feat(iv): flip, rotate and save image (AcademySoftwareFoundation#5003)

Fixes AcademySoftwareFoundation#4715 

- Added save functionality
- Added flipping and rotation capabilities via metadata.
- Hotkeys: Ctrl-Shift-R and L to rotate the image left and right. 

Note that the actual pixel data remains unchanged, so only image formats
that support the rotation metadata will reflect the changes.

I thought that it made sense for the flip and rotate to be under the
tool section, similar to where the macbook Preview app places it.
Keyboard shortcuts also follow the shortcuts that Preview uses.

Tests

Used a .jpeg photo to test:
- saving
- making changes with/without saving and re-opening the image
- flipping and rotation from different initial rotation/mirrored states

Otherwise there doesn't seem to be a test suite for iv? 

Signed-off-by: valery <71804886+vangeliq@users.noreply.github.com>

Author: vangeliq

src/iv/imageviewer.cpp

@@ -520,6 +520,22 @@ ImageViewer::createActions()
     closeupAvgPixelsBox->setToolTip(closeupAvgPixelsTooltip);
     closeupAvgPixelsLabel->setToolTip(closeupAvgPixelsTooltip);
 
+
+    rotateLeftAct = new QAction(tr("&Rotate Left"), this);
+    rotateLeftAct->setShortcut(tr("Ctrl+Shift+L"));
+    connect(rotateLeftAct, SIGNAL(triggered()), this, SLOT(rotateLeft()));
+
+    rotateRightAct = new QAction(tr("&Rotate Right"), this);
+    rotateRightAct->setShortcut(tr("Ctrl+Shift+R"));
+    connect(rotateRightAct, SIGNAL(triggered()), this, SLOT(rotateRight()));
+
+    flipHorizontalAct = new QAction(tr("&Flip Horizontal"), this);
+    connect(flipHorizontalAct, SIGNAL(triggered()), this,
+            SLOT(flipHorizontal()));
+
+    flipVerticalAct = new QAction(tr("&Flip Vertical"), this);
+    connect(flipVerticalAct, SIGNAL(triggered()), this, SLOT(flipVertical()));
+
     // Connect signals to ensure closeupAvgPixelsBox value is always <= closeupPixelsBox value
     connect(closeupPixelsBox, QOverload<int>::of(&QSpinBox::valueChanged),
             [this](int value) {
@@ -780,6 +796,11 @@ ImageViewer::createMenus()
     toolsMenu->addAction(toggleAreaSampleAct);
     toolsMenu->addMenu(slideMenu);
     toolsMenu->addMenu(sortMenu);
+    toolsMenu->addSeparator();
+    toolsMenu->addAction(rotateLeftAct);
+    toolsMenu->addAction(rotateRightAct);
+    toolsMenu->addAction(flipHorizontalAct);
+    toolsMenu->addAction(flipVerticalAct);
 
     // Menus, toolbars, & status
     // Annotate
@@ -2455,3 +2476,82 @@ ImageViewer::areaSampleMode() const
 {
     return m_areaSampleMode;
 }
+
+
+void
+ImageViewer::rotateLeft()
+{
+    IvImage* img = cur();
+    if (!img)
+        return;
+
+    ImageSpec* spec = curspecmod();
+
+    int curr_orientation = spec->get_int_attribute("Orientation", 1);
+
+    if (curr_orientation >= 1 && curr_orientation <= 8) {
+        static int next_orientation[] = { 0, 8, 5, 6, 7, 4, 1, 2, 3 };
+        curr_orientation              = next_orientation[curr_orientation];
+        spec->attribute("Orientation", curr_orientation);
+    }
+    displayCurrentImage();
+}
+
+
+void
+ImageViewer::rotateRight()
+{
+    IvImage* img = cur();
+    if (!img)
+        return;
+
+    ImageSpec* spec      = curspecmod();
+    int curr_orientation = spec->get_int_attribute("Orientation", 1);
+
+    if (curr_orientation >= 1 && curr_orientation <= 8) {
+        static int next_orientation[] = { 0, 6, 7, 8, 5, 2, 3, 4, 1 };
+        curr_orientation              = next_orientation[curr_orientation];
+        spec->attribute("Orientation", curr_orientation);
+    }
+    displayCurrentImage();
+}
+
+
+void
+ImageViewer::flipHorizontal()
+{
+    IvImage* img = cur();
+    if (!img)
+        return;
+
+    ImageSpec* spec = curspecmod();
+
+    int curr_orientation = spec->get_int_attribute("Orientation", 1);
+
+    if (curr_orientation >= 1 && curr_orientation <= 8) {
+        static int next_orientation[] = { 0, 2, 1, 4, 3, 6, 5, 8, 7 };
+        curr_orientation              = next_orientation[curr_orientation];
+        spec->attribute("Orientation", curr_orientation);
+    }
+    displayCurrentImage();
+}
+
+
+void
+ImageViewer::flipVertical()
+{
+    IvImage* img = cur();
+    if (!img)
+        return;
+
+    ImageSpec* spec = curspecmod();
+
+    int curr_orientation = spec->get_int_attribute("Orientation", 1);
+
+    if (curr_orientation >= 1 && curr_orientation <= 8) {
+        static int next_orientation[] = { 0, 4, 3, 2, 1, 8, 7, 6, 5 };
+        curr_orientation              = next_orientation[curr_orientation];
+        spec->attribute("Orientation", curr_orientation);
+    }
+    displayCurrentImage();
+}

src/iv/imageviewer.h

@@ -219,6 +219,14 @@ class ImageViewer final : public QMainWindow {
         return img ? &img->spec() : NULL;
     }
 
+    /// Return a modifiable ref to the current image spec, or NULL if there is no
+    /// current image.
+    ImageSpec* curspecmod(void) const
+    {
+        IvImage* img = cur();
+        return img ? &img->specmod() : NULL;
+    }
+
     bool pixelviewOn(void) const
     {
         return showPixelviewWindowAct && showPixelviewWindowAct->isChecked();
@@ -334,6 +342,11 @@ private slots:
     void editPreferences();      ///< Edit viewer preferences
     void toggleAreaSample();     ///< Use area probe
 
+    void rotateLeft();
+    void rotateRight();
+    void flipHorizontal();
+    void flipVertical();
+
     void useOCIOAction(bool checked);
     void ocioColorSpaceAction();
     void ocioDisplayViewAction();
@@ -404,6 +417,8 @@ private slots:
     QAction* showPixelviewWindowAct;
     QAction* toggleAreaSampleAct;
     QAction* toggleWindowGuidesAct;
+    QAction *rotateLeftAct, *rotateRightAct, *flipHorizontalAct,
+        *flipVerticalAct;
     QMenu *fileMenu, *editMenu, /**imageMenu,*/ *viewMenu, *toolsMenu,
         *helpMenu;
     QMenu* openRecentMenu;