setWindowFlags(Qt::WindowStaysOnTopHint|Qt::ToolTip);

setWindowState(Qt::WindowActive|Qt::WindowFullScreen);//全屏無框架顯示且處於啟用狀態

resize(qApp->desktop()->rect().size());

    QPolygon vt_pos;   //定義多邊形

bgpixmap=QPixmap::grabWindow(QApplication::desktop()->winId());//抓取當前螢幕的圖片

paintEvent(QPaintEvent *event)

{ 

painter.begin(this);//進行重繪

painter.drawPixmap(0,0,loadpixmap);//將背景圖片畫到窗體上

painter.setPen(QPen(Qt::blue,2,Qt::SolidLine,Qt::FlatCap));//設定畫筆

painter.drawPolygon(vt_pos);

painter.end();

}

mouseMoveEvent(QMouseEvent *event)

{

vt_pos.push_back(event.pos);//將滑鼠經過的點入棧

}

mouseReleaseEvent(QMouseEvent *event)

{

/*手動繪圖*/

path.addPolygon(vt_pos);

path.setFillRule(Qt::WindingFill);//設定填充規則(和setClipPath()配合)

QRectFrf=path.controlPointRect();//獲取路徑所在矩形區域

QPixmapmap;

map=loadpixmap.copy(rf.topLeft().x(),rf.topLeft().y(),rf.width(),rf.height());

//座標轉換以（0-rf.topLeft().x(),0-rf.topLeft().y()為座標原點）

QPainterPathpa=path.translated(0-rf.topLeft().x(),0-rf.topLeft().y());

//建立QPixmap裝置，將需要的區域map繪到QPixmap上

temp_image=QPixmap(rf.width(),rf.height());

//temp_image.fill(Qt::transparent);

temp_image.fill(QColor(255,255,255));

temp_paint.begin(&temp_image);

temp_paint.setClipping(true);

temp_paint.setClipPath(pa);//設定裁剪路徑

temp_paint.drawPixmap(0,0,map);

temp_paint.setClipping(false);

temp_paint.end();

shotPixmap=temp_image;//.copy(0,0,rf.width(),rf.height());//更新選區的Pixmap

}