Layer.java

/*
 * This is part of Geomajas, a GIS framework, http://www.geomajas.org/.
 *
 * Copyright 2008-2015 Geosparc nv, http://www.geosparc.com/, Belgium.
 *
 * The program is available in open source according to the GNU Affero
 * General Public License. All contributions in this program are covered
 * by the Geomajas Contributors License Agreement. For full licensing
 * details, see LICENSE.txt in the project root.
 */

package org.geomajas.gwt2.client.map.layer;

import org.geomajas.annotation.Api;
import org.geomajas.geometry.Bbox;
import org.geomajas.gwt2.client.map.render.LayerRenderer;

/**
 * The basic definition of a layer within the Geomajas GWT client.
 *
 * @author Pieter De Graef
 * @since 2.0.0
 */
@Api(allMethods = true)
public interface Layer {

	/**
	 * Return this layer's client ID.
	 * 
	 * @return id of the client layer
	 */
	String getId();

	/**
	 * Return the layer's title. The difference between the ID and the title, is that the ID is used behind the screens,
	 * while the title is the visible name to the user.
	 * 
	 * @return
	 */
	String getTitle();

	/**
	 * Mark this layer as selected or not. Only one layer can be selected at any given time within a map.
	 * 
	 * @param selected
	 *            The boolean value that indicates whether or not to select this layer.
	 */
	void setSelected(boolean selected);

	/**
	 * Is this layer currently marked as selected or not?
	 * 
	 * @return Returns true or false.
	 */
	boolean isSelected();

	/**
	 * Mark this layer as visible or invisible. This may toggle the visibility flag, but does not guarantee that the
	 * layer be visible. This is because other factors might intrude upon the layer visibility, such as the minimum and
	 * maximum scales between which a layer can be visible.
	 * 
	 * @param markedAsVisible
	 *            Should the layer be marked as visible or invisible?
	 */
	void setMarkedAsVisible(boolean markedAsVisible);

	/**
	 * Has the layer been marked as visible?
	 * 
	 * @return True or false.
	 */
	boolean isMarkedAsVisible();

	/**
	 * Is the layer currently showing on the map or not? In other words, can we actually look at the layer on the map? A
	 * layer may be marked as visible but other factors (such as scale) may intrude upon the actual visibility of a
	 * layer.<br/>
	 * This value will return the final result of all these factors and clearly state whether or not the layer can be
	 * seen.
	 * 
	 * @return true or false.
	 */
	boolean isShowing();

	/** Refresh this layer on the map. This method will completely erase the current contents and redraw. */
	void refresh();

	/**
	 * Return the specific renderer for the layer.
	 * 
	 * @return The layer specific renderer.
	 */
	LayerRenderer getRenderer();

	/**
	 * Apply a new opacity on the entire layer. Changing the opacity on a layer does NOT fire a layer style changed
	 * event.
	 * 
	 * @param opacity
	 *            The new opacity value. Must be a value between 0 and 1, where 0 means invisible and 1 is totally
	 *            visible.
	 */
	void setOpacity(double opacity);

	/**
	 * Get the current opacity value for this layer. Must be a value between 0 and 1, where 0 means invisible and 1 is
	 * totally visible.
	 * 
	 * @return The current opacity value for this layer.
	 */
	double getOpacity();
	
	/**
	 * Return the maximum bounds. The bounds is defined in the map CRS.
	 * 
	 * @return the maximum bounds
	 * @since 2.1.0
	 */
	Bbox getMaxBounds();

	/**
	 * Set the maximum bounds. The bounds is defined in the map CRS. For tile-based layers, only tiles within the
	 * maximum bounds will be fetched. To avoid rounding errors, the center of the tile may be used for checking the
	 * condition.
	 *
	 * @param maxBounds The maximum bounds
	 * @since 2.1.0
	 */
	void setMaxBounds(Bbox maxBounds);

	/**
	 * Returns the maximum resolution at which the layer is visible.
	 * By SLD convention, the maximum resolution value is inclusive:
	 * the layer will be visible at this specific resolution.
	 *
	 * @return resolution
	 * @since 2.3.0
	 */
	double getMaxResolution();

	/**
	 * Returns the minimum resolution at which the layer is visible.
	 * By SLD convention, the minimum resolution value is exclusive:
	 * the layer will not be visible at this specific resolution.
	 *
	 * @return resolution
	 * @since 2.3.0
	 */
	double getMinResolution();

}