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| author | Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io> | 2016-07-20 10:29:51 +0200 |
|---|---|---|
| committer | Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io> | 2016-07-22 12:14:03 +0000 |
| commit | 49926bb9ef983d4c19aed635a00b388252c065e4 (patch) | |
| tree | d64ede0eabe2112553f04bab14ffdd6aa15daaa3 /src | |
| parent | 77a71c32c9d19b87f79b208929e71282e8d8b5d9 (diff) | |
Fix performance regression when changing fonts
Change e109b8a0f3c89c595f0da689e7ee847130e2ee47 introduced a
performance regression when rapidly switching fonts as long as
the number of different fonts is over a relatively small number, since
the cost of fonts can be high compared to the limits set on the cache.
Since the original patch was intended to avoid exceeding the
open file limit when using Freetype on Windows, we add an
additional check on the number of engines in the cache as well
for the added, synchronous cache flush.
The limit is set to 256 to make it unlikely that it is exceeded
during a single paint event, but it can also be configured when
building Qt if a higher limit is needed.
[ChangeLog][QtGui][Text] Fixed performance regression when rapidly
switching between a large set of fonts.
Task-number: QTBUG-54180
Change-Id: I92b9fbe14fca4f11c9c6dfdcdbec6d19a61b86a7
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/gui/text/qfont.cpp | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/gui/text/qfont.cpp b/src/gui/text/qfont.cpp index fe68149346..ea34614cb5 100644 --- a/src/gui/text/qfont.cpp +++ b/src/gui/text/qfont.cpp @@ -70,7 +70,9 @@ QT_BEGIN_NAMESPACE - +#ifndef QFONTCACHE_DECREASE_TRIGGER_LIMIT +# define QFONTCACHE_DECREASE_TRIGGER_LIMIT 256 +#endif bool QFontDef::exactMatch(const QFontDef &other) const { @@ -2797,7 +2799,7 @@ void QFontCache::insertEngineData(const QFontDef &def, QFontEngineData *engineDa engineData->ref.ref(); // Decrease now rather than waiting - if (total_cost > min_cost * 2) + if (total_cost > min_cost * 2 && engineDataCache.size() >= QFONTCACHE_DECREASE_TRIGGER_LIMIT) decreaseCache(); engineDataCache.insert(def, engineData); @@ -2846,7 +2848,7 @@ void QFontCache::insertEngine(const Key &key, QFontEngine *engine, bool insertMu #endif engine->ref.ref(); // Decrease now rather than waiting - if (total_cost > min_cost * 2) + if (total_cost > min_cost * 2 && engineCache.size() >= QFONTCACHE_DECREASE_TRIGGER_LIMIT) decreaseCache(); Engine data(engine); |