QGraphicsRectItem and QGraphicsTextItem.

[cydside]

Hi to all,
I'm trying to build a rectangle (QGraphicsRectItem) with a text inside (QGraphicsTextItem) perfectly centered both vetically and horizontally as child, if it's the best solution. I've tried the following code:

for (int i = 0; i < 12; i++)
   {
      QGraphicsRectItem *month =
         new QGraphicsRectItem(QRect(margineX + 60 * i, endY - margineY + 2, 60, 30), 0, scene);
      month->setPen(QPen(Qt::red, 1, Qt::SolidLine));
      month->setBrush(Qt::NoBrush);
 
      QGraphicsTextItem *textMonth =
         new QGraphicsTextItem(QString("%1").arg(i + 1), month);
   }

for (int i = 0; i < 12; i++)
   {
      QGraphicsRectItem *month =
         new QGraphicsRectItem(QRect(margineX + 60 * i, endY - margineY + 2, 60, 30), 0, scene);
      month->setPen(QPen(Qt::red, 1, Qt::SolidLine));
      month->setBrush(Qt::NoBrush);

      QGraphicsTextItem *textMonth =
         new QGraphicsTextItem(QString("%1").arg(i + 1), month);
   }

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and...it doesn't work. Thanks in advance!

[Lykurg]

It's easier to subclass the paint method of the text item and draw a border yourself. Then call the base class paint method for the text drawing.

[cydside]

Thanks Lykurg. do you know where can I find an example? if it's not so much trouble

[Lykurg]

It's always better to try by yourself,but if you really want for that simple task:

class myItem : public QGraphicsTextItem
{
public:
    myItem(QGraphicsItem *parent = 0) : QGraphicsTextItem(parent)
    {}
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0)
    {
        painter->setPen(Qt::black);
        painter->setBrush(QColor(230,230,230));
        painter->drawRect(option->rect);
        QGraphicsTextItem::paint(painter, option, widget);
    }
};

class myItem : public QGraphicsTextItem
{
public:
    myItem(QGraphicsItem *parent = 0) : QGraphicsTextItem(parent)
    {}
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0)
    {
        painter->setPen(Qt::black);
        painter->setBrush(QColor(230,230,230));
        painter->drawRect(option->rect);
        QGraphicsTextItem::paint(painter, option, widget);
    }
};

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[cydside]

Thanks again Likurg, I've used your code but I've not centered the problem cause my incomplete explaination. So, I'd like to build histograms (QGraphicsRectItem) and write the value inside the rectangle (see the attachment) and I'm going on trouble to find something that works. Any idea?

[nish]

just use qpainter transforms to write vertical text

[wagmare]

create a custom QGraphicsItem with both QGraphicsRect and QGraphicsText
and in QGraphicsView class (parent)
QTransform transform;
transform.rotate( 90);
grpahicsItem->setTransform(transform);

[cydside]

create a custom QGraphicsItem with both QGraphicsRect and QGraphicsText
and in QGraphicsView class (parent)
QTransform transform;
transform.rotate( 90);
grpahicsItem->setTransform(transform);

Ok, It seems a good solution, but how to obtain a text centered both vetically and horizontally in the rectangle?

[wagmare]

but how to obtain a text centered both vetically and horizontally in the rectangle?

thats what i am suggesting .. combine both the text and rectangle into single QGraphicsItem ..

paint such that
create a custom QGraphicsItem()

class CustomItem : public QGraphicsRectItem
{
        Q_OBJECT
 
public:
        CustomItem(const QRectF &rect);
        void paint(QPainter *painter, const  QStyleOptionGraphicsItem *, QWidget *);
        QRectF boundingRect();
 
};

class CustomItem : public QGraphicsRectItem
{
        Q_OBJECT

public:
        CustomItem(const QRectF &rect);
        void paint(QPainter *painter, const  QStyleOptionGraphicsItem *, QWidget *);
        QRectF boundingRect();
   
};

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CustomItem::CustomItem(const QRectF &rect)
            : QGraphicsRectItem(rect)
{
     textItem->setDefaultTextColor(QColor(255,255,255,255));
        textItem->setPos(x, y);              //here u set position of text 
   textItem->setPlainText(message);      //set your text here   
}
 
void CustomItem::paint(QPainter *painter, const  QStyleOptionGraphicsItem *o, QWidget *widget)
{
 painter->setBrush(QBrush(QColor(21, 155, 210, 255)));
        painter->drawRect(rect());
 
}

CustomItem::CustomItem(const QRectF &rect)
            : QGraphicsRectItem(rect)
{
     textItem->setDefaultTextColor(QColor(255,255,255,255));
        textItem->setPos(x, y);              //here u set position of text 
   textItem->setPlainText(message);      //set your text here   
}

void CustomItem::paint(QPainter *painter, const  QStyleOptionGraphicsItem *o, QWidget *widget)
{
 painter->setBrush(QBrush(QColor(21, 155, 210, 255)));
        painter->drawRect(rect());

}

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now the item is ready in horizontal ... now in parent graphicsView() rotate it using previous code ...

[Lykurg]

create a custom QGraphicsItem with both QGraphicsRect and QGraphicsText
and in QGraphicsView class (parent)
QTransform transform;
transform.rotate( 90);
grpahicsItem->setTransform(transform);

Instead of setting the transformation to each item you use and in your particular case, it's better to create your own item and draw the text yourself:
In paint also draw the text via QPainter::drawText() (there are alignment flags) and then rotate the painter by 90°. And don't forget to implement the sizeHint() function.

[wagmare]

yes lykurg .. its a better option .. in paint() itself we can rotate the text and add the text in that custom item ...

[cydside]

Instead of setting the transformation to each item you use and in your particular case, it's better to create your own item and draw the text yourself:
In paint also draw the text via QPainter::drawText() (there are alignment flags) and then rotate the painter by 90°. And don't forget to implement the sizeHint() function.

QPainter will be the best solution when the rect area is smallest than the text, but if I try to create a QPainter object for that QGraphicsScene as the following code:

QGraphicsScene *scene =
      new QGraphicsScene(QRect(0, 0, endX, endY), this);
 
   for (int i = 0; i < 12; i++)
   {
      QGraphicsRectItem *mese =
         new QGraphicsRectItem(QRect(margineX + 2 + 60 * i, endY - margineY + 2, 60, 30), 0, scene);
//      mese->setPen(QPen(Qt::red, 1, Qt::SolidLine));
      mese->setPen(Qt::NoPen);
      mese->setBrush(Qt::NoBrush);
 
 
      QPainter painter(scene);
      painter.drawText(mese, Qt::AlignCenter, mesiAnno.at(i));
      painter.drawRect(mese);

QGraphicsScene *scene =
      new QGraphicsScene(QRect(0, 0, endX, endY), this);

   for (int i = 0; i < 12; i++)
   {
      QGraphicsRectItem *mese =
         new QGraphicsRectItem(QRect(margineX + 2 + 60 * i, endY - margineY + 2, 60, 30), 0, scene);
//      mese->setPen(QPen(Qt::red, 1, Qt::SolidLine));
      mese->setPen(Qt::NoPen);
      mese->setBrush(Qt::NoBrush);


      QPainter painter(scene);
      painter.drawText(mese, Qt::AlignCenter, mesiAnno.at(i));
      painter.drawRect(mese);

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the compiler is not agree with me because:

error: no matching function for call to `QPainter::QPainter(QGraphicsScene*&)'
note: candidates are: QPainter::QPainter(const QPainter&)
note:                 QPainter::QPainter(QPaintDevice*)

error: no matching function for call to `QPainter::QPainter(QGraphicsScene*&)'
note: candidates are: QPainter::QPainter(const QPainter&)
note:                 QPainter::QPainter(QPaintDevice*)

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where do i have to link my QPainter object???

thanks guys, I really appreciate your comments!

[wagmare]

where u are using the painter ...
if in QGraphicsView () class
then paint inside

void QGraphicsView::drawBackground

if in QGraphicsItem() class
then paint inside

void QGraphicsItem:aint ( QPainter * painter, const QStyleOptionGraphicsItem * option, QWidget * widget = 0 )

[Lykurg]

That is what I have meant by, do stuff (subclassing) yourself and try to understand!

Use my first example code and do the painting inside the paint function. You don't want to paint on the screen, you want to the item, and that is done inside the item!