QuickTime 4 Reference

Using a `kTweenTypePathToFixedPoint` Tween Component

To use a kTweenTypePathToFixedPoint tween component, do the following:

Create a QT atom container.
Insert a kTweenEntry atom into the QT atom container for the tween.
Insert a kTweenType atom that specifies the tween type into the kTweenEntry atom.
Insert a kTweenData atom into the kTweenEntry atom.
Perform the tweening operation, using QTDoTween.

Listing 13 shows how to create a kTweenTypePathToFixedPoint tween.

Listing 13 Creating a kTweenTypePathToFixedPoint tween container



 
err = CreateSamplePathTweenContainer( container,

                                    kTweenTypePathToFixedPoint, 2, false,

                                    duration, 0, &tweenAtom );

if ( err ) goto bail;



err = QTNewTween( &tween, container, tweenAtom, duration );

if ( err ) goto bail;



for ( tweenTime = 0; tweenTime <= duration; tweenTime++ ) {

    gxPoint absolutePoint;

    

    err = QTDoTween( tween, tweenTime, result, nil, nil, nil );

    if ( err ) goto bail;

    

    absolutePoint = *(gxPoint *)*result;

}

    

err = QTDisposeTween( tween );



bail:

    if ( container ) QTDisposeAtomContainer( container );

    if ( result ) DisposeHandle( result );

Listing 14 shows how to create a kTweenTypePathToFixedPoint tween in which the kTweenReturnDelta flag is set.

Listing 14 Creating a kTweenTypePathToFixedPoint tween container



 
err = CreateSamplePathTweenContainer( container,

                                    kTweenTypePathToFixedPoint, 2, true,

                                    duration, 0, &tweenAtom );

if ( err ) goto bail;



err = QTNewTween( &tween, container, tweenAtom, duration );

if ( err ) goto bail;



for ( tweenTime = 0; tweenTime <= duration; tweenTime++ ) {

    gxPoint deltaPoint;

    

    err = QTDoTween( tween, tweenTime, result, nil, nil, nil );

    if ( err ) goto bail;

    

    deltaPoint = *(gxPoint *)*result;

}

    

err = QTDisposeTween( tween );



bail:

    if ( container ) QTDisposeAtomContainer( container );

    if ( result ) DisposeHandle( result );

Using a kTweenTypePathToFixedPoint Tween Component

Using a `kTweenTypePathToFixedPoint` Tween Component