feat: add prev and next button

mainwindow.cpp

@@ -31,6 +31,7 @@ MainWindow::MainWindow(QWidget *parent) :
     this->setAttribute(Qt::WA_TranslucentBackground, true);
     this->setMinimumSize(710, 530);
     this->setWindowIcon(QIcon(":/icons/app-icon.svg"));
+    this->setMouseTracking(true);
 
     m_fadeOutAnimation = new QPropertyAnimation(this, "windowOpacity");
     m_fadeOutAnimation->setDuration(300);
@@ -72,13 +73,29 @@ MainWindow::MainWindow(QWidget *parent) :
     connect(m_graphicsView, &GraphicsView::requestGallery,
             this, &MainWindow::loadGalleryBySingleLocalFile);
 
-    m_closeButton = new ToolButton(m_graphicsView);
+    m_closeButton = new ToolButton(true, m_graphicsView);
     m_closeButton->setIcon(QIcon(":/icons/window-close"));
     m_closeButton->setIconSize(QSize(50, 50));
 
     connect(m_closeButton, &QAbstractButton::clicked,
             this, &MainWindow::closeWindow);
 
+    m_prevButton = new ToolButton(false, m_graphicsView);
+    m_prevButton->setIcon(QIcon(":/icons/go-previous"));
+    m_prevButton->setIconSize(QSize(75, 75));
+    m_prevButton->setVisible(false);
+    m_prevButton->setOpacity(0, false);
+    m_nextButton = new ToolButton(false, m_graphicsView);
+    m_nextButton->setIcon(QIcon(":/icons/go-next"));
+    m_nextButton->setIconSize(QSize(75, 75));
+    m_nextButton->setVisible(false);
+    m_nextButton->setOpacity(0, false);
+
+    connect(m_prevButton, &QAbstractButton::clicked,
+            this, &MainWindow::galleryPrev);
+    connect(m_nextButton, &QAbstractButton::clicked,
+            this, &MainWindow::galleryNext);
+
     m_bottomButtonGroup = new BottomButtonGroup(this);
 
     connect(m_bottomButtonGroup, &BottomButtonGroup::resetToOriginalBtnClicked,
@@ -109,6 +126,11 @@ MainWindow::MainWindow(QWidget *parent) :
     m_gv->setOpacity(0, false);
     m_closeButton->setOpacity(0, false);
 
+    connect(this, &MainWindow::galleryLoaded, this, [this]() {
+        m_prevButton->setVisible(isGalleryAvailable());
+        m_nextButton->setVisible(isGalleryAvailable());
+    });
+
     QShortcut * quitAppShorucut = new QShortcut(QKeySequence(Qt::Key_Space), this);
     connect(quitAppShorucut, &QShortcut::activated,
             std::bind(&MainWindow::quitAppAction, this, false));
@@ -222,13 +244,13 @@ void MainWindow::loadGalleryBySingleLocalFile(const QString &path)
         }
     }
 
-//    qDebug() << m_files << m_currentFileIndex;
+    emit galleryLoaded();
 }
 
 void MainWindow::galleryPrev()
 {
     int count = m_files.count();
-    if (m_currentFileIndex < 0 || m_files.isEmpty() || m_currentFileIndex >= m_files.count()) {
+    if (!isGalleryAvailable()) {
         return;
     }
 
@@ -240,7 +262,7 @@ void MainWindow::galleryPrev()
 void MainWindow::galleryNext()
 {
     int count = m_files.count();
-    if (m_currentFileIndex < 0 || m_files.isEmpty() || m_currentFileIndex >= m_files.count()) {
+    if (!isGalleryAvailable()) {
         return;
     }
 
@@ -249,6 +271,14 @@ void MainWindow::galleryNext()
     m_graphicsView->showFileFromUrl(m_files.at(m_currentFileIndex), false);
 }
 
+bool MainWindow::isGalleryAvailable()
+{
+    if (m_currentFileIndex < 0 || m_files.isEmpty() || m_currentFileIndex >= m_files.count()) {
+        return false;
+    }
+    return true;
+}
+
 void MainWindow::showEvent(QShowEvent *event)
 {
     updateWidgetsPosition();
@@ -262,6 +292,8 @@ void MainWindow::enterEvent(QEvent *event)
     m_gv->setOpacity(1);
 
     m_closeButton->setOpacity(1);
+    m_prevButton->setOpacity(1);
+    m_nextButton->setOpacity(1);
 
     return QMainWindow::enterEvent(event);
 }
@@ -272,6 +304,8 @@ void MainWindow::leaveEvent(QEvent *event)
     m_gv->setOpacity(0);
 
     m_closeButton->setOpacity(0);
+    m_prevButton->setOpacity(0);
+    m_nextButton->setOpacity(0);
 
     return QMainWindow::leaveEvent(event);
 }
@@ -537,6 +571,9 @@ void MainWindow::closeWindow()
 void MainWindow::updateWidgetsPosition()
 {
     m_closeButton->move(width() - m_closeButton->width(), 0);
+    m_prevButton->move(25, (height() - m_prevButton->height()) / 2);
+    m_nextButton->move(width() - m_nextButton->width() - 25,
+                       (height() - m_prevButton->height()) / 2);
     m_bottomButtonGroup->move((width() - m_bottomButtonGroup->width()) / 2,
                               height() - m_bottomButtonGroup->height());
     m_gv->move(width() - m_gv->width(), height() - m_gv->height());
@@ -546,6 +583,8 @@ void MainWindow::toggleProtectedMode()
 {
     m_protectedMode = !m_protectedMode;
     m_closeButton->setVisible(!m_protectedMode);
+    m_prevButton->setVisible(!m_protectedMode);
+    m_nextButton->setVisible(!m_protectedMode);
 }
 
 void MainWindow::toggleStayOnTop()