MoveViewSample.java Source code

Introduction

Here is the source code for MoveViewSample.java

Source

/*
Definitive Guide to Swing for Java 2, Second Edition
By John Zukowski       
ISBN: 1-893115-78-X
Publisher: APress
*/

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Point;
import java.awt.event.ActionEvent;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JViewport;
import javax.swing.KeyStroke;

public class MoveViewSample {

    public static final int INCREASE = 0; // direction

    public static final int DECREASE = 1; // direction

    public static final int X_AXIS = 0; // axis

    public static final int Y_AXIS = 1; // axis

    public static final int UNIT = 0; // type

    public static final int BLOCK = 1; // type

    static class MoveAction extends AbstractAction {
        JViewport viewport;

        int direction;

        int axis;

        int type;

        public MoveAction(JViewport viewport, int direction, int axis, int type) {
            if (viewport == null) {
                throw new IllegalArgumentException("null viewport not permitted");
            }
            this.viewport = viewport;
            this.direction = direction;
            this.axis = axis;
            this.type = type;
        }

        public void actionPerformed(ActionEvent actionEvent) {
            Dimension extentSize = viewport.getExtentSize();
            int horizontalMoveSize = 0;
            int verticalMoveSize = 0;
            if (axis == X_AXIS) {
                if (type == UNIT) {
                    horizontalMoveSize = 1;
                } else { // type == BLOCK
                    horizontalMoveSize = extentSize.width;
                }
            } else { // axis == Y_AXIS
                if (type == UNIT) {
                    verticalMoveSize = 1;
                } else { // type == BLOCK
                    verticalMoveSize = extentSize.height;
                }
            }
            if (direction == DECREASE) {
                horizontalMoveSize = -horizontalMoveSize;
                verticalMoveSize = -verticalMoveSize;
            }
            // Translate origin by some amount
            Point origin = viewport.getViewPosition();
            origin.x += horizontalMoveSize;
            origin.y += verticalMoveSize;
            // set new viewing origin
            viewport.setViewPosition(origin);
        }
    }

    public static void main(String args[]) {
        JFrame frame = new JFrame("JViewport Sample");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Icon icon = new ImageIcon("dog.jpg");
        JLabel dogLabel = new JLabel(icon);
        JViewport viewport = new JViewport();
        viewport.setView(dogLabel);

        InputMap inputMap = viewport.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        ActionMap actionMap = viewport.getActionMap();

        // Up key moves view up unit
        Action upKeyAction = new MoveAction(viewport, DECREASE, Y_AXIS, UNIT);
        KeyStroke upKey = KeyStroke.getKeyStroke("UP");
        inputMap.put(upKey, "up");
        actionMap.put("up", upKeyAction);

        // Down key moves view down unit
        Action downKeyAction = new MoveAction(viewport, INCREASE, Y_AXIS, UNIT);
        KeyStroke downKey = KeyStroke.getKeyStroke("DOWN");
        inputMap.put(downKey, "down");
        actionMap.put("down", downKeyAction);

        // Left key moves view left unit
        Action leftKeyAction = new MoveAction(viewport, DECREASE, X_AXIS, UNIT);
        KeyStroke leftKey = KeyStroke.getKeyStroke("LEFT");
        inputMap.put(leftKey, "left");
        actionMap.put("left", leftKeyAction);

        // Right key moves view right unit
        Action rightKeyAction = new MoveAction(viewport, INCREASE, X_AXIS, UNIT);
        KeyStroke rightKey = KeyStroke.getKeyStroke("RIGHT");
        inputMap.put(rightKey, "right");
        actionMap.put("right", rightKeyAction);

        // PgUp key moves view up block
        Action pgUpKeyAction = new MoveAction(viewport, DECREASE, Y_AXIS, BLOCK);
        KeyStroke pgUpKey = KeyStroke.getKeyStroke("PAGE_UP");
        inputMap.put(pgUpKey, "pgUp");
        actionMap.put("pgUp", pgUpKeyAction);

        // PgDn key moves view down block
        Action pgDnKeyAction = new MoveAction(viewport, INCREASE, Y_AXIS, BLOCK);
        KeyStroke pgDnKey = KeyStroke.getKeyStroke("PAGE_DOWN");
        inputMap.put(pgDnKey, "pgDn");
        actionMap.put("pgDn", pgDnKeyAction);

        // Shift-PgUp key moves view left block
        Action shiftPgUpKeyAction = new MoveAction(viewport, DECREASE, X_AXIS, BLOCK);
        KeyStroke shiftPgUpKey = KeyStroke.getKeyStroke("shift PAGE_UP");
        inputMap.put(shiftPgUpKey, "shiftPgUp");
        actionMap.put("shiftPgUp", shiftPgUpKeyAction);

        // Shift-PgDn key moves view right block
        Action shiftPgDnKeyAction = new MoveAction(viewport, INCREASE, X_AXIS, BLOCK);
        KeyStroke shiftPgDnKey = KeyStroke.getKeyStroke("shift PAGE_DOWN");
        inputMap.put(shiftPgDnKey, "shiftPgDn");
        actionMap.put("shiftPgDn", shiftPgDnKeyAction);

        Container contentPane = frame.getContentPane();
        contentPane.add(viewport, BorderLayout.CENTER);
        frame.setSize(300, 200);
        frame.setVisible(true);
    }
}