Line not being created

[Kapil]

Hi...

I am trying to create a line on canvas but it is not being displayed.. i dont understand why it is not getting created... i had created applications using the same idea and they were being created... here it is not the case.. Am i missing something...

void ImageDraw::drawLine(QPoint point1, QPoint point2)
{
     int xxPoint,xyPoint,yxPoint,yyPoint;
     m_pCanvasLine = new Q3CanvasLine(m_pCanvas);
     xxPoint = point1.x();
     xyPoint = point1.y();
     yxPoint = point2.x();
     yyPoint = point2.y();
     m_pCanvasLine->setPoints(xxPoint,xyPoint,yxPoint,yyPoint);
     m_pCanvasLine->show();
     resizeContents(400,400);
}

void ImageDraw::drawLine(QPoint point1, QPoint point2)
{
     int xxPoint,xyPoint,yxPoint,yyPoint;
     m_pCanvasLine = new Q3CanvasLine(m_pCanvas);
     xxPoint = point1.x();
     xyPoint = point1.y();
     yxPoint = point2.x();
     yyPoint = point2.y();
     m_pCanvasLine->setPoints(xxPoint,xyPoint,yxPoint,yyPoint);
     m_pCanvasLine->show();
     resizeContents(400,400);
}

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here m_pCanvas is a Canvas Object...

Thank you

Kapil

[zlatko]

You must first draw it. Use draw() method

[Kapil]

Hi...

draw() methos uses QPainter object but i have to create the line on the canvas...

I went thru the document of QCanvasLine and also the example canvas example on it...

It also does not use the draw() method..

Also i created a simple independent application wherein i just create a canvas and draw a line and it is being created.. its just here where its causing the problem and am not able to make it out why....

Thanks..

Kapil

[Kapil]

Hi..

I deleted all my code and tried again but still its not happening.. i have no clue what can be the reason for non-creation of a line on the canvas... I am putting on the code.. Please help me to sort out the error...

canvasmouse.h

#ifndef CANVASMOUSE_H
#define CANVASMOUSE_H
 
#include "ui_zoomsample.h"
#include <Q3CanvasView>
#include <Q3Canvas>
#include <Qt>
#include <QtGui>
#include <Q3CanvasLine>
 
class CanvasMouse: public Q3CanvasView
{     
      Q_OBJECT
 
      public:
             CanvasMouse(Q3Canvas *pCanvas,QFrame *frame);
             ~CanvasMouse();
 
      private:
 
              void drawLine();
              Q3Canvas *m_pCanvas;
              Q3CanvasLine *m_pCanvasLine;
};   
 
#endif

#ifndef CANVASMOUSE_H
#define CANVASMOUSE_H

#include "ui_zoomsample.h"
#include <Q3CanvasView>
#include <Q3Canvas>
#include <Qt>
#include <QtGui>
#include <Q3CanvasLine>

class CanvasMouse: public Q3CanvasView
{     
      Q_OBJECT
      
      public:
             CanvasMouse(Q3Canvas *pCanvas,QFrame *frame);
             ~CanvasMouse();
     
      private:
             
              void drawLine();
              Q3Canvas *m_pCanvas;
              Q3CanvasLine *m_pCanvasLine;
};   

#endif

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canvasmouse.cpp

#include "canvasmouse.h"
CanvasMouse::CanvasMouse(Q3Canvas *pCanvas, QFrame *frame): Q3CanvasView(frame)
{
    m_pCanvas = pCanvas;
    Q3CanvasView::setCanvas(m_pCanvas);
    m_pCanvas->setBackgroundColor(Qt::white);
    Q3CanvasView::resize(400, 400);
    drawLine();
}
CanvasMouse::~CanvasMouse()
{
}
void CanvasMouse::drawLine()
{
     m_pCanvasLine = new Q3CanvasLine(m_pCanvas);
     m_pCanvasLine->setPoints(10,10,100,10);
     m_pCanvasLine->show();   
     resizeContents(400,400);
}

#include "canvasmouse.h"
CanvasMouse::CanvasMouse(Q3Canvas *pCanvas, QFrame *frame): Q3CanvasView(frame)
{
    m_pCanvas = pCanvas;
    Q3CanvasView::setCanvas(m_pCanvas);
    m_pCanvas->setBackgroundColor(Qt::white);
    Q3CanvasView::resize(400, 400);
    drawLine();
}
CanvasMouse::~CanvasMouse()
{
}
void CanvasMouse::drawLine()
{
     m_pCanvasLine = new Q3CanvasLine(m_pCanvas);
     m_pCanvasLine->setPoints(10,10,100,10);
     m_pCanvasLine->show();   
     resizeContents(400,400);
}

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main.cpp

#include <QApplication>
#include "imagezoomer.h"
#include "ui_zoomsample.h"
 
int main(int argc, char **argv)
{
    QApplication app(argc,argv);
    QMainWindow *form = new QMainWindow;
 
    Ui::MainWindow *ui;
    ui = new Ui::MainWindow();
    ui->setupUi(form);
    Q3Canvas *pCanvas = new Q3Canvas;
    ImageZoomer imgzoom(ui,pCanvas);
    form->show();
    return app.exec();
}

#include <QApplication>
#include "imagezoomer.h"
#include "ui_zoomsample.h"

int main(int argc, char **argv)
{
    QApplication app(argc,argv);
    QMainWindow *form = new QMainWindow;
    
    Ui::MainWindow *ui;
    ui = new Ui::MainWindow();
    ui->setupUi(form);
    Q3Canvas *pCanvas = new Q3Canvas;
    ImageZoomer imgzoom(ui,pCanvas);
    form->show();
    return app.exec();
}

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imagezoomer.h

#include "imagezoomer.h"
#include <QtGui>
#include <qdir.h>
#include <QColor>
 
ImageZoomer::ImageZoomer(Ui::MainWindow *_mwin, Q3Canvas *pCanvas): mwin(_mwin),m_pCanvas(pCanvas)
{                         
     frame = new QFrame(mwin->centralwidget);
     frame->setGeometry(QRect(60, 70, 591, 571));
     frame->setFrameShape(QFrame::StyledPanel);
     frame->setFrameShadow(QFrame::Plain);
 
     canmouse = new CanvasMouse(m_pCanvas,frame);
}
ImageZoomer::~ImageZoomer()
{
}

#include "imagezoomer.h"
#include <QtGui>
#include <qdir.h>
#include <QColor>

ImageZoomer::ImageZoomer(Ui::MainWindow *_mwin, Q3Canvas *pCanvas): mwin(_mwin),m_pCanvas(pCanvas)
{                         
     frame = new QFrame(mwin->centralwidget);
     frame->setGeometry(QRect(60, 70, 591, 571));
     frame->setFrameShape(QFrame::StyledPanel);
     frame->setFrameShadow(QFrame::Plain);
 
     canmouse = new CanvasMouse(m_pCanvas,frame);
}
ImageZoomer::~ImageZoomer()
{
}

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There is no compilation error.. It has to be somewhere logical... and i am not able to catch it.. Please help me in finding it out..

Thanking you...

Kapil

[Kapil]

Hi..

I got the solution ... I was not the calling the canvas->resize() function...
Now it is executing pretty fine...

Kapil