public Dimension getPreferredScrollableViewportSize()
Returns the preferred size of the viewport for a view component.
For example, the preferred size of a JList component
is the size required to accommodate all of the cells in its list.
However, the value of preferredScrollableViewportSize
is the size required for JList.getVisibleRowCount rows.
A component without any properties that would affect the viewport
size should just return getPreferredSize here.

 public int getScrollableBlockIncrement(Rectangle visibleRect,
    int orientation,
    int direction)
Components that display logical rows or columns should compute
the scroll increment that will completely expose one block
of rows or columns, depending on the value of orientation.

Scrolling containers, like JScrollPane, will use this method
each time the user requests a block scroll.

 public boolean getScrollableTracksViewportHeight()
Return true if a viewport should always force the height of this
Scrollable to match the height of the viewport. For example a
columnar text view that flowed text in left to right columns
could effectively disable vertical scrolling by returning
true here.

Scrolling containers, like JViewport, will use this method each
time they are validated.

 public boolean getScrollableTracksViewportWidth()
Return true if a viewport should always force the width of this
Scrollable to match the width of the viewport.
For example a normal
text view that supported line wrapping would return true here, since it
would be undesirable for wrapped lines to disappear beyond the right
edge of the viewport. Note that returning true for a Scrollable
whose ancestor is a JScrollPane effectively disables horizontal
scrolling.

Scrolling containers, like JViewport, will use this method each
time they are validated.

 public int getScrollableUnitIncrement(Rectangle visibleRect,
    int orientation,
    int direction)
Components that display logical rows or columns should compute
the scroll increment that will completely expose one new row
or column, depending on the value of orientation. Ideally,
components should handle a partially exposed row or column by
returning the distance required to completely expose the item.

Scrolling containers, like JScrollPane, will use this method
each time the user requests a unit scroll.