org.eclipse.swt.widgets
Class Layout

java.lang.Object
  |
  +--org.eclipse.swt.widgets.Layout

Direct Known Subclasses:

FillLayout, FormLayout, GridLayout, PageBook.PageBookLayout, RowLayout, StackLayout, TableLayout, WizardDialog.PageContainerFillLayout

public abstract class Layout

extends Object

A layout controls the position and size of the children of a composite widget. This class is the abstract base class for layouts.

Constructor Summary

Layout()

Method Summary

protected abstract 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 abstract void	layout(Composite composite, boolean flushCache) Lays out the children of the specified composite according to this layout.

Methods inherited from class java.lang.Object

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

Constructor Detail

Layout

public Layout()

Method Detail

computeSize

protected abstract 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.

This method computes the minimum size that the client area of the composite must be in order to position all children at their minimum 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 minimum width of the client area, the layout may choose to wrap and increase height, clip, overlap, or otherwise constrain the children.

Parameters:

composite - a composite widget using this layout

wHint - width (SWT.DEFAULT for minimum)

hHint - height (SWT.DEFAULT for minimum)

flushCache - true means flush cached layout values

Returns:

a point containing the computed size (width, height)

See Also:

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

layout

protected abstract void layout(Composite composite,
                               boolean flushCache)

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 layed 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.

Parameters:

composite - a composite widget using this layout

flushCache - true means flush cached layout values