Layout (GWT 2.7.0)

java.lang.Object
- com.google.gwt.layout.client.Layout

```
public class Layout
extends Object
```
Helper class for laying out a container element and its children.
This class is typically used by higher-level widgets to implement layout on their behalf. It is intended to wrap an element (usually a <div>), and lay its children out in a predictable fashion, automatically accounting for changes to the parent's size, and for all elements' margins, borders, and padding.

To use this class, create a container element (again, usually a <div>) and pass it to Layout(Element). Rather than attaching child elements directly to the element managed by this Layout, use the attachChild(Element) method. This will attach the child element and return a Layout.Layer object which is used to manage the child.

A separate Layout.Layer instance is associated with each child element. There is a set of methods available on this class to manipulate the child element's position and size. In order for changes to a layer to take effect, you must finally call one of layout() or layout(int). This allows many changes to different layers to be applied efficiently, and to be animated.

On most browsers, this is implemented using absolute positioning. It also contains extra logic to make IE6 work properly.

Example

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

NOTE: This class is still very new, and its interface may change without warning. Use at your own risk.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`Layout.Alignment` Used to specify the alignment of child elements within a layer.
`static interface`	`Layout.AnimationCallback` Callback interface used by `layout(int, AnimationCallback)` to provide updates on animation progress.
`class`	`Layout.Layer` This class is used to set the position and size of child elements.

Constructor Summary

Constructors
Constructor and Description

Layout(Element parent)
Constructs a new layout associated with the given parent element.

Constructors
Constructor and Description
`Layout(Element parent)` Constructs a new layout associated with the given parent element.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`assertIsChild(Element elem)` Asserts that the given child element is managed by this layout.
`Layout.Layer`	`attachChild(Element child)` Attaches a child element to this layout.
`Layout.Layer`	`attachChild(Element child, Element before)` Attaches a child element to this layout.
`Layout.Layer`	`attachChild(Element child, Element before, Object userObject)` Attaches a child element to this layout.
`Layout.Layer`	`attachChild(Element child, Object userObject)` Attaches a child element to this layout.
`void`	`fillParent()` Causes the parent element to fill its own parent.
`double`	`getUnitSize(Style.Unit unit, boolean vertical)` Returns the size of one unit, in pixels, in the context of this layout.
`void`	`layout()` Updates this layout's children immediately.
`void`	`layout(int duration)` Updates the layout by animating it over time.
`void`	`layout(int duration, Layout.AnimationCallback callback)` Updates the layout by animating it over time, with a callback on each frame of the animation, and upon completion.
`void`	`onAttach()` This method must be called when the parent element becomes attached to the document.
`void`	`onDetach()` This method must be called when the parent element becomes detached from the document.
`void`	`removeChild(Layout.Layer layer)` Removes a child element from this layout.

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, toString

- Constructor Detail
  - Layout
```
public Layout(Element parent)
```
    Constructs a new layout associated with the given parent element.
    
    Parameters:
    
    parent - the element to serve as the layout parent
- Method Detail
  - assertIsChild
```
public void assertIsChild(Element elem)
```
    Asserts that the given child element is managed by this layout.
    
    Parameters:
    
    elem - the element to be tested
  - attachChild
```
public Layout.Layer attachChild(Element child)
```
    Attaches a child element to this layout.
    This method will attach the child to the layout, removing it from its current parent element. Use the Layout.Layer it returns to manipulate the child.
    
    Parameters:
    
    child - the child to be attached
    
    Returns:
    
    the Layout.Layer associated with the element
  - attachChild
```
public Layout.Layer attachChild(Element child,
                                Element before)
```
    Attaches a child element to this layout.
    This method will attach the child to the layout, removing it from its current parent element. Use the Layout.Layer it returns to manipulate the child.
    
    Parameters:
    
    child - the child to be attached
    
    before - the child element before which to insert
    
    Returns:
    
    the Layout.Layer associated with the element
  - attachChild
```
public Layout.Layer attachChild(Element child,
                                Object userObject)
```
    Attaches a child element to this layout.
    This method will attach the child to the layout, removing it from its current parent element. Use the Layout.Layer it returns to manipulate the child.
    
    Parameters:
    
    child - the child to be attached
    
    userObject - an arbitrary object to be associated with this layer
    
    Returns:
    
    the Layout.Layer associated with the element
  - attachChild
```
public Layout.Layer attachChild(Element child,
                                Element before,
                                Object userObject)
```
    Attaches a child element to this layout.
    This method will attach the child to the layout, removing it from its current parent element. Use the Layout.Layer it returns to manipulate the child.
    
    Parameters:
    
    child - the child to be attached
    
    before - the child element before which to insert
    
    userObject - an arbitrary object to be associated with this layer
    
    Returns:
    
    the Layout.Layer associated with the element
  - fillParent
```
public void fillParent()
```
    Causes the parent element to fill its own parent.
    This is most useful for top-level layouts that need to follow the size of another element, such as the <body>.
  - getUnitSize
```
public double getUnitSize(Style.Unit unit,
                          boolean vertical)
```
    Returns the size of one unit, in pixels, in the context of this layout.
    This will work for any unit type, but be aware that certain unit types, such as Style.Unit.EM, and Style.Unit.EX, will return different values based upon the parent's associated font size. Style.Unit.PCT is dependent upon the parent's actual size, and the axis to be measured.
    
    Parameters:
    
    unit - the unit type to be measured
    
    vertical - whether the unit to be measured is on the vertical or horizontal axis (this matters only for Style.Unit.PCT)
    
    Returns:
    
    the unit size, in pixels
  - layout
```
public void layout()
```
    Updates this layout's children immediately. This method must be called after updating any of its children's layers.
  - layout
```
public void layout(int duration)
```
    Updates the layout by animating it over time.
    
    Parameters:
    
    duration - the duration of the animation
    
    See Also:
    
    layout(int, AnimationCallback)
  - layout
```
public void layout(int duration,
                   Layout.AnimationCallback callback)
```
    Updates the layout by animating it over time, with a callback on each frame of the animation, and upon completion.
    
    Parameters:
    
    duration - the duration of the animation
    
    callback - the animation callback
  - onAttach
```
public void onAttach()
```
    This method must be called when the parent element becomes attached to the document.
    
    See Also:
    
    onDetach()
  - onDetach
```
public void onDetach()
```
    This method must be called when the parent element becomes detached from the document.
    
    See Also:
    
    onAttach()
  - removeChild
```
public void removeChild(Layout.Layer layer)
```
    Removes a child element from this layout.
    
    Parameters:
    
    layer - the layer associated with the child to be removed

Class Layout

Example

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Layout

Method Detail

assertIsChild

attachChild

attachChild

attachChild

attachChild

fillParent

getUnitSize

layout

layout

layout

onAttach

onDetach

removeChild