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Cache the value of GuiFontMetrics::lbearing().

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This seems to be necessary on windows, where math editing can get very
slow. Note that other methods like rbearing already use a cache.

In the future all these caches for single characters shall be unified.
This commit is contained in:
Jean-Marc Lasgouttes 2019-03-20 10:56:16 +01:00
parent b6ab5cd962
commit d3979e798c
2 changed files with 22 additions and 11 deletions
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31
src/frontends/qt4/GuiFontMetrics.cpp
View File

@ -148,20 +148,29 @@ int GuiFontMetrics::strikeoutPos() const
}
int GuiFontMetrics::lbearing(char_type c) const
{
if (!is_utf16(c))
// FIXME: QFontMetrics::leftBearing does not support the
// full unicode range. Once it does, we could use:
//return metrics_.leftBearing(toqstr(docstring(1, c)));
return 0;
return metrics_.leftBearing(ucs4_to_qchar(c));
namespace {
int const outOfLimitMetric = -10000;
}
namespace {
int const outOfLimitMetric = -10000;
int GuiFontMetrics::lbearing(char_type c) const
{
int value = lbearing_cache_.value(c, outOfLimitMetric);
if (value != outOfLimitMetric)
return value;
if (is_utf16(c))
value = metrics_.leftBearing(ucs4_to_qchar(c));
else {
// FIXME: QFontMetrics::leftBearing does not support the
// full unicode range. Once it does, we could use:
// metrics_.leftBearing(toqstr(docstring(1, c)));
value = 0;
}
lbearing_cache_.insert(c, value);
return value;
}

2
src/frontends/qt4/GuiFontMetrics.h
View File

@ -103,6 +103,8 @@ private:
/// fill in \c metrics_cache_ at specified value.
AscendDescend const fillMetricsCache(char_type) const;
/// Cache of char leftt bearings
mutable QHash<char_type, int> lbearing_cache_;
/// Cache of char right bearings
mutable QHash<char_type, int> rbearing_cache_;