Implemente um ouvinte de roda (no componente dentro de jViewport):
public void mouseWheelMoved(MouseWheelEvent e) {
boolean isCtrl = (e.getModifiersEx() & MouseWheelEvent.CTRL_DOWN_MASK) != 0;
boolean isShift = (e.getModifiersEx() & MouseWheelEvent.SHIFT_DOWN_MASK) != 0;
MouseWheelEvent eventToDispatch = e;
if (isCtrl || isShift) {
int amountMulti = 1;
int rotMulti = 1;
if (isCtrl) {
amountMulti *= 10;
if (isShift) {
amountMulti *= 5;
rotMulti *= 2;
}
}
int mod = e.getModifiers() & ~InputEvent.CTRL_MASK & ~InputEvent.SHIFT_MASK;
int modEx = e.getModifiersEx() & ~MouseWheelEvent.CTRL_DOWN_MASK & ~MouseWheelEvent.SHIFT_DOWN_MASK;
eventToDispatch = new MouseWheelEvent(this, e.getID(), e.getWhen()
, mod | modEx, e.getX(), e.getY()
, e.getXOnScreen(), e.getYOnScreen(), e.getClickCount(), e.isPopupTrigger()
, e.getScrollType(), e.getScrollAmount()*amountMulti, e.getWheelRotation()*rotMulti
, e.getPreciseWheelRotation()*amountMulti*rotMulti);
}
getParent().dispatchEvent(eventToDispatch);
}
O aumento de wheelRotation é necessário: caso contrário, o número de linhas roladas será limitado ao tamanho da tela.