CODEWITHSUNDEEP
qt4qgraphicsviewqgraphicsscene
Abhishek
Abhishek

Reputation: 388

Multiple QGraphicsView for a single QGraphicsScene

I have one QGraphicsScene to which I have added some instances of QGraphicsItem.

I need to display a particular section of my whole scene in individual views.

To do that, I want to create multiple instances of QGraphicsView each of which displays a particular section of my QGraphicsScene(not a similar portion).

How can it be done?

QGraphicsScene mcpGraphicsScene = new QGraphicsScene(this);

QGraphicsRectItem * mcpGraphicsRect = mcpGraphicsScene->addRect(5,5,200,200);

QGraphicsLineItem * mcpGraphicsLine = mcpGraphicsScene->addLine(500,500,300,300);


QGraphicsView * mcpGraphicsView1 = new QGraphicsView(this);
mcpGraphicsView1->setScene(mcpGraphicsScene);
mcpGraphicsView1->setGeometry(260,20,311,500);

QGraphicsView * mcpGraphicsView2 = new QGraphicsView(this);
mcpGraphicsView2->setScene(mcpGraphicsScene);
mcpGraphicsView2->setGeometry(260,520,311,1061);

Upvotes: 6

Views: 4756

Answers (2)

Kunal
Kunal

Reputation: 3535

QGraphicsScene has render API, which you can use to render certain portion of QGraphicsScene. You can render it over QWidget.

void QGraphicsScene::render(QPainter * painter, const QRectF & target = QRectF(), const QRectF & source = QRectF(), Qt::AspectRatioMode aspectRatioMode = Qt::KeepAspectRatio)

something like following, I tested following code works fine.

#include "mygraphicsview.h"

#include <QGraphicsScene>
#include <QPixmap>
#include <QGraphicsView>
#include <QPen>
#include <QBrush>

MyGraphicsView::MyGraphicsView(QWidget *parent) :
    QWidget(parent)
{
    setGeometry(QRect(100,100,300,300));

    scene = new QGraphicsScene(QRect(0,0,600,600));
    scene->addRect(20,20,100,100,QPen(),QBrush(Qt::black));
    scene->addRect(10,150,100,100,QPen(),QBrush(Qt::red));
}

void MyGraphicsView::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    scene->render(&painter,QRect(0,0,300,300),QRect(10,10,200,200));
}


#ifndef MYGRAPHICSVIEW_H
#define MYGRAPHICSVIEW_H

#include <QWidget>

class QGraphicsScene;

class MyGraphicsView : public QWidget
{
    Q_OBJECT
public:
    MyGraphicsView(QWidget *parent = 0);

    void paintEvent(QPaintEvent *event);
    
signals:
    
public slots:

private:
    QGraphicsScene* scene;
    
};

#endif // MYGRAPHICSVIEW_H

Upvotes: 1

Phil Hannent
Phil Hannent

Reputation: 12317

You are using the wrong function, you are using setGeometry which is telling the View where it should be placed relative to its parent (which is the widget, not the scene). To define the area of the scene that the view is responsible for showing you need to call use setSceneRect

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGraphicsScene>
#include <QGraphicsView>
#include <QLayout>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QHBoxLayout* myLayout = new QHBoxLayout(this);
    QGraphicsScene* mcpGraphicsScene = new QGraphicsScene(this);

    mcpGraphicsScene->addRect(5,5,200,200);
    mcpGraphicsScene->addLine(500,500,300,300);

    QGraphicsView * mcpGraphicsView1 = new QGraphicsView(mcpGraphicsScene, this);
    mcpGraphicsView1->setSceneRect(0,0,150,150);

    QGraphicsView * mcpGraphicsView2 = new QGraphicsView(mcpGraphicsScene, this);
    mcpGraphicsView2->setSceneRect(0,150,600,600);

    myLayout->addWidget(mcpGraphicsView1);
    myLayout->addWidget(mcpGraphicsView2);
    QWidget *window = new QWidget();
    window->setLayout(myLayout);
    setCentralWidget(window);
}

MainWindow::~MainWindow()
{
    delete ui;
}

Upvotes: 6

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