java.awt
Class ScrollPane

java.lang.Object   
  java.awt.Component   
      java.awt.Container   
          java.awt.ScrollPane

All Implemented Interfaces:

ImageObserver , MenuContainer , Serializable , Accessible

public class ScrollPane
extends Container   
implements Accessible   

A container class which implements automatic horizontal and/or vertical scrolling for a single child component. The display policy for the scrollbars can be set to:

1. as needed: scrollbars created and shown only when needed by scrollpane
2. always: scrollbars created and always shown by the scrollpane
3. never: scrollbars never created or shown by the scrollpane

The state of the horizontal and vertical scrollbars is represented by two ScrollPaneAdjustable objects (one for each dimension) which implement the Adjustable interface. The API provides methods to access those objects such that the attributes on the Adjustable object (such as unitIncrement, value, etc.) can be manipulated.

Certain adjustable properties (minimum, maximum, blockIncrement, and visibleAmount) are set internally by the scrollpane in accordance with the geometry of the scrollpane and its child and these should not be set by programs using the scrollpane.

If the scrollbar display policy is defined as "never", then the scrollpane can still be programmatically scrolled using the setScrollPosition() method and the scrollpane will move and clip the child's contents appropriately. This policy is useful if the program needs to create and manage its own adjustable controls.

The placement of the scrollbars is controlled by platform-specific properties set by the user outside of the program.

The initial size of this container is set to 100x100, but can be reset using setSize().

Scrolling with the wheel on a wheel-equipped mouse is enabled by default. This can be disabled using setWheelScrollingEnabled. Wheel scrolling can be customized by setting the block and unit increment of the horizontal and vertical Adjustables. For information on how mouse wheel events are dispatched, see the class description for MouseWheelEvent .

Insets are used to define any space used by scrollbars and any borders created by the scroll pane. getInsets() can be used to get the current value for the insets. If the value of scrollbarsAlwaysVisible is false, then the value of the insets will change dynamically depending on whether the scrollbars are currently visible or not.

See Also:

Serialized Form

Nested Class Summary

protected class

ScrollPane.AccessibleAWTScrollPane This class implements accessibility support for the ScrollPane class.

Nested classes/interfaces inherited from class java.awt.Container

Container.AccessibleAWTContainer

Nested classes/interfaces inherited from class java.awt.Component

Component.AccessibleAWTComponent , Component.BltBufferStrategy , Component.FlipBufferStrategy

Field Summary

static int	SCROLLBARS_ALWAYS Specifies that horizontal/vertical scrollbars should always be shown regardless of the respective sizes of the scrollpane and child.
static int	SCROLLBARS_AS_NEEDED Specifies that horizontal/vertical scrollbar should be shown only when the size of the child exceeds the size of the scrollpane in the horizontal/vertical dimension.
static int	SCROLLBARS_NEVER Specifies that horizontal/vertical scrollbars should never be shown regardless of the respective sizes of the scrollpane and child.

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT , CENTER_ALIGNMENT , LEFT_ALIGNMENT , RIGHT_ALIGNMENT , TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT , ALLBITS , ERROR , FRAMEBITS , HEIGHT , PROPERTIES , SOMEBITS , WIDTH

Constructor Summary

ScrollPane ()
Create a new scrollpane container with a scrollbar display policy of "as needed".

ScrollPane (int scrollbarDisplayPolicy)
Create a new scrollpane container.

Method Summary

protected void	addImpl (Component comp, Object constraints, int index) Adds the specified component to this scroll pane container.
void	addNotify () Creates the scroll pane's peer.
void	doLayout () Lays out this container by resizing its child to its preferred size.
protected boolean	eventTypeEnabled (int type) If wheel scrolling is enabled, we return true for MouseWheelEvents
AccessibleContext	getAccessibleContext () Gets the AccessibleContext associated with this ScrollPane.
Adjustable	getHAdjustable () Returns the ScrollPaneAdjustable object which represents the state of the horizontal scrollbar.
int	getHScrollbarHeight () Returns the height that would be occupied by a horizontal scrollbar, which is independent of whether it is currently displayed by the scroll pane or not.
int	getScrollbarDisplayPolicy () Returns the display policy for the scrollbars.
Point	getScrollPosition () Returns the current x,y position within the child which is displayed at the 0,0 location of the scrolled panel's view port.
Adjustable	getVAdjustable () Returns the ScrollPaneAdjustable object which represents the state of the vertical scrollbar.
Dimension	getViewportSize () Returns the current size of the scroll pane's view port.
int	getVScrollbarWidth () Returns the width that would be occupied by a vertical scrollbar, which is independent of whether it is currently displayed by the scroll pane or not.
boolean	isWheelScrollingEnabled () Indicates whether or not scrolling will take place in response to the mouse wheel.
void	layout () Deprecated. As of JDK version 1.1, replaced by doLayout().
String	paramString () Returns a string representing the state of this ScrollPane.
void	printComponents (Graphics g) Prints the component in this scroll pane.
protected void	processMouseWheelEvent (MouseWheelEvent e) Process mouse wheel events that are delivered to this ScrollPane by scrolling an appropriate amount.
void	setLayout (LayoutManager mgr) Sets the layout manager for this container.
void	setScrollPosition (int x, int y) Scrolls to the specified position within the child component.
void	setScrollPosition (Point p) Scrolls to the specified position within the child component.
void	setWheelScrollingEnabled (boolean handleWheel) Enables/disables scrolling in response to movement of the mouse wheel.

Methods inherited from class java.awt.Container

add , add , add , add , add , addContainerListener , addPropertyChangeListener , addPropertyChangeListener , applyComponentOrientation , areFocusTraversalKeysSet , countComponents , deliverEvent , findComponentAt , findComponentAt , getAlignmentX , getAlignmentY , getComponent , getComponentAt , getComponentAt , getComponentCount , getComponents , getComponentZOrder , getContainerListeners , getFocusTraversalKeys , getFocusTraversalPolicy , getInsets , getLayout , getListeners , getMaximumSize , getMinimumSize , getMousePosition , getPreferredSize , insets , invalidate , isAncestorOf , isFocusCycleRoot , isFocusCycleRoot , isFocusTraversalPolicyProvider , isFocusTraversalPolicySet , list , list , locate , minimumSize , paint , paintComponents , preferredSize , print , processContainerEvent , processEvent , remove , remove , removeAll , removeContainerListener , removeNotify , setComponentZOrder , setFocusCycleRoot , setFocusTraversalKeys , setFocusTraversalPolicy , setFocusTraversalPolicyProvider , setFont , transferFocusBackward , transferFocusDownCycle , update , validate , validateTree

Methods inherited from class java.awt.Component

action , add , addComponentListener , addFocusListener , addHierarchyBoundsListener , addHierarchyListener , addInputMethodListener , addKeyListener , addMouseListener , addMouseMotionListener , addMouseWheelListener , bounds , checkImage , checkImage , coalesceEvents , contains , contains , createImage , createImage , createVolatileImage , createVolatileImage , disable , disableEvents