path: root/src/gui/text/qfontmetrics.cpp
diff options
authorEskil Abrahamsen Blomfeldt <>2017-07-03 11:30:43 +0200
committerEskil Abrahamsen Blomfeldt <>2017-07-26 10:51:00 +0000
commit73176d2922baae1ccaa702e4900b0473071d0a96 (patch)
treefc049297630455d6ea0b7f4161acfba610aed2d1 /src/gui/text/qfontmetrics.cpp
parent8719660416986702c1ee9f65c4e347efa37ac770 (diff)
Add API to disable text shaping on fonts
In the past, we had an undocumented text flag that worked with one of the QPainter::drawText() overloads. This was never intended as public API and served a specific cause in Qt WebKit at one point. But there is a general need for such API, as disabling shaping features easily gives 25% performance improvement on text rendering even for fairly short strings. This patch adds a new style strategy flag to disable shaping and will just uses the CMAP and HDMX tables to get glyph indices and advances for the characters. In Qt 6, the TextBypassShaping flag can be removed completely and be replaced by the style strategy. [ChangeLog][QtGui][Text] Added QFont::PreferNoShaping style strategy to support improvements to performance at the expense of some cosmetic font features. Task-number: QTBUG-56728 Change-Id: I48e025dcc06afe02824bf5b5011702a7e0036f6d Reviewed-by: Simon Hausmann <>
Diffstat (limited to 'src/gui/text/qfontmetrics.cpp')
1 files changed, 2 insertions, 0 deletions
diff --git a/src/gui/text/qfontmetrics.cpp b/src/gui/text/qfontmetrics.cpp
index 8067969f56..5675d6921d 100644
--- a/src/gui/text/qfontmetrics.cpp
+++ b/src/gui/text/qfontmetrics.cpp
@@ -541,6 +541,7 @@ int QFontMetrics::width(const QString &text, int len, int flags) const
if (len == 0)
return 0;
if (flags & Qt::TextBypassShaping) {
// Skip complex shaping, only use advances
int numGlyphs = len;
@@ -554,6 +555,7 @@ int QFontMetrics::width(const QString &text, int len, int flags) const
width += glyphs.advances[i];
return qRound(width);
QStackTextEngine layout(text, QFont(;
return qRound(layout.width(0, len));