package layer;

import java.util.Collection;

/**
 * The abstract Layer class represents a layer placed over presentation content
 * used for annotation, sharing, and exporting.
 */
public abstract class Layer
{
    /**
     * The User that owns and is responsible for creating content on this Layer.
     */
    user.User owner;

    /**
     * A Layer has a collection of LayerAnnotations made by the owner
     * containing information about what they've placed on the layer.
     */
    public Collection<drawing.LayerAnnotation> annotations;

    /**
     * The opacity (or, inversely, the visible opacity of this layer.
     */
    double opacity;

    /**
     * Keeps track of whether or not this layer is currently selected for
     * drawing by the owner.
     */
    boolean hasDrawFocus;
}

/**
 * The PrivateLayer class inherits from the abstract Layer class, and it
 * represents a Layer that is only for use by the user that owns it. That is,
 * it may not be shared with the entire class.
 */
class PrivateLayer extends Layer {}

/**
 * The PublicLayer class inherits from the abstract Layer class, and it
 * represents a Layer that is annotated by its owner, and it may be shared
 * with the rest of the class at any time if the instructor selects it for
 * viewing.
 */
class PublicLayer extends Layer
{
    /**
     * Keeps track of whether or not this layer is being presented to the rest
     * of the class.
     */
    boolean isPresented;
}

/**
 * StudentLayersPair acts as a container of a student's public and private
 * layers.
 */
class StudentLayersPair
{
    /**
     * The individual student's public layer.
     */
    PublicLayer publicLayer;

    /**
     * The individual student's private layer.
     */
    PrivateLayer privateLayer;
}