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Eclipse Platform
Release 3.0

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org.eclipse.swt.layout
Class GridLayout

java.lang.Object
  org.eclipse.swt.widgets.Layout
      org.eclipse.swt.layout.GridLayout

public final class GridLayout

extends Layout

Instances of this class lay out the control children of a Composite in a grid.

GridLayout has a number of configuration fields, and the controls it lays out can have an associated layout data object, called GridData. The power of GridLayout lies in the ability to configure GridData for each control in the layout.

The following code creates a shell managed by a GridLayout with 3 columns:

         Display display = new Display();
         Shell shell = new Shell(display);
         GridLayout gridLayout = new GridLayout();
         gridLayout.numColumns = 3;
         shell.setLayout(gridLayout);
 

The numColumns field is the most important field in a GridLayout. Widgets are laid out in columns from left to right, and a new row is created when numColumns + 1 controls are added to the Composite.

See Also:

GridData

Field Summary

int	horizontalSpacing horizontalSpacing specifies the number of pixels between the right edge of one cell and the left edge of its neighbouring cell to the right.
boolean	makeColumnsEqualWidth makeColumnsEqualWidth specifies whether all columns in the layout will be forced to have the same width.
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.
int	numColumns numColumns specifies the number of cell columns in the layout.
int	verticalSpacing verticalSpacing specifies the number of pixels between the bottom edge of one cell and the top edge of its neighbouring cell underneath.

Constructor Summary

GridLayout()
Constructs a new instance of this class.

GridLayout(int numColumns, boolean makeColumnsEqualWidth)
Constructs a new instance of this class given the number of columns, and whether or not the columns should be forced to have the same width.

Method Summary

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 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

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 5.

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 5.

numColumns

public int numColumns

numColumns specifies the number of cell columns in the layout. The default value is 1.

makeColumnsEqualWidth

public boolean makeColumnsEqualWidth

makeColumnsEqualWidth specifies whether all columns in the layout will be forced to have the same width. The default value is false.

horizontalSpacing

public int horizontalSpacing

horizontalSpacing specifies the number of pixels between the right edge of one cell and the left edge of its neighbouring cell to the right. The default value is 5.

verticalSpacing

public int verticalSpacing

verticalSpacing specifies the number of pixels between the bottom edge of one cell and the top edge of its neighbouring cell underneath. The default value is 5.

Constructor Detail

GridLayout

public GridLayout()

Constructs a new instance of this class.

GridLayout

public GridLayout(int numColumns,
                  boolean makeColumnsEqualWidth)

Constructs a new instance of this class given the number of columns, and whether or not the columns should be forced to have the same width.

Parameters:

numColumns - the number of columns in the grid

makeColumnsEqualWidth - whether or not the columns will have equal width

Since:

2.0

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 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.

Specified by:

computeSize in class Layout

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

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 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.

Specified by:

layout in class Layout

Parameters:

composite - a composite widget using this layout

flushCache - true means flush cached layout values