fix(preview): Fix exif orientations

Previous exif transformations were not valid. The exif spec defines the
orientations as where the 0th row and the 0th column should end. The
previous mappings used in qTox did not respect these mappings and needed
to be updated.

CMakeLists.txt

@@ -339,6 +339,8 @@ set(${PROJECT_NAME}_SOURCES
   src/model/contact.h
   src/model/chatlogitem.cpp
   src/model/chatlogitem.h
+  src/model/exiftransform.h
+  src/model/exiftransform.cpp
   src/model/friend.cpp
   src/model/friend.h
   src/model/message.h

cmake/Testing.cmake

@@ -47,6 +47,7 @@ auto_test(model friendmessagedispatcher)
 auto_test(model groupmessagedispatcher)
 auto_test(model messageprocessor)
 auto_test(model sessionchatlog)
+auto_test(model exiftransform)
 
 if (UNIX)
   auto_test(platform posixsignalnotifier)

src/chatlog/content/filetransferwidget.cpp

@@ -26,8 +26,7 @@
 #include "src/widget/gui.h"
 #include "src/widget/style.h"
 #include "src/widget/widget.h"
-
-#include <libexif/exif-loader.h>
+#include "src/model/exiftransform.h"
 
 #include <QBuffer>
 #include <QDebug>
@@ -523,13 +522,11 @@ void FileTransferWidget::showPreview(const QString& filename)
         if (!imageFile.open(QIODevice::ReadOnly)) {
             return;
         }
+
         const QByteArray imageFileData = imageFile.readAll();
         QImage image = QImage::fromData(imageFileData);
-        const int exifOrientation =
-            getExifOrientation(imageFileData.constData(), imageFileData.size());
-        if (exifOrientation) {
-            applyTransformation(exifOrientation, image);
-        }
+        auto orientation = ExifTransform::getOrientation(imageFileData);
+        image = ExifTransform::applyTransformation(image, orientation);
 
         const QPixmap iconPixmap = scaleCropIntoSquare(QPixmap::fromImage(image), size);
 
@@ -599,59 +596,6 @@ QPixmap FileTransferWidget::scaleCropIntoSquare(const QPixmap& source, const int
     return result;
 }
 
-int FileTransferWidget::getExifOrientation(const char* data, const int size)
-{
-    ExifData* exifData = exif_data_new_from_data(reinterpret_cast<const unsigned char*>(data), size);
-
-    if (!exifData) {
-        return 0;
-    }
-
-    int orientation = 0;
-    const ExifByteOrder byteOrder = exif_data_get_byte_order(exifData);
-    const ExifEntry* const exifEntry = exif_data_get_entry(exifData, EXIF_TAG_ORIENTATION);
-    if (exifEntry) {
-        orientation = exif_get_short(exifEntry->data, byteOrder);
-    }
-    exif_data_free(exifData);
-    return orientation;
-}
-
-void FileTransferWidget::applyTransformation(const int orientation, QImage& image)
-{
-    QTransform exifTransform;
-    switch (static_cast<ExifOrientation>(orientation)) {
-    case ExifOrientation::TopLeft:
-        break;
-    case ExifOrientation::TopRight:
-        image = image.mirrored(1, 0);
-        break;
-    case ExifOrientation::BottomRight:
-        exifTransform.rotate(180);
-        break;
-    case ExifOrientation::BottomLeft:
-        image = image.mirrored(0, 1);
-        break;
-    case ExifOrientation::LeftTop:
-        exifTransform.rotate(90);
-        image = image.mirrored(0, 1);
-        break;
-    case ExifOrientation::RightTop:
-        exifTransform.rotate(-90);
-        break;
-    case ExifOrientation::RightBottom:
-        exifTransform.rotate(-90);
-        image = image.mirrored(0, 1);
-        break;
-    case ExifOrientation::LeftBottom:
-        exifTransform.rotate(90);
-        break;
-    default:
-        qWarning() << "Invalid exif orientation passed to applyTransformation!";
-    }
-    image = image.transformed(exifTransform);
-}
-
 void FileTransferWidget::updateWidget(ToxFile const& file)
 {
     assert(file == fileInfo);

src/chatlog/content/filetransferwidget.h

@@ -89,22 +89,4 @@ private:
     bool active;
     ToxFile::FileStatus lastStatus = ToxFile::INITIALIZING;
 
-    enum class ExifOrientation
-    {
-        /* do not change values, this is exif spec
-         *
-         * name corresponds to where the 0 row and 0 column is in form row-column
-         * i.e. entry 5 here means that the 0'th row corresponds to the left side of the scene and
-         * the 0'th column corresponds to the top of the captured scene. This means that the image
-         * needs to be mirrored and rotated to be displayed.
-         */
-        TopLeft = 1,
-        TopRight = 2,
-        BottomRight = 3,
-        BottomLeft = 4,
-        LeftTop = 5,
-        RightTop = 6,
-        RightBottom = 7,
-        LeftBottom = 8
-    };
 };

src/model/exiftransform.cpp

@@ -0,0 +1,103 @@
+/*
+    Copyright © 2020 by The qTox Project Contributors
+
+    This file is part of qTox, a Qt-based graphical interface for Tox.
+
+    qTox is libre software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    qTox is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with qTox.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "exiftransform.h"
+
+#include <libexif/exif-loader.h>
+
+#include <QDebug>
+
+namespace ExifTransform
+{
+    Orientation getOrientation(QByteArray imageData)
+    {
+        auto data = imageData.constData();
+        auto size = imageData.size();
+
+        ExifData* exifData = exif_data_new_from_data(reinterpret_cast<const unsigned char*>(data), size);
+
+        if (!exifData) {
+            return Orientation::TopLeft;
+        }
+
+        int orientation = 0;
+        const ExifByteOrder byteOrder = exif_data_get_byte_order(exifData);
+        const ExifEntry* const exifEntry = exif_data_get_entry(exifData, EXIF_TAG_ORIENTATION);
+        if (exifEntry) {
+            orientation = exif_get_short(exifEntry->data, byteOrder);
+        }
+        exif_data_free(exifData);
+
+        switch (orientation){
+        case 1:
+            return Orientation::TopLeft;
+        case 2:
+            return Orientation::TopRight;
+        case 3:
+            return Orientation::BottomRight;
+        case 4:
+            return Orientation::BottomLeft;
+        case 5:
+            return Orientation::LeftTop;
+        case 6:
+            return Orientation::RightTop;
+        case 7:
+            return Orientation::RightBottom;
+        case 8:
+            return Orientation::LeftBottom;
+        default:
+            qWarning() << "Invalid exif orientation";
+            return Orientation::TopLeft;
+        }
+    }
+
+    QImage applyTransformation(QImage image, Orientation orientation)
+    {
+        QTransform exifTransform;
+        switch (orientation) {
+        case Orientation::TopLeft:
+            break;
+        case Orientation::TopRight:
+            image = image.mirrored(1, 0);
+            break;
+        case Orientation::BottomRight:
+            exifTransform.rotate(180);
+            break;
+        case Orientation::BottomLeft:
+            image = image.mirrored(0, 1);
+            break;
+        case Orientation::LeftTop:
+            exifTransform.rotate(-90);
+            image = image.mirrored(1, 0);
+            break;
+        case Orientation::RightTop:
+            exifTransform.rotate(90);
+            break;
+        case Orientation::RightBottom:
+            exifTransform.rotate(90);
+            image = image.mirrored(1, 0);
+            break;
+        case Orientation::LeftBottom:
+            exifTransform.rotate(-90);
+            break;
+        }
+        image = image.transformed(exifTransform);
+        return image;
+    }
+};

src/model/exiftransform.h

@@ -0,0 +1,45 @@
+/*
+    Copyright © 2020 by The qTox Project Contributors
+
+    This file is part of qTox, a Qt-based graphical interface for Tox.
+
+    qTox is libre software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    qTox is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with qTox.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include <QPixmap>
+
+namespace ExifTransform
+{
+    enum class Orientation
+    {
+        /* name corresponds to where the 0 row and 0 column is in form row-column
+         * i.e. entry 5 here means that the 0'th row corresponds to the left side of the scene and
+         * the 0'th column corresponds to the top of the captured scene. This means that the image
+         * needs to be mirrored and rotated to be displayed.
+         */
+        TopLeft,
+        TopRight,
+        BottomRight,
+        BottomLeft,
+        LeftTop,
+        RightTop,
+        RightBottom,
+        LeftBottom
+    };
+
+    Orientation getOrientation(QByteArray imageData);
+    QImage applyTransformation(QImage image, Orientation orientation);
+};

test/model/exiftransform_test.cpp

@@ -0,0 +1,165 @@
+/*
+    Copyright © 2020 by The qTox Project Contributors
+
+    This file is part of qTox, a Qt-based graphical interface for Tox.
+
+    qTox is libre software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    qTox is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with qTox.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "src/model/exiftransform.h"
+
+#include <QPainter>
+#include <QTest>
+
+static const auto rowColor = QColor(Qt::green).rgb();
+static const auto colColor = QColor(Qt::blue).rgb();
+
+enum class Side
+{
+    top,
+    bottom,
+    left,
+    right
+};
+
+static QPoint getPosition(Side side)
+{
+    int x, y;
+    switch (side)
+    {
+    case Side::top:
+    {
+        x = 1;
+        y = 0;
+        break;
+    }
+    case Side::bottom:
+    {
+        x = 1;
+        y = 2;
+        break;
+    }
+    case Side::left:
+    {
+        x = 0;
+        y = 1;
+        break;
+    }
+    case Side::right:
+    {
+        x = 2;
+        y = 1;
+        break;
+    }
+    }
+
+    return {x, y};
+}
+
+static QRgb getColor(const QImage& image, Side side)
+{
+    return image.pixel(getPosition(side));
+}
+
+
+class TestExifTransform : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void init();
+    void testTopLeft();
+    void testTopRight();
+    void testBottomRight();
+    void testBottomLeft();
+    void testLeftTop();
+    void testRightTop();
+    void testRightBottom();
+    void testLeftBottom();
+
+private:
+    QImage inputImage;
+};
+
+void TestExifTransform::init()
+{
+    inputImage = QImage(QSize(3, 3), QImage::Format_RGB32);
+    QPainter painter(&inputImage);
+    painter.fillRect(QRect(0, 0, 3, 3), Qt::white);
+    // First row has a green dot in the middle
+    painter.setPen(rowColor);
+    painter.drawPoint(getPosition(Side::top));
+    // First column has a blue dot in the middle
+    painter.setPen(colColor);
+    painter.drawPoint(getPosition(Side::left));
+}
+
+void TestExifTransform::testTopLeft()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::TopLeft);
+    QVERIFY(getColor(image, Side::top) == rowColor);
+    QVERIFY(getColor(image, Side::left) == colColor);
+}
+
+void TestExifTransform::testTopRight()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::TopRight);
+    QVERIFY(getColor(image, Side::top) == rowColor);
+    QVERIFY(getColor(image, Side::right) == colColor);
+}
+
+void TestExifTransform::testBottomRight()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::BottomRight);
+    QVERIFY(getColor(image, Side::bottom) == rowColor);
+    QVERIFY(getColor(image, Side::right) == colColor);
+}
+
+void TestExifTransform::testBottomLeft()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::BottomLeft);
+    QVERIFY(getColor(image, Side::bottom) == rowColor);
+    QVERIFY(getColor(image, Side::left) == colColor);
+}
+
+void TestExifTransform::testLeftTop()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::LeftTop);
+    QVERIFY(getColor(image, Side::left) == rowColor);
+    QVERIFY(getColor(image, Side::top) == colColor);
+}
+
+void TestExifTransform::testRightTop()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::RightTop);
+    QVERIFY(getColor(image, Side::right) == rowColor);
+    QVERIFY(getColor(image, Side::top) == colColor);
+}
+
+void TestExifTransform::testRightBottom()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::RightBottom);
+    QVERIFY(getColor(image, Side::right) == rowColor);
+    QVERIFY(getColor(image, Side::bottom) == colColor);
+}
+
+void TestExifTransform::testLeftBottom()
+{
+    auto image = ExifTransform::applyTransformation(inputImage, ExifTransform::Orientation::LeftBottom);
+    QVERIFY(getColor(image, Side::left) == rowColor);
+    QVERIFY(getColor(image, Side::bottom) == colColor);
+}
+
+QTEST_APPLESS_MAIN(TestExifTransform)
+#include "exiftransform_test.moc"