gistfile1.cpp

// Header File

#ifndef BUBBLE_H
#define BUBBLE_H

#include <QWidget>

namespace Ui {
class Bubble;
}

class Bubble : public QWidget
{
    Q_OBJECT

public:
    explicit Bubble(QWidget *parent = 0);
    virtual QSize sizeHint() const;
    ~Bubble();
    static const int WIDTH = 300, HEIGHT = 300;

protected:
    virtual void paintEvent(QPaintEvent *paintEvent);
    void mouseMoveEvent(QMouseEvent* event);
    void mousePressEvent(QMouseEvent* event);
    void mouseReleaseEvent(QMouseEvent* event);
    void repositionBubble();

private:
    Ui::Bubble *ui;
    bool mMoving;
    QPoint offset;
};

#endif // BUBBLE_H

#include <QWidget>

// C++ File

#include "bubble.h"
#include "ui_bubble.h"
#include <QtGui>

Bubble::Bubble(QWidget *parent) :
    QWidget(parent, Qt::FramelessWindowHint),
    ui(new Ui::Bubble)
{
    
    setAttribute(Qt::WA_TranslucentBackground);
    ui->setupUi(this);
}

Bubble::~Bubble()
{
    delete ui;
}

QSize Bubble::sizeHint() const {
    return QSize(300, 300);
}

void Bubble::paintEvent(QPaintEvent *paintEvent){
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.setPen(Qt::NoPen);
    painter.setBrush(QColor(255, 255, 255, 255));
    painter.drawEllipse(0, 0, width(), height());
}

void Bubble::mousePressEvent(QMouseEvent* event)
{
    offset = event->pos();
    if(event->button() == Qt::LeftButton)
    {
        mMoving = true;
    }
}

void Bubble::mouseMoveEvent(QMouseEvent* event)
{
    if( event->buttons().testFlag(Qt::LeftButton) && mMoving)
        {
            this->move(mapToParent(event->pos() - offset));
        }
}

void Bubble::mouseReleaseEvent(QMouseEvent* event)
{
    if(event->button() == Qt::LeftButton)
    {
        mMoving = false;
    }
}

void Bubble::repositionBubble(){

}