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# QGraphicsItemAnimation Class Reference
[QtGui module]

The QGraphicsItemAnimation class provides simple animation support for QGraphicsItem. More...

Inherits QObject.

### Methods

- __init__ (self, QObject parent = None)
- clear (self)
- float horizontalScaleAt (self, float step)
- float horizontalShearAt (self, float step)
- QGraphicsItem item (self)
- QMatrix matrixAt (self, float step)
- QPointF posAt (self, float step)
- QList<QPair<double,QPointF>> posList (self)
- reset (self)
- float rotationAt (self, float step)
- QList<QPair<double,double>> rotationList (self)
- QList<QPair<double,QPointF>> scaleList (self)
- setItem (self, QGraphicsItem item)
- setPosAt (self, float step, QPointF pos)
- setRotationAt (self, float step, float angle)
- setScaleAt (self, float step, float sx, float sy)
- setShearAt (self, float step, float sh, float sv)
- setStep (self, float x)
- setTimeLine (self, QTimeLine timeLine)
- setTranslationAt (self, float step, float dx, float dy)
- QList<QPair<double,QPointF>> shearList (self)
- QTimeLine timeLine (self)
- QList<QPair<double,QPointF>> translationList (self)
- float verticalScaleAt (self, float step)
- float verticalShearAt (self, float step)
- float xTranslationAt (self, float step)
- float yTranslationAt (self, float step)

### Qt Signals

- void afterAnimationStep (double)
- void beforeAnimationStep (double)

## Detailed Description

The QGraphicsItemAnimation class provides simple animation support for QGraphicsItem.

The QGraphicsItemAnimation class animates a QGraphicsItem. You can schedule changes to the item's transformation matrix at specified steps. The QGraphicsItemAnimation class has a current step value. When this value changes the transformations scheduled at that step are performed. The current step of the animation is set with the `setStep()` function.

QGraphicsItemAnimation will do a simple linear interpolation between the nearest adjacent scheduled changes to calculate the matrix. For instance, if you set the position of an item at values 0.0 and 1.0, the animation will show the item moving in a straight line between these positions. The same is true for scaling and rotation.

It is usual to use the class with a QTimeLine. The timeline's valueChanged() signal is then connected to the `setStep()` slot. For example, you can set up an item for rotation by calling `setRotationAt()` for different step values. The animations timeline is set with the setTimeLine() function.

An example animation with a timeline follows:

         QGraphicsItem *ball = new QGraphicsEllipseItem(0, 0, 20, 20);

         QTimeLine *timer = new QTimeLine(5000);
         timer->setFrameRange(0, 100);

         QGraphicsItemAnimation *animation = new QGraphicsItemAnimation;
         animation->setItem(ball);
         animation->setTimeLine(timer);

         for (int i = 0; i < 200; ++i)
             animation->setPosAt(i / 200.0, QPointF(i, i));

         QGraphicsScene *scene = new QGraphicsScene();
         scene->setSceneRect(0, 0, 250, 250);
         scene->addItem(ball);

         QGraphicsView *view = new QGraphicsView(scene);
         view->show();

         timer->start();

Note that steps lie between 0.0 and 1.0. It may be necessary to use setUpdateInterval(). The default update interval is 40 ms. A scheduled transformation cannot be removed when set, so scheduling several transformations of the same kind (e.g., rotations) at the same step is not recommended.

See also QTimeLine and The Graphics View Framework.

## Method Documentation

### QGraphicsItemAnimation.__init__ (self, QObject parent = None)

The parent argument, if not None, causes self to be owned by Qt instead of PyQt.

Constructs an animation object with the given parent.

### QGraphicsItemAnimation.clear (self)

Clears the scheduled transformations used for the animation, but retains the item and timeline.

### float QGraphicsItemAnimation.horizontalScaleAt (self, float step)

Returns the horizontal scale for the item at the specified step value.

See also setScaleAt().

### float QGraphicsItemAnimation.horizontalShearAt (self, float step)

Returns the horizontal shear for the item at the specified step value.

See also setShearAt().

### QGraphicsItem QGraphicsItemAnimation.item (self)

Returns the item on which the animation object operates.

See also setItem().

### QMatrix QGraphicsItemAnimation.matrixAt (self, float step)

Returns the matrix used to transform the item at the specified step value.

### QPointF QGraphicsItemAnimation.posAt (self, float step)

Returns the position of the item at the given step value.

See also setPosAt().

### QList<QPair<double,QPointF>> QGraphicsItemAnimation.posList (self)

Returns all explicitly inserted positions.

See also posAt() and setPosAt().

### QGraphicsItemAnimation.reset (self)

This method is also a Qt slot with the C++ signature `void reset()`.

### float QGraphicsItemAnimation.rotationAt (self, float step)

Returns the angle at which the item is rotated at the specified step value.

See also setRotationAt().

### QList<QPair<double,double>> QGraphicsItemAnimation.rotationList (self)

Returns all explicitly inserted rotations.

See also rotationAt() and setRotationAt().

### QList<QPair<double,QPointF>> QGraphicsItemAnimation.scaleList (self)

Returns all explicitly inserted scales.

See also verticalScaleAt(), horizontalScaleAt(), and setScaleAt().

### QGraphicsItemAnimation.setItem (self, QGraphicsItem item)

Sets the specified item to be used in the animation.

See also item().

### QGraphicsItemAnimation.setPosAt (self, float step, QPointF pos)

Sets the position of the item at the given step value to the point specified.

See also posAt().

### QGraphicsItemAnimation.setRotationAt (self, float step, float angle)

Sets the rotation of the item at the given step value to the angle specified.

See also rotationAt().

### QGraphicsItemAnimation.setScaleAt (self, float step, float sx, float sy)

Sets the scale of the item at the given step value using the horizontal and vertical scale factors specified by sx and sy.

See also verticalScaleAt() and horizontalScaleAt().

### QGraphicsItemAnimation.setShearAt (self, float step, float sh, float sv)

Sets the shear of the item at the given step value using the horizontal and vertical shear factors specified by sh and sv.

See also verticalShearAt() and horizontalShearAt().

### QGraphicsItemAnimation.setStep (self, float x)

This method is also a Qt slot with the C++ signature `void setStep(double)`.

Sets the current step value for the animation, causing the transformations scheduled at this step to be performed.

### QGraphicsItemAnimation.setTimeLine (self, QTimeLine timeLine)

Sets the timeline object used to control the rate of animation to the timeLine specified.

See also timeLine().

### QGraphicsItemAnimation.setTranslationAt (self, float step, float dx, float dy)

Sets the translation of the item at the given step value using the horizontal and vertical coordinates specified by dx and dy.

See also xTranslationAt() and yTranslationAt().

### QList<QPair<double,QPointF>> QGraphicsItemAnimation.shearList (self)

Returns all explicitly inserted shears.

See also verticalShearAt(), horizontalShearAt(), and setShearAt().

### QTimeLine QGraphicsItemAnimation.timeLine (self)

Returns the timeline object used to control the rate at which the animation occurs.

See also setTimeLine().

### QList<QPair<double,QPointF>> QGraphicsItemAnimation.translationList (self)

Returns all explicitly inserted translations.

See also xTranslationAt(), yTranslationAt(), and setTranslationAt().

### float QGraphicsItemAnimation.verticalScaleAt (self, float step)

Returns the vertical scale for the item at the specified step value.

See also setScaleAt().

### float QGraphicsItemAnimation.verticalShearAt (self, float step)

Returns the vertical shear for the item at the specified step value.

See also setShearAt().

### float QGraphicsItemAnimation.xTranslationAt (self, float step)

Returns the horizontal translation of the item at the specified step value.

See also setTranslationAt().

### float QGraphicsItemAnimation.yTranslationAt (self, float step)

Returns the vertical translation of the item at the specified step value.

See also setTranslationAt().

## Qt Signal Documentation

### void afterAnimationStep (double)

This method is meant to be overridden in subclasses that need to execute additional code after a new step has taken place. The animation step is provided for use in cases where the action depends on its value.

### void beforeAnimationStep (double)

This method is meant to be overridden by subclassed that needs to execute additional code before a new step takes place. The animation step is provided for use in cases where the action depends on its value.