ImagePanel.java

package uk.org.squirm3.ui.collider;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.geom.Point2D;

import javax.swing.JPanel;
import javax.swing.Scrollable;

import uk.org.squirm3.model.Atom;
import uk.org.squirm3.model.DraggingPoint;

/**
 * TODO read
 * http://download.oracle.com/javase/tutorial/uiswing/components/scrollpane.html
 */
class ImagePanel extends JPanel implements Scrollable {
    private static final long serialVersionUID = 1L;

    private final AtomsPanel atomsPanel;

    public ImagePanel(final AtomsPanel atomsPanel) {
        this.atomsPanel = atomsPanel;
        addMouseListener(new ImageMouseListener());
        addMouseMotionListener(new ImageMouseMotionListener());
    }

    @Override
    public void paint(final Graphics g) {
        super.paint(g);
        atomsPanel.updateImage();
        final float zoom = (float) atomsPanel.scale / 100;
        g.drawImage(atomsPanel.bimg, 0, 0,
                (int) (atomsPanel.bimg.getWidth() * zoom),
                (int) (atomsPanel.bimg.getHeight() * zoom), this);
    }

    @Override
    public Dimension getPreferredScrollableViewportSize() {
        return getPreferredSize();
    }

    @Override
    public int getScrollableBlockIncrement(final Rectangle arg0,
            final int arg1, final int arg2) {
        return 1; // TODO
    }

    @Override
    public boolean getScrollableTracksViewportHeight() {
        return false;
    }

    @Override
    public boolean getScrollableTracksViewportWidth() {
        return false;
    }

    @Override
    public int getScrollableUnitIncrement(final Rectangle arg0, final int arg1,
            final int arg2) {
        return 1;
    }

    private final class ImageMouseMotionListener implements MouseMotionListener {
        @Override
        public void mouseDragged(final MouseEvent event) {
            if (atomsPanel.draggingPoint != null) {
                final float zoom = (float) atomsPanel.scale / 100;
                atomsPanel.applicationEngine
                        .setDraggingPoint(new DraggingPoint((long) (event
                                .getPoint().x / zoom),
                                (long) (event.getPoint().y / zoom),
                                atomsPanel.draggingPoint
                                        .getWhichBeingDragging()));
            }
        }
        @Override
        public void mouseMoved(final MouseEvent event) {
            if (atomsPanel.draggingPoint != null) {
                final float zoom = (float) atomsPanel.scale / 100;
                atomsPanel.applicationEngine
                        .setDraggingPoint(new DraggingPoint((long) (event
                                .getPoint().x / zoom),
                                (long) (event.getPoint().y / zoom),
                                atomsPanel.draggingPoint
                                        .getWhichBeingDragging()));
            }
        }
    }

    private final class ImageMouseListener implements MouseListener {
        @Override
        public void mouseClicked(final MouseEvent event) {
        }
        @Override
        public void mouseEntered(final MouseEvent event) {
        }
        @Override
        public void mouseExited(final MouseEvent event) {
        }
        @Override
        public void mousePressed(final MouseEvent event) {
            if (isLeftClick(event)) {
                setDraggingPoint(event);
            }

        }
        private void setDraggingPoint(final MouseEvent event) {
            final Point p = event.getPoint();
            final int R = (int) Atom.getAtomSize();
            final float zoom = (float) atomsPanel.scale / 100;
            final Point2D.Float p1 = new Point2D.Float();
            final Point2D.Float p2 = new Point2D.Float(p.x / zoom, p.y / zoom);
            for (int i = 0; i < atomsPanel.latestAtomsCopy.length; i++) {
                p1.x = atomsPanel.latestAtomsCopy[i].getPhysicalPoint()
                        .getPositionX();
                p1.y = atomsPanel.latestAtomsCopy[i].getPhysicalPoint()
                        .getPositionY();
                if (p2.distanceSq(p1) < R * R) {
                    atomsPanel.applicationEngine
                            .setDraggingPoint(new DraggingPoint((long) p2.x,
                                    (long) p2.y, i));
                    break;
                }
            }
        }
        private boolean isLeftClick(final MouseEvent event) {
            return (event.getModifiers() & InputEvent.BUTTON1_MASK) == InputEvent.BUTTON1_MASK;
        }
        @Override
        public void mouseReleased(final MouseEvent event) {
            atomsPanel.applicationEngine.setDraggingPoint(null);
        }
    }

}