diff options
Diffstat (limited to 'src/gui/image/qpixmap.cpp')
| -rw-r--r-- | src/gui/image/qpixmap.cpp | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp index 8684a1b..efb8260 100644 --- a/src/gui/image/qpixmap.cpp +++ b/src/gui/image/qpixmap.cpp @@ -674,7 +674,7 @@ void QPixmap::resize_helper(const QSize &s) pixels black. The effect of this function is undefined when the pixmap is being painted on. - This is potentially an expensive operation. + \warning This is potentially an expensive operation. \sa mask(), {QPixmap#Pixmap Transformations}{Pixmap Transformations}, QBitmap @@ -1380,6 +1380,12 @@ void QPixmap::deref() If the given \a size is empty, this function returns a null pixmap. + + In some cases it can be more beneficial to draw the pixmap to a + painter with a scale set rather than scaling the pixmap. This is + the case when the painter is for instance based on OpenGL or when + the scale factor changes rapidly. + \sa isNull(), {QPixmap#Pixmap Transformations}{Pixmap Transformations} @@ -1751,6 +1757,10 @@ int QPixmap::metric(PaintDeviceMetric metric) const The effect of this function is undefined when the pixmap is being painted on. + \warning This is potentially an expensive operation. Most usecases + for this function are covered by QPainter and compositionModes + which will normally execute faster. + \sa alphaChannel(), {QPixmap#Pixmap Transformations}{Pixmap Transformations} */ @@ -1793,6 +1803,9 @@ void QPixmap::setAlphaChannel(const QPixmap &alphaChannel) \image alphachannelimage.png The pixmap and channelImage QPixmaps + \warning This is an expensive operation. The alpha channel of the + pixmap is extracted dynamically from the pixeldata. + \sa setAlphaChannel(), {QPixmap#Pixmap Information}{Pixmap Information} */ @@ -1814,7 +1827,8 @@ QPaintEngine *QPixmap::paintEngine() const Extracts a bitmap mask from the pixmap's alphachannel. - This is potentially an expensive operation. + \warning This is potentially an expensive operation. The mask of + the pixmap is extracted dynamically from the pixeldata. \sa setMask(), {QPixmap#Pixmap Information}{Pixmap Information} */ |