| package org.eclipse.swt.widgets; | |
| /* | |
| * (c) Copyright IBM Corp. 2000, 2001. | |
| * All Rights Reserved | |
| */ | |
| import org.eclipse.swt.*; | |
| import org.eclipse.swt.graphics.*; | |
| /** | |
| * A layout controls the position and size | |
| * of the children of a composite widget. | |
| * This class is the abstract base class for | |
| * layouts. | |
| */ | |
| public abstract class Layout { | |
| /** | |
| * Computes and returns the size of the specified | |
| * composite's client area according to this layout. | |
| * <p> | |
| * 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. | |
| * </p> | |
| * <p> | |
| * 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. | |
| * </p> | |
| * | |
| * @param composite a composite widget using this layout | |
| * @param wHint width (<code>SWT.DEFAULT</code> for minimum) | |
| * @param hHint height (<code>SWT.DEFAULT</code> for minimum) | |
| * @param flushCache <code>true</code> means flush cached layout values | |
| * @return a point containing the computed size (width, height) | |
| * @see #layout | |
| */ | |
| protected abstract Point computeSize (Composite composite, int wHint, int hHint, boolean flushCache); | |
| /** | |
| * Lays out the children of the specified composite | |
| * according to this layout. | |
| * <p> | |
| * 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. | |
| * </p> | |
| * <p> | |
| * 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. | |
| * </p> | |
| * <p> | |
| * 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. | |
| * </p> | |
| * | |
| * @param composite a composite widget using this layout | |
| * @param flushCache <code>true</code> means flush cached layout values | |
| */ | |
| protected abstract void layout (Composite composite, boolean flushCache); | |
| } |