Advanced Swing Containers - The Definitive Guide to Java Swing - page 407

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[]) {
Runnable runner = new Runnable() {
public void run() {
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);