Scale a QTableWidget - c++

Question

I need to scale a QtableWidget (the behaviour should be like a zoom).
But when I reimplement the paintEvent of QtableWidget and set the scale manually, like this:
void MyTableWidget::paintEvent ( QPaintEvent * event )
{
QTableWidget::paintEvent(event);
QPainter p(viewport());
p.scale(m_scale,m_scale);
p.drawRect( 0, 0, width()-1, height()-1);
}
only the border is rescaled :
And I don't see any paintEvent on QTableWidgetItem, so how can I rescale all my table ?
Thank you in advance and have a good day.
EDIT ----------------------------------------
The behaviour may seems strange so here is some explanations:
This QT window is a child of an acrobat reader window. When I unzoom the PDF on acrobat, I resize my QT window to keep the same proportions, but I would like to scale the content of the window.
example: If I unzoom my PDF, I decrease the size of my QT window to keep the same proportions, and I want to scale the content of my QT window to this new size (decrease the display size, like an unzoom). Is it clear ? :o
But for instance the view donesn't fit the window, I have this:
And I want this:
And when I zoom on my PDF, I increase the window size and scale up the content, like this:
Thank you very much for your help and your time.

Answer 1

Use QGraphicsScene with your QTableWidget instead, but it is not very difficult:
QGraphicsScene *scene = new QGraphicsScene(this);
ui->graphicsView->setScene(scene);
QTableWidget *wgt = new QTableWidget;
wgt->setColumnCount(10);
wgt->setRowCount(10);
for (int ridx = 0 ; ridx < wgt->rowCount() ; ridx++ )
{
for (int cidx = 0 ; cidx < wgt->columnCount() ; cidx++)
{
QTableWidgetItem* item = new QTableWidgetItem();
item->setText(QString("%1").arg(ridx));
wgt->setItem(ridx,cidx,item);
}
}
QGraphicsProxyWidget *pr = scene->addWidget( wgt );
pr->moveBy(10,10);
Scale view with:
ui->graphicsView->scale(2,2);
Better way for zooming is zoom in out by wheel. Subclass view or use eventFilter. For example:
Header:
#ifndef MYQGRAPHICSVIEW_H
#define MYQGRAPHICSVIEW_H
#include <QGraphicsView>
class MyQGraphicsView : public QGraphicsView
{
Q_OBJECT
public:
explicit MyQGraphicsView(QWidget *parent = 0);
signals:
protected:
void wheelEvent(QWheelEvent* event);
};
#endif // MYQGRAPHICSVIEW_H
Cpp:
#include "myqgraphicsview.h"
#include <QPointF>
MyQGraphicsView::MyQGraphicsView(QWidget *parent) :
QGraphicsView(parent)
{
}
void MyQGraphicsView::wheelEvent(QWheelEvent* event) {
setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
// Scale the view / do the zoom
double scaleFactor = 1.15;
if(event->delta() > 0) {
// Zoom in
scale(scaleFactor, scaleFactor);
} else {
// Zooming out
scale(1.0 / scaleFactor, 1.0 / scaleFactor);
}
// Don't call superclass handler here
// as wheel is normally used for moving scrollbars
}
Usage:
MyQGraphicsView *view = new MyQGraphicsView;
view->setScene(scene);//same scene
view->show();
Result as you want:
Note that user still able to edit data etc, functionality didn't change.
Additional example, like in the Qt books.
(same MyQGraphicsView class)
#include "myqgraphicsview.h"
#include <QGraphicsProxyWidget>//and other needed includes
//just to show that signals and slots works
//with widget which placed in graphicsview
void print(int row, int column)
{
qDebug() << row+1 << column+1;
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget *widget = new QWidget;//container
QVBoxLayout *lay = new QVBoxLayout;
MyQGraphicsView * view = new MyQGraphicsView;//view as part of UI
QGraphicsScene * scene = new QGraphicsScene;
QTableWidget *wgt = new QTableWidget;//table which will be added to graphicsView
QObject::connect(wgt,&QTableWidget::cellPressed,print);//connection using Qt5 style(and power)
wgt->setColumnCount(10);
wgt->setRowCount(10);
for (int ridx = 0 ; ridx < wgt->rowCount() ; ridx++ )
{
for (int cidx = 0 ; cidx < wgt->columnCount() ; cidx++)
{
QTableWidgetItem* item = new QTableWidgetItem();
item->setText(QString("%1").arg(ridx));
wgt->setItem(ridx,cidx,item);
}
}
QPushButton *butt = new QPushButton("click");
lay->addWidget(view);
lay->addWidget(butt);
widget->setLayout(lay);
QGraphicsProxyWidget *pr = scene->addWidget( wgt );
pr->moveBy(10,10);
view->setScene(scene);
widget->show();
return a.exec();
}
Result:
As you can see, user can scale table, edit data and signals and slots works. All fine.