(C++) QTreeViewExample3

 

 

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

 

• View a screenshot of 'CppQTreeViewExample3' (png)
• Download the Qt Creator project 'CppQTreeViewExample3' (zip)

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

 

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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

 

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#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

 

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#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

 

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#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

 

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#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

 

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#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

 

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#ifndef QTMYITEM_H #define QTMYITEM_H #include <QStandardItem> struct QtMyItem : public QStandardItem {   QtMyItem(const QString &text); }; #endif // QTMYITEM_H

 

 

 

 

 

./CppQTreeViewExample3/qtmyitem.cpp

 

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#include "qtmyitem.h" QtMyItem::QtMyItem(const QString &text)   : QStandardItem(text) {   this->setEditable(true);   this->setDragEnabled(true);   this->setDropEnabled(true); }

 

 

 

 

 

./CppQTreeViewExample3/qtmytreeview.h

 

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#ifndef QTMYTREEVIEW_H #define QTMYTREEVIEW_H #include <QTreeView> struct QtMyTreeView : public QTreeView {   QtMyTreeView(QWidget * const parent = 0); }; #endif // QTMYTREEVIEW_H

 

 

 

 

 

./CppQTreeViewExample3/qtmytreeview.cpp

 

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#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); }