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Archived:Animating graphics item position in Qt

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Archived.pngArchived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.

Qt Quick should be used for all UI development on mobile devices. The approach described in this article (using C++ for the Qt app UI) is deprecated.

Article Metadata
Code ExampleTested with
Devices(s): Symbian, Windows
Compatibility
Platform(s): S60 3rd Edition, FP1
S60 3rd Edition, FP2
S60 5th Edition
Maemo
Symbian
S60 5th Edition
S60 3rd Edition FP2
S60 3rd Edition FP1
Article
Keywords: QGraphicsItem, QPropertyAnimation
Created: tepaa (16 Dec 2009)
Last edited: hamishwillee (11 Oct 2012)


Contents

Overview

This series of snippets demonstrates how to implement nice animation effects into your Qt UI application. Qt 4.6 has Qt Animation Framework as a built-in feature. Documentation can be found here: [1]

This snippet shows how to implement QGraphicsItem and animate a graphics item's position.

See full example code here: File:Animation fw.zip


Preconditions

Qt 4.6 has been installed.


Header file

The QPropertyAnimation class animates Qt properties. QPropertyAnimation interpolates over Qt properties.

#include <QtGui>
 
class PictureItem: public QObject, public QGraphicsPixmapItem
{
Q_OBJECT
 
// Change picture position property for QPropertyAnimation
Q_PROPERTY(QPointF pos READ pos WRITE setPos)
 
public:
enum
{
PictureItemType = UserType + 1
};
 
public:
PictureItem(QSizeF size, const QPixmap& pixmap = 0, QObject* parent = 0);
~PictureItem();
 
// Animate position of this class
void animatePosition(const QPointF& start, const QPointF& end);
 
QRectF boundingRect() const;
 
int type() const
{
return PictureItemType;
}
 
public slots:
void animationFinished();
 
private:
QSizeF m_size;
};


Source file

#include "mainwindow.h"
 
PictureItem::PictureItem(QSizeF size, const QPixmap& pixmap, QObject* parent) :
QObject(parent), QGraphicsPixmapItem(pixmap)
{
m_size = size;
setCacheMode(DeviceCoordinateCache);
}
 
PictureItem::~PictureItem()
{
}
 
QRectF PictureItem::boundingRect() const
{
return QRectF(0, 0, m_size.width(), m_size.height());
}
 
void PictureItem::animatePosition(const QPointF& start, const QPointF& end)
{
// Start animate this class
QPropertyAnimation* anim = new QPropertyAnimation(this, "pos");
 
// 2 second duration animation
anim->setDuration(2000);
// position to start animation
anim->setStartValue(start);
// end position of animation
anim->setEndValue(end);
// easing curve
anim->setEasingCurve(QEasingCurve::InOutElastic);
 
// Listen animation finished signal
QObject::connect(anim, SIGNAL(finished()), this, SLOT(animationFinished()));
 
// Start animation and delete QPropertyAnimation class on the end
anim->start(QAbstractAnimation::DeleteWhenStopped);
}
 
void PictureItem::animationFinished()
{
// This slot is called when animation ends
}


Postconditions

PictureItem position can be animated by calling PictureItem::animatePosition().


Animation Framework snippet series

Full example code package

This page was last modified on 11 October 2012, at 04:13.
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