我想在QT中绘制一个填充的椭圆,在放大和缩小时不会改变它的大小.现在我有以下内容:
QPen pen = painter->pen();
pen.setCosmetic(true);
pen.setWidth(5);
painter->setPen(pen);
QBrush brush = painter->brush();
brush.setStyle(Qt::SolidPattern);
painter->setBrush(brush);
painter->drawEllipse(p, 2, 2);
当我缩小边界和填充之间的间隙时.所以它看起来像2个同心圆.当我放大填充物时,边界越来越大,磁盘变得越来越大.知道如何解决这个问题吗?谢谢!
最佳答案 相反,我会寻找
ItemIgnoresTransformations
flag,这将使项目本身“化妆”,而不仅仅是笔.这是一个有效的例子:
#include <QtGui>
class NonScalingItem : public QGraphicsItem
{
public:
NonScalingItem()
{ setFlag(ItemIgnoresTransformations, true); }
QRectF boundingRect() const
{ return QRectF(-5, -5, 10, 10); }
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QPen pen = painter->pen();
pen.setCosmetic(true);
pen.setWidth(5);
pen.setColor(QColor(Qt::red));
painter->setPen(pen);
QBrush brush = painter->brush();
brush.setStyle(Qt::SolidPattern);
painter->setBrush(brush);
painter->drawEllipse(QPointF(0, 0), 10, 10);
}
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QGraphicsScene *scene = new QGraphicsScene;
QGraphicsView *view = new QGraphicsView;
NonScalingItem *item = new NonScalingItem;
scene->addItem(item);
view->setScene(scene);
/* The item will remain unchanged regardless of whether
or not you comment out the following line: */
view->scale(2000, 2000);
view->show();
return app.exec();
}