feat: support forward/back button on mouse for image navigation

app/actionmanager.cpp

@@ -38,6 +38,9 @@ void ActionManager::setupAction(MainWindow *mainWindow)
     CREATE_NEW_ICON_ACTION(mainWindow, actionToggleCheckerboard, view-background-checkerboard);
     CREATE_NEW_ICON_ACTION(mainWindow, actionRotateClockwise, object-rotate-right);
 
+    CREATE_NEW_ACTION(mainWindow, actionPrevPicture);
+    CREATE_NEW_ACTION(mainWindow, actionNextPicture);
+
     CREATE_NEW_ACTION(mainWindow, actionHorizontalFlip);
     CREATE_NEW_ACTION(mainWindow, actionFitInView);
     CREATE_NEW_ACTION(mainWindow, actionFitByWidth);
@@ -67,6 +70,9 @@ void ActionManager::retranslateUi(MainWindow *mainWindow)
     actionToggleCheckerboard->setText(QCoreApplication::translate("MainWindow", "Toggle Checkerboard", nullptr));
     actionRotateClockwise->setText(QCoreApplication::translate("MainWindow", "Rotate right", nullptr));
 
+    actionPrevPicture->setText(QCoreApplication::translate("MainWindow", "Previous image", nullptr));
+    actionNextPicture->setText(QCoreApplication::translate("MainWindow", "Next image", nullptr));
+
     actionHorizontalFlip->setText(QCoreApplication::translate("MainWindow", "Flip &Horizontally", nullptr));
     actionFitInView->setText("Fit in view"); // TODO: what should it called?
     actionFitByWidth->setText("Fit by width"); // TODO: what should it called?
@@ -83,15 +89,17 @@ void ActionManager::retranslateUi(MainWindow *mainWindow)
 
 void ActionManager::setupShortcuts()
 {
-    actionActualSize->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_0));
+    actionActualSize->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_0));
     actionZoomIn->setShortcut(QKeySequence(QKeySequence::ZoomIn));
     actionZoomOut->setShortcut(QKeySequence(QKeySequence::ZoomOut));
-    actionHorizontalFlip->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_R));
+    actionPrevPicture->setShortcut(QKeySequence(Qt::Key_PageUp));
+    actionNextPicture->setShortcut(QKeySequence(Qt::Key_PageDown));
+    actionHorizontalFlip->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_R));
     actionCopyPixmap->setShortcut(QKeySequence(QKeySequence::Copy));
     actionPaste->setShortcut(QKeySequence::Paste);
     actionHelp->setShortcut(QKeySequence::HelpContents);
     actionSettings->setShortcut(QKeySequence::Preferences);
-    actionProperties->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_I));
+    actionProperties->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_I));
     actionQuitApp->setShortcuts({
         QKeySequence(Qt::Key_Space),
         QKeySequence(Qt::Key_Escape)

app/actionmanager.h

@@ -23,6 +23,9 @@ public:
     QAction *actionToggleCheckerboard;
     QAction *actionRotateClockwise;
 
+    QAction *actionPrevPicture;
+    QAction *actionNextPicture;
+
     QAction *actionHorizontalFlip;
     QAction *actionFitInView;
     QAction *actionFitByWidth;

app/mainwindow.cpp

@@ -126,14 +126,6 @@ MainWindow::MainWindow(QWidget *parent)
         m_nextButton->setVisible(galleryFileCount > 1);
     });
 
-    QShortcut * prevPictureShorucut = new QShortcut(QKeySequence(Qt::Key_PageUp), this);
-    connect(prevPictureShorucut, &QShortcut::activated,
-            this, &MainWindow::galleryPrev);
-
-    QShortcut * nextPictureShorucut = new QShortcut(QKeySequence(Qt::Key_PageDown), this);
-    connect(nextPictureShorucut, &QShortcut::activated,
-            this, &MainWindow::galleryNext);
-
     QShortcut * fullscreenShorucut = new QShortcut(QKeySequence(QKeySequence::FullScreen), this);
     connect(fullscreenShorucut, &QShortcut::activated,
             this, &MainWindow::toggleFullscreen);
@@ -280,6 +272,15 @@ void MainWindow::mousePressEvent(QMouseEvent *event)
         event->accept();
     }
 
+    // It seems the forward/back mouse button won't generate a key event [1] so we can't use
+    // QShortcut or QKeySequence to indicate these shortcuts, so we do it here.
+    // Reference:
+    // [1]: https://codereview.qt-project.org/c/qt/qtbase/+/177475
+    if (event->buttons() & Qt::ForwardButton || event->buttons() & Qt::BackButton) {
+        event->buttons() & Qt::BackButton ? galleryNext() : galleryPrev();
+        event->accept();
+    }
+
     return FramelessWindow::mousePressEvent(event);
 }
 
@@ -308,6 +309,12 @@ void MainWindow::mouseReleaseEvent(QMouseEvent *event)
 
 void MainWindow::mouseDoubleClickEvent(QMouseEvent *event)
 {
+    // The forward/back mouse button can also used to trigger a mouse double-click event
+    // Since we use that for gallery navigation so we ignore these two buttons.
+    if (event->buttons() & Qt::ForwardButton || event->buttons() & Qt::BackButton) {
+        return;
+    }
+
     switch (Settings::instance()->doubleClickBehavior()) {
     case ActionCloseWindow:
         quitAppAction();
@@ -631,6 +638,16 @@ void MainWindow::on_actionRotateClockwise_triggered()
     m_gv->setVisible(false);
 }
 
+void MainWindow::on_actionPrevPicture_triggered()
+{
+    galleryPrev();
+}
+
+void MainWindow::on_actionNextPicture_triggered()
+{
+    galleryNext();
+}
+
 void MainWindow::on_actionToggleStayOnTop_triggered()
 {
     toggleStayOnTop();

app/mainwindow.h

@@ -75,6 +75,9 @@ private slots:
     void on_actionToggleCheckerboard_triggered();
     void on_actionRotateClockwise_triggered();
 
+    void on_actionPrevPicture_triggered();
+    void on_actionNextPicture_triggered();
+
     void on_actionHorizontalFlip_triggered();
     void on_actionFitInView_triggered();
     void on_actionFitByWidth_triggered();