QT：浮动的饼状统计图（自绘不规则窗口）

    昨天在玩手机游戏时，见到一个游戏的饼状投票统计图很漂亮，所以我今天也花了一个下午来实现了一个类似的程序娱乐一下，呵呵。

思路：
1：将窗体设为Qt::FramelessWindowHint和Qt::WA_TranslucentBackground（去掉标题栏，背景透明）。
2：重载程序的鼠标事件（移动程序）和键盘事件（模拟投票和退出）。
3：根据投票结果，在paintEvent函数中画几个扇形和其他东西。

操作说明：
1：按数字键0－9模拟投票。

2：按ESC键退出程序。

运行时截图（浅绿色的是桌面背景）：

源代码：

#include <QtGui>

class PieDialog : public QDialog
{
    Q_OBJECT
private:
    int m_Result[10];
    QColor m_Color[10];
    QPoint m_CurrentPos;
protected:
    void mousePressEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
    void paintEvent(QPaintEvent *event);
    void enterEvent(QEvent *event);
    void leaveEvent(QEvent *event);
    void keyPressEvent(QKeyEvent *event);
public:
    PieDialog(QWidget *parent = 0);
};

PieDialog::PieDialog(QWidget *parent /* = 0 */)
: QDialog(parent)
{
    m_Color[0] = Qt::red;
    m_Color[1] = Qt::green;
    m_Color[2] = Qt::blue;
    m_Color[3] = Qt::cyan;
    m_Color[4] = Qt::magenta;
    m_Color[5] = Qt::yellow;
    m_Color[6] = Qt::darkYellow;
    m_Color[7] = Qt::darkRed;
    m_Color[8] = Qt::darkGreen;
    m_Color[9] = Qt::darkCyan;
    qMemSet(m_Result, 0, sizeof(m_Result));
    setWindowTitle("Pie Dialog");
    setFixedSize(400, 300);
    //让程序背景透明
    setWindowFlags( Qt::FramelessWindowHint );
    setAttribute(Qt::WA_TranslucentBackground, true);
}

void PieDialog::mousePressEvent(QMouseEvent *event)
{
    //按住左键可以托动窗口
    if(event->button() == Qt::LeftButton)
    {
        m_CurrentPos = event->globalPos() - frameGeometry().topLeft();
        event->accept();
    }
    QDialog::mousePressEvent(event);
}

void PieDialog::mouseMoveEvent(QMouseEvent *event)
{
    if (event->buttons() && Qt::LeftButton)
    {
        move(event->globalPos() - m_CurrentPos);
        event->accept();
    }
    QDialog::mouseMoveEvent(event);
}

void PieDialog::keyPressEvent(QKeyEvent *event)
{
    //按数字键1-0相当于投票
    for(int i=0; i<10; i++)
    {
        if( Qt::Key_0+i == event->key() )
        {
            m_Result[i]++;
            break;
        }
    }
    update();
    QDialog::keyPressEvent(event);
}


void PieDialog::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    //反走样
    painter.setRenderHint(QPainter::Antialiasing, true);
    int cy = 10;
    //先画出颜色图解
    for(int i=0; i<10; i++)
    {
        painter.setBrush( m_Color[i] );
        painter.drawRect(320, cy, 30, 20);
        painter.drawText( QPoint(360, cy+15), QString::number(i) );
        cy += 28;
    }
    painter.setPen( QPen(Qt::black, 1) );
    const int FULL_CIRCLE = 5760;
    const int RADIUS = 140;
    QRect rect(10, 10, 280, 280);
    int count = 0;
    for(int i=0; i<10; i++)
    {
        count += m_Result[i];
    }
    //如果还没有投过票，那就先画一个白色的圆形
    if( 0 == count )
    {
        painter.setBrush( Qt::white );
        painter.drawEllipse(rect);
        return;
    }

    int pos = 0;
    int angle;
    for(int i=0; i<10; i++)
    {
        if( 0 == m_Result[i] )
            continue;
        painter.setBrush( m_Color[i] );
        double persent = (double)m_Result[i] / count;
        angle = FULL_CIRCLE * persent;

        //画出各个对应的扇形
        double abc = 3.14 * 2 * (double)(pos + angle/2) / FULL_CIRCLE;
        double tx = 100 * qCos(abc) + 10 + RADIUS;
        double ty = -100 * qSin(abc) + 10 + RADIUS;
        painter.drawPie(rect, pos, angle);
        //在扇形上写注释（投票数和百分比）
        QString temp;
        temp.sprintf(" (%d) ", m_Result[i]);
        painter.drawText(tx-20, ty-10, temp);
        temp.sprintf("%0.1lf%%", persent*100);
        painter.drawText(tx-20, ty, temp);
        pos += angle;
    }

}

void PieDialog::leaveEvent(QEvent *event)
{
    //鼠标离开窗口时是普通的指针
    setCursor(Qt::ArrowCursor);
}

void PieDialog::enterEvent(QEvent *event)
{
    //鼠标留在窗口上时是一个手指
    setCursor(Qt::PointingHandCursor);
}

#include "main.moc"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    PieDialog *dialog = new PieDialog;
    dialog->show();
    return app.exec();
}

http://blog.csdn.net/small_qch/article/details/7607491