source: josm/trunk/src/org/openstreetmap/josm/gui/MapMover.java@ 391

// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.gui;

import java.awt.Cursor;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;

import javax.swing.AbstractAction;
import javax.swing.JComponent;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

import org.openstreetmap.josm.data.coor.EastNorth;

/**
 * Enables moving of the map by holding down the right mouse button and drag
 * the mouse. Also, enables zooming by the mouse wheel.
 *
 * @author imi
 */
public class MapMover extends MouseAdapter implements MouseMotionListener, MouseWheelListener {

        private final class ZoomerAction extends AbstractAction {
                private final String action;
                public ZoomerAction(String action) {
                        this.action = action;
        }
            public void actionPerformed(ActionEvent e) {
                if (action.equals(".") || action.equals(",")) {
                        Point mouse = nc.getMousePosition();
                        if (mouse == null)
                                mouse = new Point((int)nc.getBounds().getCenterX(), (int)nc.getBounds().getCenterY());
                        MouseWheelEvent we = new MouseWheelEvent(nc, e.getID(), e.getWhen(), e.getModifiers(), mouse.x, mouse.y, 0, false, MouseWheelEvent.WHEEL_UNIT_SCROLL, 1, action.equals(",") ? -1 : 1);
                        mouseWheelMoved(we);
                } else {
                        EastNorth center = nc.getCenter();
                        EastNorth newcenter = nc.getEastNorth(nc.getWidth()/2+nc.getWidth()/5, nc.getHeight()/2+nc.getHeight()/5);
                        if (action.equals("left"))
                                nc.zoomTo(new EastNorth(2*center.east()-newcenter.east(), center.north()), nc.getScale());
                        else if (action.equals("right"))
                                nc.zoomTo(new EastNorth(newcenter.east(), center.north()), nc.getScale());
                        else if (action.equals("up"))
                                nc.zoomTo(new EastNorth(center.east(), 2*center.north()-newcenter.north()), nc.getScale());
                        else if (action.equals("down"))
                                nc.zoomTo(new EastNorth(center.east(), newcenter.north()), nc.getScale());
                }
            }
    }

        /**
         * The point in the map that was the under the mouse point
         * when moving around started.
         */
        private EastNorth mousePosMove;
        /**
         * The map to move around.
         */
        private final NavigatableComponent nc;
        /**
         * The old cursor when we changed it to movement cursor.
         */
        private Cursor oldCursor;

        private boolean movementInPlace = false;

        /**
         * Create a new MapMover
         */
        public MapMover(NavigatableComponent navComp, JPanel contentPane) {
                this.nc = navComp;
                nc.addMouseListener(this);
                nc.addMouseMotionListener(this);
                nc.addMouseWheelListener(this);
                
                String[] n = {",",".","up","right","down","left"};
                int[] k = {KeyEvent.VK_COMMA, KeyEvent.VK_PERIOD, KeyEvent.VK_UP, KeyEvent.VK_RIGHT, KeyEvent.VK_DOWN, KeyEvent.VK_LEFT};

                if (contentPane != null) {
                        for (int i = 0; i < n.length; ++i) {
                                contentPane.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(k[i], KeyEvent.CTRL_DOWN_MASK), "MapMover.Zoomer."+n[i]);
                                contentPane.getActionMap().put("MapMover.Zoomer."+n[i], new ZoomerAction(n[i]));
                        }
                }
        }

        /**
         * If the right (and only the right) mouse button is pressed, move the map
         */
        public void mouseDragged(MouseEvent e) {
                int offMask = MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON2_DOWN_MASK;
                if ((e.getModifiersEx() & (MouseEvent.BUTTON3_DOWN_MASK | offMask)) == MouseEvent.BUTTON3_DOWN_MASK) {
                        if (mousePosMove == null)
                                startMovement(e);
                        EastNorth center = nc.getCenter();
                        EastNorth mouseCenter = nc.getEastNorth(e.getX(), e.getY());
                        EastNorth p = new EastNorth(
                                        mousePosMove.east() + center.east() - mouseCenter.east(),
                                        mousePosMove.north() + center.north() - mouseCenter.north());
                        nc.zoomTo(p, nc.getScale());
                } else
                        endMovement();
        }

        /**
         * Start the movement, if it was the 3rd button (right button).
         */
        @Override public void mousePressed(MouseEvent e) {
                int offMask = MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON2_DOWN_MASK;
                if (e.getButton() == MouseEvent.BUTTON3 && (e.getModifiersEx() & offMask) == 0)
                        startMovement(e);
        }

        /**
         * Change the cursor back to it's pre-move cursor.
         */
        @Override public void mouseReleased(MouseEvent e) {
                if (e.getButton() == MouseEvent.BUTTON3)
                        endMovement();
        }

        /**
         * Start movement by setting a new cursor and remember the current mouse
         * position.
         * @param e The mouse event that leat to the movement from.
         */
        private void startMovement(MouseEvent e) {
                if (movementInPlace)
                        return;
                movementInPlace = true;
                mousePosMove = nc.getEastNorth(e.getX(), e.getY());
                oldCursor = nc.getCursor();
                nc.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
        }

        /**
         * End the movement. Setting back the cursor and clear the movement variables
         */
        private void endMovement() {
                if (!movementInPlace)
                        return;
                movementInPlace = false;
                if (oldCursor != null)
                        nc.setCursor(oldCursor);
                else
                        nc.setCursor(Cursor.getDefaultCursor());
                mousePosMove = null;
                oldCursor = null;
        }

        /**
         * Zoom the map by 1/5th of current zoom per wheel-delta.
         * @param e The wheel event.
         */
        public void mouseWheelMoved(MouseWheelEvent e) {
                int w = nc.getWidth();
                int h = nc.getHeight();

                double zoom = Math.max(0.1, 1 + e.getWheelRotation()/5.0);
                double zoomfactor = (zoom-1)/2+1;

                double newHalfWidth = w*zoomfactor - w/2;
                double newHalfHeight = h*zoomfactor - h/2;
                double centerx = e.getX() - (e.getX()-w/2)*newHalfWidth*2/w;
                double centery = e.getY() - (e.getY()-h/2)*newHalfHeight*2/h;
                EastNorth newCenter = nc.getEastNorth((int)centerx, (int)centery); 

                nc.zoomTo(newCenter, nc.getScale()*zoom);
        }

        /**
         * Does nothing. Only to satisfy MouseMotionListener
         */
        public void mouseMoved(MouseEvent e) {}
}