/********************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

Copyright (C) 2011 Arthur Arlt <a.arlt@stud.uni-heidelberg.de>
Copyright (C) 2012 Martin Gräßlin <mgraesslin@kde.org>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, 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 General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/

#ifndef KWIN_COMPOSITE_H
#define KWIN_COMPOSITE_H

#include <QObject>
#include <QElapsedTimer>
#include <QTimer>
#include <QBasicTimer>
#include <QRegion>

class KSelectionOwner;

namespace KWin {

class Client;
class Scene;

class Compositor : public QObject {
    Q_OBJECT
    Q_CLASSINFO("D-Bus Interface", "org.kde.kwin.Compositing")
    /**
     * @brief Whether the Compositor is active. That is a Scene is present and the Compositor is
     * not shutting down itself.
     **/
    Q_PROPERTY(bool active READ isActive)
    /**
     * @brief Whether compositing is possible. Mostly means whether the required X extensions
     * are available.
     **/
    Q_PROPERTY(bool compositingPossible READ isCompositingPossible)
    /**
     * @brief The reason why compositing is not possible. Empty String if compositing is possible.
     **/
    Q_PROPERTY(QString compositingNotPossibleReason READ compositingNotPossibleReason)
    /**
     * @brief Whether OpenGL has failed badly in the past (crash) and is considered as broken.
     **/
    Q_PROPERTY(bool openGLIsBroken READ isOpenGLBroken)
    /**
     * The type of the currently used Scene:
     * @li @c none No Compositing
     * @li @c xrender XRender
     * @li @c gl1 OpenGL 1
     * @li @c gl2 OpenGL 2
     * @li @c gles OpenGL ES 2
     **/
    Q_PROPERTY(QString compositingType READ compositingType)
public:
    enum SuspendReason { NoReasonSuspend = 0, UserSuspend = 1<<0, BlockRuleSuspend = 1<<1, ScriptSuspend = 1<<2, AllReasonSuspend = 0xff };
    Q_DECLARE_FLAGS(SuspendReasons, SuspendReason)
    ~Compositor();
    // when adding repaints caused by a window, you probably want to use
    // either Toplevel::addRepaint() or Toplevel::addWorkspaceRepaint()
    void addRepaint(const QRect& r);
    void addRepaint(const QRegion& r);
    void addRepaint(int x, int y, int w, int h);
    /**
     * Whether the Compositor is active. That is a Scene is present and the Compositor is
     * not shutting down itself.
     **/
    bool isActive();
    int xrrRefreshRate() const {
        return m_xrrRefreshRate;
    }
    void setCompositeResetTimer(int msecs);
    // returns the _estimated_ delay to the next screen update
    // good for having a rough idea to calculate transformations, bad to rely on.
    // might happen few ms earlier, might be an entire frame to short. This is NOT deterministic.
    int nextFrameDelay() const {
        return m_nextFrameDelay;
    }
    bool hasScene() const {
        return m_scene != NULL;
    }

    /**
     * Checks whether @p w is the Scene's overlay window.
     **/
    bool checkForOverlayWindow(WId w) const;
    /**
     * @returns The Scene's Overlay X Window.
     **/
    WId overlayWindow() const;
    /**
     * @returns Whether the Scene's Overlay X Window is visible.
     **/
    bool isOverlayWindowVisible() const;
    /**
     * Set's the Scene's Overlay X Window visibility to @p visible.
     **/
    void setOverlayWindowVisibility(bool visible);

    Scene *scene() {
        return m_scene;
    }

    /**
     * @brief Factory Method to create the Compositor singleton.
     *
     * This method is mainly used by Workspace to create the Compositor Singleton as a child
     * of the Workspace.
     *
     * To actually access the Compositor instance use @link self.
     *
     * @param parent The parent object
     * @return :Compositor* Created Compositor if not already created
     * @warning This method is not Thread safe.
     * @see self
     **/
    static Compositor *createCompositor(QObject *parent);
    /**
     * @brief Singleton getter for the Compositor object.
     *
     * Ensure that the Compositor has been created through createCompositor prior to access
     * this method.
     *
     * @return :Compositor* The Compositor instance
     * @see createCompositor
     **/
    static Compositor *self() {
        return s_compositor;
    }
    /**
     * @brief Checks whether the Compositor has already been created by the Workspace.
     *
     * This method can be used to check whether self will return the Compositor instance or @c null.
     *
     * @return bool @c true if the Compositor has been created, @c false otherwise
     **/
    static bool isCreated() {
        return s_compositor != NULL;
    }
    /**
     * @brief Static check to test whether the Compositor is available and active.
     *
     * @return bool @c true if there is a Compositor and it is active, @c false otherwise
     **/
    static bool compositing() {
        return s_compositor != NULL && s_compositor->isActive();
    }

    // D-Bus: getters for Properties, see documentation on the property
    bool isCompositingPossible() const;
    QString compositingNotPossibleReason() const;
    bool isOpenGLBroken() const;
    QString compositingType() const;

public Q_SLOTS:
    void addRepaintFull();
    /**
     * Called from the D-Bus interface. Does the same as slotToggleCompositing with the
     * addition to show a notification on how to revert the compositing state.
     * @see resume
     * @see suspend
     * @deprecated Use suspend or resume instead
     **/
    Q_SCRIPTABLE void toggleCompositing();
    /**
     * @brief Suspends the Compositor if it is currently active.
     *
     * Note: it is possible that the Compositor is not able to suspend. Use @link isActive to check
     * whether the Compositor has been suspended.
     *
     * @return void
     * @see resume
     * @see isActive
     **/
    Q_SCRIPTABLE inline void suspend() { suspend(ScriptSuspend); }
    void suspend(Compositor::SuspendReason reason);
    /**
     * @brief Resumes the Compositor if it is currently suspended.
     *
     * Note: it is possible that the Compositor cannot be resumed, that is there might be Clients
     * blocking the usage of Compositing or the Scene might be broken. Use @link isActive to check
     * whether the Compositor has been resumed. Also check @link isCompositingPossible and
     * @link isOpenGLBroken.
     *
     * Note: The starting of the Compositor can require some time and is partially done threaded.
     * After this method returns the setup may not have been completed.
     *
     * @return void
     * @see suspend
     * @see isActive
     * @see isCompositingPossible
     * @see isOpenGLBroken
     **/
    Q_SCRIPTABLE inline void resume() { resume(ScriptSuspend); }
    void resume(Compositor::SuspendReason reason);
    /**
     * @brief Tries to suspend or resume the Compositor based on @p active.
     *
     * In case the Compositor is already in the asked for state this method is doing nothing. In
     * case it does not match it is tried to either resume or suspend the Compositor.
     *
     * Note: these operations may fail. There is no guarantee that after calling this method to
     * enable/disable the Compositor, it actually changes to the state. Use @link isActive to check
     * the actual state of the Compositor.
     *
     * Note: The starting of the Compositor can require some time and is partially done threaded.
     * After this method returns the setup may not have been completed.
     *
     * Note: This function only impacts whether compositing is suspended or resumed by scripts
     * or dbus calls. Compositing may be suspended for user will or a window rule - no matter how
     * often you call this function!
     *
     * @param active Whether the Compositor should be resumed (@c true) or suspended (@c false)
     * @return void
     * @see suspend
     * @see resume
     * @see isActive
     * @see isCompositingPossible
     * @see isOpenGLBroken
     **/
    // NOTICE this is atm. for script usage *ONLY* and needs to be extended like resume / suspend are
    // if intended to be used from within KWin code!
    Q_SCRIPTABLE void setCompositing(bool active);
    /**
     * Actual slot to perform the toggling compositing.
     * That is if the Compositor is suspended it will be resumed and if the Compositor is active
     * it will be suspended.
     * Invoked primarily by the keybinding.
     * TODO: make private slot
     **/
    void slotToggleCompositing();
    /**
     * Re-initializes the Compositor completely.
     * Connected to the D-Bus signal org.kde.KWin /KWin reinitCompositing
     **/
    void slotReinitialize();
    /**
     * Schedules a new repaint if no repaint is currently scheduled.
     **/
    void scheduleRepaint();
    void checkUnredirect();
    void checkUnredirect(bool force);
    void updateCompositeBlocking();
    void updateCompositeBlocking(KWin::Client* c);

    // For the D-Bus interface

Q_SIGNALS:
    Q_SCRIPTABLE void compositingToggled(bool active);

protected:
    void timerEvent(QTimerEvent *te);

private Q_SLOTS:
    void setup();
    /**
     * Called from setupCompositing() when the CompositingPrefs are ready.
     **/
    void slotCompositingOptionsInitialized();
    void finish();
    /**
     * Restarts the Compositor if running.
     * That is the Compositor will be stopped and started again.
     **/
    void restart();
    void fallbackToXRenderCompositing();
    void performCompositing();
    void delayedCheckUnredirect();
    void slotConfigChanged();
    void releaseCompositorSelection();

private:
    Compositor(QObject *workspace);
    void setCompositeTimer();
    bool windowRepaintsPending() const;

    /**
     * Restarts the Window Manager in case that the Qt's GraphicsSystem need to be changed
     * for the chosen Compositing backend.
     * @param reason The reason why the Window Manager is being restarted, this is logged
     **/
    void restartKWin(const QString &reason);

    /**
     * Whether the Compositor is currently suspended, 8 bits encoding the reason
     **/
    SuspendReasons m_suspended;

    QBasicTimer compositeTimer;
    KSelectionOwner* cm_selection;
    QTimer m_releaseSelectionTimer;
    uint vBlankInterval, fpsInterval;
    int m_xrrRefreshRate;
    QElapsedTimer nextPaintReference;
    QRegion repaints_region;

    QTimer unredirectTimer;
    bool forceUnredirectCheck;
    QTimer compositeResetTimer; // for compressing composite resets
    bool m_finishing; // finish() sets this variable while shutting down
    bool m_starting; // start() sets this variable while starting
    int m_timeSinceLastVBlank, m_nextFrameDelay;
    Scene *m_scene;

    static Compositor *s_compositor;
};
}

# endif // KWIN_COMPOSITE_H