Qt 5.8 | Qt Designer Manual | World Time Clock Plugin Example | worldtimeclock.cpp Example File

Qt 5.8.0 Reference Documentation

# worldtimeclock.cpp Example File

worldtimeclockplugin/worldtimeclock.cpp

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      #include "worldtimeclock.h"

      #include <QMouseEvent>
      #include <QPainter>
      #include <QTimer>

      WorldTimeClock::WorldTimeClock(QWidget *parent)
          : QWidget(parent)
          , timeZoneOffset(0)

      {
          typedef void (QWidget::*WidgetUpdateSlot)();

          QTimer *timer = new QTimer(this);
          connect(timer, &QTimer::timeout, this, static_cast<WidgetUpdateSlot>(&QWidget::update));
          timer->start(1000);

          setWindowTitle(tr("World Time Clock"));
          resize(200, 200);
      }

      void WorldTimeClock::paintEvent(QPaintEvent *)
      {
          static const QPoint hourHand[3] = {
              QPoint(7, 8),
              QPoint(-7, 8),
              QPoint(0, -40)
          };
          static const QPoint minuteHand[3] = {
              QPoint(7, 8),
              QPoint(-7, 8),
              QPoint(0, -70)
          };

          QColor hourColor(127, 0, 127);
          QColor minuteColor(0, 127, 127, 191);

          int side = qMin(width(), height());
          QTime time = QTime::currentTime();
          time = time.addSecs(timeZoneOffset);

          QPainter painter(this);
          painter.setRenderHint(QPainter::Antialiasing);
          painter.translate(width() / 2, height() / 2);
          painter.scale(side / 200.0, side / 200.0);

          painter.setPen(Qt::NoPen);
          painter.setBrush(hourColor);

          painter.save();
          painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
          painter.drawConvexPolygon(hourHand, 3);
          painter.restore();

          painter.setPen(hourColor);

          for (int i = 0; i < 12; ++i) {
              painter.drawLine(88, 0, 96, 0);
              painter.rotate(30.0);
          }

          painter.setPen(Qt::NoPen);
          painter.setBrush(minuteColor);

          painter.save();
          painter.rotate(6.0 * (time.minute() + time.second() / 60.0));
          painter.drawConvexPolygon(minuteHand, 3);
          painter.restore();

          painter.setPen(minuteColor);

          for (int j = 0; j < 60; ++j) {
              if ((j % 5) != 0)
                  painter.drawLine(92, 0, 96, 0);
              painter.rotate(6.0);
          }

          emit updated(time);
      }

      void WorldTimeClock::setTimeZone(int hourOffset)
      {
          timeZoneOffset = qMin(qMax(-12, hourOffset), 12) * 3600;
          update();
      }