[Solved]Remember mouse track Qt

BobMarly

I am trying to draw random figures (airfoils eventually) by mouse movement in qt. At this point i am able to track my mouse and a dot appears when the mouse is clicked. However, i want the entire track i follow with my mouse button clicked to be drawn. I thought the mousecoordinates should be saved somewhere but i dont manage to do that. What is the simplest way to draw random figures?
This is my code up to now. @
#include "dewidget.h"

DeWidget::DeWidget(QWidget parent)
: QGLWidget(QGLFormat(/ Additional format options */), parent)
{
}

DeWidget::~DeWidget()
{
}

QSize DeWidget::sizeHint() const
{
return QSize(840, 480);
}
void DeWidget::mouseMoveEvent(QMouseEvent *event){
if (event->button() == Qt::LeftButton) {
setMouseTracking(true);
}

 a = event->x();

 b = event->y();
 update();
qDebug() << a<<b;

}

void DeWidget::paintEvent(QPaintEvent *)
{
setAttribute(Qt::WA_PaintOnScreen);
QPainter painter(this);
QPen linepen(Qt::red);
linepen.setCapStyle(Qt::RoundCap);
linepen.setWidth(30);
painter.setRenderHint(QPainter::Antialiasing,true);
painter.setPen(linepen);

painter.drawPoint(a,b);

}@
and

@#include <QWidget>
#include <QGLWidget>

#include <QMouseEvent>
#include <QPainter>

#include <QGraphicsView>

class DeWidget : public QGLWidget
{
Q_OBJECT

public:
DeWidget(QWidget *parent = 0);
~DeWidget();
QSize sizeHint() const;

protected:
void mouseMoveEvent(QMouseEvent *event);
void paintEvent(QPaintEvent *);

private:

float a;
float b;

};

#endif // DEWIDGET_H@

BobMarly

I also need these coordinates to later put in a CFD solver.

Asperamanca

Use QPolygon. In each Mouse move, append the current mouse coordinate. In paint, you can use painter->drawPolyline to paint the whole path.

BobMarly

I tried putting my mouse coordinates in an array but it doesnt seem to work. It does not draw anything. What is a convenient way to store mouse coordinates?
@array1[i]= event->x()
array2[i] = event ->y()@
and then i tried drawing it with a loop..:
@ for (int q=0;q<1000;q++){
QPolygon polygon;
polygon << QPoint(array1[q], array2[q])
painter.drawPolygon(polygon);}@

Asperamanca

First, I didn't see that you use QGLWidget. I don't know about this, so I cannot tell you why it doesn't draw.

Second, from what I understood, you need drawPolyline, not drawPolygon.

Also, the drawPolyline should not be inside the loop, but after the loop.

Finally, why do you store the coordinates in a separate array, and not into the QPolygon directly? QPolygon is just an array of points, so it should be just what you need.

BobMarly

It works! Thank you very much for your help!

Asperamanca

You are welcome!

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