GraphicsView Foreground

[augusbas]

Hi all,

I have sub-classed graphics view and i have implemented "draw foreground" function ..I need to draw ellipse's on the view foreground...Provided my code for reference .

Header File:

#include <QGraphicsView>
 
class MyView: public QGraphicsView
{
     Q_OBJECT
 
    public:
 
   MyView(QWidget *parent = 0);
 
    protected:
 
    void drawForeground(QPainter * painter, const QRectF & rect);
 
 
};

#include <QGraphicsView>

class MyView: public QGraphicsView
{
     Q_OBJECT

    public:

   MyView(QWidget *parent = 0);

    protected:

    void drawForeground(QPainter * painter, const QRectF & rect);


};

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Source File:

#include <QtGui>
#include <QX11Info>
 
#include "graphics.h"
 
 
MyView::MyView(QWidget *parent) : QGraphicsView(parent)
 
{
 
 
   //--- Graphics View Properties
 
   this->resize ( 768, 768 );
 
 
 
   this->setStyleSheet("background-image: url(/aegean-120km.png)");
 
/*
 
   QGraphicsScene scene;
 
   scene.setSceneRect (0,0, 768, 768 );
 
   this->setScene ( &scene );
 
*/
 
   QColor color(Qt::yellow);
 
   QBrush brush(color, Qt::SolidPattern);
 
   this->setForegroundBrush(brush);
 
 
   this->show();
 
 
 
 
}
 
 
void MyView::drawForeground(QPainter * painter, const QRectF & rect)
{
 
      QColor color1(156, 189, 176,254);
 
      painter->setPen(Qt::lightGray);                 
 
      int x,y,w,h,i;
 
      double centre_x=384, centre_y=384;
 
      double step_size=38.5; 
 
      for(i=1;i<=20 ;i++)
      {
        	x = centre_x - step_size * i ;
        	y = centre_y - step_size * i ;
 
       		w=h=step_size * i * 2;
 
        	painter->drawEllipse(x,y,w,h);
       }   
 
}

#include <QtGui>
#include <QX11Info>

#include "graphics.h"


MyView::MyView(QWidget *parent) : QGraphicsView(parent)

{

   
   //--- Graphics View Properties

   this->resize ( 768, 768 );



   this->setStyleSheet("background-image: url(/aegean-120km.png)");

/*

   QGraphicsScene scene;

   scene.setSceneRect (0,0, 768, 768 );

   this->setScene ( &scene );

*/

   QColor color(Qt::yellow);

   QBrush brush(color, Qt::SolidPattern);

   this->setForegroundBrush(brush);
 

   this->show();
  



}


void MyView::drawForeground(QPainter * painter, const QRectF & rect)
{

      QColor color1(156, 189, 176,254);

      painter->setPen(Qt::lightGray);                 

      int x,y,w,h,i;

      double centre_x=384, centre_y=384;
  
      double step_size=38.5; 

      for(i=1;i<=20 ;i++)
      {
        	x = centre_x - step_size * i ;
        	y = centre_y - step_size * i ;

       		w=h=step_size * i * 2;

        	painter->drawEllipse(x,y,w,h);
       }   

}

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I didn't get any ellipse on the foreground ....By ref to manual Whether "draw foreground " function will be applicable only to QGraphicsScene ? how the draw foreground function will get called, automatically or any update mechanism need to be added in the code ...

Please advise..

[Rachol]

Did you try this: viewport()->update(); ?

And yet remove this part:

#
QBrush brush(color, Qt::SolidPattern);
 
this->setForegroundBrush(brush);#
QBrush brush(color, Qt::SolidPattern);
 
this->setForegroundBrush(brush);

#
QBrush brush(color, Qt::SolidPattern);

this->setForegroundBrush(brush);#
QBrush brush(color, Qt::SolidPattern);

this->setForegroundBrush(brush);

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[augusbas]

Did you try this: viewport()->update(); ?

I have tried the method suggested , it didnt have any impact

viewport()->update()

Any ideas?

[mcosta]

Have you tried to draw backgroung using backgroundBrush and not using Stylesheet?

[stampede]

Try calling base-class implementation QGraphicsView::drawForeground(painter,rect) after your drawing code.

[Rachol]

I don't know if you have noticed, but I have modified my previous message. Remove this->setForegroundBrush(brush); and I am quite sure it will work.

[augusbas]

I have tried the follwing suggested by you people:

Call the base class implementation after drawing code .....QGraphicsView::drawForeground(painter,rect) ...... Didnt get any drawing ouptut on graphics view....

I have removed this "QBrush brush(color, Qt::SolidPattern); this->setForegroundBrush(brush);" .....

Didnt get any output....

Have you tried to draw backgroung using backgroundBrush and not using Stylesheet?

I haven't tried this ....Whether this will have an impact ?

[Rachol]

Might do something with your problem

[mcosta]

I tried this code

Widget::Widget(QWidget *parent)
    : QGraphicsView(parent)
{
    QPixmap px (":/images/bg.png");
    this->setBackgroundBrush (QBrush(px));
}
 
Widget::~Widget()
{
 
}
 
void Widget::drawForeground(QPainter *painter, const QRectF &rect)
{
//    QColor color1(156, 189, 176,254);
 
    painter->setPen(Qt::darkRed);
 
    double centre_x=384, centre_y=384;
 
    double step_size=38.5;
 
    int x, y, h, w;
 
    for(int i=1;i<=20 ;i++) {
        x = centre_x - step_size * i ;
        y = centre_y - step_size * i ;
 
        w=h=step_size * i * 2;
 
        painter->drawEllipse(x,y,w,h);
    }
 
}

Widget::Widget(QWidget *parent)
    : QGraphicsView(parent)
{
    QPixmap px (":/images/bg.png");
    this->setBackgroundBrush (QBrush(px));
}

Widget::~Widget()
{

}

void Widget::drawForeground(QPainter *painter, const QRectF &rect)
{
//    QColor color1(156, 189, 176,254);

    painter->setPen(Qt::darkRed);

    double centre_x=384, centre_y=384;

    double step_size=38.5;

    int x, y, h, w;

    for(int i=1;i<=20 ;i++) {
        x = centre_x - step_size * i ;
        y = centre_y - step_size * i ;

        w=h=step_size * i * 2;

        painter->drawEllipse(x,y,w,h);
    }

}

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This is the result
gg.jpg

[augusbas]

Might do something with your problem

Hi ,

Thanks to your support ...

Is my code is right completely ? Any changes need to be done....

---

Added after 5 minutes:

I tried this code

Widget::Widget(QWidget *parent)
    : QGraphicsView(parent)
{
    QPixmap px (":/images/bg.png");
    this->setBackgroundBrush (QBrush(px));
}
 
Widget::~Widget()
{
 
}
 
void Widget::drawForeground(QPainter *painter, const QRectF &rect)
{
//    QColor color1(156, 189, 176,254);
 
    painter->setPen(Qt::darkRed);
 
    double centre_x=384, centre_y=384;
 
    double step_size=38.5;
 
    int x, y, h, w;
 
    for(int i=1;i<=20 ;i++) {
        x = centre_x - step_size * i ;
        y = centre_y - step_size * i ;
 
        w=h=step_size * i * 2;
 
        painter->drawEllipse(x,y,w,h);
    }
 
}

Widget::Widget(QWidget *parent)
    : QGraphicsView(parent)
{
    QPixmap px (":/images/bg.png");
    this->setBackgroundBrush (QBrush(px));
}

Widget::~Widget()
{

}

void Widget::drawForeground(QPainter *painter, const QRectF &rect)
{
//    QColor color1(156, 189, 176,254);

    painter->setPen(Qt::darkRed);

    double centre_x=384, centre_y=384;

    double step_size=38.5;

    int x, y, h, w;

    for(int i=1;i<=20 ;i++) {
        x = centre_x - step_size * i ;
        y = centre_y - step_size * i ;

        w=h=step_size * i * 2;

        painter->drawEllipse(x,y,w,h);
    }

}

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This is the result
gg.jpg

hi mcosta,

surprise.....

I have tried the same ......

set the background brush and used the drawforeground......

I didnt get any circle and image too....

With stylesheet i could set the image and it is visible, but by background brush its not visible......

How it can be........

Are you drawing in a graphics Scene ......


If you don't mind can i have your complete source code of main and header and i will try it in my system....

---

Added after 13 minutes:

hi mcosta,

I have tried the code of yours too ....i didnt get any output.......

Any problem specific to system or code ....

[mcosta]

Hi, my code use a Resource File

gg.qrc

<RCC>
    <qresource prefix="/images">
        <file>bg.png</file>
    </qresource>
</RCC>

<RCC>
    <qresource prefix="/images">
        <file>bg.png</file>
    </qresource>
</RCC>

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This is my .pro

#-------------------------------------------------
#
# Project created by QtCreator 2011-06-23T12:06:26
#
#-------------------------------------------------
 
QT       += core gui
 
TARGET = gg
TEMPLATE = app
 
 
SOURCES += main.cpp\
        Widget.cpp
 
HEADERS  += Widget.h
 
OTHER_FILES += \
    bg.png
 
RESOURCES += \
    gg.qrc

#-------------------------------------------------
#
# Project created by QtCreator 2011-06-23T12:06:26
#
#-------------------------------------------------

QT       += core gui

TARGET = gg
TEMPLATE = app


SOURCES += main.cpp\
        Widget.cpp

HEADERS  += Widget.h

OTHER_FILES += \
    bg.png

RESOURCES += \
    gg.qrc

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and my main

#include <QtGui/QApplication>
#include <QtGui/QGraphicsScene>
 
#include "Widget.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    Q_INIT_RESOURCE (gg);
 
    QGraphicsScene scene;
    scene.setSceneRect (0, 0, 768, 768);
 
    Widget w;
    w.resize (768, 768);
    w.setScene (&scene);
 
    w.show();
 
    return a.exec();
}

#include <QtGui/QApplication>
#include <QtGui/QGraphicsScene>

#include "Widget.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    Q_INIT_RESOURCE (gg);

    QGraphicsScene scene;
    scene.setSceneRect (0, 0, 768, 768);

    Widget w;
    w.resize (768, 768);
    w.setScene (&scene);

    w.show();

    return a.exec();
}

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[augusbas]

Hi mcosta,

I tried your code and found working fine.....

Its the problem with the Qgraphicsscene ....i.e drawforeground applies to the graphics scene ....

Thanks to your support dude..

if i need to set the foreground fully opaque ... I need to set through painter ?

One more thing i found when a image is added in back ground , the complete view is having the replica of images in the background ...how can i have only one time a image in view...