QuickTime 4 Reference

Implementing the QTVideoOutputRestoreState Function

If your video output component saves custom settings with its own implementation of the QTVideoOutputSaveState function, it must also implement a QTVideoOutputRestoreState function to restore the settings. If your video output component has no custom settings, it can use the default QTVideoOutputRestoreState implementation provided by the base video output component. Listing 8 shows an implementation of the QTVideoOutputRestoreState function that restores custom settings from the QT atom container in which they are stored.

Listing 8 Restoring custom settings



 
pascal ComponentResult MyQTVideoOutputRestoreState (Globals storage,

                                        QTAtomContainer settings)

{

    OSErr err;

    QTAtom atom;



    // call default implementation

    err = QTVideoOutputRestoreState (storage->baseVideoOutput, settings);

    if (err) goto bail;



    // get custom parameter(s)

    atom = QTFindChildByID (settings, kParentAtomIsContainer, `FOOB', 

                            1, nil);

    if (atom != 0) {

        long dataSize;

        Ptr dataptr;



        QTGetAtomDataPtr (settings, atom, &dataSize, &dataPtr);

        storage->customSetting = *(SettingsType *)dataPtr;

    }

    else {

        // reset custom settings to default values

    }



bail:

    return err;

}