libwt-dev 3.1.10-1ubuntu2 / usr / include / Wt / WMenu

// This may look like C code, but it's really -*- C++ -*-
/*
 * Copyright (C) 2008 Emweb bvba, Kessel-Lo, Belgium.
 *
 * See the LICENSE file for terms of use.
 */
#ifndef WMENU_H_
#define WMENU_H_

#include <vector>

#include <Wt/WCompositeWidget>
#include <Wt/WMenuItem>

namespace Wt {

class WStackedWidget;
class WTable;

/*! \class WMenu Wt/WMenu Wt/WMenu
 *  \brief A widget that shows a menu of options.
 *
 * The %WMenu widget offers menu navigation.
 *
 * Typically, a menu is used in conjunction with a WStackedWidget (but
 * can be used without too), where different 'contents' are stacked
 * upon each other. Each choice in the menu (which is implemented as a
 * WMenuItem) corresponds to a tab in the contents stack. The contents
 * stack may contain other items, and could be shared with other WMenu
 * instances.
 *
 * When used without a contents stack, you can react to menu item
 * selection using the itemSelected() signal, to implement some custom
 * handling of item selection.
 *
 * Usage example:
 * \if cpp
 * \code
 * // create the stack where the contents will be located
 * Wt::WStackedWidget *contents = new Wt::WStackedWidget(contentsParent);
 *
 * // create a menu
 * Wt::WMenu *menu = new Wt::WMenu(contents, Wt::Vertical, menuParent);
 * menu->setRenderAsList(true);
 *
 * // add four items using the default lazy loading policy.
 * menu->addItem("Introduction", new Wt::WText("intro"));
 * menu->addItem("Download", new Wt::WText("Not yet available"));
 * menu->addItem("Demo", new DemoWidget());
 * menu->addItem(new Wt::WMenuItem("Demo2", new DemoWidget()));
 * \endcode
 * \elseif java
 * \code
 * // create the stack where the contents will be located
 * WStackedWidget contents = new WStackedWidget(contentsParent);
 *		 
 * // create a menu
 * WMenu menu = new WMenu(contents, Orientation.Vertical, menuParent);
 * menu.setRenderAsList(true);
 *		 
 * // add four items using the default lazy loading policy.
 * menu.addItem("Introduction", new WText("intro"));
 * menu.addItem("Download", new WText("Not yet available"));
 * menu.addItem("Demo", new DemoWidget());
 * menu.addItem(new WMenuItem("Demo2", new DemoWidget()));
 * \endcode
 * \endif
 *
 * Historically, a menu was implemented as a table, but \link
 * setRenderAsList() rendering as a list\endlink (<tt>&lt;ul&gt;</tt>)
 * is preferred, as it is the norm form implementations.
 *
 * After contruction, the first entry will be selected. At any time,
 * it is possible to select a particular item using select().
 *
 * Each item of %WMenu may be closeable (see WMenuItem::setCloseable(bool).
 * Like selection, at any time, it is possible to close a particular item
 * using close(). You can react to close of item by using the itemClosed()
 * signal.
 *
 * The %WMenu implementation offers fine-grained control on how
 * contents should be preloaded. By default, all contents is
 * lazy-loaded, only when needed. To improve response time, an item
 * may also be preloaded (using addItem()). In that case, the item
 * will be loaded in the background, before its first use. In any
 * case, once the contents corresponding to a menu item is loaded,
 * subsequent navigation to it is handled entirely client-side.
 *
 * The %WMenu may participate in the application's internal path,
 * which lets menu items correspond to internal URLs, see
 * setInternalPathEnabled().
 *
 * The layout of the menu may be Horizontal or Vertical. The look of
 * the items may be defined through style sheets. The default
 * WMenuItem implementation uses four style classes to distinguish
 * between inactivated, activated, closeable inactivated and closeable
 * activated menu items: <tt>"item"</tt>, <tt>"itemselected"</tt>,
 * <tt>"citem"</tt>, <tt>"citemselected"</tt>. By using CSS nested selectors,
 * a different style may be defined for items in a different menu.
 *
 * You may customize the rendering and behaviour of menu entries by
 * specializing WMenuItem.
 *
 * <h3>CSS</h3>
 *
 * Styling a menu will be different depending of the rendering mode
 * (table, list). Conventionally, menus like this are styled as a list
 * (setRenderAsList()).
 *
 * You will want to differentiate between unselected and selected items
 * based on the <tt>"item"</tt> and <tt>"itemselected"</tt> style classes
 * as well as between unselected and selected closeable items based on the
 * <tt>"citem"</tt> and <tt>"citemselected"</tt> style classes.
 *
 * For menus without closeable items a styling is pretty simple. For
 * example, assuming you set a <tt>"menu"</tt> style class for your
 * menu, you can style the items using:
 *
 * \code
.menu * .item {
  cursor: pointer; cursor: hand;
  color: blue;
  text-decoration: underline;
}

.menu * .itemselected {
  color: blue;
  text-decoration: underline;
  font-weight: bold;  
}
 * \endcode
 *
 * For menus which supports closing and/or enabling disabling of
 * items, the styling is more complex. The close icon is styled by the
 * current CSS theme and can be overriden by using
 * <tt>"Wt-closeicon"</tt> CSS class. The look of the menu, assuming
 * the default implementation for WMenuItem, can be customized by
 * using the following selectors (again assuming a menu with as
 * styleclass <tt>"menu"</tt>):
 *
 * \verbatim
.Wt-closeicon                     : a close icon

.menu                             : the list (you custom menu class)
.menu li                          : a list item
.menu span                        : spans of a list item

# not closable items:
.menu a.item span                 : the inner span of the label of an enabled item
.menu span.item                   : the label of a disabled item
.menu a.itemselected span         : the inner span the label of an enabled selected item
.menu span.itemselected           : the label of a disabled selected item

# closable items:
.menu .citem a.label span         : the inner span of the label of an enabled item
.menu .citem span.label           : the label of a disabled item
.menu .citemselected a.label span : the inner span the label of an enabled selected item
.menu .citemselected span.label   : the label of a disabled selected item
\endverbatim
 *
 * Example of styling a menu with closeable items:
 * 
 * \code
.menu {
  overflow: auto;
}

.menu li {
  display: inline;
}

.menu span {
  display: block; float: left;
}

.menu a.item span {
  cursor: pointer; cursor: hand;
  color: blue;
  margin-right: 5px;
}

.menu span.item {
  color: gray;
  margin-right: 5px;
}

.menu a.itemselected span {
  color: black;
  font-weight: bold;
  text-decoration: none;
  margin-right: 5px;
}

.menu span.itemselected {
  color: gray;
  font-weight: bold;
  text-decoration: none;
  margin-right: 5px;
}

.menu .citem a.label span {
  cursor: pointer; cursor: hand;
  color: blue;
}

.menu .citem span.label {
  color: gray;
}

.menu .citemselected a.label span {
  color: black;
  font-weight: bold;
  text-decoration: none;
}

.menu .citemselected span.label {
  color: gray;
  font-weight: bold;
  text-decoration: none;
}
 * \endcode
 * 
 * \sa WMenuItem
 */
class WT_API WMenu : public WCompositeWidget
{
public:
  /*! \brief Creates a new menu.
   *
   * Construct a menu with given \p orientation. The menu is not
   * associated with a contents stack, and thus you will want to react
   * to the itemSelected() signal to react to menu changes.
   */
  WMenu(Orientation orientation, WContainerWidget *parent = 0);

  /*! \brief Creates a new menu.
   *
   * Construct a menu to manage the widgets in \p contentsStack,
   * and sets the menu \p orientation.
   *
   * Each menu item will manage a single widget in the
   * \p contentsStack, making it the current widget when the menu
   * item is activated.
   */
  WMenu(WStackedWidget *contentsStack, Orientation orientation,
	WContainerWidget *parent = 0);

  /*! \brief Destructor.
   */
  ~WMenu();

  /*! \brief Adds an item.
   *
   * Adds a menu item with given \p contents, which is added to the
   * menu's associated contents stack.
   *
   * \p contents may be \c 0 for two reasons:
   * - if the menu is not associated with a contents stack, then you cannot
   *   associate a menu item with a contents widget
   * - or, you may have one or more items which which are not associated with
   *   a contents widget in the contents stack.
   *
   * Returns the corresponding WMenuItem.
   *
   * \sa addItem(WMenuItem *)
   */
  WMenuItem *addItem(const WString& name, WWidget *contents,
		     WMenuItem::LoadPolicy policy = WMenuItem::LazyLoading);

  /*! \brief Adds an item.
   *
   * Adds a menu item. Use this form to add specialized WMenuItem
   * implementations.
   *
   * \sa addItem(const WString&, WWidget *, WMenuItem::LoadPolicy)
   */
  WMenuItem *addItem(WMenuItem *item);

  /*! \brief Removes an item.
   *
   * Removes the given item. The item and its contents is not deleted.
   *
   * \sa addItem()
   */
  void removeItem(WMenuItem *item);

  /*! \brief Selects an item.
   *
   * Select the menu item \p item.
   *
   * \sa select(int), currentItem(), WMenuItem::select()
   */
  void select(WMenuItem *item);

  /*! \brief Selects an item.
   *
   * Menu items in a menu with \p N items are numbered from 0 to
   * \p N - 1.
   *
   * \sa select(WMenuItem *), currentIndex()
   */
  void select(int index);

  /*! \brief %Signal which indicates that a new item was selected.
   *
   * This signal is emitted when an item was selected. It is emitted
   * both when the user activated an item, or when select() was
   * invoked.
   *
   * \sa itemSelectRendered()
   */
  Signal<WMenuItem *>& itemSelected() { return itemSelected_; }

  /*! \brief %Signal which indicates that a new selected item is rendered.
   *
   * This signal is similar to \link WMenu::itemSelected
   * itemSelected\endlink, but is emitted from within a stateless
   * slot. Therefore, any slot connected to this signal will be
   * optimized to client-side JavaScript, and must support the
   * contract of a stateless slot (i.e., be idempotent).
   *
   * If you are unsure what is the difference with the \link
   * WMenu::itemSelected itemSelected\endlink signal, you'll probably
   * need the latter instead.
   *
   * \sa itemSelected()
   */
  Signal<WMenuItem *>& itemSelectRendered() { return itemSelectRendered_; }

  /*! \brief Closes an item.
   *
   * Close the menu item \p item. Only \link WMenuItem::setCloseable(bool)
   * closeable\endlink items can be closed.
   *
   * \sa close(int), WMenuItem::close()
   */
  void close(WMenuItem *item);

  /*! \brief Closes an item.
   *
   * Menu items in a menu with \p N items are numbered from 0 to
   * \p N - 1.
   *
   * \sa close(WMenuItem *)
   */
  void close(int index);

  /*! \brief Returns the items.
   *
   * Returns the list of menu items in this menu.
   */
  const std::vector<WMenuItem *>& items() const { return items_; }

  /*! \brief %Signal which indicates that an item was closed.
   *
   * This signal is emitted when an item was closed. It is emitted
   * both when the user closes an item, or when close() was
   * invoked.
   */
  Signal<WMenuItem *>& itemClosed() { return itemClosed_; }

  /*! \brief Hides an item.
   *
   * Hides the menu item \p item. By default, all menu items are
   * visible.
   *
   * If the item was currently selected, then the next item to be selected
   * is determined by nextAfterHide().
   *
   * \sa setItemHidden(int, bool), WMenuItem::hide()
   */
  void setItemHidden(WMenuItem *item, bool hidden);

  /*! \brief Hides an item.
   *
   * Menu items in a menu with \p N items are numbered from 0 to \p N - 1.
   *
   * \sa setItemHidden(WMenuItem *, bool)
   */
  void setItemHidden(int index, bool hidden);

  /*! \brief Returns whether the item widget of the given item is hidden.
   *
   * \sa setItemHidden()
   */
  bool isItemHidden(WMenuItem *item) const;

  /*! \brief Returns whether the item widget of the given index is hidden.
   *
   * Menu items in a menu with \p N items are numbered from 0 to \p N - 1.
   *
   * \sa setItemHidden()
   */
  bool isItemHidden(int index) const;

  /*! \brief Disables an item.
   *
   * Disables the menu item \p item. Only an item that is enabled can
   * be selected. By default, all menu items are enabled.
   *
   * \sa setItemDisabled(int, bool), WMenuItem::setDisabled()
   */
  void setItemDisabled(WMenuItem *item, bool disabled);

  /*! \brief Disables an item.
   *
   * Menu items in a menu with \p N items are numbered from 0 to
   * \p N - 1.
   *
   * \sa setItemDisabled(WMenuItem *, bool)
   */
  void setItemDisabled(int index, bool disabled);

  /*! \brief Returns whether the item widget of the given item is disabled.
   *
   * \sa setItemDisabled()
   */
  bool isItemDisabled(WMenuItem *item) const;

  /*! \brief Returns whether the item widget of the given index is disabled.
   *
   * Menu items in a menu with \p N items are numbered from 0 to
   * \p N - 1.
   *
   * \sa setItemDisabled()
   */
  bool isItemDisabled(int index) const;

  /*! \brief Returns the currently selected item.
   *
   * \sa currentIndex(), select(WMenuItem *)
   */
  WMenuItem *currentItem() const;

  /*! \brief Returns the index of the currently selected item.
   *
   * \sa currentItem(), select(int)
   */
  int currentIndex() const { return current_; }

  /*! \brief Returns the orientation.
   *
   * The orientation is set at time of construction.
   */
  Orientation orientation() const { return orientation_; }

  /*! \brief Renders using an HTML list.
   *
   * By default, the the menu is rendered using an HTML
   * <tt>&lt;table&gt;</tt> element for layout. Setting this option
   * enables rendering using <tt>&lt;ul&gt;</tt> and
   * <tt>&lt;il&gt;</tt> elements, as is commonly done for CSS-based
   * designs.
   *
   * \note You cannot use this method after items have been added to
   * the menu.
   */
  void setRenderAsList(bool enable);

  /*! \brief Returns whether the menu is rendered as an HTML list.
   *
   * \sa setRenderAsList(bool)
   */
  bool renderAsList() const { return renderAsList_; }

  /*! \brief Enables internal paths for items.
   *
   * The menu participates in the internal path by changing the
   * internal path when an item has been selected, and listening for
   * path changes to react to path selections. As a consequence this
   * allows the user to bookmark the current menu selection and
   * revisit it later, use back/forward buttons to navigate through
   * history of visited menu items, and allows indexing of pages.
   *
   * For each menu item, WMenuItem::pathComponent() is appended to the
   * internal base path (internalBasePath()), which defaults to the
   * internal path (WApplication::internalPath()) but may be changed
   * using setInternalBasePath(), with a '/' appended to turn it into
   * a folder, if needed.
   *
   * By default, menu interaction does not change the application
   * internal path.
   *
   * \sa WMenuItem::setPathComponent().
   */
  void setInternalPathEnabled(const std::string& basePath = "");

  /*! \brief Returns whether the menu generates internal paths entries.
   *
   * \sa setInternalPathEnabled()
   */
  bool internalPathEnabled() const { return internalPathEnabled_; }

  /*! \brief Sets the internal base path.
   *
   * A '/' is appended to turn it into a folder, if needed.
   *
   * \sa setInternalPathEnabled(), internalBasePath()
   */
  void setInternalBasePath(const std::string& basePath);

  /*! \brief Returns the internal base path.
   *
   * The default value is the application's internalPath
   * (WApplication::internalPath()) that was recorded when
   * setInternalPathEnabled() was called, and together with each
   * WMenuItem::pathComponent() determines the paths for each item.
   *
   * For example, if internalBasePath() is <tt>"/examples/"</tt> and
   * pathComponent() for a particular item is <tt>"charts/"</tt>, then
   * the internal path for that item will be
   * <tt>"/examples/charts/"</tt>.
   *
   * \sa setInternalPathEnabled()
   */
  const std::string& internalBasePath() const { return basePath_; }

  /*! \brief Returns the contents stack associated with the menu.
   */
  WStackedWidget *contentsStack() const { return contentsStack_; }

protected:
  virtual void enableAjax();
  virtual void render(WFlags<RenderFlag> flags);

  /*! \brief Handling of internal path changes.
   *
   * This methods makes the menu react to internal path changes (and also
   * the initial internal path).
   *
   * You may want to reimplement this if you want to customize the internal
   * path handling.
   */
  virtual void internalPathChanged(const std::string& path);

  /*! \brief Returns the index of the item to be selected after hides.
   *
   * Returns the index of the item to be selected after the item with given
   * index will be hidden.
   *
   * By default, if the given index is an index of currently selected item,
   * returns an index of the first visible item to the right of it. If it is not
   * found, returns the index of the first visible item to the left of it. If
   * there are no visible items around the currently selected item, returns the
   * index of currently selected item.
   *
   * You may want to reimplement this if you want to customize the algorithm
   * of determining the index of the item to be selected after hiding the item
   * with given index.
   */
  virtual int nextAfterHide(int index);

private:
  WWidget          *impl_;
  WStackedWidget   *contentsStack_;
  Orientation       orientation_;
  bool              renderAsList_;
  bool              internalPathEnabled_;
  bool              emitPathChange_;
  std::string       basePath_, previousInternalPath_;

  Signal<WMenuItem *> itemSelected_, itemSelectRendered_;
  Signal<WMenuItem *> itemClosed_;

  std::vector<WMenuItem *> items_;

  void select(int index, bool changePath);

  boost::signals::connection contentsStackConnection_;
  void contentsDestroyed();

  int current_;
  int previousCurrent_;
  int previousStackIndex_;
  bool needSelectionEventUpdate_;

  int indexOf(WMenuItem *item) const;

  void itemPathChanged(WMenuItem *item);
  void selectVisual(WMenuItem *item);
  void selectVisual(int item, bool changePath);
  void undoSelectVisual();

  friend class WMenuItem;
  friend class WSubMenuItem;

  void recreateItem(int index);
  void recreateItem(WMenuItem *item);
  void doSetHiddenItem(int index, bool hidden);
  void doSetHiddenItem(WMenuItem *item, bool hidden);
  void updateItems();
  void updateSelectionEvent();
};

}

#endif // WMENU_H_