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-rw-r--r--src/gui/image/qimage.cpp26
1 files changed, 20 insertions, 6 deletions
diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index 558d574..c7a20db 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -3607,6 +3607,9 @@ int QImage::pixelIndex(int x, int y) const
If the \a position is not valid, the results are undefined.
+ \warning This function is expensive when used for massive pixel
+ manipulations.
+
\sa setPixel(), valid(), {QImage#Pixel Manipulation}{Pixel
Manipulation}
*/
@@ -4937,10 +4940,12 @@ int QImage::dotsPerMeterY() const
meter, to \a x.
Together with dotsPerMeterY(), this number defines the intended
- scale and aspect ratio of the image.
+ scale and aspect ratio of the image, and determines the scale
+ at which QPainter will draw graphics on the image. It does not
+ change the scale or aspect ratio of the image when it is rendered
+ on other paint devices.
- \sa dotsPerMeterX(), {QImage#Image Information}{Image
- Information}
+ \sa dotsPerMeterX(), {QImage#Image Information}{Image Information}
*/
void QImage::setDotsPerMeterX(int x)
{
@@ -4957,10 +4962,12 @@ void QImage::setDotsPerMeterX(int x)
to \a y.
Together with dotsPerMeterX(), this number defines the intended
- scale and aspect ratio of the image.
+ scale and aspect ratio of the image, and determines the scale
+ at which QPainter will draw graphics on the image. It does not
+ change the scale or aspect ratio of the image when it is rendered
+ on other paint devices.
- \sa dotsPerMeterY(), {QImage#Image Information}{Image
- Information}
+ \sa dotsPerMeterY(), {QImage#Image Information}{Image Information}
*/
void QImage::setDotsPerMeterY(int y)
{
@@ -5577,6 +5584,8 @@ bool QImage::isDetached() const
Use one of the composition mods in QPainter::CompositionMode instead.
+ \warning This function is expensive.
+
\sa alphaChannel(), {QImage#Image Transformations}{Image
Transformations}, {QImage#Image Formats}{Image Formats}
*/
@@ -5659,6 +5668,11 @@ void QImage::setAlphaChannel(const QImage &alphaChannel)
\l{QPixmap::}{alphaChannel()}, which works in the same way as
this function on QPixmaps.
+ Most usecases for this function can be replaced with QPainter and
+ using composition modes.
+
+ \warning This is an expensive function.
+
\sa setAlphaChannel(), hasAlphaChannel(),
{QPixmap#Pixmap Information}{Pixmap},
{QImage#Image Transformations}{Image Transformations}