Package 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.

Since:
1.0
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    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
    marginBottom
    marginBottom specifies the number of pixels of vertical margin that will be placed along the bottom edge of the layout.
    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
    marginLeft
    marginLeft specifies the number of pixels of horizontal margin that will be placed along the left edge of the layout.
    int
    marginRight
    marginRight specifies the number of pixels of horizontal margin that will be placed along the right edge of the layout.
    int
    marginTop
    marginTop specifies the number of pixels of vertical margin that will be placed along the top edge 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

    Constructors
    Constructor
    Description
    GridLayout()
    Constructs a new instance of this class with a single column.
    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

    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

    • numColumns

      public int numColumns
      numColumns specifies the number of cell columns in the layout. If numColumns has a value less than 1, the layout will not set the size and position of any controls. 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.

    • 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.

    • marginLeft

      public int marginLeft
      marginLeft specifies the number of pixels of horizontal margin that will be placed along the left edge of the layout. The default value is 0.

    • marginTop

      public int marginTop
      marginTop specifies the number of pixels of vertical margin that will be placed along the top edge of the layout. The default value is 0.

    • marginRight

      public int marginRight
      marginRight specifies the number of pixels of horizontal margin that will be placed along the right edge of the layout. The default value is 0.

    • marginBottom

      public int marginBottom
      marginBottom specifies the number of pixels of vertical margin that will be placed along the bottom edge of the layout. The default value is 0.

    • 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 Details

    • GridLayout

      public GridLayout()
      Constructs a new instance of this class with a single column.

    • 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. If numColumns has a value less than 1, the layout will not set the size and position of any controls.
      Parameters:
      numColumns - the number of columns in the grid
      makeColumnsEqualWidth - whether or not the columns will have equal width

  • 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:

    • 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