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java.awt
Class ScrollPane

java.lang.Object
 |
 +--java.awt.Component
 |
 +--java.awt.Container
 |
 +--java.awt.ScrollPane

All Implemented Interfaces:

Accessible, java.awt.image.ImageObserver, MenuContainer, Serializable

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public class ScrollPane

extends Container

implements Accessible

Unsafe:

See Also:

Serialized Form

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SCROLLBARS_AS_NEEDED

public static final int SCROLLBARS_AS_NEEDED

Enabled: 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.

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SCROLLBARS_ALWAYS

public static final int SCROLLBARS_ALWAYS

Enabled: Specifies that horizontal/vertical scrollbars should always be shown regardless of the respective sizes of the scrollpane and child.

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SCROLLBARS_NEVER

public static final int SCROLLBARS_NEVER

Enabled: Specifies that horizontal/vertical scrollbars should never be shown regardless of the respective sizes of the scrollpane and child.

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scrollbarDisplayPolicy

private int scrollbarDisplayPolicy

There are 3 ways in which a scroll bar can be displayed. This integer will represent one of these 3 displays - (SCROLLBARS_ALWAYS, SCROLLBARS_AS_NEEDED, SCROLLBARS_NEVER)

See Also:

getScrollbarDisplayPolicy()

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vAdjustable

private ScrollPaneAdjustable vAdjustable

An adjustable vertical scrollbar. It is important to note that you must NOT call 3 Adjustable methods, namely: setMinimum(), setMaximum(), setVisibleAmount().

See Also:

getVAdjustable()

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hAdjustable

private ScrollPaneAdjustable hAdjustable

An adjustable horizontal scrollbar. It is important to note that you must NOT call 3 Adjustable methods, namely: setMinimum(), setMaximum(), setVisibleAmount().

See Also:

getHAdjustable()

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base

private static final String base

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nameCounter

private static int nameCounter

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defaultWheelScroll

private static final boolean defaultWheelScroll

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wheelScrollingEnabled

private boolean wheelScrollingEnabled

Indicates whether or not scrolling should take place when a MouseWheelEvent is received.

Since:

1.4

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serialVersionUID

private static final long serialVersionUID

ScrollPane

public ScrollPane()
 throws HeadlessException

Suppressed: Create a new scrollpane container with a scrollbar display policy of "as needed".

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true

See Also:

java.awt.GraphicsEnvironment#isHeadless

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ScrollPane

public ScrollPane(int scrollbarDisplayPolicy)
 throws HeadlessException

Suppressed: Create a new scrollpane container.

Parameters:

scrollbarDisplayPolicy - policy for when scrollbars should be shown

Throws:

IllegalArgumentException - if the specified scrollbar display policy is invalid

HeadlessException - if GraphicsEnvironment.isHeadless() returns true

See Also:

java.awt.GraphicsEnvironment#isHeadless

initIDs

private static void initIDs()

Initialize JNI field and method IDs

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constructComponentName

String constructComponentName()

Construct a name for this component. Called by getName() when the name is null.

Overrides:

constructComponentName in class Component

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addImpl

protected final void addImpl(Component comp,
 Object constraints,
 int index)

Adds the specified component to this scroll pane container. If the scroll pane has an existing child component, that component is removed and the new one is added.

Overrides:

addImpl in class Container

Parameters:

comp - the component to be added

constraints - not applicable

index - position of child component (must be <= 0)

See Also:

Container.add(Component), Container.add(Component, int), Container.add(Component, java.lang.Object), LayoutManager, LayoutManager2

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getScrollbarDisplayPolicy

public int getScrollbarDisplayPolicy()

Suppressed: Returns the display policy for the scrollbars.

Returns:

the display policy for the scrollbars

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getViewportSize

public Dimension getViewportSize()

Suppressed: Returns the current size of the scroll pane's view port.

Returns:

the size of the view port in pixels

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getHScrollbarHeight

public int getHScrollbarHeight()

Suppressed: 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.

Returns:

the height of a horizontal scrollbar in pixels

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getVScrollbarWidth

public int getVScrollbarWidth()

Suppressed: 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.

Returns:

the width of a vertical scrollbar in pixels

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getVAdjustable

public Adjustable getVAdjustable()

Suppressed: Returns the ScrollPaneAdjustable object which represents the state of the vertical scrollbar. The declared return type of this method is Adjustable to maintain backward compatibility.

See Also:

java.awt.ScrollPaneAdjustable

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getHAdjustable

public Adjustable getHAdjustable()

Suppressed: Returns the ScrollPaneAdjustable object which represents the state of the horizontal scrollbar. The declared return type of this method is Adjustable to maintain backward compatibility.

See Also:

java.awt.ScrollPaneAdjustable

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setScrollPosition

public void setScrollPosition(int x,
 int y)

Suppressed: Scrolls to the specified position within the child component. A call to this method is only valid if the scroll pane contains a child. Specifying a position outside of the legal scrolling bounds of the child will scroll to the closest legal position. Legal bounds are defined to be the rectangle: x = 0, y = 0, width = (child width - view port width), height = (child height - view port height). This is a convenience method which interfaces with the Adjustable objects which represent the state of the scrollbars.

Parameters:

x - the x position to scroll to

y - the y position to scroll to

Throws:

NullPointerException - if the scrollpane does not contain a child

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setScrollPosition

public void setScrollPosition(Point p)

Suppressed: Scrolls to the specified position within the child component. A call to this method is only valid if the scroll pane contains a child and the specified position is within legal scrolling bounds of the child. Specifying a position outside of the legal scrolling bounds of the child will scroll to the closest legal position. Legal bounds are defined to be the rectangle: x = 0, y = 0, width = (child width - view port width), height = (child height - view port height). This is a convenience method which interfaces with the Adjustable objects which represent the state of the scrollbars.

Parameters:

p - the Point representing the position to scroll to

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getScrollPosition

public Point getScrollPosition()

Suppressed: Returns the current x,y position within the child which is displayed at the 0,0 location of the scrolled panel's view port. This is a convenience method which interfaces with the adjustable objects which represent the state of the scrollbars.

Returns:

the coordinate position for the current scroll position

Throws:

NullPointerException - if the scrollpane does not contain a child

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setLayout

public final void setLayout(LayoutManager mgr)

Suppressed: Sets the layout manager for this container. This method is overridden to prevent the layout mgr from being set.

Overrides:

setLayout in class Container

Parameters:

mgr - the specified layout manager

See Also:

Container.doLayout(), Container.getLayout()

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doLayout

public void doLayout()

Suppressed: Lays out this container by resizing its child to its preferred size. If the new preferred size of the child causes the current scroll position to be invalid, the scroll position is set to the closest valid position.

Overrides:

doLayout in class Container

See Also:

Component.validate()

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calculateChildSize

Dimension calculateChildSize()

Determine the size to allocate the child component. If the viewport area is bigger than the childs preferred size then the child is allocated enough to fill the viewport, otherwise the child is given it's preferred size.

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layout

public void layout()

Suppressed: @deprecated As of JDK version 1.1, replaced by doLayout().

Overrides:

layout in class Container

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printComponents

public void printComponents(Graphics g)

Suppressed: Prints the component in this scroll pane.

Overrides:

printComponents in class Container

Parameters:

g - the specified Graphics window

See Also:

Component.print(java.awt.Graphics), Component.printAll(java.awt.Graphics)

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addNotify

public void addNotify()

Suppressed: Creates the scroll pane's peer.

Overrides:

addNotify in class Container

See Also:

Component.isDisplayable(), Container.removeNotify()

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paramString

public String paramString()

Suppressed: Returns a string representing the state of this 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.

Overrides:

paramString in class Container

Returns:

the parameter string of this scroll pane

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autoProcessMouseWheel

void autoProcessMouseWheel(MouseWheelEvent e)

Overrides:

autoProcessMouseWheel in class Component

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processMouseWheelEvent

protected void processMouseWheelEvent(MouseWheelEvent e)

Process mouse wheel events that are delivered to this ScrollPane by scrolling an appropriate amount.

Note that if the event parameter is null the behavior is unspecified and may result in an exception.

Overrides:

processMouseWheelEvent in class Component

Parameters:

e - the mouse wheel event

Since:

1.4

See Also:

java.awt.event.MouseWheelEvent, java.awt.event.MouseWheelListener, Component.addMouseWheelListener(java.awt.event.MouseWheelListener), Component.enableEvents(long)

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eventTypeEnabled

protected boolean eventTypeEnabled(int type)

If wheel scrolling is enabled, we return true for MouseWheelEvents

Overrides:

eventTypeEnabled in class Component

Since:

1.4

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setWheelScrollingEnabled

public void setWheelScrollingEnabled(boolean handleWheel)

Suppressed: Enables/disables scrolling in response to movement of the mouse wheel. Wheel scrolling is enabled by default.

Parameters:

handleWheel - true if scrolling should be done automatically for a MouseWheelEvent, false otherwise.

Since:

1.4

See Also:

isWheelScrollingEnabled(), java.awt.event.MouseWheelEvent, java.awt.event.MouseWheelListener

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isWheelScrollingEnabled

public boolean isWheelScrollingEnabled()

Suppressed: Indicates whether or not scrolling will take place in response to the mouse wheel. Wheel scrolling is enabled by default.

Since:

1.4

See Also:

setWheelScrollingEnabled(boolean)

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writeObject

private void writeObject(ObjectOutputStream s)
 throws IOException

Writes default serializable fields to stream.

Parameters:

s - the ObjectOutputStream to write

IOException

See Also:

AWTEventMulticaster.save(java.io.ObjectOutputStream, java.lang.String, java.util.EventListener), Component.containerListenerK, Container.readObject(java.io.ObjectInputStream)

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readObject

private void readObject(ObjectInputStream s)
 throws ClassNotFoundException,
 IOException,
 HeadlessException

Reads default serializable fields to stream.

Parameters:

s - the ObjectInputStream to read

ClassNotFoundException

IOException

HeadlessException

See Also:

java.awt.GraphicsEnvironment#isHeadless

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getAccessibleContext

public AccessibleContext getAccessibleContext()

Suppressed: Gets the AccessibleContext associated with this ScrollPane. For scroll panes, the AccessibleContext takes the form of an AccessibleAWTScrollPane. A new AccessibleAWTScrollPane instance is created if necessary.

Specified by:

getAccessibleContext in interface Accessible

Overrides:

getAccessibleContext in class Component

Returns:

an AccessibleAWTScrollPane that serves as the AccessibleContext of this ScrollPane

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