org.geomajas.gwt2.client.controller.TouchNavigationController Maven / Gradle / Ivy

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/*
 * This is part of Geomajas, a GIS framework, http://www.geomajas.org/.
 *
 * Copyright 2008-2013 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.controller;

import org.geomajas.geometry.Coordinate;
import org.geomajas.gwt.client.map.RenderSpace;
import org.geomajas.gwt2.client.map.MapPresenter;

import com.google.gwt.event.dom.client.GestureChangeEvent;
import com.google.gwt.event.dom.client.GestureEndEvent;
import com.google.gwt.event.dom.client.GestureStartEvent;
import com.google.gwt.event.dom.client.TouchCancelEvent;
import com.google.gwt.event.dom.client.TouchEndEvent;
import com.google.gwt.event.dom.client.TouchEvent;
import com.google.gwt.event.dom.client.TouchMoveEvent;
import com.google.gwt.event.dom.client.TouchStartEvent;

/**
 * Generic controller that is used on touch mobile devices. Note that gestures and multi touch are not supported by some
 * mobile browsers.
 * 
 * @author Dosi Bingov
 * @since 1.0.0
 */
public class TouchNavigationController extends AbstractMapController {

	protected Coordinate touchedOrigin;

	protected Coordinate lastTouchedPosition;

	protected boolean zooming;

	protected boolean dragging;

	private double lastScale;

	// middle point of a gesture spike !only for multi-touch supported browsers
	private Coordinate midPoint;

	public TouchNavigationController() {
		super(false);
	}

	// ------------------------------------------------------------------------
	// Touch events:
	// ------------------------------------------------------------------------

	@Override
	public void onTouchStart(TouchStartEvent event) {
		event.preventDefault();
		lastTouchedPosition = getLocation(event, RenderSpace.WORLD);
		touchedOrigin = getLocation(event, RenderSpace.SCREEN);
	}

	@Override
	public void onTouchEnd(TouchEndEvent event) {
		updateView(event, true);
	}

	@Override
	public void onTouchMove(TouchMoveEvent event) {
		event.preventDefault();
		midPoint = mapPresenter.getViewPort().transform(getMidPoint(event), RenderSpace.SCREEN, RenderSpace.WORLD);
		updateView(event, true); // TODO second argument should be false but onTouchEnd is not fired
	}

	@Override
	public void onTouchCancel(TouchCancelEvent event) {
	}

	// ------------------------------------------------------------------------
	// Gesture events:
	// ------------------------------------------------------------------------

	@Override
	public void onGestureStart(GestureStartEvent event) {
		event.preventDefault();
		lastScale = mapPresenter.getViewPort().getScale();
		zoomTo(event.getScale(), false);
	}

	@Override
	public void onGestureEnd(GestureEndEvent event) {
		event.preventDefault();
		zoomTo(event.getScale(), true);
	}

	@Override
	public void onGestureChange(GestureChangeEvent event) {
		event.preventDefault();
		zoomTo(event.getScale(), false);
	}

	private void zoomTo(double scale, boolean isGestureEnded) {
		if (midPoint != null) {
			if (isGestureEnded) {
				mapPresenter.getViewPort().applyScale(scale * lastScale, midPoint);
			} else {
				mapPresenter.getViewPort().dragToScale(scale * lastScale, midPoint);
			}
		} else {
			if (isGestureEnded) {
				mapPresenter.getViewPort().applyScale(scale * lastScale);
			} else {
				mapPresenter.getViewPort().dragToScale(scale * lastScale);
			}
		}
	}

	// ------------------------------------------------------------------------
	// Methods:
	// ------------------------------------------------------------------------

	@Override
	public void onActivate(MapPresenter mapPresenter) {
		this.mapPresenter = mapPresenter;
		this.eventParser = mapPresenter.getMapEventParser();
	}

	@Override
	public void onDeactivate(MapPresenter mapPresenter) {
	}

	/**
	 * Method used to calculate exact middle point between multiple touches of a touch events.
	 * 
	 * @param event a touch event
	 * @return middle point
	 */
	private Coordinate getMidPoint(TouchEvent event) {
		Coordinate[] coords = new Coordinate[event.getTouches().length()];
		for (int i = 0; i < event.getTargetTouches().length(); i++) {
			coords[i] = new Coordinate(event.getTouches().get(i).getClientX(), event.getTouches().get(i).getClientY());
		}

		double x = 0;
		double y = 0;

		for (Coordinate coord : coords) {
			x += coord.getX();
			y += coord.getY();
		}

		x /= coords.length;
		y /= coords.length;

		return new Coordinate(x, y);
	}

	/**
	 * 
	 * Update the view of the map when touching and dragging.
	 * 
	 * @param event
	 */
	protected void updateView(TouchEvent event, boolean isTouchEnded) {
		Coordinate end = getMidPoint(event);

		Coordinate beginWorld = mapPresenter.getViewPort().transform(touchedOrigin, RenderSpace.SCREEN,
				RenderSpace.WORLD);
		Coordinate endWorld = mapPresenter.getViewPort().transform(end, RenderSpace.SCREEN, RenderSpace.WORLD);
		double x = mapPresenter.getViewPort().getPosition().getX() + beginWorld.getX() - endWorld.getX();
		double y = mapPresenter.getViewPort().getPosition().getY() + beginWorld.getY() - endWorld.getY();

		if (isTouchEnded) {
			mapPresenter.getViewPort().applyPosition(new Coordinate(x, y));
		} else {
			mapPresenter.getViewPort().dragToPosition(new Coordinate(x, y));
		}

		touchedOrigin = end;
	}

}