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author | Gunnar Sletta <gunnar@trolltech.com> | 2010-02-11 14:16:44 (GMT) |
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committer | Gunnar Sletta <gunnar@trolltech.com> | 2010-02-11 14:16:44 (GMT) |
commit | 2acc883b3a339b716da9249a1366b08225acbd8a (patch) | |
tree | cb6d27afa7428712207acef5044a143538055bd8 /src/gui/image | |
parent | 3e7f05c1a07441a4b0e9ade893c519a050e5b8de (diff) | |
download | Qt-2acc883b3a339b716da9249a1366b08225acbd8a.zip Qt-2acc883b3a339b716da9249a1366b08225acbd8a.tar.gz Qt-2acc883b3a339b716da9249a1366b08225acbd8a.tar.bz2 |
document the slowness of QPixmap::hasAlpha()
Reviewed-by: Kim
Diffstat (limited to 'src/gui/image')
-rw-r--r-- | src/gui/image/qpixmap.cpp | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp index d1e5c40..1df7946 100644 --- a/src/gui/image/qpixmap.cpp +++ b/src/gui/image/qpixmap.cpp @@ -1670,10 +1670,9 @@ QPixmap QPixmap::transformed(const QMatrix &matrix, Qt::TransformationMode mode) \o The hasAlphaChannel() returns true if the pixmap has a format that - respects the alpha channel, otherwise returns false, while the - hasAlpha() function returns true if the pixmap has an alpha - channel \e or a mask (otherwise false). The mask() function returns - the mask as a QBitmap object, which can be set using setMask(). + respects the alpha channel, otherwise returns false. The hasAlpha(), + setMask() and mask() functions are legacy and should not be used. + They are potentially very slow. The createHeuristicMask() function creates and returns a 1-bpp heuristic mask (i.e. a QBitmap) for this pixmap. It works by @@ -1760,6 +1759,8 @@ QPixmap QPixmap::transformed(const QMatrix &matrix, Qt::TransformationMode mode) Returns true if this pixmap has an alpha channel, \e or has a mask, otherwise returns false. + \warning This is potentially an expensive operation. + \sa hasAlphaChannel(), mask() */ bool QPixmap::hasAlpha() const |