Simplest example for QGraphicsPixmapItem

[sincnarf]

Hello I really need help. I need the simplest possible example for QGraphicsPixmapItem.

Maybe simple can be defined this way (but this is for QGraphicsEllipseItem)

#include <QGraphicsEllipseItem>
#include <QGraphicsScene>
#include <QGraphicsView>
 
int main( int argc, char **argv )
{
    QApplication app(argc, argv);
 
    QGraphicsScene scene;
    scene.setSceneRect( -100.0, -100.0, 200.0, 200.0 );
 
    QGraphicsEllipseItem *item = new QGraphicsEllipseItem( 0, &scene );
    item->setRect( -50.0, -50.0, 100.0, 100.0 );
 
    QGraphicsView view( &scene );
    view.setRenderHints( QPainter::Antialiasing );
    view.show();
 
    return app.exec();

#include <QGraphicsEllipseItem>
#include <QGraphicsScene>
#include <QGraphicsView>

int main( int argc, char **argv )
{
    QApplication app(argc, argv);

    QGraphicsScene scene;
    scene.setSceneRect( -100.0, -100.0, 200.0, 200.0 );

    QGraphicsEllipseItem *item = new QGraphicsEllipseItem( 0, &scene );
    item->setRect( -50.0, -50.0, 100.0, 100.0 );

    QGraphicsView view( &scene );
    view.setRenderHints( QPainter::Antialiasing );
    view.show();

    return app.exec();

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[wysota]

Substitute lines 12 and 13 with:

QGraphicsPixmapItem *item = new QGraphicsPixmapItem(QPixmap("yourpixmapfilehere.png"), &scene);

QGraphicsPixmapItem *item = new QGraphicsPixmapItem(QPixmap("yourpixmapfilehere.png"), &scene);

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[spud]

How about

#include <QtGui>
 
int main( int argc, char **argv )
{
	QApplication app(argc, argv);
    QGraphicsScene scene;
	QGraphicsView view(&scene);
	QPixmap pixmap(":/trolltech/styles/commonstyle/images/standardbutton-help-32.png");
 
	for (int i=0;i<50;i++){
		QGraphicsPixmapItem* item = scene.addPixmap(pixmap);
		item->moveBy(qrand()%200-100, qrand()%200-100);
		item->rotate(qrand()%360);
		item->setFlag(QGraphicsItem::ItemIsMovable);
	}
 
    view.setRenderHints( QPainter::SmoothPixmapTransform );
	view.show();
	return app.exec(); 
}

#include <QtGui>
 
int main( int argc, char **argv )
{
	QApplication app(argc, argv);
    QGraphicsScene scene;
	QGraphicsView view(&scene);
	QPixmap pixmap(":/trolltech/styles/commonstyle/images/standardbutton-help-32.png");

	for (int i=0;i<50;i++){
		QGraphicsPixmapItem* item = scene.addPixmap(pixmap);
		item->moveBy(qrand()%200-100, qrand()%200-100);
		item->rotate(qrand()%360);
		item->setFlag(QGraphicsItem::ItemIsMovable);
	}
	
    view.setRenderHints( QPainter::SmoothPixmapTransform );
	view.show();
	return app.exec(); 
}

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or if you're going for brevity

#include <QtGui>
 
int main( int argc, char **argv )
{
	QApplication app(argc, argv);
	QGraphicsView view(new QGraphicsScene );
	view.scene()->addPixmap(QPixmap(":/trolltech/styles/commonstyle/images/standardbutton-help-32.png"));
	view.show();
	return app.exec(); 
}

#include <QtGui>
 
int main( int argc, char **argv )
{
	QApplication app(argc, argv);
	QGraphicsView view(new QGraphicsScene );
	view.scene()->addPixmap(QPixmap(":/trolltech/styles/commonstyle/images/standardbutton-help-32.png"));
	view.show();
	return app.exec(); 
}

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[sincnarf]

problem solved at last.

@wysota Thank you very much for all your help. Sorry for sending duplicate stuff to your inbox.

@spud Thanks too.

I can't thank all of you enough. Thanks thanks thanks.

[bootchk]

FYI you must supply a valid path to the file. At least in PySide, after translating the example to Python: No exception is thrown if the file path is wrong, and the view displays blank (without an image).

That seems like a bug. One of the preconditions to QPixmap(filename) constructor should be: the file exists.
Maybe it is a limitation of the PySide binding: maybe the C++ function returns an error code.

[d_stranz]

This thread has been rotting in its grave for over 5 years. Why dig it up now?

The behaviour of the QPixmap( filename ) constructor when the file does not exist (or no plugin is available to render the image in it) is not a bug; it takes a graceful approach to resolving the problem by simply displaying an empty pixmap, rather than blowing up your program for you. C++ constructors cannot return error codes, they can only throw exceptions or set some flag inside the new instance to indicate that the object could not be constructed in a valid internal state. There is no convention for this, and the Qt approach is much more user friendly than throwing an exception.

[bootchk]

Sorry, you're correct. I didn't read the documentation for QPixmap.

But then the documentation for QGraphicsPixmapItem() is weak: it could say "If the passed pixmap is null, the QGraphicsPixmapItem will not be visible at any scale." (If thats how it behaves.) I suppose "there exists some scale at which the item is visible" is not an invariant of the QGraphicsItem class.

[wysota]

If the passed pixmap is null, the QGraphicsPixmapItem will not be visible at any scale.

Hmm... isn't that obvious? What else exactly would you expect to see when passing a null pixmap?