tdelibs/kdeui/kpanelapplet.h

/*****************************************************************

Copyright (c) 2000 Matthias Elter

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******************************************************************/

#ifndef __kpanelapplet_h__
#define __kpanelapplet_h__

class KConfig;
class QPopupMenu;

#include <qframe.h>
#include <kconfig.h>

/**
 * @short %KDE Panel Applet class
 *
 * Panel applets
 *   @li Are small applications living in the %KDE panel.
 *   @li Are implemented as DSOs (Dynamic Shared Objects).
 *
 * Note: For security and stability reasons the panel won't load
 * untrusted third party applets directly into its namespace but via an
 * external wrapper process.
 *
 * The panel locates available applets by searching for applet desktop
 * files in (ALL_DIRS)/share/apps/kicker/applets. Every panel applet should
 * install a desktop file there to be recognized by the panel.
 *
 * Besides standard keys like "Name", "Comment" and "Icon" there are
 * two panel applet specific keys:
 *
 * \b X-KDE-Library \n
 *
 * Used by the panel to locate the applet DSO (Dynamic Shared Object)
 * Example: X-KDE-Library=libexampleapplet
 *
 * \b X-KDE-UniqueApplet \n
 *
 * Similar to KApplication and KUniqueApplication there are
 * two types of panel applets. Use unique applets when it makes no
 * sence to run more than one instance of a applet in the panel. A
 * good example for unique applets is the taskbar applet.  Use normal
 * applets when you need instance specific configuration. An example
 * is the koolclock applet where you might want to run two instances
 * in your panel, one configured as analog clock, the other one as
 * digital clock. X-KDE-UniqueApplet is a boolean key which defaults
 * to "false".  Example: X-KDE-UniqueApplet=true
 *
 * Back to panel applet DSOs, the following conventions are used for %KDE:
 * Name:    lib<appletname>applet.la
 * LDFLAGS: -module -no-undefined
 *
 * To implement a panel applet it is not enough to write a class
 * inheriting from KPanelApplet but you also have to provide a
 * factory function in your DSO.  A sample factory function could look
 * like this:
 *
 * \code
 *
 * extern "C"
 * {
 *     KPanelApplet* init(QWidget *parent, const QString& configFile)
 *     {
 *         KGlobal::locale()->insertCatalogue("exampleapplet");
 *         return new ExampleApplet(configFile, KPanelApplet::Normal,
 *                       KPanelApplet::About | KPanelApplet::Help | KPanelApplet::Preferences,
 *                       parent, "exampleapplet");
 *     }
 * }
 *
 * \endcode
 *
 * Note: Don't change the factory function signature or the panel will
 * fail to load your applet.
 *
 * @author Matthias Elter <elter@kde.org>
 **/
class KDEUI_EXPORT KPanelApplet : public QFrame
{
    Q_OBJECT

public:

    /**
     * This enum describes the type of the applet.
     */
    enum Type { Normal = 0, Stretch };
    /**
     * This enum holds flags which can be ORed together to describe
     * which items the context menu over the applet handle contains.
     */
    // KDE4: Merge these with KPanelExtension's enums
    enum Action { About = 1, Help = 2, Preferences = 4, ReportBug = 8 };
    enum Position { pLeft = 0, pRight, pTop, pBottom };
    enum Alignment { LeftTop = 0, Center, RightBottom };
    enum Direction { Up = 0, Down, Left, Right };

    /**
     * Constructs a KPanelApplet just like any other widget.
     *
     * @param configFile The configFile handed over in the factory function.
     * @param t The applet type().
     * @param actions Standard RMB menu actions supported by the applet (see action() ).
     * @param parent The pointer to the parent widget handed over in the factory function.
     * @param name A Qt object name for your applet.
     * @param f Window control flags
     **/
    KPanelApplet(const QString& configFile, Type t = Normal,
                 int actions = 0, QWidget *parent = 0, const char *name = 0,
                 WFlags f = 0);

    /**
     * Destructor.
     **/
    ~KPanelApplet();

    /**
     * Returns a suggested width for a given height.
     *
     * Every applet should reimplement this function.
     *
     * Depending on the panel orientation the height (horizontal panel) or the
     * width (vertical panel) of the applets is fixed.
     * The exact values of the fixed size component depend on the panel size.
     *
     * On a horizontal panel the applet height is fixed, the panel will
     * call widthForHeight(int height) with @p height
     * equal to 'the fixed applet height'
     * when laying out the applets.
     *
     * The applet can now choose the other size component (width)
     * based on the given height.
     *
     * The width you return is granted.
     **/
    virtual int widthForHeight(int height) const { return height; }

    /**
     * @return A suggested height for a given width.
     *
     * Every applet should reimplement this function.
     *
     * Depending on the panel orientation the height (horizontal panel) or the
     * width (vertical panel) of the applets is fixed.
     * The exact values of the fixed size component depend on the panel size.
     *
     * On a vertical panel the applet width is fixed, the panel will
     * call heightForWidth(int width) with @p width
     * equal to 'the fixed applet width'
     * when laying out the applets.
     *
     * The applet can now choose the other size component (height)
     * based on the given width.
     *
     * The height you return is granted.
     **/
    virtual int heightForWidth(int width) const { return width; }

    /**
     * Always use this KConfig object to save/load your applet's configuration.
     *
     * For unique applets this config object will write to a config file called
     * \<appletname\>rc in the user's local %KDE directory.
     *
     * For normal applets this config object will write to a instance specific config file
     * called \<appletname\>\<instanceid\>rc in the user's local %KDE directory.
     **/
    KConfig* config() const { return _config; }
    KSharedConfig::Ptr sharedConfig() const;

    /**
     * @return Type indicating the applet's type.
     * Type
     **/
    Type type() const { return _type; }

    /**
     * @return int indicating the supported RMB menu actions.
     * Action
     **/
    int actions() const { return _actions; }

    /**
     * Generic action dispatcher. Called  when the user selects an item
     * from the applet's RMB menu.
     *
     * Reimplement this function to handle actions.
     *
     * For About, Help, Preferences and ReportBug, use the convenience handlers
     * ref about(), help(), preferences(), reportBug()
     *
     **/
    virtual void action( Action a );

    /**
     * @return the applet's custom menu, usually the same as the context menu, or 0 if none
     * see setCustomMenu(QPopupMenu*)
     */
    const QPopupMenu* customMenu() const;

    /**
     * @internal
     **/
    void setPosition( Position p );
    /**
     * @internal
     **/
    void setAlignment( Alignment a );

signals:
    /**
     * Emit this signal to make the panel relayout all applets, when
     * you want to change your width (horizontal panel) or
     * height (vertical panel).
     *
     * The panel is going to relayout all applets based on their
     * widthForHeight(int height) (horizontal panel) or
     * heightForWidth(int width) (vertical panel).
     *
     * Please note that the panel may change the applet's location
     * if the new widthForHeight(int height) (horizontal panel) or
     * heightForWidth(int width) (vertical panel) does not fit into the
     * current panel layout.
     **/
    void updateLayout();

    /**
     * Request keyboard focus from the panel.
     * @deprecated
     **/
    void requestFocus();

    /**
     * Request keyboard focus from the panel. Applets should never call this directly
     * but rather call needsFocus(bool)
     * @see needsFocus
     * @param focus activate the window and ensure the panel remains visible when true
     * Each and ever time a requestFocus(true) is emitted, it MUST be paired eventually
     * with a requestFocus(false) otherwise the panel may end up never hiding
     * @since 3.4
     **/
    void requestFocus(bool focus);

protected:

    /**
     * Is called when the user selects "About" from the applet's RMB menu.
     * Reimplement this function to launch a about dialog.
     *
     * Note that this is called only when your applet supports the About action.
     * See Action and KPanelApplet().
     **/
    virtual void about() {}

    /**
     * Is called when the user selects "Help" from the applet's RMB menu.
     * Reimplement this function to launch a manual or help page.
     *
     * Note that this is called only when your applet supports the Help action.
     * See Action and KPanelApplet().
     **/
    virtual void help() {}

    /**
     * Is called when the user selects "Preferences" from the applet's RMB menu.
     * Reimplement this function to launch a preferences dialog or kcontrol module.
     *
     * Note that this is called only when your applet supports the preferences action.
     * See Action and KPanelApplet().
     **/
    virtual void preferences() {}

    /**
     * Is called when the user selects "Report bug" from the applet's RMB menu.
     * Reimplement this function to launch a bug reporting dialog.
     *
     * Note that this is called only when your applet supports the ReportBug
     * action.
     * See Action and KPanelApplet()
     **/
   virtual void reportBug() {}

    /**
     * @return the applet's orientation. (horizontal or vertical)
     **/
    Orientation orientation() const;
    /**
     * @return the applet's position. (top, left, bottom, or right)
     **/
    Position position() const { return _position; }
    /**
     * @return the applet's alignment. (top/left, center, or bottom/right)
     **/
    Alignment alignment() const { return _alignment; }

    /**
     * The panel on which this applet resides has changed its position.
     * Reimplement this change handler in order to adjust the look of your
     * applet.
     **/
    virtual void positionChange( Position p );

    /**
     * The panel on which this applet resides has changed its alignment.
     * Reimplement this change handler in order to adjust the look of your
     * applet.
     **/
    virtual void alignmentChange( Alignment /*a*/ ) {}

    /**
     * Use this method to set the custom menu for this applet so that it can be shown
     * in the applet handle menu and other appropriate places that the applet many not itself
     * be aware of. The applet itself is still responsible for deleting and managing the
     * the menu.
     *
     * If the menu is deleted during the life of the applet, be sure to call this method again
     * with the new menu (or 0) to avoid crashes
     */
    void setCustomMenu(const QPopupMenu*);

    /**
     * Register widgets that can receive keyboard focus with this this method
     * This call results in an eventFilter being places on the widget.
     * @param widget the widget to watch for keyboard focus
     * @param watch whether to start watching the widget, or to stop doing so
     * @since 3.4
     */
    void watchForFocus(QWidget* widget, bool watch = true);

    /**
     * Call this whenever focus is needed or not needed. You do not have to call this method
     * for widgets that have been registered with watchForFocus
     * @param focus whether to or not to request focus
     * @since 3.4
     */
    void needsFocus(bool focus);

    /**
     * The orientation changed to @p orientation. Reimplement this
     * change handler in order to adjust the look of your applet.
     *
     * @deprecated Reimplement positionChange instead.
     **/
    // FIXME: Remove for KDE 4
    virtual KDE_DEPRECATED void orientationChange( Orientation /* orientation*/) {}

    /**
     * A convenience method that translates the position of the applet into which
     * direction to show a popup.
     **/
    Direction popupDirection();

    /**
     * The popup direction changed to @p direction. Reimplement this
     * change handler in order to adjust the look of your applet.
     *
     * @deprecated Reimplement positionChange instead.
     **/
    // FIXME: Remove for KDE 4
    virtual KDE_DEPRECATED void popupDirectionChange( Direction /*direction*/ ) {}

    bool eventFilter(QObject *, QEvent *);

private:
    Type         _type;
    Position     _position;
    Alignment    _alignment;
    KConfig*     _config;
    int          _actions;
protected:
    virtual void virtual_hook( int id, void* data );
    class KPanelAppletPrivate;
    KPanelAppletPrivate *d;
};

#endif