Class ColumnLayout

  • All Implemented Interfaces:
    ILayoutExtension

    public final class ColumnLayout
    extends Layout
    implements ILayoutExtension
    This layout manager arranges children of the composite parent in vertical columns. All the columns are identical size and children are stretched horizontally to fill the column width. The goal is to give layout some reasonable range of column numbers to allow it to handle various parent widths. That way, column number will drop to the lowest number in the range when width decreases, and grow up to the highest number in the range when allowed by the parent width.

    In addition, the layout attempts to 'fill the space' equally i.e. to avoid large gaps at the and of the last column.

    Child controls are layed out according to their 'natural' (preferred) size. For 'stretchy' controls that do not have natural preferred size, it is possible to set width and/or height hints using ColumnLayoutData objects.

    Since:
    3.0
    See Also:
    ColumnLayoutData
    • Field Detail

      • minNumColumns

        public int minNumColumns
        Minimum number of columns (default is 1).
      • maxNumColumns

        public int maxNumColumns
        Maximum number of columns (default is 3).
      • horizontalSpacing

        public int horizontalSpacing
        Horizontal spacing between columns (default is 5).
      • verticalSpacing

        public int verticalSpacing
        Vertical spacing between controls (default is 5).
      • topMargin

        public int topMargin
        Top margin (default is 5).
      • leftMargin

        public int leftMargin
        Left margin (default is 5).
      • bottomMargin

        public int bottomMargin
        Bottom margin (default is 5).
      • rightMargin

        public int rightMargin
        Right margin (default is 5).
    • Constructor Detail

      • ColumnLayout

        public ColumnLayout()
        Creates a new instance of the column layout.
    • 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"
      • layout

        protected void layout​(Composite parent,
                              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:
        parent - a composite widget using this layout
        flushCache - true means flush cached layout values
      • computeMaximumWidth

        public int computeMaximumWidth​(Composite parent,
                                       boolean changed)
        Description copied from interface: ILayoutExtension
        Computes the maximum width of the parent. All widgets capable of word wrapping should return the length of the entire text with wrapping turned off.
        Specified by:
        computeMaximumWidth in interface ILayoutExtension
        Parameters:
        parent - the parent composite
        changed - true if the cached information should be flushed, false otherwise.
        Returns:
        the maximum width of the parent composite
      • computeMinimumWidth

        public int computeMinimumWidth​(Composite parent,
                                       boolean changed)
        Description copied from interface: ILayoutExtension
        Computes the minimum width of the parent. All widgets capable of word wrapping should return the width of the longest word that cannot be broken any further.
        Specified by:
        computeMinimumWidth in interface ILayoutExtension
        Parameters:
        parent - the parent composite
        changed - true if the cached information should be flushed, false otherwise.
        Returns:
        the minimum width of the parent composite