QFontCache Class Reference

#include <qfont_p.h>

Inheritance diagram for QFontCache:

Classes
struct	Engine
struct	Key

Public Types
typedef QMap< Key, Engine >	EngineCache
typedef QMap< Key, QFontEngineData * >	EngineDataCache

Public Functions
void	cleanupPrinterFonts ()
void	clear ()
QFontEngine *	findEngine (const Key &key)
QFontEngineData *	findEngineData (const Key &key) const
void	insertEngine (const Key &key, QFontEngine *engine)
void	insertEngineData (const Key &key, QFontEngineData *engineData)
	QFontCache ()
void	removeEngineForFont (const QByteArray &fontName)
	~QFontCache ()
Public Functions inherited from QObject
bool	blockSignals (bool b)
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). More...
const QObjectList &	children () const
	Returns a list of child objects. More...
bool	connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool	disconnect (const char *signal=0, const QObject *receiver=0, const char *member=0)
bool	disconnect (const QObject *receiver, const char *member=0)
void	dumpObjectInfo ()
	Dumps information about signal connections, etc. More...
void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...
QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...
virtual bool	event (QEvent *)
	This virtual function receives events to an object and should return true if the event e was recognized and processed. More...
virtual bool	eventFilter (QObject *, QEvent *)
	Filters events if this object has been installed as an event filter for the watched object. More...
template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...
template<typename T >
QList< T >	findChildren (const QString &aName=QString()) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. More...
template<typename T >
QList< T >	findChildren (const QRegExp &re) const
bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false. More...
void	installEventFilter (QObject *)
	Installs an event filter filterObj on this object. More...
bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false. More...
void	killTimer (int id)
	Kills the timer with timer identifier, id. More...
virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...
void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...
QString	objectName () const
QObject *	parent () const
	Returns a pointer to the parent object. More...
QVariant	property (const char *name) const
	Returns the value of the object's name property. More...
Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...
void	removeEventFilter (QObject *)
	Removes an event filter object obj from this object. More...
void	setObjectName (const QString &name)
void	setParent (QObject *)
	Makes the object a child of parent. More...
bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value. More...
void	setUserData (uint id, QObjectUserData *data)
bool	signalsBlocked () const
	Returns true if signals are blocked; otherwise returns false. More...
int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...
QThread *	thread () const
	Returns the thread in which the object lives. More...
QObjectUserData *	userData (uint id) const
virtual	~QObject ()
	Destroys the object, deleting all its child objects. More...

Static Public Functions
static void	cleanup ()
static QFontCache *	instance ()
Static Public Functions inherited from QObject
static bool	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...
static bool	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
static bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
	Disconnects signal in object sender from method in object receiver. More...
static bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
static uint	registerUserData ()
static QString	tr (const char *sourceText, const char *comment=0, int n=-1)
static QString	trUtf8 (const char *sourceText, const char *comment=0, int n=-1)

Public Variables
EngineCache	engineCache
EngineDataCache	engineDataCache

Private Functions
void	decreaseCost (uint cost)
void	increaseCost (uint cost)
void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object. More...

Properties
uint	current_timestamp
bool	fast
uint	max_cost
int	timer_id
uint	total_cost

Static Private Attributes
static const uint	min_cost = 4*1024

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...
Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...
Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...
Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...
virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...
virtual void	customEvent (QEvent *)
	This event handler can be reimplemented in a subclass to receive custom events. More...
virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...
	QObject (QObjectPrivate &dd, QObject *parent=0)
int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal. More...
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. More...
int	senderSignalIndex () const
Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr
Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject
Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()
T *	qobject_cast (QObject *object)
	QObjectList
void *	qt_find_obj_child (QObject *parent, const char *type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

Definition at line 213 of file qfont_p.h.

Typedefs

EngineCache

typedef QMap<Key,Engine> QFontCache::EngineCache

Definition at line 266 of file qfont_p.h.

EngineDataCache

typedef QMap<Key,QFontEngineData*> QFontCache::EngineDataCache

Definition at line 250 of file qfont_p.h.

Constructors and Destructors

QFontCache()

QFontCache::QFontCache

(

)

Definition at line 2940 of file qfont.cpp.

    : QObject(), total_cost(0), max_cost(min_cost),
      current_timestamp(0), fast(false), timer_id(-1)
{
}

~QFontCache()

QFontCache::~QFontCache

(

)

Definition at line 2946 of file qfont.cpp.

{
    clear();
    {
        EngineDataCache::ConstIterator it = engineDataCache.constBegin(),
                                 end = engineDataCache.constEnd();
        while (it != end) {
            if (it.value()->ref == 0)
                delete it.value();
            else
                FC_DEBUG("QFontCache::~QFontCache: engineData %p still has refcount %d",
                         it.value(), int(it.value()->ref));
            ++it;
        }
    }
    EngineCache::ConstIterator it = engineCache.constBegin(),
                         end = engineCache.constEnd();
    while (it != end) {
        if (--it.value().data->cache_count == 0) {
            if (it.value().data->ref == 0) {
                FC_DEBUG("QFontCache::~QFontCache: deleting engine %p key=(%d / %g %g %d %d %d)",
                         it.value().data, it.key().script, it.key().def.pointSize,
                         it.key().def.pixelSize, it.key().def.weight, it.key().def.style,
                         it.key().def.fixedPitch);

                delete it.value().data;
            } else {
                FC_DEBUG("QFontCache::~QFontCache: engine = %p still has refcount %d",
                         it.value().data, int(it.value().data->ref));
            }
        }
        ++it;
    }
}

Functions

cleanup()

void QFontCache::cleanup ( )

static

Definition at line 2927 of file qfont.cpp.

Referenced by QFont::cleanup(), pointSize(), and qt_x11_set_fallback_font_family().

{
    QThreadStorage<QFontCache *> *cache = 0;
    QT_TRY {
        cache = theFontCache();
    } QT_CATCH (const std::bad_alloc &) {
        // no cache - just ignore
    }
    if (cache && cache->hasLocalData())
        cache->setLocalData(0);
}

cleanupPrinterFonts()

void QFontCache::cleanupPrinterFonts

(

)

Definition at line 3123 of file qfont.cpp.

{
    FC_DEBUG("QFontCache::cleanupPrinterFonts");

    {
        FC_DEBUG("  CLEAN engine data:");

        // clean out all unused engine data
        EngineDataCache::Iterator it = engineDataCache.begin(),
                                 end = engineDataCache.end();
        while (it != end) {
            if (it.key().screen == 0) {
                ++it;
                continue;
            }

            if(it.value()->ref != 0) {
                for(int i = 0; i < QUnicodeTables::ScriptCount; ++i) {
                    if(it.value()->engines[i]) {
                        it.value()->engines[i]->ref.deref();
                        it.value()->engines[i] = 0;
                    }
                }
                ++it;
            } else {

                EngineDataCache::Iterator rem = it++;

                decreaseCost(sizeof(QFontEngineData));

                FC_DEBUG("    %p", rem.value());

                delete rem.value();
                engineDataCache.erase(rem);
            }
        }
    }

    EngineCache::Iterator it = engineCache.begin(),
                         end = engineCache.end();
    while(it != end) {
        if (it.value().data->ref != 0 || it.key().screen == 0) {
            ++it;
            continue;
        }

        FC_DEBUG("    %p: timestamp %4u hits %2u ref %2d/%2d, type '%s'",
                 it.value().data, it.value().timestamp, it.value().hits,
                 int(it.value().data->ref), it.value().data->cache_count,
                 it.value().data->name());

        if (--it.value().data->cache_count == 0) {
            FC_DEBUG("    DELETE: last occurrence in cache");

            decreaseCost(it.value().data->cache_cost);
            delete it.value().data;
        }

        engineCache.erase(it++);
    }
}

clear()

void QFontCache::clear

(

)

Definition at line 2981 of file qfont.cpp.

Referenced by QFontDatabasePrivate::invalidate(), removeEngineForFont(), and ~QFontCache().

{
    {
        EngineDataCache::Iterator it = engineDataCache.begin(),
                                 end = engineDataCache.end();
        while (it != end) {
            QFontEngineData *data = it.value();
#if !defined(Q_WS_MAC)
            for (int i = 0; i < QUnicodeTables::ScriptCount; ++i) {
                if (data->engines[i]) {
                    data->engines[i]->ref.deref();
                    data->engines[i] = 0;
                }
            }
#else
            if (data->engine) {
                data->engine->ref.deref();
                data->engine = 0;
            }
#endif
            ++it;
        }
    }

    for (EngineCache::Iterator it = engineCache.begin(), end = engineCache.end();
         it != end; ++it) {
        if (it->data->ref == 0) {
            delete it->data;
            it->data = 0;
        }
    }

    for (EngineCache::Iterator it = engineCache.begin(), end = engineCache.end();
         it != end; ++it) {
        if (it->data && it->data->ref == 0) {
            delete it->data;
            it->data = 0;
        }
    }

    engineCache.clear();
}

decreaseCost()

void QFontCache::decreaseCost ( uint  cost )

private

Definition at line 3111 of file qfont.cpp.

Referenced by cleanupPrinterFonts(), and timerEvent().

{
    cost = (cost + 512) / 1024; // cost is stored in kb
    cost = cost > 0 ? cost : 1;
    Q_ASSERT(cost <= total_cost);
    total_cost -= cost;

    FC_DEBUG("  COST: decreased %u kb, total_cost %u kb, max_cost %u kb",
            cost, total_cost, max_cost);
}

findEngine()

QFontEngine * QFontCache::findEngine

(

const Key &

key

)

Definition at line 3054 of file qfont.cpp.

Referenced by QFontDatabase::findFont(), QFontDatabase::load(), QFontEngineMultiFT::loadEngine(), loadSingleEngine(), loadWin(), QFontDatabase::loadXlfd(), and qt_load_font_engine_win().

{
    EngineCache::Iterator it = engineCache.find(key),
                         end = engineCache.end();
    if (it == end) return 0;

    // found... update the hitcount and timestamp
    it.value().hits++;
    it.value().timestamp = ++current_timestamp;

    FC_DEBUG("QFontCache: found font engine\n"
             "  %p: timestamp %4u hits %3u ref %2d/%2d, type '%s'",
             it.value().data, it.value().timestamp, it.value().hits,
             int(it.value().data->ref), it.value().data->cache_count,
             it.value().data->name());

    return it.value().data;
}

findEngineData()

QFontEngineData * QFontCache::findEngineData

(

const Key &

key

)

const

Definition at line 3036 of file qfont.cpp.

Referenced by getEngineData(), QFontDatabase::load(), and registerFont().

{
    EngineDataCache::ConstIterator it = engineDataCache.find(key),
                                  end = engineDataCache.end();
    if (it == end) return 0;

    // found
    return it.value();
}

increaseCost()

void QFontCache::increaseCost ( uint  cost )

private

Definition at line 3089 of file qfont.cpp.

Referenced by insertEngine(), and insertEngineData().

{
    cost = (cost + 512) / 1024; // store cost in kb
    cost = cost > 0 ? cost : 1;
    total_cost += cost;

    FC_DEBUG("  COST: increased %u kb, total_cost %u kb, max_cost %u kb",
            cost, total_cost, max_cost);

    if (total_cost > max_cost) {
        max_cost = total_cost;

        if (timer_id == -1 || ! fast) {
            FC_DEBUG("  TIMER: starting fast timer (%d ms)", fast_timeout);

            if (timer_id != -1) killTimer(timer_id);
            timer_id = startTimer(fast_timeout);
            fast = true;
        }
    }
}

insertEngine()

void QFontCache::insertEngine	(	const Key &	key,
		QFontEngine *	engine
	)

Definition at line 3073 of file qfont.cpp.

Referenced by QFontDatabase::load(), QFontEngineMultiFT::loadEngine(), loadSingleEngine(), loadWin(), QFontDatabase::loadXlfd(), and registerFont().

{
    FC_DEBUG("QFontCache: inserting new engine %p", engine);

    Engine data(engine);
    data.timestamp = ++current_timestamp;

    engineCache.insert(key, data);

    // only increase the cost if this is the first time we insert the engine
    if (engine->cache_count == 0)
        increaseCost(engine->cache_cost);

    ++engine->cache_count;
}

insertEngineData()

void QFontCache::insertEngineData	(	const Key &	key,
		QFontEngineData *	engineData
	)

Definition at line 3046 of file qfont.cpp.

Referenced by getEngineData(), QFontDatabase::load(), and registerFont().

{
    FC_DEBUG("QFontCache: inserting new engine data %p", engineData);

    engineDataCache.insert(key, engineData);
    increaseCost(sizeof(QFontEngineData));
}

instance()

QFontCache * QFontCache::instance ( )

static

Definition at line 2919 of file qfont.cpp.

Referenced by QFontPrivate::engineForScript(), QFontDatabase::findFont(), getEngineData(), QFontDatabasePrivate::invalidate(), QFontDatabase::load(), QFontEngineMultiFT::loadEngine(), loadSingleEngine(), loadWin(), QFontDatabase::loadXlfd(), qt_load_font_engine_win(), QApplication::qwsProcessEvent(), and registerFont().

{
    QFontCache *&fontCache = theFontCache()->localData();
    if (!fontCache)
        fontCache = new QFontCache;
    return fontCache;
}

removeEngineForFont()

void QFontCache::removeEngineForFont

(

const QByteArray &

fontName

)

Definition at line 3025 of file qfont.cpp.

Referenced by QApplication::qwsProcessEvent().

{

    /* This could be optimized but the code becomes much more complex if we want to handle multi
     * font engines and it is probably not worth it. Therefore we just clear the entire font cache.
     */
    Q_UNUSED(_fontName);
    clear();
}

timerEvent()

void QFontCache::timerEvent ( QTimerEvent *  event )

privatevirtual

This event handler can be reimplemented in a subclass to receive timer events for the object.

QTimer provides a higher-level interface to the timer functionality, and also more general information about timers. The timer event is passed in the event parameter.

See also

startTimer(), killTimer(), event()

Reimplemented from QObject.

Definition at line 3186 of file qfont.cpp.

{
    FC_DEBUG("QFontCache::timerEvent: performing cache maintenance (timestamp %u)",
              current_timestamp);

    if (total_cost <= max_cost && max_cost <= min_cost) {
        FC_DEBUG("  cache redused sufficiently, stopping timer");

        killTimer(timer_id);
        timer_id = -1;
        fast = false;

        return;
    }

    // go through the cache and count up everything in use
    uint in_use_cost = 0;

    {
        FC_DEBUG("  SWEEP engine data:");

        // make sure the cost of each engine data is at least 1kb
        const uint engine_data_cost =
            sizeof(QFontEngineData) > 1024 ? sizeof(QFontEngineData) : 1024;

        EngineDataCache::ConstIterator it = engineDataCache.constBegin(),
                                      end = engineDataCache.constEnd();
        for (; it != end; ++it) {
#ifdef QFONTCACHE_DEBUG
            FC_DEBUG("    %p: ref %2d", it.value(), int(it.value()->ref));

#  if defined(Q_WS_X11) || defined(Q_WS_WIN)
            // print out all engines
            for (int i = 0; i < QUnicodeTables::ScriptCount; ++i) {
                if (! it.value()->engines[i])
                    continue;
                FC_DEBUG("      contains %p", it.value()->engines[i]);
            }
#  endif // Q_WS_X11 || Q_WS_WIN
#endif // QFONTCACHE_DEBUG

            if (it.value()->ref != 0)
                in_use_cost += engine_data_cost;
        }
    }

    {
        FC_DEBUG("  SWEEP engine:");

        EngineCache::ConstIterator it = engineCache.constBegin(),
                                  end = engineCache.constEnd();
        for (; it != end; ++it) {
            FC_DEBUG("    %p: timestamp %4u hits %2u ref %2d/%2d, cost %u bytes",
                     it.value().data, it.value().timestamp, it.value().hits,
                     int(it.value().data->ref), it.value().data->cache_count,
                     it.value().data->cache_cost);

            if (it.value().data->ref != 0)
                in_use_cost += it.value().data->cache_cost / it.value().data->cache_count;
        }

        // attempt to make up for rounding errors
        in_use_cost += engineCache.size();
    }

    in_use_cost = (in_use_cost + 512) / 1024; // cost is stored in kb

    /*
      calculate the new maximum cost for the cache

      NOTE: in_use_cost is *not* correct due to rounding errors in the
      above algorithm.  instead of worrying about getting the
      calculation correct, we are more interested in speed, and use
      in_use_cost as a floor for new_max_cost
    */
    uint new_max_cost = qMax(qMax(max_cost / 2, in_use_cost), min_cost);

    FC_DEBUG("  after sweep, in use %u kb, total %u kb, max %u kb, new max %u kb",
              in_use_cost, total_cost, max_cost, new_max_cost);

    if (new_max_cost == max_cost) {
        if (fast) {
            FC_DEBUG("  cannot shrink cache, slowing timer");

            killTimer(timer_id);
            timer_id = startTimer(slow_timeout);
            fast = false;
        }

        return;
    } else if (! fast) {
        FC_DEBUG("  dropping into passing gear");

        killTimer(timer_id);
        timer_id = startTimer(fast_timeout);
        fast = true;
    }

    max_cost = new_max_cost;

    {
        FC_DEBUG("  CLEAN engine data:");

        // clean out all unused engine data
        EngineDataCache::Iterator it = engineDataCache.begin(),
                                 end = engineDataCache.end();
        while (it != end) {
            if (it.value()->ref != 0) {
                ++it;
                continue;
            }

            EngineDataCache::Iterator rem = it++;

            decreaseCost(sizeof(QFontEngineData));

            FC_DEBUG("    %p", rem.value());

            delete rem.value();
            engineDataCache.erase(rem);
        }
    }

    // clean out the engine cache just enough to get below our new max cost
    uint current_cost;
    do {
        current_cost = total_cost;

        EngineCache::Iterator it = engineCache.begin(),
                             end = engineCache.end();
        // determine the oldest and least popular of the unused engines
        uint oldest = ~0u;
        uint least_popular = ~0u;

        for (; it != end; ++it) {
            if (it.value().data->ref != 0)
                continue;

            if (it.value().timestamp < oldest &&
                 it.value().hits <= least_popular) {
                oldest = it.value().timestamp;
                least_popular = it.value().hits;
            }
        }

        FC_DEBUG("    oldest %u least popular %u", oldest, least_popular);

        for (it = engineCache.begin(); it != end; ++it) {
            if (it.value().data->ref == 0 &&
                 it.value().timestamp == oldest &&
                 it.value().hits == least_popular)
                break;
        }

        if (it != end) {
            FC_DEBUG("    %p: timestamp %4u hits %2u ref %2d/%2d, type '%s'",
                     it.value().data, it.value().timestamp, it.value().hits,
                     int(it.value().data->ref), it.value().data->cache_count,
                     it.value().data->name());

            if (--it.value().data->cache_count == 0) {
                FC_DEBUG("    DELETE: last occurrence in cache");

                decreaseCost(it.value().data->cache_cost);
                delete it.value().data;
            } else {
                /*
                  this particular font engine is in the cache multiple
                  times...  set current_cost to zero, so that we can
                  keep looping to get rid of all occurrences
                */
                current_cost = 0;
            }

            engineCache.erase(it);
        }
    } while (current_cost != total_cost && total_cost > max_cost);
}

Properties

current_timestamp

uint QFontCache::current_timestamp

private

Definition at line 283 of file qfont_p.h.

Referenced by findEngine(), insertEngine(), and timerEvent().

engineCache

EngineCache QFontCache::engineCache

Definition at line 267 of file qfont_p.h.

Referenced by cleanupPrinterFonts(), clear(), findEngine(), insertEngine(), timerEvent(), and ~QFontCache().

engineDataCache

EngineDataCache QFontCache::engineDataCache

Definition at line 251 of file qfont_p.h.

Referenced by cleanupPrinterFonts(), clear(), findEngineData(), insertEngineData(), timerEvent(), and ~QFontCache().

fast

bool QFontCache::fast

private

Definition at line 284 of file qfont_p.h.

Referenced by increaseCost(), and timerEvent().

max_cost

uint QFontCache::max_cost

private

Definition at line 282 of file qfont_p.h.

Referenced by decreaseCost(), increaseCost(), and timerEvent().

min_cost

const uint QFontCache::min_cost = 4*1024

staticprivate

Definition at line 281 of file qfont_p.h.

Referenced by timerEvent().

timer_id

int QFontCache::timer_id

private

Definition at line 285 of file qfont_p.h.

Referenced by increaseCost(), and timerEvent().

total_cost

uint QFontCache::total_cost

private

Definition at line 282 of file qfont_p.h.

Referenced by decreaseCost(), increaseCost(), and timerEvent().

---

The documentation for this class was generated from the following files:

• /src/gui/text/qfont_p.h
• /src/gui/text/qfont.cpp