From ba323b04cd78fb43e9e63b891e973d24b08250af Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
Date: Mon, 4 May 2015 13:32:32 +0200
Subject: 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>
---
 src/gui/image/qimagereader.cpp | 63 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

(limited to 'src/gui/image/qimagereader.cpp')

diff --git a/src/gui/image/qimagereader.cpp b/src/gui/image/qimagereader.cpp
index c2795cc38d..ba79bf40e5 100644
--- a/src/gui/image/qimagereader.cpp
+++ b/src/gui/image/qimagereader.cpp
@@ -533,6 +533,11 @@ public:
     int quality;
     QMap<QString, QString> text;
     void getText();
+    enum {
+        UsePluginDefault,
+        ApplyTransform,
+        DoNotApplyTransform
+    } autoTransform;
 
     // error
     QImageReader::ImageReaderError imageReaderError;
@@ -552,6 +557,7 @@ QImageReaderPrivate::QImageReaderPrivate(QImageReader *qq)
     handler = 0;
     quality = -1;
     imageReaderError = QImageReader::UnknownError;
+    autoTransform = UsePluginDefault;
 
     q = qq;
 }
@@ -1143,6 +1149,59 @@ QList<QByteArray> QImageReader::supportedSubTypes() const
     return QList<QByteArray>();
 }
 
+/*!
+    \since 5.5
+
+    Returns the transformation metadata of the image, including image orientation. If the format
+    does not support transformation metadata \c QImageIOHandler::Transformation_None is returned.
+
+    \sa setAutoTransform(), autoTransform()
+*/
+QImageIOHandler::Transformations QImageReader::transformation() const
+{
+    int option = QImageIOHandler::TransformationNone;
+    if (d->initHandler() && d->handler->supportsOption(QImageIOHandler::ImageTransformation))
+        option = d->handler->option(QImageIOHandler::ImageTransformation).toInt();
+    return QImageIOHandler::Transformations(option);
+}
+
+/*!
+    \since 5.5
+
+    Sets if images returned by read() should have transformation metadata automatically applied.
+
+    \sa autoTransform(), transform(), read()
+*/
+void QImageReader::setAutoTransform(bool enabled)
+{
+    d->autoTransform = enabled ? QImageReaderPrivate::ApplyTransform
+                               : QImageReaderPrivate::DoNotApplyTransform;
+}
+
+/*!
+    \since 5.5
+
+    Returns \c true if the image handler will apply transformation metadata on read().
+
+    \sa setAutoTransform(), transformation(), read()
+*/
+bool QImageReader::autoTransform() const
+{
+    switch (d->autoTransform) {
+    case QImageReaderPrivate::ApplyTransform:
+        return true;
+    case QImageReaderPrivate::DoNotApplyTransform:
+        return false;
+    case QImageReaderPrivate::UsePluginDefault:
+        if (d->initHandler())
+            return d->handler->supportsOption(QImageIOHandler::TransformedByDefault);
+        // no break
+    default:
+        break;
+    }
+    return false;
+}
+
 /*!
     Returns \c true if an image can be read for the device (i.e., the
     image format is supported, and the device seems to contain valid
@@ -1185,6 +1244,8 @@ QImage QImageReader::read()
     return read(&image) ? image : QImage();
 }
 
+extern void qt_imageTransform(QImage &src, QImageIOHandler::Transformations orient);
+
 /*!
     \overload
 
@@ -1294,6 +1355,8 @@ bool QImageReader::read(QImage *image)
     if (!disable2xImageLoading && QFileInfo(fileName()).baseName().endsWith(QLatin1String("@2x"))) {
            image->setDevicePixelRatio(2.0);
     }
+    if (autoTransform())
+        qt_imageTransform(*image, transformation());
 
     return true;
 }
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