Calcul de surface quelconque
Bonjour,
Je suis à la recherche d’un algorithme qui calcule une surface quelconque, j'utilise les méthodes de QPainter.
Ci-dessous l'exemple :
Code:
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|
class Drawing : public QMainWindow
{
Q_OBJECT
public:
Drawing(QWidget *parent = 0, Qt::WFlags flags = 0);
~Drawing();
private:
Ui::DrawingClass ui;
QPoint dtPnt;
bool blLftbtnPrsd ;
QVector<QPoint> polyPoints;
QRect echlRct;
int extrmX;
int extrmY;
protected:
void mouseMoveEvent(QMouseEvent *e);
void paintEvent(QPaintEvent *e);
void mouseReleaseEvent ( QMouseEvent *e );
void mousePressEvent ( QMouseEvent *e ) ;
};
#endif // DRAWING_H
#include "drawing.h"
Drawing::Drawing(QWidget *parent, Qt::WFlags flags)
: QMainWindow(parent, flags)
{
ui.setupUi(this);
blLftbtnPrsd = false;
}
Drawing::~Drawing()
{
}
void Drawing::mousePressEvent ( QMouseEvent *e )
{
if (e->button() == Qt::LeftButton)
{
blLftbtnPrsd = true;
polyPoints.clear();
}
if (e->button() == Qt::RightButton)
{
polyPoints.clear();
extrmX = 0;
extrmY = 0;
update();
}
}
void Drawing::mouseReleaseEvent ( QMouseEvent *e )
{
blLftbtnPrsd = false;
if (!polyPoints.isEmpty())
{
polyPoints << polyPoints.at(0);
extrmX = 0 ;
extrmY = 0;
if (!polyPoints.isEmpty())
{
extrmX = this->width();
foreach(QPoint pnt, polyPoints)
{
if (pnt.x() < extrmX)
extrmX = pnt.x();
if (pnt.y() > extrmY)
extrmY = pnt.y();
}
}
update();
}
}
void Drawing::mouseMoveEvent(QMouseEvent *e)
{
if (blLftbtnPrsd && e->state() == Qt::LeftButton)
{
dtPnt.setX(e->x());
dtPnt.setY(e->y());
polyPoints << dtPnt ;
update();
}
}
void Drawing::paintEvent(QPaintEvent* e)
{
QPainter painter(this);
// Grille
int siUnte = 10;
int siHght = this->height() - 80;
int siWdth = this->width() - 80;
int nbItrHght = (int)(siHght / siUnte);
int nbItrWdth = (int)(siWdth / siUnte);
QVector<QPoint> vectQdrlgHrz;
painter.setPen(Qt::gray);
for(int i = 1; i <= nbItrHght; i++)
painter.drawLine (40, ((i * siUnte)+40), siWdth+40, ((i * siUnte)+40));
for(int i = 1; i <= nbItrWdth; i++)
painter.drawLine (((i * siUnte)+40), 40, ((i * siUnte)+40), siHght+40);
// Courbe
painter.setPen(Qt::blue);
painter.drawPolyline( polyPoints );
// Axe
if (extrmX > 0 && extrmY > 0)
{
painter.setPen(Qt::red);
painter.drawLine ( extrmX, 80, extrmX, extrmY + 10);
painter.drawLine ( extrmX - 10, extrmY , this->width() - 80, extrmY);
}
} |
Comment pourrais je calculer la surface dessinée à partir de cet exemple (http://www.casimages.com/img.php?i=1...3810854071.png)?
Merci d'avance.
