diff options
author | Mitch Curtis <mitch.curtis@qt.io> | 2024-03-15 16:37:06 +0800 |
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committer | Qt Cherry-pick Bot <cherrypick_bot@qt-project.org> | 2024-03-19 14:19:18 +0000 |
commit | bb53c6705aa6bc3c04babdb0882b4462ecf97557 (patch) | |
tree | ce66b4eaed3fd9d4487bb75b38f708c8a8ba5fd7 | |
parent | d9f4fc510d8eef56113c36cd0d3b75eddd206f6b (diff) |
Doc: explain how to check for the existence of a font family
bb6d68703b67e042e2a7254c2ca6a004a1441cc5 fixed warnings in the
Universal style by using a faster alternative. It's possible that users
will run into these warnings too, and they should be provided with
information to make a more informed choice about which approach they
can use.
Fixes: QTBUG-123360
Pick-to: 6.5
Change-Id: I4170e9ade40c4b54dbc2bd73d124b2ade4d8c939
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
(cherry picked from commit ce9f06c1579efda7ae0d259bfaa565f99d89e4f7)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 78b7b0472cb086f4be157ffee8d6c26bff8502ca)
-rw-r--r-- | src/gui/text/qfont.cpp | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/src/gui/text/qfont.cpp b/src/gui/text/qfont.cpp index 05225d1408..68b564c164 100644 --- a/src/gui/text/qfont.cpp +++ b/src/gui/text/qfont.cpp @@ -2750,6 +2750,35 @@ QDataStream &operator>>(QDataStream &s, QFont &font) info object is \e not updated. \endlist + \section1 Checking for the existence of a font + + Sometimes it can be useful to check if a font exists before attempting + to use it. The most thorough way of doing so is by using \l {exactMatch()}: + + \code + const QFont segoeFont(QLatin1String("Segoe UI")); + if (QFontInfo(segoeFont).exactMatch()) { + // Use the font... + } + \endcode + + However, this deep search of families can be expensive on some platforms. + \c QFontDatabase::families().contains() is a faster, but less thorough + alternative: + + \code + const QLatin1String segoeUiFamilyName("Segoe UI"); + if (QFontDatabase::families().contains(segoeUiFamilyName)) { + const QFont segoeFont(segoeUiFamilyName); + // Use the font... + } + \endcode + + It's less thorough because it's not a complete search: some font family + aliases may be missing from the list. However, this approach results in + faster application startup times, and so should always be preferred if + possible. + \sa QFont, QFontMetrics, QFontDatabase */ @@ -2766,6 +2795,8 @@ QDataStream &operator>>(QDataStream &s, QFont &font) Use QPainter::fontInfo() to get the font info when painting. This will give correct results also when painting on paint device that is not screen-compatible. + + \sa {Checking for the existence of a font} */ QFontInfo::QFontInfo(const QFont &font) : d(font.d) @@ -2807,7 +2838,7 @@ QFontInfo &QFontInfo::operator=(const QFontInfo &fi) /*! Returns the family name of the matched window system font. - \sa QFont::family() + \sa QFont::family(), {Checking for the existence of a font} */ QString QFontInfo::family() const { |