javax.swing
Class ScrollPaneLayout

java.lang.Object
  javax.swing.ScrollPaneLayout

All Implemented Interfaces:

java.awt.LayoutManager, ScrollPaneConstants, java.io.Serializable

public class ScrollPaneLayout

extends java.lang.Object

implements java.awt.LayoutManager, ScrollPaneConstants, java.io.Serializable

The layout manager used by JScrollPane. JScrollPaneLayout is responsible for nine components: a viewport, two scrollbars, a row header, a column header, and four "corner" components.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans^TM has been added to the java.beans package. Please see java.beans.XMLEncoder.

See Also:

JScrollPane, JViewport

Field Summary

protected JViewport	colHead The column header child.
protected JScrollBar	hsb The scrollpane's horizontal scrollbar child.
protected java.awt.Component	lowerLeft The component to display in the lower left corner.
protected java.awt.Component	lowerRight The component to display in the lower right corner.
protected JViewport	rowHead The row header child.
protected java.awt.Component	upperLeft The component to display in the upper left corner.
protected java.awt.Component	upperRight The component to display in the upper right corner.
protected JViewport	viewport The scrollpane's viewport child.
protected JScrollBar	vsb The scrollpane's vertical scrollbar child.

Fields inherited from interface javax.swing.ScrollPaneConstants

COLUMN_HEADER, HORIZONTAL_SCROLLBAR, HORIZONTAL_SCROLLBAR_ALWAYS, HORIZONTAL_SCROLLBAR_AS_NEEDED, HORIZONTAL_SCROLLBAR_NEVER, HORIZONTAL_SCROLLBAR_POLICY, LOWER_LEADING_CORNER, LOWER_LEFT_CORNER, LOWER_RIGHT_CORNER, LOWER_TRAILING_CORNER, ROW_HEADER, UPPER_LEADING_CORNER, UPPER_LEFT_CORNER, UPPER_RIGHT_CORNER, UPPER_TRAILING_CORNER, VERTICAL_SCROLLBAR, VERTICAL_SCROLLBAR_ALWAYS, VERTICAL_SCROLLBAR_AS_NEEDED, VERTICAL_SCROLLBAR_NEVER, VERTICAL_SCROLLBAR_POLICY, VIEWPORT

Constructor Summary

ScrollPaneLayout()
The display policy for the horizontal scrollbar.

Method Summary

void	addLayoutComponent(java.lang.String s, java.awt.Component c) Adds the specified component to the layout.
protected java.awt.Component	addSingletonComponent(java.awt.Component oldC, java.awt.Component newC) Removes an existing component.
JViewport	getColumnHeader() Returns the JViewport object that is the column header.
java.awt.Component	getCorner(java.lang.String key) Returns the Component at the specified corner.
JScrollBar	getHorizontalScrollBar() Returns the JScrollBar object that handles horizontal scrolling.
JViewport	getRowHeader() Returns the JViewport object that is the row header.
JScrollBar	getVerticalScrollBar() Returns the JScrollBar object that handles vertical scrolling.
JViewport	getViewport() Returns the JViewport object that displays the scrollable contents.
void	layoutContainer(java.awt.Container parent) Lays out the scrollpane.
Dimension	minimumLayoutSize(java.awt.Container parent) The minimum size of a ScrollPane is the size of the insets plus minimum size of the viewport, plus the scrollpane's viewportBorder insets, plus the minimum size of the visible headers, plus the minimum size of the scrollbars whose displayPolicy isn't NEVER.
Dimension	preferredLayoutSize(java.awt.Container parent) The preferred size of a ScrollPane is the size of the insets, plus the preferred size of the viewport, plus the preferred size of the visible headers, plus the preferred size of the scrollbars that will appear given the current view and the current scrollbar displayPolicies.
void	removeLayoutComponent(java.awt.Component c) Removes the specified component from the layout.
void	syncWithScrollPane(JScrollPane sp) This method is invoked after the ScrollPaneLayout is set as the LayoutManager of a JScrollPane.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

viewport

protected JViewport viewport

The scrollpane's viewport child. Default is an empty JViewport.

See Also:

JScrollPane.setViewport(javax.swing.JViewport)

vsb

protected JScrollBar vsb

The scrollpane's vertical scrollbar child. Default is a JScrollBar.

See Also:

JScrollPane.setVerticalScrollBar(javax.swing.JScrollBar)

hsb

protected JScrollBar hsb

The scrollpane's horizontal scrollbar child. Default is a JScrollBar.

See Also:

JScrollPane.setHorizontalScrollBar(javax.swing.JScrollBar)

rowHead

protected JViewport rowHead

The row header child. Default is null.

See Also:

JScrollPane.setRowHeader(javax.swing.JViewport)

colHead

protected JViewport colHead

The column header child. Default is null.

See Also:

JScrollPane.setColumnHeader(javax.swing.JViewport)

lowerLeft

protected java.awt.Component lowerLeft

The component to display in the lower left corner. Default is null.

See Also:

JScrollPane.setCorner(java.lang.String, java.awt.Component)

lowerRight

protected java.awt.Component lowerRight

The component to display in the lower right corner. Default is null.

See Also:

JScrollPane.setCorner(java.lang.String, java.awt.Component)

upperLeft

protected java.awt.Component upperLeft

The component to display in the upper left corner. Default is null.

See Also:

JScrollPane.setCorner(java.lang.String, java.awt.Component)

upperRight

protected java.awt.Component upperRight

The component to display in the upper right corner. Default is null.

See Also:

JScrollPane.setCorner(java.lang.String, java.awt.Component)

Constructor Detail

ScrollPaneLayout

public ScrollPaneLayout()

The display policy for the horizontal scrollbar. The default is JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED.

This field is obsolete, please use the JScrollPane field instead.

See Also:

JScrollPane.setHorizontalScrollBarPolicy(int)

Method Detail

syncWithScrollPane

public void syncWithScrollPane(JScrollPane sp)

This method is invoked after the ScrollPaneLayout is set as the LayoutManager of a JScrollPane. It initializes all of the internal fields that are ordinarily set by addLayoutComponent. For example:

 ScrollPaneLayout mySPLayout = new ScrollPanelLayout() {
     public void layoutContainer(Container p) {
         super.layoutContainer(p);
         // do some extra work here ...
     }
 };
 scrollpane.setLayout(mySPLayout):
 

addSingletonComponent

protected java.awt.Component addSingletonComponent(java.awt.Component oldC,
                                                   java.awt.Component newC)

Removes an existing component. When a new component, such as the left corner, or vertical scrollbar, is added, the old one, if it exists, must be removed.

This method returns newC. If oldC is not equal to newC and is non-null, it will be removed from its parent.

Parameters:

oldC - the Component to replace

newC - the Component to add

Returns:

the newC

addLayoutComponent

public void addLayoutComponent(java.lang.String s,
                               java.awt.Component c)

Adds the specified component to the layout. The layout is identified using one of:

• JScrollPane.VIEWPORT
• JScrollPane.VERTICAL_SCROLLBAR
• JScrollPane.HORIZONTAL_SCROLLBAR
• JScrollPane.ROW_HEADER
• JScrollPane.COLUMN_HEADER
• JScrollPane.LOWER_LEFT_CORNER
• JScrollPane.LOWER_RIGHT_CORNER
• JScrollPane.UPPER_LEFT_CORNER
• JScrollPane.UPPER_RIGHT_CORNER

Specified by:

addLayoutComponent in interface java.awt.LayoutManager

Parameters:

s - the component identifier

c - the the component to be added

Throws:

java.lang.IllegalArgumentException - if s is an invalid key

removeLayoutComponent

public void removeLayoutComponent(java.awt.Component c)

Removes the specified component from the layout.

Specified by:

removeLayoutComponent in interface java.awt.LayoutManager

Parameters:

c - the component to remove

getViewport

public JViewport getViewport()

Returns the JViewport object that displays the scrollable contents.

Returns:

the JViewport object that displays the scrollable contents

See Also:

JScrollPane.getViewport()

getHorizontalScrollBar

public JScrollBar getHorizontalScrollBar()

Returns the JScrollBar object that handles horizontal scrolling.

Returns:

the JScrollBar object that handles horizontal scrolling

See Also:

JScrollPane.getHorizontalScrollBar()

getVerticalScrollBar

public JScrollBar getVerticalScrollBar()

Returns the JScrollBar object that handles vertical scrolling.

Returns:

the JScrollBar object that handles vertical scrolling

See Also:

JScrollPane.getVerticalScrollBar()

getRowHeader

public JViewport getRowHeader()

Returns the JViewport object that is the row header.

Returns:

the JViewport object that is the row header

See Also:

JScrollPane.getRowHeader()

getColumnHeader

public JViewport getColumnHeader()

Returns the JViewport object that is the column header.

Returns:

the JViewport object that is the column header

See Also:

JScrollPane.getColumnHeader()

getCorner

public java.awt.Component getCorner(java.lang.String key)

Returns the Component at the specified corner.

Parameters:

key - the String specifying the corner

Returns:

the Component at the specified corner, as defined in ScrollPaneConstants; if key is not one of the four corners, null is returned

See Also:

JScrollPane.getCorner(java.lang.String)

preferredLayoutSize

public Dimension preferredLayoutSize(java.awt.Container parent)

The preferred size of a ScrollPane is the size of the insets, plus the preferred size of the viewport, plus the preferred size of the visible headers, plus the preferred size of the scrollbars that will appear given the current view and the current scrollbar displayPolicies.

Note that the rowHeader is calculated as part of the preferred width and the colHeader is calculated as part of the preferred size.

Specified by:

preferredLayoutSize in interface java.awt.LayoutManager

Parameters:

parent - the Container that will be laid out

Returns:

a Dimension object specifying the preferred size of the viewport and any scrollbars

See Also:

ViewportLayout, LayoutManager

minimumLayoutSize

public Dimension minimumLayoutSize(java.awt.Container parent)

The minimum size of a ScrollPane is the size of the insets plus minimum size of the viewport, plus the scrollpane's viewportBorder insets, plus the minimum size of the visible headers, plus the minimum size of the scrollbars whose displayPolicy isn't NEVER.

Specified by:

minimumLayoutSize in interface java.awt.LayoutManager

Parameters:

parent - the Container that will be laid out

Returns:

a Dimension object specifying the minimum size

layoutContainer

public void layoutContainer(java.awt.Container parent)

Lays out the scrollpane. The positioning of components depends on the following constraints:

• The row header, if present and visible, gets its preferred width and the viewport's height.
• The column header, if present and visible, gets its preferred height and the viewport's width.
• If a vertical scrollbar is needed, i.e. if the viewport's extent height is smaller than its view height or if the displayPolicy is ALWAYS, it's treated like the row header with respect to its dimensions and is made visible.
• If a horizontal scrollbar is needed, it is treated like the column header (see the paragraph above regarding the vertical scrollbar).
• If the scrollpane has a non-null viewportBorder, then space is allocated for that.
• The viewport gets the space available after accounting for the previous constraints.
• The corner components, if provided, are aligned with the ends of the scrollbars and headers. If there is a vertical scrollbar, the right corners appear; if there is a horizontal scrollbar, the lower corners appear; a row header gets left corners, and a column header gets upper corners.

Specified by:

layoutContainer in interface java.awt.LayoutManager

Parameters:

parent - the Container to lay out