QtableView content disapears after associated PrintDialog got cancelled

**schall_l** · 24th July 2009, 21:04

Hi,

My PrintableTableView class deriving from QTableView is using QWebView to print the content of my model:

Qt Code:

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#ifndef PRINTABLETABLEVIEW_H
#define PRINTABLETABLEVIEW_H
 
// QT includes
#include <QtWebKit>
#include <QtGui>
 
// non QT includes
 
class PrintableTableView : public QTableView {
  Q_OBJECT
 
public:	
  PrintableTableView ( QWidget * parent = 0 ); 
  ~PrintableTableView();
 
public slots:
  virtual void print();
  void printHtml(bool ok); 
 
protected:
  // Webkit things for printing the identifiers
  QString readFile(const QString &name);
  QWebView *m_webview;
  QString m_htmlTemplate;
  QUrl m_baseUrl;
};
 
#endif

#ifndef PRINTABLETABLEVIEW_H
#define PRINTABLETABLEVIEW_H

// QT includes
#include <QtWebKit>
#include <QtGui>

// non QT includes

class PrintableTableView : public QTableView {
  Q_OBJECT

public:	
  PrintableTableView ( QWidget * parent = 0 ); 
  ~PrintableTableView();

public slots:
  virtual void print();
  void printHtml(bool ok); 

protected:
  // Webkit things for printing the identifiers
  QString readFile(const QString &name);
  QWebView *m_webview;
  QString m_htmlTemplate;
  QUrl m_baseUrl;
};

#endif

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Qt Code:

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// non QT includes
#include "PrintableTableView.h"
#include "mainWindow.h"
 
PrintableTableView::PrintableTableView( QWidget * parent ): QTableView(parent){	
  m_webview = new QWebView(this);
  m_webview->setVisible(false);
}
 
PrintableTableView::~PrintableTableView(){
}
 
void 
PrintableTableView::print() {
  QString html;
  MainWindow *mainWindow = MainWindow::instance();
 
  // Header
  html= QString("\
  <div id=header>\
    <div id=logo>\
      <table border=0>\
        <tr>\
          <th><h1>Empty page</h1></th>\
          <th><h2>from %1</h2></th>\
        </tr>\
      </table>\
      <h3>printed on %2</h3>\
    </div>\
  </div>").arg(mainWindow->currentProjectName()).arg(QDate::currentDate().toString());
 
  m_htmlTemplate = readFile(QLatin1String(":/identifiers.html"));
  m_htmlTemplate.replace(QLatin1String("<!-- CONTENT -->"), html);
  m_baseUrl = QUrl(QLatin1String("qrc:/identifiers.html"));
  connect(m_webview, SIGNAL(loadFinished(bool)),this, SLOT(printHtml(bool)));
  m_webview->setHtml(m_htmlTemplate, m_baseUrl);
}
 
void 
PrintableTableView::printHtml(bool ok) {
  disconnect(m_webview, SIGNAL(loadFinished(bool)),this, SLOT(printHtml(bool)));
  QPrinter printer;  
  QPrintDialog printDialog(&printer, this);
  printDialog.setOption(QAbstractPrintDialog::PrintSelection,false);
  printDialog.setOption(QAbstractPrintDialog::PrintPageRange,false);
  if (printDialog.exec() == QDialog::Accepted) {
    m_webview->print(&printer);
  }
}
 
QString 
PrintableTableView::readFile(const QString &name)
{
  QFile f(name);
  if (!f.open(QIODevice::ReadOnly)) {
    qWarning("Unable to open %s: %s", name.toUtf8().constData(), f.errorString().toUtf8().constData());
    return QString();
  }
  QTextStream ts(&f);
  return ts.readAll();
}

// non QT includes
#include "PrintableTableView.h"
#include "mainWindow.h"

PrintableTableView::PrintableTableView( QWidget * parent ): QTableView(parent){	
  m_webview = new QWebView(this);
  m_webview->setVisible(false);
}

PrintableTableView::~PrintableTableView(){
}

void 
PrintableTableView::print() {
  QString html;
  MainWindow *mainWindow = MainWindow::instance();

  // Header
  html= QString("\
  <div id=header>\
    <div id=logo>\
      <table border=0>\
        <tr>\
          <th><h1>Empty page</h1></th>\
          <th><h2>from %1</h2></th>\
        </tr>\
      </table>\
      <h3>printed on %2</h3>\
    </div>\
  </div>").arg(mainWindow->currentProjectName()).arg(QDate::currentDate().toString());

  m_htmlTemplate = readFile(QLatin1String(":/identifiers.html"));
  m_htmlTemplate.replace(QLatin1String("<!-- CONTENT -->"), html);
  m_baseUrl = QUrl(QLatin1String("qrc:/identifiers.html"));
  connect(m_webview, SIGNAL(loadFinished(bool)),this, SLOT(printHtml(bool)));
  m_webview->setHtml(m_htmlTemplate, m_baseUrl);
}

void 
PrintableTableView::printHtml(bool ok) {
  disconnect(m_webview, SIGNAL(loadFinished(bool)),this, SLOT(printHtml(bool)));
  QPrinter printer;  
  QPrintDialog printDialog(&printer, this);
  printDialog.setOption(QAbstractPrintDialog::PrintSelection,false);
  printDialog.setOption(QAbstractPrintDialog::PrintPageRange,false);
  if (printDialog.exec() == QDialog::Accepted) {
    m_webview->print(&printer);
  }
}

QString 
PrintableTableView::readFile(const QString &name)
{
  QFile f(name);
  if (!f.open(QIODevice::ReadOnly)) {
    qWarning("Unable to open %s: %s", name.toUtf8().constData(), f.errorString().toUtf8().constData());
    return QString();
  }
  QTextStream ts(&f);
  return ts.readAll();
}

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The content of the QTableView is displayed correctly before and while I have the printDialog open. Sometimes (yes sometimes, not everytime) it happens that the content of the QTableView disapear if I cancel the printDialog.

What I am doing wrong ?

**wysota** · 24th July 2009, 21:17

How is the model for the view defined? Also, how do you instantiate your view?

**schall_l** · 24th July 2009, 21:38

Here is how the model for the view is defined and instantiated.

Qt Code:

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class CommunicationModel : public QAbstractTableModel
{
  Q_OBJECT
 
public:
  static CommunicationModel* instance(QWidget* parent = 0);
 
  int rowCount( const QModelIndex &index) const;
  int columnCount( const QModelIndex &index) const;
 
  QVariant data(const QModelIndex &index, int role) const;
  QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const;
  Qt::ItemFlags flags( const QModelIndex& ) const ;
 
  bool insertRows(int position, int rows, const QModelIndex &index=QModelIndex());
  bool removeRows(int position, int rows, const QModelIndex &index=QModelIndex());
  bool addFrame(const Can_Frame &frame);
  void clear();
 
  void sort (int column, Qt::SortOrder order = Qt::AscendingOrder );
 
private:
  CommunicationModel(QObject *parent = 0);
 
  IdentifiersModel* id_model;
  QList<Can_Frame> m_communication; // Communication log
 
};

class CommunicationModel : public QAbstractTableModel
{
  Q_OBJECT

public:
  static CommunicationModel* instance(QWidget* parent = 0);
	
  int rowCount( const QModelIndex &index) const;
  int columnCount( const QModelIndex &index) const;
	
  QVariant data(const QModelIndex &index, int role) const;
  QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const;
  Qt::ItemFlags flags( const QModelIndex& ) const ;
	
  bool insertRows(int position, int rows, const QModelIndex &index=QModelIndex());
  bool removeRows(int position, int rows, const QModelIndex &index=QModelIndex());
  bool addFrame(const Can_Frame &frame);
  void clear();
		
  void sort (int column, Qt::SortOrder order = Qt::AscendingOrder );

private:
  CommunicationModel(QObject *parent = 0);
	
  IdentifiersModel* id_model;
  QList<Can_Frame> m_communication; // Communication log

};

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Qt Code:

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CommunicationView::CommunicationView( QWidget* parent ) :
  PrintableTableView(parent)
{
  m_model = CommunicationModel::instance(this);	
  setModel(m_model);
 
  m_delegate = new CommunicationDelegate(this);
  setItemDelegate(m_delegate);

CommunicationView::CommunicationView( QWidget* parent ) :
  PrintableTableView(parent)
{
  m_model = CommunicationModel::instance(this);	
  setModel(m_model);

  m_delegate = new CommunicationDelegate(this);
  setItemDelegate(m_delegate);

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.. and how I do instantiate my view ...

Qt Code:

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WidgetCommunication::WidgetCommunication( QWidget* parent ) :
        QWidget( parent )
{
 
    // Title
    title = new TitleFrame(this,"Communication log",true);
    // Body
    body = CommunicationView::instance(this);
    // Status
    quickSend = new QuickSend(this);
 
    // Layout
    mainLayout = new QVBoxLayout(this);
    mainLayout->addWidget(title);
    mainLayout->addWidget(body);
    mainLayout->addWidget(quickSend);
 
    mainLayout->setContentsMargins (0, 0, 0, 0);
    setLayout(mainLayout);
}

WidgetCommunication::WidgetCommunication( QWidget* parent ) :
        QWidget( parent )
{

    // Title
    title = new TitleFrame(this,"Communication log",true);
    // Body
    body = CommunicationView::instance(this);
    // Status
    quickSend = new QuickSend(this);

    // Layout
    mainLayout = new QVBoxLayout(this);
    mainLayout->addWidget(title);
    mainLayout->addWidget(body);
    mainLayout->addWidget(quickSend);

    mainLayout->setContentsMargins (0, 0, 0, 0);
    setLayout(mainLayout);
}

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**wysota** · 24th July 2009, 21:57

And what's the relation between WidgetCommunication and the print dialog?

**schall_l** · 24th July 2009, 22:13

??..Well PrintDialog is a child of QtableView...

Qt Code:

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void 
PrintableTableView::printHtml(bool ok) {
  disconnect(m_webview, SIGNAL(loadFinished(bool)),this, SLOT(printHtml(bool)));
  QPrinter printer;  
  QPrintDialog printDialog(&printer, this);
  printDialog.setOption(QAbstractPrintDialog::PrintSelection,false);
  printDialog.setOption(QAbstractPrintDialog::PrintPageRange,false);
  if (printDialog.exec() == QDialog::Accepted) {
    m_webview->print(&printer);
  }
}

void 
PrintableTableView::printHtml(bool ok) {
  disconnect(m_webview, SIGNAL(loadFinished(bool)),this, SLOT(printHtml(bool)));
  QPrinter printer;  
  QPrintDialog printDialog(&printer, this);
  printDialog.setOption(QAbstractPrintDialog::PrintSelection,false);
  printDialog.setOption(QAbstractPrintDialog::PrintPageRange,false);
  if (printDialog.exec() == QDialog::Accepted) {
    m_webview->print(&printer);
  }
}

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