org.eclipse.swt.custom

Class StackLayout

java.lang.Object

org.eclipse.swt.widgets.Layout

org.eclipse.swt.custom.StackLayout

public class StackLayout
extends Layout

This Layout stacks all the controls one on top of the other and resizes all controls to have the same size and location. The control specified in topControl is visible and all other controls are not visible. Users must set the topControl value to flip between the visible items and then call layout() on the composite which has the StackLayout.

Here is an example which places ten buttons in a stack layout and flips between them:

 public static void main( String[] args ) {
   Display display = new Display();
   Shell shell = new Shell( display );
   shell.setLayout( new GridLayout() );
   final Composite parent = new Composite( shell, SWT.NONE );
   parent.setLayoutData( new GridData( GridData.FILL_BOTH ) );
   final StackLayout layout = new StackLayout();
   parent.setLayout( layout );
   final Button[] bArray = new Button[ 10 ];
   for( int i = 0; i < 10; i++ ) {
     bArray[ i ] = new Button( parent, SWT.PUSH );
     bArray[ i ].setText( "Button " + i );
   }
   layout.topControl = bArray[ 0 ];
   Button b = new Button( shell, SWT.PUSH );
   b.setText( "Show Next Button" );
   final int[] index = new int[ 1 ];
   b.addListener( SWT.Selection, new Listener() {
 
     public void handleEvent( Event e ) {
       index[ 0 ] = ( index[ 0 ] + 1 ) % 10;
       layout.topControl = bArray[ index[ 0 ] ];
       parent.layout();
     }
   } );
   shell.open();
   while( shell != null && !shell.isDisposed() ) {
     if( !display.readAndDispatch() )
       display.sleep();
   }
 }
 

Field Summary

Fields

Modifier and Type	Field and Description
int	marginHeight marginHeight specifies the number of pixels of vertical margin that will be placed along the top and bottom edges of the layout.
int	marginWidth marginWidth specifies the number of pixels of horizontal margin that will be placed along the left and right edges of the layout.
Control	topControl topControl the Control that is displayed at the top of the stack.

Constructor Summary

Constructors

Constructor and Description
StackLayout()

Method Summary

Modifier and Type	Method and Description
protected Point	computeSize(Composite composite, int wHint, int hHint, boolean flushCache) Computes and returns the size of the specified composite's client area according to this layout.
protected boolean	flushCache(Control control) Instruct the layout to flush any cached values associated with the control specified in the argument control.
protected void	layout(Composite composite, boolean flushCache) Lays out the children of the specified composite according to this layout.
java.lang.String	toString() Returns a string containing a concise, human-readable description of the receiver.

Methods inherited from class java.lang.Object

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

Field Detail

marginWidth

public int marginWidth

marginWidth specifies the number of pixels of horizontal margin that will be placed along the left and right edges of the layout. The default value is 0.

marginHeight

public int marginHeight

marginHeight specifies the number of pixels of vertical margin that will be placed along the top and bottom edges of the layout. The default value is 0.

topControl

public Control topControl

topControl the Control that is displayed at the top of the stack. All other controls that are children of the parent composite will not be visible.

Constructor Detail

StackLayout

public StackLayout()

Method Detail

computeSize

protected Point computeSize(Composite composite,
                            int wHint,
                            int hHint,
                            boolean flushCache)

Description copied from class: Layout

Computes and returns the size of the specified composite's client area according to this layout.

This method computes the size that the client area of the composite must be in order to position all children at their preferred size inside the composite according to the layout algorithm encoded by this layout.

When a width or height hint is supplied, it is used to constrain the result. For example, if a width hint is provided that is less than the width of the client area, the layout may choose to wrap and increase height, clip, overlap, or otherwise constrain the children.

Specified by:

computeSize in class Layout

Parameters:

composite - a composite widget using this layout

wHint - width (SWT.DEFAULT for preferred size)

hHint - height (SWT.DEFAULT for preferred size)

flushCache - true means flush cached layout values

Returns:

a point containing the computed size (width, height)

See Also:

Layout.layout(org.eclipse.swt.widgets.Composite, boolean), Control.getBorderWidth(), Control.getBounds(), Control.getSize(), Control.pack(boolean), "computeTrim, getClientArea for controls that implement them"

flushCache

protected boolean flushCache(Control control)

Description copied from class: Layout

Instruct the layout to flush any cached values associated with the control specified in the argument control.

Overrides:

flushCache in class Layout

Parameters:

control - a control managed by this layout

Returns:

true if the Layout has flushed all cached information associated with control

layout

protected void layout(Composite composite,
                      boolean flushCache)

Description copied from class: Layout

Lays out the children of the specified composite according to this layout.

This method positions and sizes the children of a composite using the layout algorithm encoded by this layout. Children of the composite are positioned in the client area of the composite. The position of the composite is not altered by this method.

When the flush cache hint is true, the layout is instructed to flush any cached values associated with the children. Typically, a layout will cache the preferred sizes of the children to avoid the expense of computing these values each time the widget is laid out.

When layout is triggered explicitly by the programmer the flush cache hint is true. When layout is triggered by a resize, either caused by the programmer or by the user, the hint is false.

Specified by:

layout in class Layout

Parameters:

composite - a composite widget using this layout

flushCache - true means flush cached layout values

toString

public java.lang.String toString()

Returns a string containing a concise, human-readable description of the receiver.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the layout