How to draw rectangle with all corners rounded ?

tushu

I am trying to draw rectangle in the QGraphicsScene.
It is coming like this.

But I want all its 4 corner rounded.
How to do that ?

I have created rectangle this way:

myRect.h

class myRect: public QGraphicsRectItem {
explicit myRect(QRectF &rectPoints,  QGraphicsScene *_scene,
                              QGraphicsItem *parent = nullptr)
        : QGraphicsRectItem(rectPoints, parent),  _scene(_scene)
    {}
CreateRect(QRectF);
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);

}

myRect.cpp

void myRect::CreateRect(QRectF rect)
{
    QPen mPen;
    mPen.setWidth(1);
    mPen.setBrush(Qt::blue);
    this->setPen(mPen);
    this->setFlag(QGraphicsItem::ItemIsSelectable);
}

void myRect::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    auto copied_option = *option;
    copied_option.state &= ~QStyle::State_Selected;
    auto selected = option->state & QStyle::State_Selected;
    QGraphicsRectItem::paint(painter, &copied_option, widget);
    if (selected) {
        painter->save();
        painter->setBrush(Qt::NoBrush);
        painter->setPen(QPen(option->palette.windowText(), 0, Qt::SolidLine));
        painter->drawPath(shape());
        painter->restore();
    }
}

myView.cpp

QRectF Rect( some co-ordinates);
myRect* rect = new myRect(Rect, _scene);
rect->CreateRect(Rect);

JoeCFD

@tushu https://stackoverflow.com/questions/29196610/qt-drawing-a-filled-rounded-rectangle-with-border

tushu

@JoeCFD Thanks for your reply.
I had seen that link but did not get how to use

addRoundedRect()

Because it is called by QPainterPath. And I do not have QPainterPath.

And I am drawing rectangle through constructor.
How to use QpainterPath in such case ?

JonB

@tushu said in How to draw rectangle with all corners rounded ?:

Because it is called by QPainterPath. And I do not have QPainterPath.

Both the examples in the link show they create a QPainterPath as a local variable. The second one shows a complete paintEvent() override.

And I am drawing rectangle through constructor.

You can't. Drawing is done in paintEvent() as shown.

EDIT I had not looked closely enough at your situation with graphics as opposed to the SO link for widgets. My bad.

tushu

@JonB Thanks for reply.
I tried to create QPainterPath variable in constructor where I have rectangle co-ordinates. But I could not succeed.

So another thought was to create in PaintEvent()
But in my paintEvent() , how will I get co-ordinates of rectangle ?
Because , it is virtual method, and does not accept co-ordinates in parameter.

JoeCFD

@tushu You are not drawing it in the constructor. Your code overrides paint func. Therefore, the rect is drawn in paint(). Since the code in the link needs only painter and you have it in the paint(), I guess you can do the same thing. There is no paintEvent() for QGraphicsRectItem.

tushu

@JoeCFD @JonB

I have added following code in paint() , but did not get any effect.

QRectF rect = QRectF(widget->rect());
QPainterPath path;
path.addRoundedRect(rect, 10, 10);

JoeCFD

@tushu add print message or set break point there to check if the func is called. Also show your full code of this func.

tushu

@JoeCFD
my current output

And code in paint()

void myRect::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    QRectF rect = QRectF(widget->rect());
    QPainterPath path;
    painter->drawRoundedRect(rect, 10, 10);
auto copied_option = *option;
    copied_option.state &= ~QStyle::State_Selected;
    auto selected = option->state & QStyle::State_Selected;
    QGraphicsRectItem::paint(painter, &copied_option, widget);
    if (selected) {
        painter->save();
        painter->setBrush(Qt::NoBrush);
        painter->setPen(QPen(option->palette.windowText(), 0, Qt::SolidLine));
        painter->drawPath(shape());
        painter->restore();
    }

tushu

@JoeCFD
Some big rectangle is getting drawn.
I think that is because of

QRectF rect = QRectF(widget->rect());

I am taking widget->rect().
But I am expecting, every rectangle in the scene should have rounded corner.

JoeCFD

@tushu

Something like this.

void myRect::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    QRectF rect = QRectF(widget->rect());
    QPainterPath path;
    path->drawRoundedRect(rect, 10, 10); /* path not painter */
    auto copied_option = *option;
    copied_option.state &= ~QStyle::State_Selected;
    auto selected = option->state & QStyle::State_Selected;
    //QGraphicsRectItem::paint(painter, &copied_option, widget);  /* you do not call this one  */
    painter->save();
    if (selected) {
        painter->setBrush(Qt::NoBrush);
        painter->setPen(QPen(option->palette.windowText(), 0, Qt::SolidLine));
   }
   else {
       set pen color;
   }       
   painter->drawPath(path); 
   painter->restore();
}

tushu

@JoeCFD

I have used

painter.drawRoundedRect(rect, 10, 10);

because QPainterPath does not have drawRoundedRect()

current output

Below lines creating difference.

//QGraphicsRectItem::paint(painter, &copied_option, widget);  /* you do not call this one  */

JoeCFD

@tushu

void myRect::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    QRectF rect = QRectF(widget->rect());
    QPainterPath path;
    path->addRoundedRect(rect, 10, 10); /* add not draw sorry */
    auto copied_option = *option;
    copied_option.state &= ~QStyle::State_Selected;
    auto selected = option->state & QStyle::State_Selected;
    //QGraphicsRectItem::paint(painter, &copied_option, widget);  /* drawing is finished here and no need to call parent->paint()  */
    painter->save();
    if (selected) {
        painter->setBrush(Qt::NoBrush);
        painter->setPen(QPen(option->palette.windowText(), 0, Qt::SolidLine));
   }
   else {
       set pen color;
   }       
   painter->drawPath(path); 
   painter->restore();
}

JoeCFD

@tushu You also need to try the example first

void myRect::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
painter->setRenderHint(QPainter::Antialiasing);
QPainterPath path;
path.addRoundedRect(QRectF(10, 10, 100, 50), 10, 10);
QPen pen(Qt::black, 10);
painter->setPen(pen);
painter->fillPath(path, Qt::red);
painter->drawPath(path);
}

tushu

@JoeCFD
For this , getting the same above output.
(i.e. No border of any rectangle)

JoeCFD

@tushu did you try the example?

tushu

@JoeCFD

Example's output

I have just removed

//painter->fillPath(path, Qt::red);

tushu

@JoeCFD
Is the below line correct ?

QRectF rect = QRectF(widget->rect());

because of the above line , it is creating bigger rectangle ?
But bigger rectangle ( outermost ) has curved corner.

JoeCFD

@tushu you know the size of your rects, right? I do not know.

tushu

@JoeCFD
Your rectangle size suggestion worked.
Current output.

Now I want to round corner of middle 5 rectangle only ( i.e. sw1,sw2,PD_blue, PD_green,PD_yellow)
But left side rectangle ( small ) also got changed and looking like circle.

I think, I will need to set some flag and will have to decide, which rectangle's corner should be rounded.

But now main concern is PD_blue, PD_green,PD_yellow rectangles color is not visible.

I set their color, after creating rectangle using setBrush(). I do not set their color in paint(). After creating rectangle, if they are full filling some criteria, then I set color on them.

Why that color is not visible ?

Here is my paint()

void guiSchematicRect::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    Q_UNUSED(option);
    Q_UNUSED(widget);
    QRectF rect = QRectF(_polyRect);
    QPainterPath path;
    path.addRoundedRect(rect, 4, 4);
   auto copied_option = *option;
    copied_option.state &= ~QStyle::State_Selected;
    auto selected = option->state & 
   QStyle::State_Selected;
    painter->save();
    if (selected) {
        painter->setBrush(Qt::NoBrush);
        painter->setPen(QPen(option->palette.windowText(), 1, Qt::SolidLine));
   }
   else {
       painter->setPen(Qt::blue);
   }
   painter->drawPath(path);
   painter->restore();
}