Circle Widget : QWidget « Qt « C++

1. C++
2. Qt
3. QWidget

Circle Widget

  
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#ifndef CIRCLEWIDGET_H
#define CIRCLEWIDGET_H

#include <QWidget>


class CircleWidget : public QWidget
{
    Q_OBJECT

public:
    CircleWidget(QWidget *parent = 0);

    void setFloatBased(bool floatBased);
    void setAntialiased(bool antialiased);

    QSize minimumSizeHint() const;
    QSize sizeHint() const;

public slots:
    void nextAnimationFrame();

protected:
    void paintEvent(QPaintEvent *event);

private:
    bool floatBased;
    bool antialiased;
    int frameNo;
};


#endif






#include <QtGui>

#include "circlewidget.h"

#include <stdlib.h>


CircleWidget::CircleWidget(QWidget *parent)
    : QWidget(parent)
{
    floatBased = false;
    antialiased = false;
    frameNo = 0;

    setBackgroundRole(QPalette::Base);
    setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
}



void CircleWidget::setFloatBased(bool floatBased)
{
    this->floatBased = floatBased;
    update();
}



void CircleWidget::setAntialiased(bool antialiased)
{
    this->antialiased = antialiased;
    update();
}



QSize CircleWidget::minimumSizeHint() const
{
    return QSize(50, 50);
}



QSize CircleWidget::sizeHint() const
{
    return QSize(180, 180);
}



void CircleWidget::nextAnimationFrame()
{
    ++frameNo;
    update();
}



void CircleWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing, antialiased);
    painter.translate(width() / 2, height() / 2);



    for (int diameter = 0; diameter < 256; diameter += 9) {
        int delta = abs((frameNo % 128) - diameter / 2);
        int alpha = 255 - (delta * delta) / 4 - diameter;
 
        if (alpha > 0) {
            painter.setPen(QPen(QColor(0, diameter / 2, 127, alpha), 3));

            if (floatBased) {
                painter.drawEllipse(QRectF(-diameter / 2.0, -diameter / 2.0,
                                           diameter, diameter));
            } else {
                painter.drawEllipse(QRect(-diameter / 2, -diameter / 2,
                                          diameter, diameter));
            }
        }
    }
}






#ifndef WINDOW_H
#define WINDOW_H

#include <QWidget>

QT_BEGIN_NAMESPACE
class QLabel;
QT_END_NAMESPACE
class CircleWidget;


class Window : public QWidget
{
    Q_OBJECT

public:
    Window();

private:
    QLabel *createLabel(const QString &text);

    QLabel *aliasedLabel;
    QLabel *antialiasedLabel;
    QLabel *intLabel;
    QLabel *floatLabel;
    CircleWidget *circleWidgets[2][2];
};


#endif





#include <QtGui>

#include "circlewidget.h"
#include "window.h"


Window::Window()
{
    aliasedLabel = createLabel(tr("Aliased"));
    antialiasedLabel = createLabel(tr("Antialiased"));
    intLabel = createLabel(tr("Int"));
    floatLabel = createLabel(tr("Float"));

    QGridLayout *layout = new QGridLayout;
    layout->addWidget(aliasedLabel, 0, 1);
    layout->addWidget(antialiasedLabel, 0, 2);
    layout->addWidget(intLabel, 1, 0);
    layout->addWidget(floatLabel, 2, 0);



    QTimer *timer = new QTimer(this);

    for (int i = 0; i < 2; ++i) {
        for (int j = 0; j < 2; ++j) {
            circleWidgets[i][j] = new CircleWidget;
            circleWidgets[i][j]->setAntialiased(j != 0);
            circleWidgets[i][j]->setFloatBased(i != 0);

            connect(timer, SIGNAL(timeout()),
                    circleWidgets[i][j], SLOT(nextAnimationFrame()));

            layout->addWidget(circleWidgets[i][j], i + 1, j + 1);
        }
    }
 
    timer->start(100);
    setLayout(layout);

    setWindowTitle(tr("Concentric Circles"));
}



QLabel *Window::createLabel(const QString &text)
{
    QLabel *label = new QLabel(text);
    label->setAlignment(Qt::AlignCenter);
    label->setMargin(2);
    label->setFrameStyle(QFrame::Box | QFrame::Sunken);
    return label;
}






#include <QApplication>

#include "window.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    Window window;
    window.show();
    return app.exec();
}

   
    
  

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