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## com.google.gwt.user.client.ui
Class LayoutPanel

    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.LayoutPanel

All Implemented Interfaces:
  HasHandlers, EventListener, AnimatedLayout, HasWidgets, IndexedPanel, ProvidesResize, RequiresResize, java.lang.Iterable<Widget>

Direct Known Subclasses:
  RootLayoutPanel

    public class LayoutPanel

extends ComplexPanel
implements AnimatedLayout, RequiresResize, ProvidesResize

A panel that lays its children out in arbitrary `layers` using the `Layout` class.

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 LayoutPanelExample implements EntryPoint {

>       public void onModuleLoad() {
>         // Attach two child widgets to a LayoutPanel, laying them out horizontally,
>         // splitting at 50%.
>         Widget childOne = new HTML("left"), childTwo = new HTML("right");
>         LayoutPanel p = new LayoutPanel();
>         p.add(childOne);
>         p.add(childTwo);

>         p.setWidgetLeftWidth(childOne, 0, PCT, 50, PCT);
>         p.setWidgetRightWidth(childTwo, 0, PCT, 50, PCT);

>         // 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

LayoutPanel elements in `UiBinder` templates lay out their children with arbitrary constraints, using <g:layer> elements. Each layer may have any of the following constraint attributes specified as CSS length attributes: `left`, `top`, `right`, `bottom`, `width` , and `height`.

Precisely zero or two constraints are required for each axis (horizontal and vertial). Specifying no constraints implies that the child should fill that axis completely.

The valid sets of horizontal constraints are:

(none)
  Fill the parent's horizontal axis
left, width
  Fixed width, positioned from parent's left edge
right, width
  Fixed width, positioned from parent's right edge
left, right
  Width implied by fixed distance from parent's left and right edges

The valid sets of vertical constraints are:

(none)
  Fill the parent's vertical axis
top, height
  Fixed height, positioned from parent's top edge
bottom, height
  Fixed height, positioned from parent's bottom edge
top, bottom
  Height implied by fixed distance from parent's top and bottom edges

The values of constraint attributes can be any valid CSS length, such as `1px`, `3em`, or `0` (zero lengths require no units).

For example:

     <g:LayoutPanel>
       <!-- No constraints causes the layer to fill the parent -->
       <g:layer>
         <g:Label>Lorem ipsum...</g:Label>
       </g:layer>
       <!-- Position horizontally 25% from each edge;
            Vertically 4px from the top and 10em tall. -->
       <g:layer left='25%' right='25%' top='4px' height='10em'>
         <g:Label>Header</g:Label>
       </g:layer>
     </g:LayoutPanel>

Nested Class Summary

Nested classes/interfaces inherited from class com.google.gwt.user.client.ui.UIObject
`UIObject.DebugIdImpl, UIObject.DebugIdImplEnabled`

Field Summary

Fields inherited from class com.google.gwt.user.client.ui.UIObject
`DEBUG_ID_PREFIX`

Constructor Summary
`LayoutPanel()` Creates an empty layout panel.

Method Summary
`void` | `add(Widget widget)` Adds a widget to this panel.
`void` | `animate(int duration)` Layout children, animating over the specified period of time.
`void` | `animate(int duration, com.google.gwt.layout.client.Layout.AnimationCallback callback)` Layout children, animating over the specified period of time.
`void` | `forceLayout()` Layout children immediately.
`Element` | `getWidgetContainerElement(Widget child)` Gets the container element wrapping the given child widget.
`void` | `insert(Widget widget, int beforeIndex)` Inserts a widget before the specified index.
`protected void` | `onLoad()` A Panel's onLoad method will be called after all of its children are attached.
`void` | `onResize()` This method must be called whenever the implementor's size has been modified.
`protected void` | `onUnload()` A Panel's onUnload method will be called before its children become detached themselves.
`boolean` | `remove(Widget w)` Removes a child widget.
`void` | `setWidgetBottomHeight(Widget child, double bottom, Style.Unit bottomUnit, double height, Style.Unit heightUnit)` Sets the child widget's bottom and height values.
`void` | `setWidgetHorizontalPosition(Widget child, com.google.gwt.layout.client.Layout.Alignment position)` Sets the child widget's horizontal position within its layer.
`void` | `setWidgetLeftRight(Widget child, double left, Style.Unit leftUnit, double right, Style.Unit rightUnit)` Sets the child widget's left and right values.
`void` | `setWidgetLeftWidth(Widget child, double left, Style.Unit leftUnit, double width, Style.Unit widthUnit)` Sets the child widget's left and width values.
`void` | `setWidgetRightWidth(Widget child, double right, Style.Unit rightUnit, double width, Style.Unit widthUnit)` Sets the child widget's right and width values.
`void` | `setWidgetTopBottom(Widget child, double top, Style.Unit topUnit, double bottom, Style.Unit bottomUnit)` Sets the child widget's top and bottom values.
`void` | `setWidgetTopHeight(Widget child, double top, Style.Unit topUnit, double height, Style.Unit heightUnit)` Sets the child widget's top and height values.
`void` | `setWidgetVerticalPosition(Widget child, com.google.gwt.layout.client.Layout.Alignment position)` Sets the child widget's vertical position within its layer.

Methods inherited from class com.google.gwt.user.client.ui.ComplexPanel
`add, adjustIndex, checkIndexBoundsForAccess, checkIndexBoundsForInsertion, getChildren, getWidget, getWidgetCount, getWidgetIndex, insert, insert, iterator, remove`

Methods inherited from class com.google.gwt.user.client.ui.Panel
`adopt, adopt, clear, disown, doAttachChildren, doDetachChildren, orphan`

Methods inherited from class com.google.gwt.user.client.ui.Widget
`addDomHandler, addHandler, delegateEvent, fireEvent, getHandlerCount, getLayoutData, getParent, isAttached, isOrWasAttached, onAttach, onBrowserEvent, onDetach, removeFromParent, setLayoutData, sinkEvents`

Methods inherited from class com.google.gwt.user.client.ui.UIObject
`addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, setElement, setElement, setHeight, setPixelSize, setSize, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, toString, unsinkEvents`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### LayoutPanel

    public LayoutPanel()

  Creates an empty layout panel.

Method Detail

### add

    public void add(Widget widget)

  Adds a widget to this panel.

  By default, each child will fill the panel. To build more interesting layouts, set child widgets' layout constraints using `#setWidgetLeftRight(Widget, double, Unit, double, Unit)` and related methods.

  Specified by:
    `add` in interface `HasWidgets`
  Overrides:
    `add` in class `Panel`
  Parameters:
    `widget` - the widget to be added
  See Also:
    `HasWidgets.add(Widget)`

### 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,
                        com.google.gwt.layout.client.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:
    `AnimatedLayout.animate(int)`, `#animate(int, AnimationCallback)`

### getWidgetContainerElement

    public Element getWidgetContainerElement(Widget child)

  Gets the container element wrapping the given child widget.

  Parameters:
    `child` -
  Returns:
    the widget's container element

### insert

    public void insert(Widget widget,
                       int beforeIndex)

  Inserts a widget before the specified index.

  By default, each child will fill the panel. To build more interesting layouts, set child widgets' layout constraints using `#setWidgetLeftRight(Widget, double, Unit, double, Unit)` and related methods.

  Inserting a widget in this way has no effect on the DOM structure, but can be useful for other panels that wrap LayoutPanel to maintain insertion order.

  Parameters:
    `widget` - the widget to be inserted
    `beforeIndex` - the index before which it will be inserted
  Throws:
    `java.lang.IndexOutOfBoundsException` - if `beforeIndex` is out of range

### 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

### setWidgetBottomHeight

    public void setWidgetBottomHeight(Widget child,
                                      double bottom,
                                      Style.Unit bottomUnit,
                                      double height,
                                      Style.Unit heightUnit)

  Sets the child widget's bottom and height values.

  Parameters:
    `child` -
    `bottom` -
    `bottomUnit` -
    `height` -
    `heightUnit` -

### setWidgetHorizontalPosition

    public void setWidgetHorizontalPosition(Widget child,
                                            com.google.gwt.layout.client.Layout.Alignment position)

  Sets the child widget's horizontal position within its layer.

  Parameters:
    `child` -
    `position` -

### setWidgetLeftRight

    public void setWidgetLeftRight(Widget child,
                                   double left,
                                   Style.Unit leftUnit,
                                   double right,
                                   Style.Unit rightUnit)

  Sets the child widget's left and right values.

  Parameters:
    `child` -
    `left` -
    `leftUnit` -
    `right` -
    `rightUnit` -

### setWidgetLeftWidth

    public void setWidgetLeftWidth(Widget child,
                                   double left,
                                   Style.Unit leftUnit,
                                   double width,
                                   Style.Unit widthUnit)

  Sets the child widget's left and width values.

  Parameters:
    `child` -
    `left` -
    `leftUnit` -
    `width` -
    `widthUnit` -

### setWidgetRightWidth

    public void setWidgetRightWidth(Widget child,
                                    double right,
                                    Style.Unit rightUnit,
                                    double width,
                                    Style.Unit widthUnit)

  Sets the child widget's right and width values.

  Parameters:
    `child` -
    `right` -
    `rightUnit` -
    `width` -
    `widthUnit` -

### setWidgetTopBottom

    public void setWidgetTopBottom(Widget child,
                                   double top,
                                   Style.Unit topUnit,
                                   double bottom,
                                   Style.Unit bottomUnit)

  Sets the child widget's top and bottom values.

  Parameters:
    `child` -
    `top` -
    `topUnit` -
    `bottom` -
    `bottomUnit` -

### setWidgetTopHeight

    public void setWidgetTopHeight(Widget child,
                                   double top,
                                   Style.Unit topUnit,
                                   double height,
                                   Style.Unit heightUnit)

  Sets the child widget's top and height values.

  Parameters:
    `child` -
    `top` -
    `topUnit` -
    `height` -
    `heightUnit` -

### setWidgetVerticalPosition

    public void setWidgetVerticalPosition(Widget child,
                                          com.google.gwt.layout.client.Layout.Alignment position)

  Sets the child widget's vertical position within its layer.

  Parameters:
    `child` -
    `position` -

### onLoad

    protected void onLoad()

  Description copied from class: `Panel`
  A Panel's onLoad method will be called after all of its children are attached.

  Overrides:
    `onLoad` in class `Panel`
  See Also:
    `Widget.onLoad()`

### onUnload

    protected void onUnload()

  Description copied from class: `Panel`
  A Panel's onUnload method will be called before its children become detached themselves.

  Overrides:
    `onUnload` in class `Panel`
  See Also:
    `Widget.onLoad()`

Overview | Package | Class | Tree | Deprecated | Index | Help
| GWT 2.0.3
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