Package org.eclipse.ui.forms.widgets

Class TableWrapLayout

  • All Implemented Interfaces:
    ILayoutExtension
    public final class TableWrapLayout
extends Layout
implements ILayoutExtension
    This implementation of the layout algorithm attempts to position controls in the composite using a two-pass autolayout HTML table algorithm recommended by HTML 4.01 W3C specification (see http://www.w3.org/TR/html4/appendix/notes.html#h-B.5.2.2). The main differences with GridLayout is that it has two passes and that width and height are not calculated in the same pass.

    The advantage of the algorithm over GridLayout is that it is capable of flowing text controls capable of line wrap. These controls do not have natural 'preferred size'. Instead, they are capable of providing the required height if the width is set. Consequently, this algorithm first calculates the widths that will be assigned to columns, and then passes those widths to the controls to calculate the height. When a composite with this layout is a child of the scrolling composite, they should interact in such a way that reduction in the scrolling composite width results in the reflow and increase of the overall height.

    If none of the columns contain expandable and wrappable controls, the end-result will be similar to the one provided by GridLayout. The difference will show up for layouts that contain controls whose minimum and maximum widths are not the same.

    Since:
    3.0
    See Also:
    TableWrapData

    • Field Detail

      • numColumns

        public int numColumns
        Number of columns to use when positioning children (default is 1).

      • leftMargin

        public int leftMargin
        Left margin variable (default is 5).

      • rightMargin

        public int rightMargin
        Right margin variable (default is 5).

      • topMargin

        public int topMargin
        Top margin variable (default is 5).

      • bottomMargin

        public int bottomMargin
        Botom margin variable (default is 5).

      • horizontalSpacing

        public int horizontalSpacing
        Horizontal spacing (default is 5).

      • verticalSpacing

        public int verticalSpacing
        Vertical spacing (default is 5).

      • makeColumnsEqualWidth

        public boolean makeColumnsEqualWidth
        If set to true, all the columns will have the same width. Otherwise, column widths will be computed based on controls in them and their layout data (default is false).

    • Constructor Detail

      • TableWrapLayout

        public TableWrapLayout()

    • Method Detail

      • computeMinimumWidth

        public int computeMinimumWidth​(Composite parent,
                               boolean changed)
        Implements ILayoutExtension. Should not be called directly.
        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
        See Also:
        ILayoutExtension

      • computeMaximumWidth

        public int computeMaximumWidth​(Composite parent,
                               boolean changed)
        Implements ILayoutExtension. Should not be called directly.
        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
        See Also:
        ILayoutExtension

      • layout

        protected void layout​(Composite parent,
                      boolean changed)
        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
        changed - true means flush cached layout values
        See Also:
        Layout.layout(Composite, boolean)

      • computeSize

        protected Point computeSize​(Composite parent,
                            int wHint,
                            int hHint,
                            boolean changed)
        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:
        parent - a composite widget using this layout
        wHint - width (SWT.DEFAULT for preferred size)
        hHint - height (SWT.DEFAULT for preferred size)
        changed - true means flush cached layout values
        Returns:
        a point containing the computed size (width, height)
        See Also:
        Layout.computeSize(Composite, int, int, boolean)