/*
 *   Copyright 2006-2007 Aaron Seigo <aseigo@kde.org>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as
 *   published by the Free Software Foundation; either version 2, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the
 *   Free Software Foundation, Inc.,
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#ifndef PLASMA_THEME_H
#define PLASMA_THEME_H

#include <QtCore/QObject>
#include <QtGui/QFont>
#include <QtGui/QFontMetrics>

#include <ksharedconfig.h>

#include <plasma/plasma_export.h>
#include <plasma/packagestructure.h>

namespace Plasma
{

class ThemePrivate;

/**
 * @class Theme plasma/theme.h <Plasma/Theme>
 *
 * @short Interface to the Plasma theme
 *
 * Accessed via Plasma::Theme::defaultTheme() e.g:
 * \code
 * QString imagePath = Plasma::Theme::defaultTheme()->imagePath("widgets/clock")
 * \endcode
 *
 * Plasma::Theme provides access to a common and standardized set of graphic
 * elements stored in SVG format. This allows artists to create single packages
 * of SVGs that will affect the look and feel of all workspace components.
 *
 * Plasma::Svg uses Plasma::Theme internally to locate and load the appropriate
 * SVG data. Alternatively, Plasma::Theme can be used directly to retrieve
 * file system paths to SVGs by name.
 */
class PLASMA_EXPORT Theme : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString themeName READ themeName)

    public:
        enum ColorRole {
            TextColor = 0, /**<  the text color to be used by items resting on the background */
            HighlightColor = 1, /**<  the text higlight color to be used by items resting
                                   on the background */
            BackgroundColor = 2, /**< the default background color */
            ButtonTextColor = 4, /** text color for buttons */
            ButtonBackgroundColor = 8 /** background color for buttons*/
        };

        enum FontRole {
            DefaultFont = 0, /**< The standard text font */
            DesktopFont /**< The standard text font */
        };

        /**
         * Singleton pattern accessor
         **/
        static Theme *defaultTheme();

        /**
         * Default constructor. Usually you want to use the singleton instead.
         */
        explicit Theme(QObject *parent = 0);
        ~Theme();

        /**
         * @return a package structure representing a Theme
         */
        static PackageStructure::Ptr packageStructure();

        /**
         * Sets the current theme being used.
         */
        void setThemeName(const QString &themeName);

        /**
         * @return the name of the theme.
         */
        QString themeName() const;

        /**
         * Retrieve the path for an SVG image in the current theme.
         *
         * @arg name the name of the file in the theme directory (without the
         *           ".svg" part or a leading slash)
         * @return the full path to the requested file for the current theme
         */
        Q_INVOKABLE QString imagePath(const QString &name) const;

        /**
         * Retreives the default wallpaper associated with this theme.
         *
         * @arg size the target height and width of the wallpaper; if an invalid size
         *           is passed in, then a default size will be provided instead.
         * @return the full path to the wallpaper image
         */
        Q_INVOKABLE QString wallpaperPath(const QSize &size = QSize()) const;

        /**
         * Checks if this theme has an image named in a certain way
         *
         * @arg name the name of the file in the theme directory (without the
         *           ".svg" part or a leading slash)
         * @return true if the image exists for this theme
         */
        Q_INVOKABLE bool currentThemeHasImage(const QString &name) const;

        /**
         * Returns the color scheme configurationthat goes along this theme.
         * This can be used with KStatefulBrush and KColorScheme to determine
         * the proper colours to use along with the visual elements in this theme.
         */
        Q_INVOKABLE KSharedConfigPtr colorScheme() const;

        /**
         * Returns the text color to be used by items resting on the background
         *
         * @arg role which role (usage pattern) to get the color for
         */
        Q_INVOKABLE QColor color(ColorRole role) const;

        /**
         * Sets the default font to be used with themed items. Defaults to
         * the application wide default font.
         *
         * @arg font the new font
         * @arg role which role (usage pattern) to set the font for
         */
        Q_INVOKABLE void setFont(const QFont &font, FontRole role = DefaultFont);

        /**
         * Returns the font to be used by themed items
         *
         * @arg role which role (usage pattern) to get the font for
         */
        Q_INVOKABLE QFont font(FontRole role) const;

        /**
         * Returns the font metrics for the font to be used by themed items
         */
        Q_INVOKABLE QFontMetrics fontMetrics() const;

        /**
         * Returns if the window manager effects (e.g. translucency, compositing) is active or not
         */
        Q_INVOKABLE bool windowTranslucencyEnabled() const;

        /**
         * Tells the theme whether to follow the global settings or use application
         * specific settings
         *
         * @arg useGlobal pass in true to follow the global settings
         */
        void setUseGlobalSettings(bool useGlobal);

        /**
         * @return true if the global settings are followed, false if application
         * specific settings are used.
         */
        bool useGlobalSettings() const;

        /**
         * Tries to load pixmap with the specified key from cache.
         * @return true when pixmap was found and loaded from cache, false otherwise
         **/
        bool findInCache(const QString &key, QPixmap &pix);

        /**
         * Insert specified pixmap into the cache.
         * If the cache already contains pixmap with the specified key then it is
         *  overwritten.
         **/
        void insertIntoCache(const QString& key, const QPixmap& pix);

        /**
         * Sets the maximum size of the cache (in kilobytes). If cache gets bigger
         * the limit then some entries are removed
         * Setting cache limit to 0 disables automatic cache size limiting.
         *
         * Note that the cleanup might not be done immediately, so the cache might
         *  temporarily (for a few seconds) grow bigger than the limit.
         **/
        void setCacheLimit(int kbytes);

        /**
         * Tries to load the rect of a sub element from a disk cache
         *
         * @arg image path of the image we want to check
         * @arg element sub element we want to retrieve
         * @arg rect output parameter of the element rect found in cache 
         *           if not found or if we are sure it doesn't exist it will be QRect()
         * @return true if the element was found in cache or if we are sure the element doesn't exist
         **/
        bool findInRectsCache(const QString &image, const QString &element, QRectF &rect) const;

        /**
         * Inserts a rectangle of a sub element of an image into a disk cache
         *
         * @arg image path of the image we want to insert information
         * @arg element sub element we want insert the rect
         * @arg rect element rectangle
         **/
        void insertIntoRectsCache(const QString& image, const QString &element, const QRectF &rect);

        /**
         * Discards all the information about a given image from the rectangle disk cache
         *
         * @arg image the path to the image the cache is assoiated with
         **/
        void invalidateRectsCache(const QString &image);

        /**
         * Frees up memory used by cached information for a given image without removing
         * the permenant record of it on disk.
         * @see invalidateRectsCache
         *
         * @arg image the path to the image the cache is assoiated with
         */
        void releaseRectsCache(const QString &image);

    Q_SIGNALS:
        /**
         * Emitted when the user changes the theme. SVGs should be reloaded at
         * that point
         */
        void themeChanged();

    public Q_SLOTS:
        /**
         * Notifies the Theme object that the theme settings have changed
         * and should be read from the config file
         **/
        void settingsChanged();

    private:
        friend class ThemeSingleton;
        friend class ThemePrivate;
        ThemePrivate *const d;

        Q_PRIVATE_SLOT(d, void compositingChanged())
        Q_PRIVATE_SLOT(d, void discardCache())
        Q_PRIVATE_SLOT(d, void colorsChanged())
};

} // Plasma namespace

#endif // multiple inclusion guard

