ScrollPaneLayout
Class ScrollPaneLayout
- java.lang.Object
-
- javax.swing.ScrollPaneLayout
- All Implemented Interfaces:
- LayoutManager, Serializable, ScrollPaneConstants
- Direct Known Subclasses:
- ScrollPaneLayout.UIResource
public class ScrollPaneLayout extends Object implements LayoutManager, ScrollPaneConstants, 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™ has been added to the java.beans
package. Please see XMLEncoder
.
- See Also:
-
JScrollPane
,JViewport
Nested Classes
Modifier and Type | Class and Description |
---|---|
static class |
ScrollPaneLayout.UIResource The UI resource version of |
Fields
viewport
protected JViewport viewport
The scrollpane's viewport child. Default is an empty JViewport
.
vsb
protected JScrollBar vsb
The scrollpane's vertical scrollbar child. Default is a JScrollBar
.
hsb
protected JScrollBar hsb
The scrollpane's horizontal scrollbar child. Default is a JScrollBar
.
rowHead
protected JViewport rowHead
The row header child. Default is null
.
colHead
protected JViewport colHead
The column header child. Default is null
.
lowerLeft
protected Component lowerLeft
The component to display in the lower left corner. Default is null
.
lowerRight
protected Component lowerRight
The component to display in the lower right corner. Default is null
.
upperLeft
protected Component upperLeft
The component to display in the upper left corner. Default is null
.
upperRight
protected Component upperRight
The component to display in the upper right corner. Default is null
.
vsbPolicy
protected int vsbPolicy
The display policy for the vertical scrollbar. The default is ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED
.
This field is obsolete, please use the JScrollPane
field instead.
hsbPolicy
protected int hsbPolicy
The display policy for the horizontal scrollbar. The default is ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED
.
This field is obsolete, please use the JScrollPane
field instead.
Constructors
ScrollPaneLayout
public ScrollPaneLayout()
Methods
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 Component addSingletonComponent(Component oldC, 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
- theComponent
to replace -
newC
- theComponent
to add - Returns:
- the
newC
addLayoutComponent
public void addLayoutComponent(String s, Component c)
Adds the specified component to the layout. The layout is identified using one of:
- ScrollPaneConstants.VIEWPORT
- ScrollPaneConstants.VERTICAL_SCROLLBAR
- ScrollPaneConstants.HORIZONTAL_SCROLLBAR
- ScrollPaneConstants.ROW_HEADER
- ScrollPaneConstants.COLUMN_HEADER
- ScrollPaneConstants.LOWER_LEFT_CORNER
- ScrollPaneConstants.LOWER_RIGHT_CORNER
- ScrollPaneConstants.UPPER_LEFT_CORNER
- ScrollPaneConstants.UPPER_RIGHT_CORNER
- Specified by:
-
addLayoutComponent
in interfaceLayoutManager
- Parameters:
-
s
- the component identifier -
c
- the the component to be added - Throws:
-
IllegalArgumentException
- ifs
is an invalid key
removeLayoutComponent
public void removeLayoutComponent(Component c)
Removes the specified component from the layout.
- Specified by:
-
removeLayoutComponent
in interfaceLayoutManager
- Parameters:
-
c
- the component to remove
getVerticalScrollBarPolicy
public int getVerticalScrollBarPolicy()
Returns the vertical scrollbar-display policy.
- Returns:
- an integer giving the display policy
- See Also:
setVerticalScrollBarPolicy(int)
setVerticalScrollBarPolicy
public void setVerticalScrollBarPolicy(int x)
Sets the vertical scrollbar-display policy. The options are:
- ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED
- ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER
- ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS
JScrollPane
version of this method. It only exists for backwards compatibility with the Swing 1.0.2 (and earlier) versions of this class. - Parameters:
-
x
- an integer giving the display policy - Throws:
-
IllegalArgumentException
- ifx
is an invalid vertical scroll bar policy, as listed above
getHorizontalScrollBarPolicy
public int getHorizontalScrollBarPolicy()
Returns the horizontal scrollbar-display policy.
- Returns:
- an integer giving the display policy
- See Also:
setHorizontalScrollBarPolicy(int)
setHorizontalScrollBarPolicy
public void setHorizontalScrollBarPolicy(int x)
Sets the horizontal scrollbar-display policy. The options are:
- ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED
- ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER
- ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS
JScrollPane
version of this method. It only exists for backwards compatibility with the Swing 1.0.2 (and earlier) versions of this class. - Parameters:
-
x
- an int giving the display policy - Throws:
-
IllegalArgumentException
- ifx
is not a valid horizontal scrollbar policy, as listed above
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 Component getCorner(String key)
Returns the Component
at the specified corner.
- Parameters:
-
key
- theString
specifying the corner - Returns:
- the
Component
at the specified corner, as defined inScrollPaneConstants
; ifkey
is not one of the four corners,null
is returned - See Also:
JScrollPane.getCorner(java.lang.String)
preferredLayoutSize
public Dimension preferredLayoutSize(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 interfaceLayoutManager
- Parameters:
-
parent
- theContainer
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(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 interfaceLayoutManager
- Parameters:
-
parent
- theContainer
that will be laid out - Returns:
- a
Dimension
object specifying the minimum size - See Also:
LayoutManager.preferredLayoutSize(java.awt.Container)
layoutContainer
public void layoutContainer(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 interfaceLayoutManager
- Parameters:
-
parent
- theContainer
to lay out
getViewportBorderBounds
@Deprecated public Rectangle getViewportBorderBounds(JScrollPane scrollpane)
Deprecated. As of JDK version Swing1.1 replaced by JScrollPane.getViewportBorderBounds()
.
Returns the bounds of the border around the specified scroll pane's viewport.
- Returns:
- the size and position of the viewport border
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