows - 1));

  if (item) m_text = item->text().toStdString();

  m_model->removeRow(n_rows - 1);

  m_view->setCurrentIndex(m_prev_index);

}

./CppQTreeViewExample3/qtdialog.h


#ifndef QTDIALOG_H

#define QTDIALOG_H



#include <QDialog>



namespace Ui {

  class QtDialog;

}



struct QStandardItemModel;

struct QUndoStack;

struct QtMyTreeView;



class QtDialog : public QDialog

{

  Q_OBJECT

  

public:

  explicit QtDialog(QWidget *parent = 0);

  ~QtDialog();



protected:

  void keyPressEvent(QKeyEvent *);

  

private slots:

  void on_button_clicked();



private:

  Ui::QtDialog *ui;

  QStandardItemModel * const m_model;

  QUndoStack * const m_undo_stack;

  QtMyTreeView * const m_view;

};



#endif // QTDIALOG_H

./CppQTreeViewExample3/qtdialog.cpp


#include "qtdialog.h"



#include <cassert>



#include <boost/lexical_cast.hpp>



#include <QKeyEvent>

#include <QStandardItemModel>

#include <QStyledItemDelegate>

#include <QUndoStack>



#include "qtaddrowcommand.h"

#include "ui_qtdialog.h"

#include "qtmytreeview.h"

#include "qtmyitem.h"



QtDialog::QtDialog(QWidget *parent) :

  QDialog(parent),

  ui(new Ui::QtDialog),

  m_model(new QStandardItemModel),

  m_undo_stack(new QUndoStack),

  m_view(new QtMyTreeView)

{

  ui->setupUi(this);

  assert(ui->scrollAreaWidgetContents->layout());

  ui->scrollAreaWidgetContents->layout()->addWidget(m_view);

  m_view->setModel(m_model);

  m_view->setItemDelegate(new QStyledItemDelegate);



  //Initial the QtMyTreeView with some items

  for (int i=0; i!=26; ++i)

  {

    QtAddRowCommand * const cmd

      = new QtAddRowCommand(

        m_model,

        m_view,

        boost::lexical_cast<std::string,char>('A' + i));

    m_undo_stack->push(cmd);

  }



}



QtDialog::~QtDialog()

{

  delete ui;

  delete m_model;

  delete m_undo_stack;

  delete m_view;

}



void QtDialog::keyPressEvent(QKeyEvent * e)

{

  if (e->key() == Qt::Key_Escape) { close(); return; }

  if ( (e->modifiers() & Qt::ControlModifier)

    && !(e->modifiers() & Qt::ShiftModifier)

    && e->key() == Qt::Key_Z)

  {

    m_undo_stack->undo();

    return;

  }

  if ( (e->modifiers() & Qt::ControlModifier)

    && (e->modifiers() & Qt::ShiftModifier)

    && e->key() == Qt::Key_Z)

  {

    m_undo_stack->redo();

    return;

  }

}



void QtDialog::on_button_clicked()

{

  QtAddRowCommand * const cmd = new QtAddRowCommand(m_model,m_view);

  m_undo_stack->push(cmd);



  const int n_rows = m_model->rowCount();

  QtMyItem * const item = dynamic_cast<QtMyItem*>(m_model->item(n_rows - 1));

  assert(item);

  m_view->edit(item->index());



}

./CppQTreeViewExample3/qtmain.cpp


#include <QApplication>

#include "qtdialog.h"



int main(int argc, char *argv[])

{

  QApplication a(argc, argv);

  QtDialog w;

  w.show();

  

  return a.exec();

}

./CppQTreeViewExample3/qtmyitem.h


#ifndef QTMYITEM_H

#define QTMYITEM_H



#include <QStandardItem>



struct QtMyItem : public QStandardItem

{

  QtMyItem(const QString &text);

};



#endif // QTMYITEM_H

./CppQTreeViewExample3/qtmyitem.cpp


#include "qtmyitem.h"



QtMyItem::QtMyItem(const QString &text)

  : QStandardItem(text)

{

  this->setEditable(true);

  this->setDragEnabled(true);

  this->setDropEnabled(true);

}

./CppQTreeViewExample3/qtmytreeview.h


#ifndef QTMYTREEVIEW_H

#define QTMYTREEVIEW_H



#include <QTreeView>



struct QtMyTreeView : public QTreeView

{

  QtMyTreeView(QWidget * const parent = 0);

};



#endif // QTMYTREEVIEW_H

./CppQTreeViewExample3/qtmytreeview.cpp


#include "qtmytreeview.h"



#include <QDragEnterEvent>

#include <QDropEvent>

#include <QDragMoveEvent>



QtMyTreeView::QtMyTreeView(QWidget * const parent)

  : QTreeView(parent)

{

  this->setAcceptDrops(true);

  this->setAlternatingRowColors(true);

  this->setAnimated(true);

  this->setDragDropMode(QAbstractItemView::InternalMove);

  this->setDragEnabled(true);

  this->setDropIndicatorShown(true);

  this->setExpandsOnDoubleClick(true);

  this->setHeaderHidden(true);

  this->setItemsExpandable(true);

  this->setSelectionMode(QAbstractItemView::SingleSelection);

  this->setWordWrap(true);

}

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(C++) QTreeViewExample3

Technical facts

Qt project file: ./CppQTreeViewExample3/CppQTreeViewExample3.pro

./CppQTreeViewExample3/qtaddrowcommand.h

./CppQTreeViewExample3/qtaddrowcommand.cpp

./CppQTreeViewExample3/qtdialog.h

./CppQTreeViewExample3/qtdialog.cpp

./CppQTreeViewExample3/qtmain.cpp

./CppQTreeViewExample3/qtmyitem.h

./CppQTreeViewExample3/qtmyitem.cpp

./CppQTreeViewExample3/qtmytreeview.h

./CppQTreeViewExample3/qtmytreeview.cpp