Qt 5.6 | Qt Widgets | Lighting Effect Example | lighting.cpp Example File

Qt 5.6.2 Reference Documentation

# lighting.cpp Example File

effects/lighting/lighting.cpp

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      #include "lighting.h"

      #include <QtWidgets>
      #include <QtCore/qmath.h>

      #ifndef M_PI
      #define M_PI 3.14159265358979323846
      #endif

      Lighting::Lighting(QWidget *parent): QGraphicsView(parent), angle(0.0)
      {
          setScene(&m_scene);

          setupScene();

          QTimer *timer = new QTimer(this);
          connect(timer, SIGNAL(timeout()), SLOT(animate()));
          timer->setInterval(30);
          timer->start();

          setRenderHint(QPainter::Antialiasing, true);
          setFrameStyle(QFrame::NoFrame);
      }

      void Lighting::setupScene()
      {
          m_scene.setSceneRect(-300, -200, 600, 460);

          QLinearGradient linearGrad(QPointF(-100, -100), QPointF(100, 100));
          linearGrad.setColorAt(0, QColor(255, 255, 255));
          linearGrad.setColorAt(1, QColor(192, 192, 255));
          setBackgroundBrush(linearGrad);

          QRadialGradient radialGrad(30, 30, 30);
          radialGrad.setColorAt(0, Qt::yellow);
          radialGrad.setColorAt(0.2, Qt::yellow);
          radialGrad.setColorAt(1, Qt::transparent);
          QPixmap pixmap(60, 60);
          pixmap.fill(Qt::transparent);
          QPainter painter(&pixmap);
          painter.setPen(Qt::NoPen);
          painter.setBrush(radialGrad);
          painter.drawEllipse(0, 0, 60, 60);
          painter.end();

          m_lightSource = m_scene.addPixmap(pixmap);
          m_lightSource->setZValue(2);

          for (int i = -2; i < 3; ++i)
              for (int j = -2; j < 3; ++j) {
                  QAbstractGraphicsShapeItem *item;
                  if ((i + j) & 1)
                      item = new QGraphicsEllipseItem(0, 0, 50, 50);
                  else
                      item = new QGraphicsRectItem(0, 0, 50, 50);

                  item->setPen(QPen(Qt::black, 1));
                  item->setBrush(QBrush(Qt::white));
                  QGraphicsDropShadowEffect *effect = new QGraphicsDropShadowEffect;
                  effect->setBlurRadius(8);
                  item->setGraphicsEffect(effect);
                  item->setZValue(1);
                  item->setPos(i * 80, j * 80);
                  m_scene.addItem(item);
                  m_items << item;
              }

      }

      void Lighting::animate()
      {
          angle += (M_PI / 30);
          qreal xs = 200 * qSin(angle) - 40 + 25;
          qreal ys = 200 * qCos(angle) - 40 + 25;
          m_lightSource->setPos(xs, ys);

          for (int i = 0; i < m_items.size(); ++i) {
              QGraphicsItem *item = m_items.at(i);
              Q_ASSERT(item);
              QGraphicsDropShadowEffect *effect = static_cast<QGraphicsDropShadowEffect *>(item->graphicsEffect());
              Q_ASSERT(effect);

              QPointF delta(item->x() - xs, item->y() - ys);
              effect->setOffset(delta.toPoint() / 30);

              qreal dx = delta.x();
              qreal dy = delta.y();
              qreal dd = qSqrt(dx * dx + dy * dy);
              QColor color = effect->color();
              color.setAlphaF(qBound(0.4, 1 - dd / 200.0, 0.7));
              effect->setColor(color);
          }

          m_scene.update();
      }

      void Lighting::resizeEvent(QResizeEvent * /* event */)
      {
      }