public class ScrollPane extends Container implements Accessible
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.
Modifier and Type | Class and Description |
---|---|
protected class |
ScrollPane.AccessibleAWTScrollPane
This class implements accessibility support for the
ScrollPane class. |
Container.AccessibleAWTContainer
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
Modifier and Type | Field and Description |
---|---|
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.
|
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
Constructor and Description |
---|
ScrollPane()
Create a new scrollpane container with a scrollbar display
policy of "as needed".
|
ScrollPane(int scrollbarDisplayPolicy)
Create a new scrollpane container.
|
Modifier and Type | Method and Description |
---|---|
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.
|
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, isValidateRoot, list, list, locate, minimumSize, paint, paintComponents, preferredSize, print, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, removeNotify, setComponentZOrder, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setFont, transferFocusDownCycle, update, validate, validateTree
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, disable, disableEvents, dispatchEvent, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle
public static final int SCROLLBARS_AS_NEEDED
public static final int SCROLLBARS_ALWAYS
public static final int SCROLLBARS_NEVER
public ScrollPane() throws HeadlessException
HeadlessException
- if GraphicsEnvironment.isHeadless()
returns trueGraphicsEnvironment.isHeadless()
@ConstructorProperties(value="scrollbarDisplayPolicy") public ScrollPane(int scrollbarDisplayPolicy) throws HeadlessException
scrollbarDisplayPolicy
- policy for when scrollbars should be shownIllegalArgumentException
- if the specified scrollbar
display policy is invalidHeadlessException
- if GraphicsEnvironment.isHeadless()
returns trueGraphicsEnvironment.isHeadless()
protected final void addImpl(Component comp, Object constraints, int index)
addImpl
in class Container
comp
- the component to be addedconstraints
- not applicableindex
- position of child component (must be <= 0)Container.add(Component)
,
Container.add(Component, int)
,
Container.add(Component, java.lang.Object)
,
Container.invalidate()
,
LayoutManager
,
LayoutManager2
public int getScrollbarDisplayPolicy()
public Dimension getViewportSize()
public int getHScrollbarHeight()
public int getVScrollbarWidth()
public Adjustable getVAdjustable()
ScrollPaneAdjustable
object which
represents the state of the vertical scrollbar.
The declared return type of this method is
Adjustable
to maintain backward compatibility.ScrollPaneAdjustable
public Adjustable getHAdjustable()
ScrollPaneAdjustable
object which
represents the state of the horizontal scrollbar.
The declared return type of this method is
Adjustable
to maintain backward compatibility.ScrollPaneAdjustable
public void setScrollPosition(int x, int y)
x
- the x position to scroll toy
- the y position to scroll toNullPointerException
- if the scrollpane does not contain
a childpublic void setScrollPosition(Point p)
p
- the Point representing the position to scroll toNullPointerException
- if p
is null
public Point getScrollPosition()
NullPointerException
- if the scrollpane does not contain
a childpublic final void setLayout(LayoutManager mgr)
setLayout
in class Container
mgr
- the specified layout managerContainer.doLayout()
,
Container.getLayout()
,
Container.invalidate()
public void doLayout()
doLayout
in class Container
Component.validate()
@Deprecated public void layout()
doLayout()
.public void printComponents(Graphics g)
printComponents
in class Container
g
- the specified Graphics windowComponent.print(java.awt.Graphics)
,
Component.printAll(java.awt.Graphics)
public void addNotify()
addNotify
in class Container
Component.isDisplayable()
,
Container.removeNotify()
public String paramString()
ScrollPane
. This
method is intended to be used only for debugging purposes, and the
content and format of the returned string may vary between
implementations. The returned string may be empty but may not be
null
.paramString
in class Container
protected void processMouseWheelEvent(MouseWheelEvent e)
ScrollPane
by scrolling an appropriate amount.
Note that if the event parameter is null
the behavior is unspecified and may result in an
exception.
processMouseWheelEvent
in class Component
e
- the mouse wheel eventMouseWheelEvent
,
MouseWheelListener
,
Component.addMouseWheelListener(java.awt.event.MouseWheelListener)
,
Component.enableEvents(long)
protected boolean eventTypeEnabled(int type)
public void setWheelScrollingEnabled(boolean handleWheel)
handleWheel
- true
if scrolling should be done
automatically for a MouseWheelEvent,
false
otherwise.isWheelScrollingEnabled()
,
MouseWheelEvent
,
MouseWheelListener
public boolean isWheelScrollingEnabled()
setWheelScrollingEnabled(boolean)
public AccessibleContext getAccessibleContext()
getAccessibleContext
in interface Accessible
getAccessibleContext
in class Component
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