Package com.google.gwt.user.client.ui

Class DockLayoutPanel

java.lang.Object
com.google.gwt.user.client.ui.UIObject
com.google.gwt.user.client.ui.Widget
com.google.gwt.user.client.ui.Panel
com.google.gwt.user.client.ui.ComplexPanel
com.google.gwt.user.client.ui.DockLayoutPanel
All Implemented Interfaces:
HasAttachHandlers, HasHandlers, EventListener, AnimatedLayout, HasVisibility, HasWidgets, HasWidgets.ForIsWidget, IndexedPanel, IndexedPanel.ForIsWidget, IsWidget, ProvidesResize, RequiresResize, Iterable<Widget>
Direct Known Subclasses:
SplitLayoutPanel
public class DockLayoutPanel extends ComplexPanel implements AnimatedLayout, RequiresResize, ProvidesResize
A panel that lays its child widgets out "docked" at its outer edges, and allows its last widget to take up the remaining space in its center.

This widget will only work in standards mode, which requires that the HTML page in which it is run have an explicit <!DOCTYPE> declaration.

Example

public class DockLayoutPanelExample implements EntryPoint {

  public void onModuleLoad() {
    // Attach five widgets to a DockLayoutPanel, one in each direction. Lay
    // them out in 'em' units.
    DockLayoutPanel p = new DockLayoutPanel(Unit.EM);
    p.addNorth(new HTML("north"), 2);
    p.addSouth(new HTML("south"), 2);
    p.addEast(new HTML("east"), 2);
    p.addWest(new HTML("west"), 2);
    p.add(new HTML("center"));

    // Attach the LayoutPanel to the RootLayoutPanel. The latter will listen for
    // resize events on the window to ensure that its children are informed of
    // possible size changes.
    RootLayoutPanel rp = RootLayoutPanel.get();
    rp.add(p);
  }
}

Use in UiBinder Templates

DockLayoutPanel elements in UiBinder templates lay out their children in elements tagged with the cardinal directions, and center:

<g:center>
<g:north>
<g:south>
<g:west>
<g:east>

Each child can hold only widget, and there can be only one <g:center>. However, there can be any number of the directional children.

(Note that the tags of the child elements are not capitalized. This is meant to signal that they are not runtime objects, and so cannot have a ui:field attribute.)

For example:

 <g:DockLayoutPanel unit='EM'>
   <g:north size='5'>
     <g:Label>Top</g:Label>
   </g:north>
   <g:center>
     <g:Label>Body</g:Label>
   </g:center>
   <g:west size='192'>
     <g:HTML>
       <ul>
         <li>Sidebar</li>
         <li>Sidebar</li>
         <li>Sidebar</li>
       </ul>
     </g:HTML>
   </g:west>
 </g:DockLayoutPanel>

  • Constructor Details

    • DockLayoutPanel

      public DockLayoutPanel(Style.Unit unit)
      Creates an empty dock panel.
      Parameters:
      unit - the unit to be used for layout

  • Method Details

    • add

      public void add(Widget widget)
      Adds a widget at the center of the dock. No further widgets may be added after this one.
      Specified by:
      add in interface HasWidgets
      Overrides:
      add in class Panel
      Parameters:
      widget - the widget to be added
      See Also:

    • addEast

      public void addEast(Widget widget, double size)
      Adds a widget to the east edge of the dock.
      Parameters:
      widget - the widget to be added
      size - the child widget's size

    • addEast

      public void addEast(IsWidget widget, double size)
      Overloaded version for IsWidget.
      See Also:

    • addLineEnd

      public void addLineEnd(Widget widget, double size)
      Adds a widget to the end of the line. In LTR mode, the widget is added to the east. In RTL mode, the widget is added to the west.
      Parameters:
      widget - the widget to be added
      size - the child widget's size

    • addLineStart

      public void addLineStart(Widget widget, double size)
      Adds a widget to the start of the line. In LTR mode, the widget is added to the west. In RTL mode, the widget is added to the east.
      Parameters:
      widget - the widget to be added
      size - the child widget's size

    • addNorth

      public void addNorth(Widget widget, double size)
      Adds a widget to the north edge of the dock.
      Parameters:
      widget - the widget to be added
      size - the child widget's size

    • addNorth

      public void addNorth(IsWidget widget, double size)
      Overloaded version for IsWidget.
      See Also:

    • addSouth

      public void addSouth(Widget widget, double size)
      Adds a widget to the south edge of the dock.
      Parameters:
      widget - the widget to be added
      size - the child widget's size

    • addSouth

      public void addSouth(IsWidget widget, double size)
      Overloaded version for IsWidget.
      See Also:

    • addWest

      public void addWest(Widget widget, double size)
      Adds a widget to the west edge of the dock.
      Parameters:
      widget - the widget to be added
      size - the child widget's size

    • addWest

      public void addWest(IsWidget widget, double size)
      Overloaded version for IsWidget.
      See Also:

    • animate

      public void animate(int duration)
      Description copied from interface: AnimatedLayout
      Layout children, animating over the specified period of time.
      Specified by:
      animate in interface AnimatedLayout
      Parameters:
      duration - the animation duration, in milliseconds

    • animate

      public void animate(int duration, Layout.AnimationCallback callback)
      Description copied from interface: AnimatedLayout
      Layout children, animating over the specified period of time.

      This method provides a callback that will be informed of animation updates. This can be used to create more complex animation effects.

      Specified by:
      animate in interface AnimatedLayout
      Parameters:
      duration - the animation duration, in milliseconds
      callback - the animation callback

    • forceLayout

      public void forceLayout()
      Description copied from interface: AnimatedLayout
      Layout children immediately.

      This is not normally necessary, unless you want to update child widgets' positions explicitly to create a starting point for a subsequent call to AnimatedLayout.animate(int).

      Specified by:
      forceLayout in interface AnimatedLayout
      See Also:

    • getWidgetContainerElement

      public Element getWidgetContainerElement(Widget child)
      Gets the container element wrapping the given child widget.
      Parameters:
      child -
      Returns:
      the widget's container element

    • getWidgetDirection

      public DockLayoutPanel.Direction getWidgetDirection(Widget child)
      Gets the layout direction of the given child widget.
      Parameters:
      child - the widget to be queried
      Returns:
      the widget's layout direction, or null if it is not a child of this panel
      Throws:
      AssertionError - if the widget is not a child and assertions are enabled

    • getWidgetSize

      public Double getWidgetSize(Widget child)
      Gets the layout size of the given child widget.
      Parameters:
      child - the widget to be queried
      Returns:
      the widget's layout size, or null if it is not a child of this panel
      Throws:
      AssertionError - if the widget is not a child and assertions are enabled

    • insertEast

      public void insertEast(Widget widget, double size, Widget before)
      Adds a widget to the east edge of the dock, inserting it before an existing widget.
      Parameters:
      widget - the widget to be added
      size - the child widget's size
      before - the widget before which to insert the new child, or null to append

    • insertLineEnd

      public void insertLineEnd(Widget widget, double size, Widget before)
      Adds a widget to the start of the line, inserting it before an existing widget. In LTR mode, the widget is added to the east. In RTL mode, the widget is added to the west.
      Parameters:
      widget - the widget to be added
      size - the child widget's size
      before - the widget before which to insert the new child, or null to append

    • insertLineStart

      public void insertLineStart(Widget widget, double size, Widget before)
      Adds a widget to the end of the line, inserting it before an existing widget. In LTR mode, the widget is added to the west. In RTL mode, the widget is added to the east.
      Parameters:
      widget - the widget to be added
      size - the child widget's size
      before - the widget before which to insert the new child, or null to append

    • insertNorth

      public void insertNorth(Widget widget, double size, Widget before)
      Adds a widget to the north edge of the dock, inserting it before an existing widget.
      Parameters:
      widget - the widget to be added
      size - the child widget's size
      before - the widget before which to insert the new child, or null to append

    • insertSouth

      public void insertSouth(Widget widget, double size, Widget before)
      Adds a widget to the south edge of the dock, inserting it before an existing widget.
      Parameters:
      widget - the widget to be added
      size - the child widget's size
      before - the widget before which to insert the new child, or null to append

    • insertWest

      public void insertWest(Widget widget, double size, Widget before)
      Adds a widget to the west edge of the dock, inserting it before an existing widget.
      Parameters:
      widget - the widget to be added
      size - the child widget's size
      before - the widget before which to insert the new child, or null to append

    • onResize

      public void onResize()
      Description copied from interface: RequiresResize
      This method must be called whenever the implementor's size has been modified.
      Specified by:
      onResize in interface RequiresResize

    • remove

      public boolean remove(Widget w)
      Description copied from class: Panel
      Removes a child widget.

      How to Override this Method

      There are several important things that must take place in the correct order to properly remove a Widget from a Panel. Not all of these steps will be relevant to every Panel, but all of the steps must be considered.

      1. Validate: Make sure this Panel is actually the parent of the child Widget; return false if it is not.
      2. Orphan: Call Panel.orphan(Widget) first while the child Widget is still attached.
      3. Physical Detach: Adjust the DOM to account for the removal of the child Widget. The Widget's Element must be physically removed from the DOM.
      4. Logical Detach: Update the Panel's state variables to reflect the removal of the child Widget. Example: the Widget is removed from the Panel's WidgetCollection.

      Specified by:
      remove in interface HasWidgets
      Overrides:
      remove in class ComplexPanel
      Parameters:
      w - the widget to be removed
      Returns:
      true if the child was present

    • setWidgetHidden

      public void setWidgetHidden(Widget widget, boolean hidden)
      Sets whether or not the given widget should be hidden.
      Parameters:
      widget - the widget to hide or display
      hidden - true to hide the widget, false to display it

    • setWidgetSize

      public void setWidgetSize(Widget widget, double size)
      Updates the size of the widget passed in as long as it is not the center widget and updates the layout of the dock.
      Parameters:
      widget - the widget that needs to update its size
      size - the size to update the widget to

    • getCenter

      protected Widget getCenter()

    • getCenterHeight

      protected double getCenterHeight()

    • getCenterWidth

      protected double getCenterWidth()

    • getResolvedDirection

      protected DockLayoutPanel.Direction getResolvedDirection(DockLayoutPanel.Direction direction)
      Resolve the specified direction based on the current locale. If the direction is DockLayoutPanel.Direction.LINE_START or DockLayoutPanel.Direction.LINE_END, the return value will be one of DockLayoutPanel.Direction.EAST or DockLayoutPanel.Direction.WEST depending on the RTL mode of the locale. For all other directions, the specified value is returned.
      Parameters:
      direction - the specified direction
      Returns:
      the locale

    • getUnit

      protected Style.Unit getUnit()

    • insert

      protected void insert(Widget widget, DockLayoutPanel.Direction direction, double size, Widget before)
      Adds a widget to the specified edge of the dock. If the widget is already a child of this panel, this method behaves as though remove(Widget) had already been called.
      Parameters:
      widget - the widget to be added
      direction - the widget's direction in the dock
      before - the widget before which to insert the new child, or null to append

    • onAttach

      protected void onAttach()
      Description copied from class: Widget

      This method is called when a widget is attached to the browser's document. To receive notification after a Widget has been added to the document, override the Widget.onLoad() method or use Widget.addAttachHandler(com.google.gwt.event.logical.shared.AttachEvent.Handler).

      It is strongly recommended that you override Widget.onLoad() or Widget.doAttachChildren() instead of this method to avoid inconsistencies between logical and physical attachment states.

      Subclasses that override this method must call super.onAttach() to ensure that the Widget has been attached to its underlying Element.

      Overrides:
      onAttach in class Widget
      See Also:

    • onDetach

      protected void onDetach()
      Description copied from class: Widget

      This method is called when a widget is detached from the browser's document. To receive notification before a Widget is removed from the document, override the Widget.onUnload() method or use Widget.addAttachHandler(com.google.gwt.event.logical.shared.AttachEvent.Handler).

      It is strongly recommended that you override Widget.onUnload() or Widget.doDetachChildren() instead of this method to avoid inconsistencies between logical and physical attachment states.

      Subclasses that override this method must call super.onDetach() to ensure that the Widget has been detached from the underlying Element. Failure to do so will result in application memory leaks due to circular references between DOM Elements and JavaScript objects.

      Overrides:
      onDetach in class Widget
      See Also:

    • assertIsChild

      void assertIsChild(Widget widget)