Implement SourceChanger?!

[tischi]

@NicoKiaru

Do you think this could be useful? If it works I think it could avoid quite some code duplication:

public class SourceChanger< T > implements Supplier< SourceAndConverter< ? > >
{
    private final SourceAndConverter< ? > sourceAndConverter;
    private final Function< Source< ? >, Source< ? > > sourceConverter;

    public SourceChanger( SourceAndConverter< T > sourceAndConverter, Function< Source< ? >, Source< ? > > sourceConverter )
    {
        this.sourceAndConverter = sourceAndConverter;
        this.sourceConverter = sourceConverter;
    }

    public SourceAndConverter< ? > get()
    {
        Source< ? > src = sourceConverter.apply( sourceAndConverter.getSpimSource() );

        if ( sourceAndConverter.asVolatile() != null )
        {
            Source< ? > vsrc = sourceConverter.apply( sourceAndConverter.asVolatile().getSpimSource() );

            SourceAndConverter< ? > vsac = new SourceAndConverter( vsrc, sourceAndConverter.asVolatile().getConverter(), sourceAndConverter.asVolatile() );

            final SourceAndConverter< ? > sourceAndConverter = new SourceAndConverter( src, this.sourceAndConverter.getConverter(), vsac );
            
            return sourceAndConverter;
        }
        else
        {
            final SourceAndConverter< ? > sourceAndConverter = new SourceAndConverter( src, this.sourceAndConverter.getConverter() );
            
            return sourceAndConverter;
        }
    }
}

The Function< Source< ? >, Source< ? > > sourceConverter would for example return a TransformedSource or a WarpedSource, given an input Source.

For this one needs to create a SourceTransformer implements Function< Source< ? >, Source< ? > > and a SourceWarper implements Function< Source< ? >, Source< ? > >. But we needed this anyway (see e.g. SourceResampler). The advantage would be that with above code the SourceResampler does not need to deal with the generic is of creating also the Volatile versions.

[tischi]

I played with it and it is working.

Here is an improved version of the class:

public class SourceChanger< T > implements Function< SourceAndConverter< ? >,  SourceAndConverter< ? > >
{
    private final Function< Source< ? >, Source< ? > > sourceConverter;

    public SourceChanger( Function< Source< ? >, Source< ? > > sourceConverter )
    {
        this.sourceConverter = sourceConverter;
    }

    @Override
    public SourceAndConverter< ? > apply( SourceAndConverter< ? > inputSourceAndConverter )
    {
        Source< ? > outputSource = sourceConverter.apply( inputSourceAndConverter.getSpimSource() );

        if ( inputSourceAndConverter.asVolatile() != null )
        {
            final Source< ? > volatileOutputSource = sourceConverter.apply( inputSourceAndConverter.asVolatile().getSpimSource() );

            final SourceAndConverter< ? > volatileOutputSourceAndConverter = new SourceAndConverter( volatileOutputSource, inputSourceAndConverter.asVolatile().getConverter() );

            final SourceAndConverter< ? > outputSourceAndConverter = new SourceAndConverter( outputSource, inputSourceAndConverter.getConverter(), volatileOutputSourceAndConverter );

            return outputSourceAndConverter;
        }
        else
        {
            return new SourceAndConverter( outputSource, inputSourceAndConverter.getConverter() );
        }
    }
}

One can use this now even with a lambda, for example like this:

final SourceAndConverter< T > croppedSourceAndConverter = new SourceChanger( ( Function< Source< ? >, Source< ? > > ) source -> new CroppedSource( source, "someName", new FinalRealInterval( min, max ), shiftToOrigin ) ).apply( sourceAndConverter );

That means one only has to implement the class the converts the source and the rest can be done by the SourceChanger.

[NicoKiaru]

Looks good! Do you think it's better as an action or it could fit as a static function in sourceandconverter helper.

Also : regarding the converter, I uses the clone converter function instead of reusing the same converter. Do you have a good reason not to clone it ? Should we make this optional (clone or reuse?)

[tischi]

Do you think it's better as an action or it could fit as a static function in sourceandconverter helper.

I think it should be a class, because otherwise we cannot implement the apply functional interface which can be handy. In addition, it is a pendant to the ConverterChanger which also is a class.
If you agree to make it a class, where should I put it?

Should we make this optional (clone or reuse?)

Yes, should be optional, one needs both I think. I can amend the code to enable cloning.

[NicoKiaru]

go for it, with optional converter cloning ! 👍

[tischi]

But in which package should I put it?

[NicoKiaru]

Here https://github.com/bigdataviewer/bigdataviewer-playground/tree/master/src/main/java/sc/fiji/bdvpg ? Within a new source package ?

[tischi]

I'll be on holidays from tomorrow for one week 🌴 ⛰️
I'll do this once I am back!