Package org.eclipse.swt.layout

Class RowLayout

java.lang.Object

org.eclipse.swt.widgets.Layout

org.eclipse.swt.layout.RowLayout

public final class RowLayout
extends Layout

Instances of this class determine the size and position of the children of a Composite by placing them either in horizontal rows or vertical columns within the parent Composite.

RowLayout aligns all controls in one row if the type is set to horizontal, and one column if it is set to vertical. It has the ability to wrap, and provides configurable margins and spacing. RowLayout has a number of configuration fields. In addition, the height and width of each control in a RowLayout can be specified by setting a RowData object into the control using setLayoutData ().

The following example code creates a RowLayout, sets all of its fields to non-default values, and then sets it into a Shell.

                RowLayout rowLayout = new RowLayout();
                rowLayout.wrap = false;
                rowLayout.pack = false;
                rowLayout.justify = true;
                rowLayout.type = SWT.VERTICAL;
                rowLayout.marginLeft = 5;
                rowLayout.marginTop = 5;
                rowLayout.marginRight = 5;
                rowLayout.marginBottom = 5;
                rowLayout.spacing = 0;
                shell.setLayout(rowLayout);
 

If you are using the default field values, you only need one line of code:

                shell.setLayout(new RowLayout());
 

See Also:

• RowData
• RowLayout snippets
• SWT Example: LayoutExample
• Sample code and further information

Field Summary

Fields

Modifier and Type	Field	Description
boolean	center	center specifies whether the controls in a row should be centered vertically in each cell for horizontal layouts, or centered horizontally in each cell for vertical layouts.
boolean	fill	fill specifies whether the controls in a row should be all the same height for horizontal layouts, or the same width for vertical layouts.
boolean	justify	justify specifies whether the controls in a row should be fully justified, with any extra space placed between the controls.
int	marginBottom	marginBottom specifies the number of points of vertical margin that will be placed along the bottom edge of the layout.
int	marginHeight	marginHeight specifies the number of points of vertical margin that will be placed along the top and bottom edges of the layout.
int	marginLeft	marginLeft specifies the number of points of horizontal margin that will be placed along the left edge of the layout.
int	marginRight	marginRight specifies the number of points of horizontal margin that will be placed along the right edge of the layout.
int	marginTop	marginTop specifies the number of points of vertical margin that will be placed along the top edge of the layout.
int	marginWidth	marginWidth specifies the number of points of horizontal margin that will be placed along the left and right edges of the layout.
boolean	pack	pack specifies whether all controls in the layout take their preferred size.
int	spacing	spacing specifies the number of points between the edge of one cell and the edge of its neighbouring cell.
int	type	type specifies whether the layout places controls in rows or columns.
boolean	wrap	wrap specifies whether a control will be wrapped to the next row if there is insufficient space on the current row.

Constructor Summary

Constructors

Constructor	Description
RowLayout()	Constructs a new instance of this class with type HORIZONTAL.
RowLayout(int type)	Constructs a new instance of this class given the type.

Method Summary

Modifier and Type	Method	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.
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 Details

type

public int type

type specifies whether the layout places controls in rows or columns. The default value is HORIZONTAL. Possible values are:

• HORIZONTAL: Position the controls horizontally from left to right
• VERTICAL: Position the controls vertically from top to bottom

Since:

2.0

marginWidth

public int marginWidth

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

Since:

3.0

marginHeight

public int marginHeight

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

Since:

3.0

spacing

public int spacing

spacing specifies the number of points between the edge of one cell and the edge of its neighbouring cell. The default value is 3.

wrap

public boolean wrap

wrap specifies whether a control will be wrapped to the next row if there is insufficient space on the current row. The default value is true.

pack

public boolean pack

pack specifies whether all controls in the layout take their preferred size. If pack is false, all controls will have the same size which is the size required to accommodate the largest preferred height and the largest preferred width of all the controls in the layout. The default value is true.

fill

public boolean fill

fill specifies whether the controls in a row should be all the same height for horizontal layouts, or the same width for vertical layouts. The default value is false.

Since:

3.0

center

public boolean center

center specifies whether the controls in a row should be centered vertically in each cell for horizontal layouts, or centered horizontally in each cell for vertical layouts. The default value is false.

Since:

3.4

justify

public boolean justify

justify specifies whether the controls in a row should be fully justified, with any extra space placed between the controls. The default value is false.

marginLeft

public int marginLeft

marginLeft specifies the number of points of horizontal margin that will be placed along the left edge of the layout. The default value is 3.

marginTop

public int marginTop

marginTop specifies the number of points of vertical margin that will be placed along the top edge of the layout. The default value is 3.

marginRight

public int marginRight

marginRight specifies the number of points of horizontal margin that will be placed along the right edge of the layout. The default value is 3.

marginBottom

public int marginBottom

marginBottom specifies the number of points of vertical margin that will be placed along the bottom edge of the layout. The default value is 3.

Constructor Details

RowLayout

public RowLayout()

Constructs a new instance of this class with type HORIZONTAL.

RowLayout

public RowLayout(int type)

Constructs a new instance of this class given the type.

Parameters:

type - the type of row layout

Since:

2.0

Method Details

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 String toString()

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

Overrides:

toString in class Object

Returns:

a string representation of the layout