Unable to call Qrect class into my main dialog
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dialog.obj:-1: error: LNK2001: unresolved external symbol "public: __thiscall MyCell::MyCell(void)" (??0MyCell@@QAE@XZ)
[code]#ifndef MYCELL_H
#define MYCELL_H
#include <QDialog>
#include <QtCore>
#include <QtGui>
#include <QPainter>
#include <QGraphicsItem>
#include <QGraphicsScene>
#include <QWidget>
#include <QPaintDevice>class MyCell : public QGraphicsItem
{
public:
MyCell();
QRectF boundingRect()const;
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);protected:
//how many phases or step to advance
void advance(int phase);private:
qreal angle;
qreal speed;
void DoCollision();};[/code]
that's the header
and this is the main dialog
[code]#include "dialog.h"
#include "ui_dialog.h"Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);scene = new QGraphicsScene(this); ui ->graphicsView->setScene(scene); //Anti Aliasing -- smooths it out. ui->graphicsView->setRenderHint(QPainter::Antialiasing); // set size of the scene within the view // 0 is centere scene->setSceneRect(-200,-200,300,300); QPen mypen = QPen(Qt::red);// sets a line that goes around the scene rect
// the 4 will make a box.
QLineF TopLine(scene->sceneRect().topLeft(),scene->sceneRect().topRight());
QLineF LeftLine(scene->sceneRect().topLeft(),scene->sceneRect().bottomLeft());
QLineF RightLine(scene->sceneRect().topRight(),scene->sceneRect().bottomRight());
QLineF BottomLine(scene->sceneRect().bottomLeft(),scene->sceneRect().bottomRight());// makes the above lines show scene->addLine(TopLine,mypen); scene->addLine(LeftLine,mypen); scene->addLine(RightLine,mypen); scene->addLine(BottomLine,mypen); MyCell *item = new MyCell(); timer = new QTimer(this); //scenes advance slot notifys objects its time to advance ( noo need to click) connect(timer, SIGNAL(timeout()),scene,SLOT(advance())); //milliseconds timer->start(100);}
Dialog::~Dialog()
{
delete ui;
}[/code]
error comes because of this bit of code
[code] MyCell *item = new MyCell();
[/code] -
You didn't show two important parts of the code - mycell.cpp and dialog.h
First - linker can't find the definition of MyClell constructor. Do you have it in mycell.cpp or did you forgot it?
Second - since you're using MyCell in Dialog, you should have an include for "mycell.h" somewhere. You don't have it in dialog.cpp so do you have it in the dialog.h or did you forgot it?
Btw. Why do you have so many includes in the mycell.h? You're not using all of them and some of the things like class pointers you can forward-declare. Keeping includes clean will greatly benefit your compile times when your project grows.
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[code]#ifndef DIALOG_H
#define DIALOG_H
#include <QDialog>
#include <QtCore>
#include <QtGui>
#include <QPainter>
#include <QGraphicsItem>
#include <QGraphicsScene>
#include <QWidget>
#include <QDebug>
#include "mycell.h"namespace Ui {
class Dialog;
}class Dialog : public QDialog
{
Q_OBJECTpublic:
explicit Dialog(QWidget *parent = 0);
~Dialog();private:
Ui::Dialog *ui;
QGraphicsScene *scene;
QTimer *timer;
MyCell *item;};
#endif // DIALOG_H
[/code]
that's dialog[code]
#include "mycell.h"MyCell::MyCell()
{
//rndom rotation
// q rand makes a random number
// modulus of upto 360angle = (qrand() % 360); setRotation(angle); //set speed // how many pixels at a time per advance. speed = 5; //randm position // x position int StartX = 0; // y pos int StartY = 0; // randomly true or false. if ((qrand() % 1)){ // random x and y between 0 and 200 StartX = (qrand() % 200); StartY = (qrand() % 200); } else{ StartX = (qrand() % -100); StartY = (qrand() % -100); } setPos(mapToParent(StartX,StartY));}
QRectF MyCell::boundingRect() const
{
//max size of the rect;
return QRect(0,0,20,20);
}void MyCell::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QRectF rec = boundingRect();
QBrush Brush (Qt::blue);// collision detection //scene tells you which items are collidiing //if empty means no collision if (scene()->collidingItems(this).isEmpty()){ // no collision Brush.setColor(Qt::yellow); } else { // there is collision Brush.setColor(Qt::red); // call do colision DoCollision(); } painter->fillRect(rec,Brush); painter->drawRect(rec);}
void MyCell::advance(int phase)
{
if(!phase) return;//this tells us where the object is. QPointF location = this->pos(); //maps current coords to the scenes x and y coordinates. setPos(mapToParent(0,-(speed)));}
void MyCell::DoCollision()
{
//Get a new position//Change the angle with a little randomness if(((qrand() %1))) { setRotation(rotation() + (180 + (qrand() % 10))); } else { setRotation(rotation() + (180 + (qrand() % -10))); } //see if the new position is in bounds QPointF newpoint = mapToParent(-(boundingRect().width()), -(boundingRect().width() + 2)); if(!scene()->sceneRect().contains((newpoint))) { //move it back in bounds newpoint = mapToParent(0,0); } else { //set the new position setPos(newpoint); }}
[/code] -
Sorry you do not need the Q_OBJECT macro in MyCell as QGraphicsItem is NOT derived from QObject. (Dialog is derived from QObject -as QDialog is - and the definition of the class begins with the Q_OBJECT macro).
I have tried to compile and link your code with no error.
Is there more code?, if it is the case try just what you have sent, (you should also include the a ui file that include a QGraphicView).
If the code still do not compile then you should try an example from Qt examples (one with QWidgets and QGraphicsView should be fine). If it do not compiles then check your Qt installation. If it compiles ok then it should be something in your code. -
this code is more or less from copy and paste from an online tutorial. im pretty sure its something to do with my qt creator as I had the same problem with another file where I tried to use my own qgraphics item class but it didn't work and then I made a new one in a different folder d drive and it worked but for this it wont? if any of that makes sense
