Package org.eclipse.swt.layout

Class 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:
    GridData, GridLayout snippets, SWT Example: LayoutExample, Sample code and further information

    • 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

      All Methods Instance Methods Concrete Methods 
      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.
      java.lang.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 Detail

      • 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 Detail

      • 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 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"

      • 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 java.lang.String toString()
        Returns a string containing a concise, human-readable description of the receiver.
        Overrides:
        toString in class java.lang.Object
        Returns:
        a string representation of the layout