Optionally apply orientation on QImage read

Make it possible to read images with EXIF orientation automatically
applied. This was originally implemented without opt-out in Qt 5.4, but
reverted. Here it is implemented as opt-in for JPEG, and opt-out for TIFF
to keep behavioral consistency.

The EXIF support for JPEG was written by Rainer Keller.

[ChangeLog][QtGui][Image plugins] An option has been added to
QImageReader to enable automatic application of EXIF orientation.
This behavior was default in Qt 5.4.1, but reverted in Qt 5.4.2.

Task-number: QTBUG-37946
Task-number: QTBUG-43563
Task-number: QTBUG-45552
Task-number: QTBUG-45865
Change-Id: Iaafd2519b63ede66ecc1f8aa4c7118081312b8f5
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/src/gui/image/qimageiohandler.cpp b/src/gui/image/qimageiohandler.cpp
index cc9a6ae2a1..22b4bcf560 100644
--- a/src/gui/image/qimageiohandler.cpp
+++ b/src/gui/image/qimageiohandler.cpp
@@ -159,6 +159,43 @@
 
     \value ProgressiveScanWrite. A handler which supports
     this option is expected to write the image as a progressive scan image.
+
+    \value ImageTransformation. A handler which supports this option can read
+    the transformation metadata of an image. A handler that supports this option
+    should not apply the transformation itself.
+
+    \value TransformedByDefault. A handler that reports support for this feature
+    will have image transformation metadata applied by default on read.
+*/
+
+/*! \enum QImageIOHandler::Transformation
+    \since 5.5
+
+    This enum describes the different transformations or orientations
+    supported by some image formats, usually through EXIF.
+
+    \value TransformationNone No transformation should be applied.
+
+    \value TransformationMirror Mirror the image horizontally.
+
+    \value TransformationFlip Mirror the image vertically.
+
+    \value TransformationRotate180 Rotate the image 180 degrees.
+    This is the same as mirroring it both horizontally and vertically.
+
+    \value TransformationRotate90 Rotate the image 90 degrees.
+
+    \value TransformationMirrorAndRotate90 Mirror the image horizontally
+    and then rotate it 90 degrees.
+
+    \value TransformationFlipAndRotate90 Mirror the image vertically
+    and then rotate it 90 degrees.
+
+    \value TransformationRotate270 Rotate the image 270 degrees.
+    This is the same as mirroring it both horizontally, vertically and
+    then rotating it 90 degrees.
+
+    \sa QImageReader::transformation(), QImageReader::setAutoTransform(), QImageWriter::setTransformation()
 */
 
 /*!