kwin/src/focuschain.h
2022-07-21 15:16:40 +02:00

232 lines
9 KiB
C++

/*
KWin - the KDE window manager
This file is part of the KDE project.
SPDX-FileCopyrightText: 2012 Martin Gräßlin <mgraesslin@kde.org>
SPDX-License-Identifier: GPL-2.0-or-later
*/
#ifndef KWIN_FOCUS_CHAIN_H
#define KWIN_FOCUS_CHAIN_H
// KWin
#include <kwinglobals.h>
// Qt
#include <QHash>
#include <QObject>
namespace KWin
{
// forward declarations
class Window;
class Output;
class VirtualDesktop;
/**
* @brief Singleton class to handle the various focus chains.
*
* A focus chain is a list of Windows containing information on which Window should be activated.
*
* Internally this FocusChain holds multiple independent chains. There is one chain of most recently
* used Windows which is primarily used by TabBox to build up the list of Windows for navigation.
* The chains are organized as a normal QList of Windows with the most recently used Window being the
* last item of the list, that is a LIFO like structure.
*
* In addition there is one chain for each virtual desktop which is used to determine which Window
* should get activated when the user switches to another virtual desktop.
*
* Furthermore this class contains various helper methods for the two different kind of chains.
*/
class FocusChain : public QObject
{
Q_OBJECT
public:
enum Change {
MakeFirst,
MakeLast,
Update,
MakeFirstMinimized = MakeFirst
};
explicit FocusChain() = default;
/**
* @brief Updates the position of the @p window according to the requested @p change in the
* focus chain.
*
* This method affects both the most recently used focus chain and the per virtual desktop focus
* chain.
*
* In case the window does no longer want to get focus, it is removed from all chains. In case
* the window is on all virtual desktops it is ensured that it is present in each of the virtual
* desktops focus chain. In case it's on exactly one virtual desktop it is ensured that it is only
* in the focus chain for that virtual desktop.
*
* Depending on @p change the Window is inserted at different positions in the focus chain. In case
* of @c MakeFirst it is moved to the first position of the chain, in case of
* @c MakeLast it is moved to the last position of the chain. In all other cases it
* depends on whether the @p window is the currently active Window. If it is the active Window it
* becomes the first Window in the chain, otherwise it is inserted at the second position that is
* directly after the currently active Window.
*
* @param window The Window which should be moved inside the chains.
* @param change Where to move the Window
* @return void
*/
void update(Window *window, Change change);
/**
* @brief Moves @p window behind the @p reference Window in all focus chains.
*
* @param window The Window to move in the chains
* @param reference The Window behind which the @p window should be moved
* @return void
*/
void moveAfterWindow(Window *window, Window *reference);
/**
* @brief Finds the best Window to become the new active Window in the focus chain for the given
* virtual @p desktop.
*
* In case that separate screen focus is used only Windows on the current screen are considered.
* If no Window for activation is found @c null is returned.
*
* @param desktop The virtual desktop to look for a Window for activation
* @return :X11Window *The Window which could be activated or @c null if there is none.
*/
Window *getForActivation(VirtualDesktop *desktop) const;
/**
* @brief Finds the best Window to become the new active Window in the focus chain for the given
* virtual @p desktop on the given @p screen.
*
* This method makes only sense to use if separate screen focus is used. If separate screen focus
* is disabled the @p screen is ignored.
* If no Window for activation is found @c null is returned.
*
* @param desktop The virtual desktop to look for a Window for activation
* @param output The screen to constrain the search on with separate screen focus
* @return :X11Window *The Window which could be activated or @c null if there is none.
*/
Window *getForActivation(VirtualDesktop *desktop, Output *output) const;
/**
* @brief Checks whether the most recently used focus chain contains the given @p window.
*
* Does not consider the per-desktop focus chains.
* @param window The Window to look for.
* @return bool @c true if the most recently used focus chain contains @p window, @c false otherwise.
*/
bool contains(Window *window) const;
/**
* @brief Checks whether the focus chain for the given @p desktop contains the given @p window.
*
* Does not consider the most recently used focus chain.
*
* @param window The Window to look for.
* @param desktop The virtual desktop whose focus chain should be used
* @return bool @c true if the focus chain for @p desktop contains @p window, @c false otherwise.
*/
bool contains(Window *window, VirtualDesktop *desktop) const;
/**
* @brief Queries the most recently used focus chain for the next Window after the given
* @p reference Window.
*
* The navigation wraps around the borders of the chain. That is if the @p reference Window is
* the last item of the focus chain, the first Window will be returned.
*
* If the @p reference Window cannot be found in the focus chain, the first element of the focus
* chain is returned.
*
* @param reference The start point in the focus chain to search
* @return :X11Window *The relatively next Window in the most recently used chain.
*/
Window *nextMostRecentlyUsed(Window *reference) const;
/**
* @brief Queries the focus chain for @p desktop for the next Window in relation to the given
* @p reference Window.
*
* The method finds the first usable Window which is not the @p reference Window. If no Window
* can be found @c null is returned
*
* @param reference The reference Window which should not be returned
* @param desktop The virtual desktop whose focus chain should be used
* @return :X11Window *The next usable Window or @c null if none can be found.
*/
Window *nextForDesktop(Window *reference, VirtualDesktop *desktop) const;
/**
* @brief Returns the first Window in the most recently used focus chain. First Window in this
* case means really the first Window in the chain and not the most recently used Window.
*
* @return :X11Window *The first Window in the most recently used chain.
*/
Window *firstMostRecentlyUsed() const;
bool isUsableFocusCandidate(Window *window, Window *prev) const;
public Q_SLOTS:
/**
* @brief Removes @p window from all focus chains.
*
* @param window The Window to remove from all focus chains.
* @return void
*/
void remove(KWin::Window *window);
void setSeparateScreenFocus(bool enabled);
void setActiveWindow(KWin::Window *window);
void setCurrentDesktop(VirtualDesktop *desktop);
void addDesktop(VirtualDesktop *desktop);
void removeDesktop(VirtualDesktop *desktop);
private:
using Chain = QList<Window *>;
/**
* @brief Makes @p window the first Window in the given focus @p chain.
*
* This means the existing position of @p window is dropped and @p window is appended to the
* @p chain which makes it the first item.
*
* @param window The Window to become the first in @p chain
* @param chain The focus chain to operate on
* @return void
*/
void makeFirstInChain(Window *window, Chain &chain);
/**
* @brief Makes @p window the last Window in the given focus @p chain.
*
* This means the existing position of @p window is dropped and @p window is prepended to the
* @p chain which makes it the last item.
*
* @param window The Window to become the last in @p chain
* @param chain The focus chain to operate on
* @return void
*/
void makeLastInChain(Window *window, Chain &chain);
void moveAfterWindowInChain(Window *window, Window *reference, Chain &chain);
void updateWindowInChain(Window *window, Change change, Chain &chain);
void insertWindowIntoChain(Window *window, Chain &chain);
Chain m_mostRecentlyUsed;
QHash<VirtualDesktop *, Chain> m_desktopFocusChains;
bool m_separateScreenFocus = false;
Window *m_activeWindow = nullptr;
VirtualDesktop *m_currentDesktop = nullptr;
};
inline bool FocusChain::contains(Window *window) const
{
return m_mostRecentlyUsed.contains(window);
}
inline void FocusChain::setSeparateScreenFocus(bool enabled)
{
m_separateScreenFocus = enabled;
}
inline void FocusChain::setActiveWindow(Window *window)
{
m_activeWindow = window;
}
inline void FocusChain::setCurrentDesktop(VirtualDesktop *desktop)
{
m_currentDesktop = desktop;
}
} // namespace
#endif // KWIN_FOCUS_CHAIN_H