VolumeRendering
QPainter Example
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QPainter is a Qt class that serves as a renderer for 2D graphic primitives like lines, polygons and text. It renders either into pixmaps (QPixmap), images (QImage) or into a widget, which inherits from QPixmap, as well.
In the following we create a new widget type by deriving from QWidget and draw a green text as background of the new widget. For that purpose we need to override the paintEvent() method, which is called whenever the widget’s graphical representation needs to be repainted:
#include <QtGui/QWidget>
class PainterWidget: public QWidget
{
public:
//! default ctor
PainterWidget(QWidget *parent = 0)
: QWidget(parent)
{}
//! dtor
~PainterWidget()
{}
//! return preferred minimum window size
QSize minimumSizeHint() const
{
return(QSize(100, 100));
}
//! return preferred window size
QSize sizeHint() const
{
return(QSize(512, 512));
}
protected:
//! reimplemented paint event
void paintEvent(QPaintEvent *)
{
QPainter painter(this);
painter.setPen(Qt::green);
painter.setFont(QFont("Arial", 100));
painter.drawText(rect(), Qt::AlignCenter, "Qt");
}
};
class PainterWidget: public QWidget
{
public:
//! default ctor
PainterWidget(QWidget *parent = 0)
: QWidget(parent)
{}
//! dtor
~PainterWidget()
{}
//! return preferred minimum window size
QSize minimumSizeHint() const
{
return(QSize(100, 100));
}
//! return preferred window size
QSize sizeHint() const
{
return(QSize(512, 512));
}
protected:
//! reimplemented paint event
void paintEvent(QPaintEvent *)
{
QPainter painter(this);
painter.setPen(Qt::green);
painter.setFont(QFont("Arial", 100));
painter.drawText(rect(), Qt::AlignCenter, "Qt");
}
};
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