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Eclipse Platform
Release 3.5

org.eclipse.ui.forms.widgets
Class ColumnLayout

java.lang.Object
  extended by 

org.eclipse.swt.widgets.Layout
      extended by 
org.eclipse.ui.forms.widgets.ColumnLayout
All Implemented Interfaces:
ILayoutExtension

public final class ColumnLayout
extends Layout
implements ILayoutExtension

This layout manager arranges children of the composite parent in vertical columns. All the columns are identical size and children are stretched horizontally to fill the column width. The goal is to give layout some reasonable range of column numbers to allow it to handle various parent widths. That way, column number will drop to the lowest number in the range when width decreases, and grow up to the highest number in the range when allowed by the parent width.

In addition, the layout attempts to 'fill the space' equally i.e. to avoid large gaps at the and of the last column.

Child controls are layed out according to their 'natural' (preferred) size. For 'stretchy' controls that do not have natural preferred size, it is possible to set width and/or height hints using ColumnLayoutData objects.

Since:
3.0
See Also:
ColumnLayoutData

Field Summary
 int bottomMargin
          Bottom margin (default is 5).
 int horizontalSpacing
          Horizontal spacing between columns (default is 5).
 int leftMargin
          Left margin (default is 5).
 int maxNumColumns
          Maximum number of columns (default is 3).
 int minNumColumns
          Minimum number of columns (default is 1).
 int rightMargin
          Right margin (default is 5).
 int topMargin
          Top margin (default is 5).
 int verticalSpacing
          Vertical spacing between controls (default is 5).
 
Constructor Summary
ColumnLayout ()
          Creates a new instance of the column layout.
 
Method Summary
 int computeMaximumWidth ( Composite parent, boolean changed)
          Computes the maximum width of the parent.
 int computeMinimumWidth ( Composite parent, boolean changed)
          Computes the minimum width of the parent.
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  void layout ( Composite parent, boolean flushCache)
          Lays out the children of the specified composite according to this layout.
 
Methods inherited from class org.eclipse.swt.widgets. Layout
flushCache
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

minNumColumns

public int minNumColumns
Minimum number of columns (default is 1).


maxNumColumns

public int maxNumColumns
Maximum number of columns (default is 3).


horizontalSpacing

public int horizontalSpacing
Horizontal spacing between columns (default is 5).


verticalSpacing

public int verticalSpacing
Vertical spacing between controls (default is 5).


topMargin

public int topMargin
Top margin (default is 5).


leftMargin

public int leftMargin
Left margin (default is 5).


bottomMargin

public int bottomMargin
Bottom margin (default is 5).


rightMargin

public int rightMargin
Right margin (default is 5).

Constructor Detail

ColumnLayout

public ColumnLayout()
Creates a new instance of the column layout.

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"

layout

protected void layout(
Composite parent,
                      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:
parent - a composite widget using this layout
flushCache - true means flush cached layout values

computeMaximumWidth

public int computeMaximumWidth(
Composite parent,
                               boolean changed)
Description copied from interface: ILayoutExtension
Computes the maximum width of the parent. All widgets capable of word wrapping should return the length of the entire text with wrapping turned off.

Specified by:
computeMaximumWidth in interface ILayoutExtension
Parameters:
parent - the parent composite
changed - true if the cached information should be flushed, false otherwise.
Returns:
the maximum width of the parent composite

computeMinimumWidth

public int computeMinimumWidth(
Composite parent,
                               boolean changed)
Description copied from interface: ILayoutExtension
Computes the minimum width of the parent. All widgets capable of word wrapping should return the width of the longest word that cannot be broken any further.

Specified by:
computeMinimumWidth in interface ILayoutExtension
Parameters:
parent - the parent composite
changed - true if the cached information should be flushed, false otherwise.
Returns:
the minimum width of the parent composite

Eclipse Platform
Release 3.5

Guidelines for using Eclipse APIs.

Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.


 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire