QT:浮动的饼状统计图(自绘不规则窗口)

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) :
FnqeUf.jpg

#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 */)
{
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(); 
}