Basic Graphics Layouts Example | Qt Widgets 5.13.0

Qt 5.13 | Qt Widgets | Basic Graphics Layouts Example

Qt 5.13.0 Reference Documentation

# Basic Graphics Layouts Example

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      #include "layoutitem.h"

      #include <QGradient>
      #include <QGraphicsLinearLayout>
      #include <QPainter>

      LayoutItem::LayoutItem(QGraphicsItem *parent/* = 0*/)
          : QGraphicsLayoutItem(), QGraphicsItem(parent)
      {
          m_pix = new QPixmap(QLatin1String(":/images/block.png"));
          setGraphicsItem(this);
      }

      LayoutItem::~LayoutItem()
      {
          delete m_pix;
      }

      void LayoutItem::paint(QPainter *painter,
          const QStyleOptionGraphicsItem *option, QWidget *widget /*= 0*/)
      {
          Q_UNUSED(widget);
          Q_UNUSED(option);

          QRectF frame(QPointF(0,0), geometry().size());
          qreal w = m_pix->width();
          qreal h = m_pix->height();
          QGradientStops stops;

          // paint a background rect (with gradient)
          QLinearGradient gradient(frame.topLeft(), frame.topLeft() + QPointF(200,200));
          stops << QGradientStop(0.0, QColor(60, 60,  60));
          stops << QGradientStop(frame.height() / 2 / frame.height(), QColor(102, 176, 54));

          //stops << QGradientStop(((frame.height() + h)/2 )/frame.height(), QColor(157, 195,  55));
          stops << QGradientStop(1.0, QColor(215, 215, 215));
          gradient.setStops(stops);
          painter->setBrush(QBrush(gradient));
          painter->drawRoundedRect(frame, 10.0, 10.0);

          // paint a rect around the pixmap (with gradient)
          QPointF pixpos = frame.center() - (QPointF(w, h) / 2);
          QRectF innerFrame(pixpos, QSizeF(w, h));
          innerFrame.adjust(-4, -4, 4, 4);
          gradient.setStart(innerFrame.topLeft());
          gradient.setFinalStop(innerFrame.bottomRight());
          stops.clear();
          stops << QGradientStop(0.0, QColor(215, 255, 200));
          stops << QGradientStop(0.5, QColor(102, 176, 54));
          stops << QGradientStop(1.0, QColor(0, 0,  0));
          gradient.setStops(stops);
          painter->setBrush(QBrush(gradient));
          painter->drawRoundedRect(innerFrame, 10.0, 10.0);
          painter->drawPixmap(pixpos, *m_pix);
      }

      QRectF LayoutItem::boundingRect() const
      {
          return QRectF(QPointF(0,0), geometry().size());
      }

      void LayoutItem::setGeometry(const QRectF &geom)
      {
          prepareGeometryChange();
          QGraphicsLayoutItem::setGeometry(geom);
          setPos(geom.topLeft());
      }

      QSizeF LayoutItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const
      {
          switch (which) {
          case Qt::MinimumSize:
          case Qt::PreferredSize:
              // Do not allow a size smaller than the pixmap with two frames around it.
              return m_pix->size() + QSize(12, 12);
          case Qt::MaximumSize:
              return QSizeF(1000,1000);
          default:
              break;
          }
          return constraint;
      }