com.sun.dtv.lwuit.layouts
Class GroupLayout

java.lang.Object
  com.sun.dtv.lwuit.layouts.Layout
      com.sun.dtv.lwuit.layouts.GroupLayout

public class GroupLayout
extends Layout

GroupLayout is a LayoutManager that hierarchically groups components to achieve common, and not so common, layouts. Grouping is done by instances of the Group class. GroupLayout supports two types of groups:

Sequential:	A sequential group positions its child elements sequentially, one after another.
Parallel:	A parallel group positions its child elements in the same space on top of each other. Parallel groups can also align the child elements along their baseline.

Each Group can contain any number of child groups, Components or gaps. GroupLayout treats each axis independently. That is, there is a group representing the horizontal axis, and a separate group representing the vertical axis. The horizontal group is responsible for setting the x and width of its contents, where as the vertical group is responsible for setting the y and height of its contents.

The following code builds a simple layout consisting of two labels in one column, followed by two textfields in the next column:

   Form panel = ...;
   GroupLayout layout = new GroupLayout(panel);
   panel.setLayout(layout);
   layout.setAutocreateGaps(true);
   layout.setAutocreateContainerGaps(true);
   GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup();
   hGroup.add(layout.createParallelGroup().add(label1).add(label2)).
          add(layout.createParallelGroup().add(tf1).add(tf2));
   layout.setHorizontalGroup(hGroup);
   GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup();
   vGroup.add(layout.createParallelGroup(GroupLayout.BASELINE).add(label1).add(tf1)).
          add(layout.createParallelGroup(GroupLayout.BASELINE).add(label2).add(tf2));
   layout.setVerticalGroup(vGroup);
 

This layout consists of the following:

• The horizontal axis consists of a sequential group containing two parallel groups. The first parallel group consists of the labels, with the second parallel group consisting of the text fields.
• The vertical axis similarly consists of a sequential group containing two parallel groups. The parallel groups align their contents along the baseline. The first parallel group consists of the first label and text field, and the second group consists of the second label and text field.

There are a couple of things to notice in this code:

• You need not explicitly add the components to the container, this is indirectly done by using one of the add methods.
• The various add methods of Groups return themselves. This allows for easy chaining of invocations. For example, group.add(label1).add(label2); is equivalent to group.add(label1);group.add(label2);.
• There are no public constructors for the Groups, instead use the create methods of GroupLayout.

GroupLayout offer the ability to automatically insert the appropriate gap between components. This can be turned on using the setAutocreateGaps() method. Similarly you can use the setAutocreateContainerGaps() method to insert gaps between the components and the container.

Nested Class Summary

class	GroupLayout.Group Group provides for commonality between the two types of operations supported by GroupLayout: laying out components one after another (SequentialGroup) or layout on top of each other (ParallelGroup).
class	GroupLayout.ParallelGroup A Group that lays out its elements on top of each other.
class	GroupLayout.SequentialGroup A Group that lays out its elements sequentially, one after another.
class	GroupLayout.Spring Spring consists of a range: min, pref and max a value some where in the middle of that and a location.

Field Summary

static int	BASELINE Possible alignment type.
static int	CENTER Possible alignment type.
static int	DEFAULT_SIZE Possible value for the add methods that takes a Component.
static int	EAST Compass-direction east (right).
static int	HORIZONTAL Possible argument when linking sizes of components.
static int	LEADING Possible alignment type.
static int	NORTH Compass-direction North (up).
static int	PREFERRED_SIZE Possible value for the add methods that takes a Component.
static int	SOUTH Compass-direction south (down).
static int	TRAILING Possible alignment type.
static int	VERTICAL Possible argument when linking sizes of components.
static int	WEST Compass-direction west (left).

Constructor Summary

GroupLayout(Container host)
Creates a GroupLayout for the specified JComponent.

Method Summary

GroupLayout.ParallelGroup	createBaselineGroup(boolean resizable, boolean anchorBaselineToTop) Creates and returns a ParallelGroup that aligns its elements along the baseline.
GroupLayout.ParallelGroup	createParallelGroup() Creates and returns a ParallelGroup with a LEADING alignment.
GroupLayout.ParallelGroup	createParallelGroup(int alignment) Creates and returns an ParallelGroup.
GroupLayout.ParallelGroup	createParallelGroup(int alignment, boolean resizable) Creates and returns an ParallelGroup.
GroupLayout.SequentialGroup	createSequentialGroup() Creates and returns a SequentialGroup.
boolean	getAutocreateContainerGaps() Returns whether or not gaps between the container and the first/last components should automatically be created.
boolean	getAutocreateGaps() Returns true if gaps between components are automatically be created.
boolean	getHonorsVisibility() Returns whether component visibility is considered when sizing and positioning components.
GroupLayout.Group	getHorizontalGroup() Returns the Group that is responsible for layout along the horizontal axis.
LayoutStyle	getLayoutStyle() Returns the LayoutStyle instance to use.
Dimension	getPreferredSize(Container parent) Returns the preferred size for the specified container.
GroupLayout.Group	getVerticalGroup() Returns the ParallelGroup that is responsible for layout along the vertical axis.
void	layoutContainer(Container parent) Lays out the specified container.
void	linkSize(Component[] components) Forces the set of components to have the same size.
void	linkSize(Component[] components, int axis) Forces the set of components to have the same size.
void	removeLayoutComponent(Component component) Notification that a Component has been removed from the parent container.
void	replace(Component existingComponent, Component newComponent) Removes an existing component replacing it with the specified component.
void	setAutocreateContainerGaps(boolean autocreatePadding) Sets whether or not gaps between the container and the first/last components should automatically be created.
void	setAutocreateGaps(boolean autocreatePadding) Sets whether or not a gap between components should automatically be created.
void	setHonorsVisibility(boolean honorsVisibility) Sets whether component visibility is considered when sizing and positioning components.
void	setHonorsVisibility(Component component, Boolean honorsVisibility) Sets whether the component's visibility is considered for sizing and positioning.
void	setHorizontalGroup(GroupLayout.Group group) Sets the Group that is responsible for layout along the horizontal axis.
void	setLayoutStyle(LayoutStyle layoutStyle) Sets the LayoutStyle this GroupLayout is to use.
void	setVerticalGroup(GroupLayout.Group group) Sets the Group that is responsible for layout along the vertical axis.
String	toString() Returns a textual description of this GroupLayout.

Methods inherited from class com.sun.dtv.lwuit.layouts.Layout

addLayoutComponent, getComponentConstraint, isOverlapSupported

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NORTH

public static final int NORTH

Compass-direction North (up).

See Also:

Constant Field Values

EAST

public static final int EAST

Compass-direction east (right).

See Also:

Constant Field Values

SOUTH

public static final int SOUTH

Compass-direction south (down).

See Also:

Constant Field Values

WEST

public static final int WEST

Compass-direction west (left).

See Also:

Constant Field Values

HORIZONTAL

public static final int HORIZONTAL

Possible argument when linking sizes of components. Specifies the the two component should share the same size along the horizontal axis.

See Also:

linkSize(Component[], int), Constant Field Values

VERTICAL

public static final int VERTICAL

Possible argument when linking sizes of components. Specifies the the two component should share the same size along the vertical axis.

See Also:

linkSize(Component[],int), Constant Field Values

LEADING

public static final int LEADING

Possible alignment type. Indicates the elements should be aligned to the origin. For the horizontal axis with a left to right orientation this means aligned to the left.

See Also:

createParallelGroup(int), Constant Field Values

TRAILING

public static final int TRAILING

Possible alignment type. Indicates the elements should be aligned to the end. For the horizontal axis with a left to right orientation this means aligned to the right.

See Also:

createParallelGroup(int), Constant Field Values

CENTER

public static final int CENTER

Possible alignment type. Indicates the elements should centered in the spaced provided.

See Also:

createParallelGroup(int), Constant Field Values

BASELINE

public static final int BASELINE

Possible alignment type. Indicates the elements should aligned along their baseline.

See Also:

createParallelGroup(int), Constant Field Values

DEFAULT_SIZE

public static final int DEFAULT_SIZE

Possible value for the add methods that takes a Component. Indicates the size from the component should be used.

See Also:

Constant Field Values

PREFERRED_SIZE

public static final int PREFERRED_SIZE

Possible value for the add methods that takes a Component. Indicates the preferred size should be used.

See Also:

Constant Field Values

Constructor Detail

GroupLayout

public GroupLayout(Container host)

Creates a GroupLayout for the specified JComponent.

Parameters:

host - the Container to layout

Throws:

IllegalArgumentException - if host is null

Method Detail

setHonorsVisibility

public void setHonorsVisibility(boolean honorsVisibility)

Sets whether component visibility is considered when sizing and positioning components. A value of true indicates that non-visible components should not be treated as part of the layout. A value of false indicates that components should be positioned and sized regardless of visibility.

A value of false is useful when the visibility of components is dynamically adjusted and you don't want surrounding components and the sizing to change.

The specified value is used for components that do not have an explicit visibility specified.

The default is true.

Parameters:

honorsVisibility - whether component visibility is considered when sizing and positioning components

See Also:

setHonorsVisibility(Component,Boolean), getHonorsVisibility()

getHonorsVisibility

public boolean getHonorsVisibility()

Returns whether component visibility is considered when sizing and positioning components.

Returns:

whether component visibility is considered when sizing and positioning components

See Also:

setHonorsVisibility(boolean), setHonorsVisibility(com.sun.dtv.lwuit.Component, java.lang.Boolean)

setHonorsVisibility

public void setHonorsVisibility(Component component,
                                Boolean honorsVisibility)

Sets whether the component's visibility is considered for sizing and positioning. A value of Boolean.TRUE indicates that if component is not visible it should not be treated as part of the layout. A value of false indicates that component is positioned and sized regardless of it's visibility. A value of null indicates the value specified by the single argument method setHonorsVisibility should be used.

If component is not a child of the Container this GroupLayout is managing, it will be added to the Container.

Parameters:

component - the component

honorsVisibility - whether component's visibility should be considered for sizing and positioning

Throws:

IllegalArgumentException - if component is null

See Also:

setHonorsVisibility(boolean), getHonorsVisibility()

toString

public String toString()

Returns a textual description of this GroupLayout. The return value is intended for debugging purposes only.

Overrides:

toString in class Object

Returns:

textual description of this GroupLayout

setAutocreateGaps

public void setAutocreateGaps(boolean autocreatePadding)

Sets whether or not a gap between components should automatically be created. For example, if this is true and you add two components to a SequentialGroup a gap between the two will automatically be created. The default is false.

Parameters:

autocreatePadding - whether or not to automatically created a gap between components and the container

See Also:

getAutocreateGaps()

getAutocreateGaps

public boolean getAutocreateGaps()

Returns true if gaps between components are automatically be created.

Returns:

true if gaps between components should automatically be created

See Also:

setAutocreateGaps(boolean)

setAutocreateContainerGaps

public void setAutocreateContainerGaps(boolean autocreatePadding)

Sets whether or not gaps between the container and the first/last components should automatically be created. The default is false.

Parameters:

autocreatePadding - whether or not to automatically create gaps between the container and first/last components.

See Also:

getAutocreateContainerGaps()

getAutocreateContainerGaps

public boolean getAutocreateContainerGaps()

Returns whether or not gaps between the container and the first/last components should automatically be created. The default is false.

Returns:

whether or not the gaps between the container and the first/last components should automatically be created

See Also:

setAutocreateContainerGaps(boolean)

setHorizontalGroup

public void setHorizontalGroup(GroupLayout.Group group)

Sets the Group that is responsible for layout along the horizontal axis.

Parameters:

group - Group responsible for layout along the horizontal axis

Throws:

IllegalArgumentException - if group is null

See Also:

getHorizontalGroup()

getHorizontalGroup

public GroupLayout.Group getHorizontalGroup()

Returns the Group that is responsible for layout along the horizontal axis.

Returns:

ParallelGroup responsible for layout along the horizontal axis.

See Also:

setHorizontalGroup(com.sun.dtv.lwuit.layouts.GroupLayout.Group)

setVerticalGroup

public void setVerticalGroup(GroupLayout.Group group)

Sets the Group that is responsible for layout along the vertical axis.

Parameters:

group - Group responsible for layout along the vertical axis.

Throws:

IllegalArgumentException - if group is null.

See Also:

getVerticalGroup()

getVerticalGroup

public GroupLayout.Group getVerticalGroup()

Returns the ParallelGroup that is responsible for layout along the vertical axis.

Returns:

ParallelGroup responsible for layout along the vertical axis.

See Also:

setVerticalGroup(com.sun.dtv.lwuit.layouts.GroupLayout.Group)

createSequentialGroup

public GroupLayout.SequentialGroup createSequentialGroup()

Creates and returns a SequentialGroup.

Returns:

a new SequentialGroup

createParallelGroup

public GroupLayout.ParallelGroup createParallelGroup()

Creates and returns a ParallelGroup with a LEADING alignment. This is a cover method for the more general createParallelGroup(int) method.

Returns:

a new ParallelGroup

See Also:

createParallelGroup(int)

createParallelGroup

public GroupLayout.ParallelGroup createParallelGroup(int alignment)

Creates and returns an ParallelGroup. The alignment specifies how children elements should be positioned when the the parallel group is given more space than necessary. For example, if a ParallelGroup with an alignment of TRAILING is given 100 pixels and a child only needs 50 pixels, the child will be positioned at the position 50.

Parameters:

alignment - alignment for the elements of the Group, one of LEADING, TRAILING, CENTER or BASELINE.

Returns:

a new ParallelGroup

Throws:

IllegalArgumentException - if alignment is not one of LEADING, TRAILING, CENTER or BASELINE

createParallelGroup

public GroupLayout.ParallelGroup createParallelGroup(int alignment,
                                                     boolean resizable)

Creates and returns an ParallelGroup. The alignment specifies how children elements should be positioned when the the parallel group is given more space than necessary. For example, if a ParallelGroup with an alignment of TRAILING is given 100 pixels and a child only needs 50 pixels, the child will be positioned at the position 50.

Parameters:

alignment - alignment for the elements of the Group, one of LEADING, TRAILING, CENTER or BASELINE.

resizable - whether or not the group is resizable. If the group is not resizable the min/max size will be the same as the preferred.

Returns:

a new ParallelGroup

Throws:

IllegalArgumentException - if alignment is not one of LEADING, TRAILING, CENTER or BASELINE

createBaselineGroup

public GroupLayout.ParallelGroup createBaselineGroup(boolean resizable,
                                                     boolean anchorBaselineToTop)

Creates and returns a ParallelGroup that aligns its elements along the baseline.

Parameters:

resizable - whether the group is resizable

anchorBaselineToTop - whether the baseline is anchored to the top or bottom of the group

Returns:

a ParallelGroup that aligns its elements along the baseline.

See Also:

createBaselineGroup(boolean, boolean), GroupLayout.ParallelGroup

linkSize

public void linkSize(Component[] components)

Forces the set of components to have the same size. This can be used multiple times to force any number of components to share the same size.

Linked Components are not be resizable.

Parameters:

components - Components to force to have same size.

Throws:

IllegalArgumentException - if components is null, or contains null.

linkSize

public void linkSize(Component[] components,
                     int axis)

Forces the set of components to have the same size. This can be used multiple times to force any number of components to share the same size.

Linked Components are not be resizable.

Parameters:

components - Components to force to have same size.

axis - Axis to bind size, one of HORIZONTAL, VERTICAL or HORIZONTAL | VERTICAL

Throws:

IllegalArgumentException - if components is null, or contains null.

IllegalArgumentException - if axis does not contain HORIZONTAL or VERTICAL

replace

public void replace(Component existingComponent,
                    Component newComponent)

Removes an existing component replacing it with the specified component.

Parameters:

existingComponent - the Component that should be removed and replaced with newComponent

newComponent - the Component to put in existingComponents place

Throws:

IllegalArgumentException - is either of the Components are null or if existingComponent is not being managed by this layout manager

setLayoutStyle

public void setLayoutStyle(LayoutStyle layoutStyle)

Sets the LayoutStyle this GroupLayout is to use. A value of null can be used to indicate the shared instance of LayoutStyle should be used.

Parameters:

layoutStyle - the LayoutStyle to use

See Also:

getLayoutStyle()

getLayoutStyle

public LayoutStyle getLayoutStyle()

Returns the LayoutStyle instance to use.

Returns:

the LayoutStyle instance to use

See Also:

setLayoutStyle(com.sun.dtv.lwuit.layouts.LayoutStyle)

removeLayoutComponent

public void removeLayoutComponent(Component component)

Notification that a Component has been removed from the parent container. You should not invoke this method directly, instead invoke removeComponent on the parent Container.

Overrides:

removeLayoutComponent in class Layout

Parameters:

component - the component to be removed

See Also:

Container.removeComponent(com.sun.dtv.lwuit.Component)

getPreferredSize

public Dimension getPreferredSize(Container parent)

Returns the preferred size for the specified container.

Specified by:

getPreferredSize in class Layout

Parameters:

parent - the container to return size for

Returns:

the preferred size

Throws:

IllegalArgumentException - if parent is not the same Container that this was created with

IllegalStateException - if any of the components added to this layout are not in both a horizontal and vertical group

See Also:

Component.getPreferredSize()

layoutContainer

public void layoutContainer(Container parent)

Lays out the specified container.

Specified by:

layoutContainer in class Layout

Parameters:

parent - the container to be laid out

Throws:

IllegalStateException - if any of the components added to this layout are not in both a horizontal and vertical group