/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jface.action;

import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.CoolBar;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.ToolBar;

/**
 * A contribution item represents a contribution to a shared UI resource such as a
 * menu or tool bar. More generally, contribution items are managed by a contribution
 * manager.
 * For instance, in a tool bar a contribution item is a tool bar button or a separator.
 * In a menu bar a contribution item is a menu, and in a menu a contribution item 
 * is a menu item or separator.
 * <p>
 * A contribution item can realize itself in different SWT widgets, using the different 
 * <code>fill</code> methods.  The same type of contribution item can be used with a 
 * <code>MenuBarManager</code>, <code>ToolBarManager</code>, <code>CoolBarManager</code>, 
 * </code>or a <code>StatusLineManager</code>.
 * </p>
 * <p>
 * This interface is internal to the framework; it should not be implemented outside
 * the framework.
 * </p>
 *
 * @see IContributionManager
 */
public interface IContributionItem {

    /**
     * Disposes of this contribution item. Called by the parent
     * contribution manager when the manager is being disposed.
     * Clients should not call this method directly.
     * 
     * @since 2.1
     */
    public void dispose();

    /**
     * Fills the given composite control with controls representing this 
     * contribution item.  Used by <code>StatusLineManager</code>.
     *
     * @param parent the parent control
     */
    public void fill(Composite parent);

    /**
     * Fills the given menu with controls representing this contribution item.
     * Used by <code>MenuManager</code>.
     *
     * @param parent the parent menu
     * @param index the index where the controls are inserted,
     *   or <code>-1</code> to insert at the end
     */
    public void fill(Menu parent, int index);

    /**
     * Fills the given tool bar with controls representing this contribution item.
     * Used by <code>ToolBarManager</code>.
     *
     * @param parent the parent tool bar
     * @param index the index where the controls are inserted,
     *   or <code>-1</code> to insert at the end
     */
    public void fill(ToolBar parent, int index);

    /**
     * Fills the given cool bar with controls representing this contribution item.
     * Used by <code>CoolBarManager</code>.
     *
     * @param parent the parent cool bar
     * @param index the index where the controls are inserted,
     *   or <code>-1</code> to insert at the end
     * @since 3.0
     */
    public void fill(CoolBar parent, int index);

    /**
     * Returns the identifier of this contribution item.
     * The id is used for retrieving an item from its manager.
     *
     * @return the contribution item identifier, or <code>null</code>
     *   if none
     */
    public String getId();

    /**
     * Returns whether this contribution item is enabled.
     * 
     * @return <code>true</code> if this item is enabled
     */
    public boolean isEnabled();

    /**
     * Returns whether this contribution item is dirty. A dirty item will be
     * recreated when the action bar is updated.
     * 
     * @return <code>true</code> if this item is dirty
     */
    public boolean isDirty();

    /**
     * Returns whether this contribution item is dynamic. A dynamic contribution
     * item contributes items conditionally, dependent on some internal state.
     *
     * @return <code>true</code> if this item is dynamic, and
     *  <code>false</code> for normal items
     */
    public boolean isDynamic();

    /**
     * Returns whether this contribution item is a group marker.
     * This information is used when adding items to a group.
     *
     * @return <code>true</code> if this item is a group marker, and
     *  <code>false</code> for normal items
     *
     * @see GroupMarker
     * @see IContributionManager#appendToGroup(String, IContributionItem)
     * @see IContributionManager#prependToGroup(String, IContributionItem)
     */
    public boolean isGroupMarker();

    /**
     * Returns whether this contribution item is a separator.
     * This information is used to enable hiding of unnecessary separators.
     *
     * @return <code>true</code> if this item is a separator, and
     *  <code>false</code> for normal items
     * @see Separator
     */
    public boolean isSeparator();

    /**
     * Returns whether this contribution item is visibile within its manager.
     *
     * @return <code>true</code> if this item is visible, and
     *  <code>false</code> otherwise
     */
    public boolean isVisible();

    /**
     * Saves any state information of the control(s) owned by this contribution item.
     * The contribution manager calls this method before disposing of the controls.
     * 
     * @since 3.0
     */
    public void saveWidgetState();

    /**
     * Sets the parent manager of this item
     * 
     * @param parent the parent contribution manager
     * @since 2.0
     */
    public void setParent(IContributionManager parent);

    /**
     * Sets whether this contribution item is visibile within its manager.
     *
     * @param visible <code>true</code> if this item should be visible, and
     *  <code>false</code> otherwise
     */
    public void setVisible(boolean visible);

    /**
     * Updates any SWT controls cached by this contribution item with any
     * changes which have been made to this contribution item since the last update.
     * Called by contribution manager update methods.
     */
    public void update();

    /**
     * Updates any SWT controls cached by this contribution item with changes
     * for the the given property. 
     * 
     * @param id the id of the changed property
     * @since 2.0
     */
    public void update(String id);
}