Qt-interest Archive, July 2007
Problem with positioning of QGraphicsLineItem
Message 1 in thread
Hi,
I have a QGraphicsLineItem that I want should move only along
x-direction.
To do so I override the mouseMoveEvent handler and do a setPos() to
position it correctly.
This does not give the desired result. It moves along x-direction all
right, but there it is a lot of flicker and positioning issues.
I am attaching a small compilable piece of code to show the problem.
Please let me know if what I am doing is correct, or if there is a
better way to do this.
Thnx
Prateek
//Header File
#pragma once
#include <QGraphicsLineItem>
#include <QGraphicsSceneMouseEvent>
#include <QLineF>
#include <QGraphicsScene>
#include <QGraphicsItem>
#include <QGraphicsView>
class Arrow : public QGraphicsLineItem
{
protected:
virtual void mouseMoveEvent(QGraphicsSceneMouseEvent* event);
public:
Arrow( QLineF & line, QGraphicsItem * parent = 0, QGraphicsScene * scene
= 0 );
};
//cpp file
#include <qapplication.h>
#include "myview.h"
Arrow::Arrow(QLineF &line, QGraphicsItem *parent, QGraphicsScene *scene)
: QGraphicsLineItem(line, parent, scene)
{
setFlag(QGraphicsItem::ItemIsSelectable);
setFlag(QGraphicsItem::ItemIsMovable);
}
void Arrow::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
setPos(event->pos());
}
int main(int argc, char** argv)
{
QApplication app(argc,argv);
QGraphicsScene *scene = new QGraphicsScene();
scene->setSceneRect(QRectF(0,0,500,500));
QGraphicsView m_view(scene);
m_view.show();
Arrow * arrow = new Arrow(QLineF(0,0,100,100), NULL, scene);
arrow->setPos(50,50);
return app.exec();
}
Message 2 in thread
Hi,
Change event->pos() to event->scenePos() in mouseMoveEvent.
Sincerely,
Bo Thorsen.
Thorsen Consulting - http://www.qt-experts.com
Prateek Tiwari skrev:
> Hi,
>
> I have a QGraphicsLineItem that I want should move only along x-direction.
> To do so I override the mouseMoveEvent handler and do a setPos() to
> position it correctly.
>
> This does not give the desired result. It moves along x-direction all
> right, but there it is a lot of flicker and positioning issues.
>
> I am attaching a small compilable piece of code to show the problem.
>
> Please let me know if what I am doing is correct, or if there is a
> better way to do this.
>
> Thnx
> Prateek
>
> //Header File
>
>
> #pragma once
> #include <QGraphicsLineItem>
> #include <QGraphicsSceneMouseEvent>
> #include <QLineF>
> #include <QGraphicsScene>
> #include <QGraphicsItem>
> #include <QGraphicsView>
>
> class Arrow : public QGraphicsLineItem
> {
> protected:
> virtual void mouseMoveEvent(QGraphicsSceneMouseEvent* event);
> public:
> Arrow( QLineF & line, QGraphicsItem * parent = 0, QGraphicsScene *
> scene = 0 );
> };
>
> //cpp file
>
>
> #include <qapplication.h>
> #include "myview.h"
>
> Arrow::Arrow(QLineF &line, QGraphicsItem *parent, QGraphicsScene
> *scene) : QGraphicsLineItem(line, parent, scene)
> {
> setFlag(QGraphicsItem::ItemIsSelectable);
> setFlag(QGraphicsItem::ItemIsMovable);
> }
>
> void Arrow::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
> {
> setPos(event->pos());
> }
>
>
> int main(int argc, char** argv)
> {
> QApplication app(argc,argv);
> QGraphicsScene *scene = new QGraphicsScene();
> scene->setSceneRect(QRectF(0,0,500,500));
> QGraphicsView m_view(scene);
> m_view.show();
>
> Arrow * arrow = new Arrow(QLineF(0,0,100,100), NULL, scene);
> arrow->setPos(50,50);
>
> return app.exec();
> }
>
--
[ signature omitted ]
Message 3 in thread
Works perfectly now !
Thanx a lot
Prateek
-----Original Message-----
From: Bo Thorsen [mailto:bo@xxxxxxxxxxxxxxxxxxxxx]
Sent: Thursday, July 19, 2007 2:45 PM
To: Prateek Tiwari
Cc: qt-interest@xxxxxxxxxxxxx
Subject: Re: Problem with positioning of QGraphicsLineItem
Hi,
Change event->pos() to event->scenePos() in mouseMoveEvent.
Sincerely,
Bo Thorsen.
Thorsen Consulting - http://www.qt-experts.com
Prateek Tiwari skrev:
> Hi,
>
> I have a QGraphicsLineItem that I want should move only along
x-direction.
> To do so I override the mouseMoveEvent handler and do a setPos() to
> position it correctly.
>
> This does not give the desired result. It moves along x-direction all
> right, but there it is a lot of flicker and positioning issues.
>
> I am attaching a small compilable piece of code to show the problem.
>
> Please let me know if what I am doing is correct, or if there is a
> better way to do this.
>
> Thnx
> Prateek
>
> //Header File
>
>
> #pragma once
> #include <QGraphicsLineItem>
> #include <QGraphicsSceneMouseEvent>
> #include <QLineF>
> #include <QGraphicsScene>
> #include <QGraphicsItem>
> #include <QGraphicsView>
>
> class Arrow : public QGraphicsLineItem {
> protected:
> virtual void mouseMoveEvent(QGraphicsSceneMouseEvent* event);
> public:
> Arrow( QLineF & line, QGraphicsItem * parent = 0, QGraphicsScene *
> scene = 0 ); };
>
> //cpp file
>
>
> #include <qapplication.h>
> #include "myview.h"
>
> Arrow::Arrow(QLineF &line, QGraphicsItem *parent, QGraphicsScene
> *scene) : QGraphicsLineItem(line, parent, scene) {
> setFlag(QGraphicsItem::ItemIsSelectable);
> setFlag(QGraphicsItem::ItemIsMovable);
> }
>
> void Arrow::mouseMoveEvent(QGraphicsSceneMouseEvent *event) {
> setPos(event->pos());
> }
>
>
> int main(int argc, char** argv)
> {
> QApplication app(argc,argv);
> QGraphicsScene *scene = new QGraphicsScene();
> scene->setSceneRect(QRectF(0,0,500,500));
> QGraphicsView m_view(scene);
> m_view.show();
>
> Arrow * arrow = new Arrow(QLineF(0,0,100,100), NULL, scene);
> arrow->setPos(50,50);
>
> return app.exec();
> }
>
--
[ signature omitted ]
