GoldenCheetah/qwt/examples/refreshtest/mainwindow.cpp

#include <qstatusbar.h>
#include <qlabel.h>
#include <qlayout.h>
#include <qevent.h>
#include <qdatetime.h>
#include <qwt_plot_canvas.h>
#include "panel.h"
#include "plot.h"
#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent):
    QMainWindow(parent)
{
    QWidget *w = new QWidget(this);

    d_panel = new Panel(w);

    d_plot = new Plot(w);
    d_plot->canvas()->installEventFilter(this);

    QHBoxLayout *hLayout = new QHBoxLayout(w);
    hLayout->addWidget(d_panel);
    hLayout->addWidget(d_plot, 10);

    setCentralWidget(w);

    d_frameCount = new QLabel(this);
    statusBar()->addWidget(d_frameCount, 10);

    d_plot->setSettings(d_panel->settings());

    connect(d_panel, SIGNAL(settingsChanged(const Settings &)),
        d_plot, SLOT(setSettings(const Settings &)));
}

bool MainWindow::eventFilter(QObject *object, QEvent *event)
{
    if ( object == d_plot->canvas() && event->type() == QEvent::Paint )
    {
        static int counter;
        static QTime timeStamp;

        if ( !timeStamp.isValid() )
        {
            timeStamp.start();
            counter = 0;
        }
        else
        {
            counter++;

            const double elapsed = timeStamp.elapsed() / 1000.0;
            if ( elapsed >= 1 )
            {
                QString fps;
                fps.setNum(qRound(counter / elapsed));
                fps += " Fps";

                d_frameCount->setText(fps);

                counter = 0;
                timeStamp.start();
            }
        }
    }

    return QMainWindow::eventFilter(object, event);
};