Standard Widget Toolkit for GTK 3.125.0 · org.eclipse.swt.layout.FormLayout

Instances of this class control the position and size of the children of a composite control by using FormAttachments to optionally configure the left, top, right and bottom edges of each child.

The following example code creates a FormLayout and then sets it into a Shell:

 		Display display = new Display ();
		Shell shell = new Shell(display);
		FormLayout layout = new FormLayout();
		layout.marginWidth = 3;
		layout.marginHeight = 3;
		shell.setLayout(layout);

To use a FormLayout, create a FormData with FormAttachment for each child of Composite. The following example code attaches button1 to the top and left edge of the composite and button2 to the right edge of button1 and the top and right edges of the composite:

		FormData data1 = new FormData();
		data1.left = new FormAttachment(0, 0);
		data1.top = new FormAttachment(0, 0);
		button1.setLayoutData(data1);
		FormData data2 = new FormData();
		data2.left = new FormAttachment(button1);
		data2.top = new FormAttachment(0, 0);
		data2.right = new FormAttachment(100, 0);
		button2.setLayoutData(data2);

Each side of a child control can be attached to a position in the parent composite, or to other controls within the Composite by creating instances of FormAttachment and setting them into the top, bottom, left, and right fields of the child's FormData.

If a side is not given an attachment, it is defined as not being attached to anything, causing the child to remain at its preferred size. If a child is given no attachment on either the left or the right or top or bottom, it is automatically attached to the left and top of the composite respectively. The following code positions button1 and button2 but relies on default attachments:

		FormData data2 = new FormData();
		data2.left = new FormAttachment(button1);
		data2.right = new FormAttachment(100, 0);
		button2.setLayoutData(data2);

Important Note

Do not define circular attachments. For example, do not attach the right edge of button1 to the left edge of button2 and then attach the left edge of button2 to the right edge of button1. This will over constrain the layout, causing undefined behavior. The algorithm will terminate, but the results are undefined.

Field Summary

Modifier and Type	Field and Description
public int	marginBottom marginBottom specifies the number of points of vertical margin that will be placed along the bottom edge of the layout.
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.
public int	marginLeft marginLeft specifies the number of points of horizontal margin that will be placed along the left edge of the layout.
public int	marginRight marginRight specifies the number of points of horizontal margin that will be placed along the right edge of the layout.
public int	marginTop marginTop specifies the number of points of vertical margin that will be placed along the top edge of the layout.
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.
public int	spacing spacing specifies the number of points between the edge of one control and the edge of its neighbouring control.

Constructor Summary

Access	Constructor and Description
public	FormLayout() Constructs a new instance of this class.

Method Summary

Modifier and Type	Method and Description
pack-priv int	computeHeight(Control control, FormData data, boolean flushCache)
protected Point	computeSize(Composite a composite widget using this layout composite, int width (`SWT.DEFAULT` for preferred size) wHint, int height (`SWT.DEFAULT` for preferred size) hHint, boolean `true` means flush cached layout values flushCache) Implements abstract org.eclipse.swt.widgets.Layout.computeSize. Computes and returns the size of the specified composite's client area according to this layout.
pack-priv int	computeWidth(Control control, FormData data, boolean flushCache)
protected boolean	flushCache(Control a control managed by this layout control) Overrides org.eclipse.swt.widgets.Layout.flushCache. Instruct the layout to flush any cached values associated with the control specified in the argument `control`.
pack-priv String	getName()
protected void	layout(Composite a composite widget using this layout composite, boolean `true` means flush cached layout values flushCache) Implements abstract org.eclipse.swt.widgets.Layout.layout. Lays out the children of the specified composite according to this layout.
pack-priv Point	layout(Composite composite, boolean move, int x, int y, int width, int height, boolean flushCache)
public String	Returns: a string representation of the layout toString() Overrides java.lang.Object.toString. Returns a string containing a concise, human-readable description of the receiver.

Field Detail

marginBottom	back to summary
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 0. Since 3.1

marginBottom

back to summary

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 0.

Since: 3.1

marginHeight	back to summary
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.

marginLeft	back to summary
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 0. Since 3.1

marginLeft

back to summary

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 0.

Since: 3.1

marginRight	back to summary
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 0. Since 3.1

marginRight

back to summary

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 0.

Since: 3.1

marginTop	back to summary
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 0. Since 3.1

marginTop

back to summary

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 0.

Since: 3.1

marginWidth	back to summary
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.

spacing	back to summary
public int spacing spacing specifies the number of points between the edge of one control and the edge of its neighbouring control. The default value is 0. Since 3.0

spacing

back to summary

public int spacing

spacing specifies the number of points between the edge of one control and the edge of its neighbouring control. The default value is 0.

Since: 3.0

Constructor Detail

FormLayout	back to summary
public FormLayout() Constructs a new instance of this class.

Method Detail

computeHeight	back to summary
pack-priv int computeHeight(Control control, FormData data, boolean flushCache)

computeSize back to summary

computeSize	back to summary
protected Point computeSize(Composite composite, int wHint, int hHint, boolean flushCache) Implements abstract org.eclipse.swt.widgets.Layout.computeSize. Doc from org.eclipse.swt.widgets.Layout.computeSize. 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. Parameters composite:Composite a composite widget using this layout wHint:int width (`SWT.DEFAULT` for preferred size) hHint:int height (`SWT.DEFAULT` for preferred size) flushCache:boolean `true` means flush cached layout values Returns:Point a point containing the computed size (width, height) Annotations @Override

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

Implements abstract org.eclipse.swt.widgets.Layout.computeSize.

Doc from org.eclipse.swt.widgets.Layout.computeSize.

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.

Parameters

composite:Composite: a composite widget using this layout
wHint:int: width (SWT.DEFAULT for preferred size)
hHint:int: height (SWT.DEFAULT for preferred size)
flushCache:boolean: true means flush cached layout values

Returns:Point

a point containing the computed size (width, height)

Annotations

@Override

computeWidth	back to summary
pack-priv int computeWidth(Control control, FormData data, boolean flushCache)

flushCache back to summary

flushCache	back to summary
protected boolean flushCache(Control control) Overrides org.eclipse.swt.widgets.Layout.flushCache. Doc from org.eclipse.swt.widgets.Layout.flushCache. Instruct the layout to flush any cached values associated with the control specified in the argument `control`. Parameters control:Control a control managed by this layout Returns:boolean true if the Layout has flushed all cached information associated with control Annotations @Override

protected boolean flushCache(Control control)

Overrides org.eclipse.swt.widgets.Layout.flushCache.

Doc from org.eclipse.swt.widgets.Layout.flushCache.

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

Parameters

control:Control: a control managed by this layout

Returns:boolean

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

Annotations

@Override

getName	back to summary
pack-priv String getName()

layout back to summary

layout	back to summary
protected void layout(Composite composite, boolean flushCache) Implements abstract org.eclipse.swt.widgets.Layout.layout. Doc from org.eclipse.swt.widgets.Layout.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. Parameters composite:Composite a composite widget using this layout flushCache:boolean `true` means flush cached layout values Annotations @Override

protected void layout(Composite composite, boolean flushCache)

Implements abstract org.eclipse.swt.widgets.Layout.layout.

Doc from org.eclipse.swt.widgets.Layout.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.

Parameters

composite:Composite: a composite widget using this layout
flushCache:boolean: true means flush cached layout values

Annotations

@Override

layout	back to summary
pack-priv Point layout(Composite composite, boolean move, int x, int y, int width, int height, boolean flushCache)

layout

back to summary

pack-priv Point layout(Composite composite, boolean move, int x, int y, int width, int height, boolean flushCache)

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Returns a string containing a concise, human-readable description of the receiver. Returns:String a string representation of the layout Annotations @Override

toString

back to summary

public String toString()

Overrides java.lang.Object.toString.

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

Returns:String

a string representation of the layout

Annotations

@Override

public final Class FormLayout

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail