#ifndef resizeable_textedit_hpp_included
#define resizeable_textedit_hpp_included

#include <QtGui>

class resizeable_textedit : public QTextEdit {
Q_OBJECT
public:
  resizeable_textedit( QWidget* parent = 0 );

protected:
  void paintEvent( QPaintEvent* event );
  void mousePressEvent( QMouseEvent* event );
  void mouseMoveEvent( QMouseEvent* event );
  void mouseReleaseEvent( QMouseEvent* event );

  QSize sizeHint() const;
  QSize minimumSizeHint() const;

private:
  bool left_button_down_;
  QPoint pos_at_down_;
  QSize size_hint_;
};

#endif

#include "resizeable_textedit.hpp"

resizeable_textedit::resizeable_textedit( QWidget* parent )
  : QTextEdit( parent )
{
  left_button_down_ = false;
}

void resizeable_textedit::paintEvent( QPaintEvent* event )
{
  QTextEdit::paintEvent( event );

  QPainter painter( viewport() );

  painter.setPen( Qt::lightGray );
  painter.setBrush( QBrush( Qt::lightGray, Qt::SolidPattern ) );

  QRect region = viewport()->geometry();

  int x = region.bottomRight().x();
  int y = region.bottomRight().y();

  const QPoint points[3] = {
    QPoint( x, y ),
    QPoint( x, y-15 ),
    QPoint( x-15, y )
  };

  painter.drawPolygon( points, 3 );
}

void resizeable_textedit::mousePressEvent( QMouseEvent* event )
{
  if ( event->button() == Qt::LeftButton ) {
    QApplication::setOverrideCursor( Qt::SizeVerCursor );
    const QPoint pos = event->pos();
    const QRect region = viewport()->geometry();

    if ( pos.x() >= region.bottomRight().x() - 15 &&
         pos.y() >= region.bottomRight().y() - 15 ) {
      left_button_down_ = true;
      pos_at_down_ = pos;
    }
  }
}

void resizeable_textedit::mouseReleaseEvent( QMouseEvent* event )
{
  QApplication::setOverrideCursor( Qt::ArrowCursor );
  left_button_down_ = false;
}

void resizeable_textedit::mouseMoveEvent( QMouseEvent* event )
{
  if ( left_button_down_ ) {
    const QPoint pos = event->pos();
    int h_diff = pos_at_down_.y() - pos.y();
    setGeometry( x(), y(), width(), height()-h_diff );
    size_hint_ = QSize( width(), height()-h_diff );
    pos_at_down_ = pos;
  }
}

QSize resizeable_textedit::sizeHint() const
{
  if ( size_hint_.isValid() )
  {
    return size_hint_;
  }

  return QTextEdit::sizeHint();
}

QSize resizeable_textedit::minimumSizeHint() const
{
  return QSize( 0, 0 );
}

#include <QApplication>
#include <QtGui>
#include "resizeable_textedit.hpp"

int main( int argc, char* argv[] )
{
  QApplication app( argc, argv );

  QWidget* window = new QWidget();
  resizeable_textedit* edit = new resizeable_textedit( window );
  QGridLayout* grid = new QGridLayout( window );
  window->setLayout( grid );
  QPalette p = window->palette();
  p.setColor( window->backgroundRole(), Qt::yellow );
  window->setPalette( p );
  QPushButton* b = new QPushButton( window );
  b->setText( "HELLO" );
  grid->addWidget( edit );
  grid->addWidget( b );

  window->show();

  return app.exec();
}