META-INF.modules.java.desktop.classes.javax.swing.Scrollable Maven / Gradle / Ivy
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package javax.swing;
import java.awt.Dimension;
import java.awt.Rectangle;
/**
* An interface that provides information to a scrolling container
* like JScrollPane. A complex component that's likely to be used
* as a viewing a JScrollPane viewport (or other scrolling container)
* should implement this interface.
*
* @see JViewport
* @see JScrollPane
* @see JScrollBar
* @author Hans Muller
* @since 1.2
*/
public interface Scrollable
{
/**
* 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.
*
* @return the preferredSize of a JViewport whose view
* is this Scrollable
* @see JViewport#getPreferredSize
*/
Dimension getPreferredScrollableViewportSize();
/**
* 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.
*
* @param visibleRect The view area visible within the viewport
* @param orientation Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.
* @param direction Less than zero to scroll up/left, greater than zero for down/right.
* @return The "unit" increment for scrolling in the specified direction.
* This value should always be positive.
* @see JScrollBar#setUnitIncrement
*/
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 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.
*
* @param visibleRect The view area visible within the viewport
* @param orientation Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.
* @param direction Less than zero to scroll up/left, greater than zero for down/right.
* @return The "block" increment for scrolling in the specified direction.
* This value should always be positive.
* @see JScrollBar#setBlockIncrement
*/
int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction);
/**
* 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.
*
* @return True if a viewport should force the Scrollables width to match its own.
*/
boolean getScrollableTracksViewportWidth();
/**
* 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.
*
* @return True if a viewport should force the Scrollables height to match its own.
*/
boolean getScrollableTracksViewportHeight();
}