kwin/focuschain.h
2020-08-07 19:57:56 +00:00

242 lines
9.5 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 <QObject>
#include <QHash>
namespace KWin
{
// forward declarations
class AbstractClient;
/**
* @brief Singleton class to handle the various focus chains.
*
* A focus chain is a list of Clients containing information on which Client should be activated.
*
* Internally this FocusChain holds multiple independent chains. There is one chain of most recently
* used Clients which is primarily used by TabBox to build up the list of Clients for navigation.
* The chains are organized as a normal QList of Clients with the most recently used Client 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 Client
* 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
};
~FocusChain() override;
/**
* @brief Updates the position of the @p client 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 client does no longer want to get focus, it is removed from all chains. In case
* the client 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 Client 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 client is the currently active Client. If it is the active Client it
* becomes the first Client in the chain, otherwise it is inserted at the second position that is
* directly after the currently active Client.
*
* @param client The Client which should be moved inside the chains.
* @param change Where to move the Client
* @return void
*/
void update(AbstractClient *client, Change change);
/**
* @brief Moves @p client behind the @p reference Client in all focus chains.
*
* @param client The Client to move in the chains
* @param reference The Client behind which the @p client should be moved
* @return void
*/
void moveAfterClient(AbstractClient *client, AbstractClient *reference);
/**
* @brief Finds the best Client to become the new active Client in the focus chain for the given
* virtual @p desktop.
*
* In case that separate screen focus is used only Clients on the current screen are considered.
* If no Client for activation is found @c null is returned.
*
* @param desktop The virtual desktop to look for a Client for activation
* @return :X11Client *The Client which could be activated or @c null if there is none.
*/
AbstractClient *getForActivation(uint desktop) const;
/**
* @brief Finds the best Client to become the new active Client 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 Client for activation is found @c null is returned.
*
* @param desktop The virtual desktop to look for a Client for activation
* @param screen The screen to constrain the search on with separate screen focus
* @return :X11Client *The Client which could be activated or @c null if there is none.
*/
AbstractClient *getForActivation(uint desktop, int screen) const;
/**
* @brief Checks whether the most recently used focus chain contains the given @p client.
*
* Does not consider the per-desktop focus chains.
* @param client The Client to look for.
* @return bool @c true if the most recently used focus chain contains @p client, @c false otherwise.
*/
bool contains(AbstractClient *client) const;
/**
* @brief Checks whether the focus chain for the given @p desktop contains the given @p client.
*
* Does not consider the most recently used focus chain.
*
* @param client The Client 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 client, @c false otherwise.
*/
bool contains(AbstractClient *client, uint desktop) const;
/**
* @brief Queries the most recently used focus chain for the next Client after the given
* @p reference Client.
*
* The navigation wraps around the borders of the chain. That is if the @p reference Client is
* the last item of the focus chain, the first Client will be returned.
*
* If the @p reference Client 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 :X11Client *The relatively next Client in the most recently used chain.
*/
AbstractClient *nextMostRecentlyUsed(AbstractClient *reference) const;
/**
* @brief Queries the focus chain for @p desktop for the next Client in relation to the given
* @p reference Client.
*
* The method finds the first usable Client which is not the @p reference Client. If no Client
* can be found @c null is returned
*
* @param reference The reference Client which should not be returned
* @param desktop The virtual desktop whose focus chain should be used
* @return :X11Client *The next usable Client or @c null if none can be found.
*/
AbstractClient *nextForDesktop(AbstractClient *reference, uint desktop) const;
/**
* @brief Returns the first Client in the most recently used focus chain. First Client in this
* case means really the first Client in the chain and not the most recently used Client.
*
* @return :X11Client *The first Client in the most recently used chain.
*/
AbstractClient *firstMostRecentlyUsed() const;
public Q_SLOTS:
/**
* @brief Resizes the per virtual desktop focus chains from @p previousSize to @p newSize.
* This means that for each virtual desktop between previous and new size a new focus chain is
* created and in case the number is reduced the focus chains are destroyed.
*
* @param previousSize The previous number of virtual desktops
* @param newSize The new number of virtual desktops
* @return void
*/
void resize(uint previousSize, uint newSize);
/**
* @brief Removes @p client from all focus chains.
*
* @param client The Client to remove from all focus chains.
* @return void
*/
void remove(KWin::AbstractClient *client);
void setSeparateScreenFocus(bool enabled);
void setActiveClient(KWin::AbstractClient *client);
void setCurrentDesktop(uint previous, uint newDesktop);
bool isUsableFocusCandidate(AbstractClient *c, AbstractClient *prev) const;
private:
using Chain = QList<AbstractClient*>;
/**
* @brief Makes @p client the first Client in the given focus @p chain.
*
* This means the existing position of @p client is dropped and @p client is appended to the
* @p chain which makes it the first item.
*
* @param client The Client to become the first in @p chain
* @param chain The focus chain to operate on
* @return void
*/
void makeFirstInChain(AbstractClient *client, Chain &chain);
/**
* @brief Makes @p client the last Client in the given focus @p chain.
*
* This means the existing position of @p client is dropped and @p client is prepended to the
* @p chain which makes it the last item.
*
* @param client The Client to become the last in @p chain
* @param chain The focus chain to operate on
* @return void
*/
void makeLastInChain(AbstractClient *client, Chain &chain);
void moveAfterClientInChain(AbstractClient *client, AbstractClient *reference, Chain &chain);
void updateClientInChain(AbstractClient *client, Change change, Chain &chain);
void insertClientIntoChain(AbstractClient *client, Chain &chain);
Chain m_mostRecentlyUsed;
QHash<uint, Chain> m_desktopFocusChains;
bool m_separateScreenFocus;
AbstractClient *m_activeClient;
uint m_currentDesktop;
KWIN_SINGLETON_VARIABLE(FocusChain, s_manager)
};
inline
bool FocusChain::contains(AbstractClient *client) const
{
return m_mostRecentlyUsed.contains(client);
}
inline
void FocusChain::setSeparateScreenFocus(bool enabled)
{
m_separateScreenFocus = enabled;
}
inline
void FocusChain::setActiveClient(AbstractClient *client)
{
m_activeClient = client;
}
inline
void FocusChain::setCurrentDesktop(uint previous, uint newDesktop)
{
Q_UNUSED(previous)
m_currentDesktop = newDesktop;
}
} // namespace
#endif // KWIN_FOCUS_CHAIN_H