How to extend QML Rectangle in C++ - qt

Question

When I want to create a new Qt Quick Item in C++ in I extend QQuickItem. It happens that I want my new item to have the same basic properties of a Rectangle. Is there any class I can extend to have a Rectangle directly?

Answer 1

Rectangle is actually QQuickRectangle, but it is not exported to be used in C++. The header file is QtQuick\private\qquickrectangle_p.h.

Answer 2

Check my version of an AdvancedRectangle that can have a different radius for each corner. I had to re-implement Rectangle's behavior.
advancedrectangle.h
#ifndef ADVANCEDRECTANGLE_H
#define ADVANCEDRECTANGLE_H
#include <QQuickPaintedItem>
#include <QPainter>
#include <QPen>
class AdvancedRectangle : public QQuickPaintedItem
{
Q_OBJECT
public:
explicit AdvancedRectangle(QQuickItem *parent = 0);
Q_PROPERTY(QColor color READ color WRITE setColor NOTIFY colorChanged)
QColor color() const;
void setColor(QColor color);
Q_PROPERTY(qreal radius READ radius WRITE setRadius NOTIFY radiusChanged)
qreal radius() const;
void setRadius(qreal r);
Q_PROPERTY(qreal radiusTopLeft READ radiusTopLeft WRITE setRadiusTopLeft NOTIFY radiusTopLeftChanged)
qreal radiusTopLeft() const;
void setRadiusTopLeft(qreal r);
Q_PROPERTY(qreal radiusTopRight READ radiusTopRight WRITE setRadiusTopRight NOTIFY radiusTopRightChanged)
qreal radiusTopRight() const;
void setRadiusTopRight(qreal r);
Q_PROPERTY(qreal radiusBottomRight READ radiusBottomRight WRITE setRadiusBottomRight NOTIFY radiusBottomRightChanged)
qreal radiusBottomRight() const;
void setRadiusBottomRight(qreal r);
Q_PROPERTY(qreal radiusBottomLeft READ radiusBottomLeft WRITE setRadiusBottomLeft NOTIFY radiusBottomLeftChanged)
qreal radiusBottomLeft() const;
void setRadiusBottomLeft(qreal r);
void paint(QPainter *painter);
enum START_ANGELS {
START_E = 0,
START_N = 90,
START_W = 180,
START_S = 270
};
signals:
void colorChanged();
void radiusChanged();
void radiusTopLeftChanged();
void radiusTopRightChanged();
void radiusBottomRightChanged();
void radiusBottomLeftChanged();
public slots:
private:
QColor color_ = QColor(255, 255, 255);
qreal radius_ = 0.0;
qreal radiusTopLeft_ = -1;
qreal radiusTopRight_ = -1;
qreal radiusBottomRight_ = -1;
qreal radiusBottomLeft_ = -1;
private slots:
void onAppearanceChanged();
};
#endif // ADVANCEDRECTANGLE_H
advancedrectangle.cpp
#include "advancedrectangle.h"
AdvancedRectangle::AdvancedRectangle(QQuickItem *parent) :
QQuickPaintedItem(parent)
{
connect(this, SIGNAL(widthChanged()), SLOT(onAppearanceChanged()));
connect(this, SIGNAL(heightChanged()), SLOT(onAppearanceChanged()));
connect(this, SIGNAL(colorChanged()), SLOT(onAppearanceChanged()));
}
QColor AdvancedRectangle::color() const
{
return color_;
}
void AdvancedRectangle::setColor(QColor color)
{
if (color_ == color) return;
color_ = color;
emit colorChanged();
}
qreal AdvancedRectangle::radius() const
{
return radius_;
}
void AdvancedRectangle::setRadius(qreal r)
{
if (r == radius_) return;
radius_ = r;
emit radiusChanged();
}
qreal AdvancedRectangle::radiusTopLeft() const
{
if (radiusTopLeft_ >= 0) return radiusTopLeft_;
else return radius_;
}
void AdvancedRectangle::setRadiusTopLeft(qreal r)
{
if (r == radiusTopLeft_) return;
radiusTopLeft_ = r;
emit radiusTopLeftChanged();
}
qreal AdvancedRectangle::radiusTopRight() const
{
if (radiusTopRight_ >= 0) return radiusTopRight_;
else return radius_;
}
void AdvancedRectangle::setRadiusTopRight(qreal r)
{
if (r == radiusTopRight_) return;
radiusTopRight_ = r;
emit radiusTopRightChanged();
}
qreal AdvancedRectangle::radiusBottomRight() const
{
if (radiusBottomRight_ >= 0) return radiusBottomRight_;
else return radius_;
}
void AdvancedRectangle::setRadiusBottomRight(qreal r)
{
if (r == radiusBottomRight_) return;
radiusBottomRight_ = r;
emit radiusBottomRightChanged();
}
qreal AdvancedRectangle::radiusBottomLeft() const
{
if (radiusBottomLeft_ >= 0) return radiusBottomLeft_;
else return radius_;
}
void AdvancedRectangle::setRadiusBottomLeft(qreal r)
{
if (r == radiusBottomLeft_) return;
radiusBottomLeft_ = r;
emit radiusBottomLeftChanged();
}
void AdvancedRectangle::paint(QPainter *painter)
{
QPen pen(Qt::NoPen);
painter->setPen(pen);
QBrush brush(color_);
painter->setBrush(brush);
painter->setRenderHints(QPainter::Antialiasing, true);
int _width = width();
int _height = height();
QRectF rectangle;
// top-left
rectangle = QRectF(0, 0, 2*radiusTopLeft(), 2*radiusTopLeft());
painter->drawPie(rectangle, START_W * 16, 90 * -1 * 16);
// top-right
rectangle = QRectF(_width-2*radiusTopRight(), 0, 2*radiusTopRight(), 2*radiusTopRight());
painter->drawPie(rectangle, START_N * 16, 90 * -1 * 16);
// bottom-right
rectangle = QRectF(_width-2*radiusBottomRight(), _height-2*radiusBottomRight(), 2*radiusBottomRight(), 2*radiusBottomRight());
painter->drawPie(rectangle, START_E * 16, 90 * -1 * 16);
// bottom-left
rectangle = QRectF(0, _height-2*radiusBottomLeft(), 2*radiusBottomLeft(), 2*radiusBottomLeft());
painter->drawPie(rectangle, START_S * 16, 90 * -1 * 16);
QPointF points[12] = {
QPointF(radiusTopLeft(), 0),
QPointF(radiusTopLeft(), radiusTopLeft()),
QPointF(0, radiusTopLeft()),
QPointF(0, _height-radiusBottomLeft()),
QPointF(radiusBottomLeft(), _height-radiusBottomLeft()),
QPointF(radiusBottomLeft(), _height),
QPointF(_width-radiusBottomRight(), _height),
QPointF(_width-radiusBottomRight(), _height-radiusBottomRight()),
QPointF(_width, _height-radiusBottomRight()),
QPointF(_width, radiusTopRight()),
QPointF(_width-radiusTopRight(), radiusTopRight()),
QPointF(_width-radiusTopRight(), 0)
};
painter->drawPolygon(points, 12);
}
void AdvancedRectangle::onAppearanceChanged()
{
int new_width = width();
int new_height = height();
update(QRect(0, 0, new_width, new_height));
}
Let me know if you need that MIT licensed.