Undefined Reference error!!!

[Kapil]

hi,

i have re-implemented the mouseMoveEvent(QMouseEvent *event), mousePressEvent(QMouseEvent *event), mouseReleaseEvent(QMouseEvent *event)
and am just trying to pop-up a message box whenever the mouse moves over the widget but there is no response.. i went thru quite a few docs and also examples and all have done something similar to what i have done but there is still no response...

why is it so????

thanking you,
Kapil

[zlatko]

Have you declare this events handler in protected section ?

[Kapil]

Have you declare this events handler in protected section ?

yes,

they are declared in the protected section...

[zlatko]

So if i have undestand you we talk about ImageZoomer class?
Who is his parent?

[Kapil]

So if i have undestand you we talk about ImageZoomer class?
Who is his parent?

This class inherits the QMainWindow class and the header file for the class is :
ImageZoomer.h

class ImageZoomer : public QMainWindow
{
      Q_OBJECT
 
      public:
             ImageZoomer(Ui::MainWindow *_mw);
             ~ImageZoomer();
             void scaleImage(double factor);
             void adjustScrollBar(QScrollBar *sbar, double factor);
 
      protected:
             void contentsMousePressEvent(QMouseEvent*);
 
      public slots:
 
             void open();
             void zoomIn();
             void zoomOut();
             void zoomNormal();
             void fitToWindow();
 
      private:
 
              QFrame *frame;
              QScrollArea *sarea;
              Q3ScrollView *sview;
              double scalefactor;
              Ui_MainWindow *mwin;
              QPixmap fromImage;
              Q3Canvas *canvas;
              Q3CanvasView *canview;
              QMouseEvent *mEvent;
              Q3CanvasItem* moving;
              QPoint moving_start;
              QImage image;
};

class ImageZoomer : public QMainWindow
{
      Q_OBJECT
      
      public:
             ImageZoomer(Ui::MainWindow *_mw);
             ~ImageZoomer();
             void scaleImage(double factor);
             void adjustScrollBar(QScrollBar *sbar, double factor);
                   
      protected:
             void contentsMousePressEvent(QMouseEvent*);
                             
      public slots:
             
             void open();
             void zoomIn();
             void zoomOut();
             void zoomNormal();
             void fitToWindow();
     
      private:
              
              QFrame *frame;
              QScrollArea *sarea;
              Q3ScrollView *sview;
              double scalefactor;
              Ui_MainWindow *mwin;
              QPixmap fromImage;
              Q3Canvas *canvas;
              Q3CanvasView *canview;
              QMouseEvent *mEvent;
              Q3CanvasItem* moving;
              QPoint moving_start;
              QImage image;
};

To copy to clipboard, switch view to plain text mode 

[zlatko]

QMainWindow doesnt have slot void contentsMousePressEvent(QMouseEvent*);

[Kapil]

QMainWindow doesnt have slot void contentsMousePressEvent(QMouseEvent*);

Hi,

Okay.. This means that i will have to also inherit the class QCanvasView 'coz it contains the method contentsMousePressEvents(QMouseEvent *)...

Is it so?????

[incubator]

no, you just dont capture mouse events on a main window.

If you want to capture them in your canvas, make a class that extends QCanvas and override its mouse events.

[Kapil]

no, you just dont capture mouse events on a main window.

If you want to capture them in your canvas, make a class that extends QCanvas and override its mouse events.

Hi,

It means that i would make another class and its structure would look like this..
[HTML]
#include "imagezoomer.h"
class Sample : public QCanvas
{
public:
Sample();
protected:
void contentsMousePressEvent(QMouseEvent *);
private:
ImageZoomer *zoom;
};
Sample::Sample()
{
ImageZoomer zoom = new ImageZoomer;
}
void Sample::contentsMousePressEvent(QMouseEvent *event)
{
code
}
[/HTML]

Is it so??????????????

[incubator]

sort of, but your ImageZoomer extends a main window, so that class should have a private member MyCanvas that extends a QCanvas (if you use Qt4 its Q3Canvas I think)

and in that MyCanvas class you override your mouse events.

[Kapil]

Hi...

The new class which i have created is CanvasMouse..

Now in my ImageZoomer i have created a CanvasMouse *canmouse variable which would call the CanvasMouse which inherits the Q3CanvasView....

In imageZoomer i have created a Q3CanvasView and have passed in the constructor of the CanvasMouse which reads this
CanvasMouse(Q3CanvasView *canview): canvasview(canview)

Now class CanvasMouse contains all the canvas related functionalities...

is this approach correct ?????

[zlatko]

In imageZoomer i have created a Q3CanvasView and have passed in the constructor of the CanvasMouse which reads this
CanvasMouse(Q3CanvasView *canview): canvasview(canview)

You sholdn't give Q3CanvasView parametr. You need give only pointer on parent class.

CanvasMouse *canmous = new CanvasMouse(this);
 
  *****
CanvasMouse(ImageZoomer*p): canvasview(p)
{
}

CanvasMouse *canmous = new CanvasMouse(this);

  *****
CanvasMouse(ImageZoomer*p): canvasview(p)
{
}

To copy to clipboard, switch view to plain text mode 

p.s. also you could give any parametres (if you dont need it in future )