Module java.desktop
Package javax.swing

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.

Since:
1.2
See Also:
JScrollPane, JViewport

  • Field Details

  • Constructor Details

    • ScrollPaneLayout

      public ScrollPaneLayout()
      Constructs a ScrollPaneLayout.

  • Method Details

    • 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):
      Parameters:
      sp - an instance of the JScrollPane

    • 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 - the Component to replace
      newC - the Component 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 interface LayoutManager
      Parameters:
      s - the component identifier
      c - the component to be added
      Throws:
      IllegalArgumentException - if s is an invalid key

    • removeLayoutComponent

      public void removeLayoutComponent​(Component c)
      Removes the specified component from the layout.
      Specified by:
      removeLayoutComponent in interface LayoutManager
      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
      Note: Applications should use the 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 - if x 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
      Note: Applications should use the 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 - if x 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 - 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​(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 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​(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 LayoutManager
      Parameters:
      parent - the Container 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 interface LayoutManager
      Parameters:
      parent - the Container 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.
      Parameters:
      scrollpane - an instance of the JScrollPane
      Returns:
      the size and position of the viewport border