source: osm/applications/editors/josm/plugins/touchscreenhelper/src/touchscreenhelper/BrowseAction.java

// License: GPL. For details, see LICENSE file.
package touchscreenhelper;

import static org.openstreetmap.josm.tools.I18n.tr;

import java.awt.Cursor;
import java.awt.event.KeyEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import org.openstreetmap.josm.actions.mapmode.MapMode;
import org.openstreetmap.josm.data.coor.EastNorth;
import org.openstreetmap.josm.gui.MainApplication;
import org.openstreetmap.josm.gui.MapFrame;
import org.openstreetmap.josm.tools.Shortcut;

public class BrowseAction extends MapMode implements MouseListener,
    MouseMotionListener, MapFrame.MapModeChangeListener {

    private MapMode oldMapMode;
    private TimedKeyReleaseListener listener;

    public BrowseAction() {
        super(tr("Browse"), "browse", tr("Browse map with left button"),
            Shortcut.registerShortcut("touchscreenhelper:browse", tr("Mode: {0}", tr("Browse map with left button")),
                KeyEvent.VK_T, Shortcut.DIRECT),
            Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
        MapFrame.addMapModeChangeListener(this);
    }

    @Override
    public void mapModeChange(MapMode oldMapMode, MapMode newMapMode) {
        this.oldMapMode = oldMapMode;
    }

    @Override public void enterMode() {
        super.enterMode();
        MainApplication.getMap().mapView.addMouseListener(this);
        MainApplication.getMap().mapView.addMouseMotionListener(this);

        listener = new TimedKeyReleaseListener() {
            @Override
            protected void doKeyReleaseEvent(KeyEvent evt) {
                if (evt.getKeyCode() == getShortcut().getKeyStroke().getKeyCode()) {
                    if (oldMapMode != null && !(oldMapMode instanceof BrowseAction))
                    MainApplication.getMap().selectMapMode(oldMapMode);
                }
            }
        };
    }

    @Override public void exitMode() {
        super.exitMode();

        MainApplication.getMap().mapView.removeMouseListener(this);
        MainApplication.getMap().mapView.removeMouseMotionListener(this);
        listener.stop();
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        if ((e.getModifiersEx() & MouseEvent.BUTTON1_DOWN_MASK) !=
            MouseEvent.BUTTON1_DOWN_MASK) {
            endMovement();
            return;
        }

        if (mousePosMove == null)
            startMovement(e);
        EastNorth center = MainApplication.getMap().mapView.getCenter();
        EastNorth mouseCenter = MainApplication.getMap().mapView.getEastNorth(e.getX(), e.getY());
        MainApplication.getMap().mapView.zoomTo(new EastNorth(
            mousePosMove.east() + center.east() - mouseCenter.east(),
            mousePosMove.north() + center.north() - mouseCenter.north()));
    }

    @Override public void mousePressed(MouseEvent e) {
        if (e.getButton() == MouseEvent.BUTTON1)
            startMovement(e);
    }

    @Override public void mouseReleased(MouseEvent e) {
        if (e.getButton() == MouseEvent.BUTTON1)
            endMovement();
    }

    private EastNorth mousePosMove;
    private boolean movementInPlace = false;

    private void startMovement(MouseEvent e) {
        if (movementInPlace)
            return;
        movementInPlace = true;
        mousePosMove = MainApplication.getMap().mapView.getEastNorth(e.getX(), e.getY());
    }

    private void endMovement() {
        if (!movementInPlace)
            return;
        movementInPlace = false;
        mousePosMove = null;
    }
}