JViewport: Move and View
/*
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);
}
}
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