revert: revert feature about saving image as new file with different format.

This reverts commit 5b2255e903.

The feature about saving image as new file with different format is not the goal of an image viewer.
There is no need to keep feature diversity in this fork.
So I simply remove it.

app/actionmanager.cpp

@@ -55,7 +55,6 @@ void ActionManager::setupAction(MainWindow *mainWindow)
     CREATE_NEW_ACTION(mainWindow, actionAnimationNextFrame);
 
     CREATE_NEW_THEMEICON_ACTION(mainWindow, actionOpen, document-open);
-    CREATE_NEW_THEMEICON_ACTION(mainWindow, actionSaveAs, document-save-as);
     CREATE_NEW_ACTION(mainWindow, actionHorizontalFlip);
     CREATE_NEW_ACTION(mainWindow, actionFitInView);
     CREATE_NEW_ACTION(mainWindow, actionFitByWidth);
@@ -85,7 +84,6 @@ void ActionManager::retranslateUi(MainWindow *mainWindow)
     Q_UNUSED(mainWindow);
 
     actionOpen->setText(QCoreApplication::translate("MainWindow", "&Open...", nullptr));
-    actionSaveAs->setText(QCoreApplication::translate("MainWindow", "Save &As...", nullptr));
 
     actionActualSize->setText(QCoreApplication::translate("MainWindow", "Actual size", nullptr));
     actionToggleMaximize->setText(QCoreApplication::translate("MainWindow", "Toggle maximize", nullptr));
@@ -131,7 +129,6 @@ void ActionManager::retranslateUi(MainWindow *mainWindow)
 void ActionManager::setupShortcuts()
 {
     actionOpen->setShortcut(QKeySequence::Open);
-    actionSaveAs->setShortcut(QKeySequence::SaveAs);
     actionActualSize->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_0));
     actionZoomIn->setShortcut(QKeySequence::ZoomIn);
     actionZoomOut->setShortcut(QKeySequence::ZoomOut);

app/actionmanager.h

@@ -23,7 +23,6 @@ public:
 
 public:
     QAction *actionOpen;
-    QAction *actionSaveAs;
 
     QAction *actionActualSize;
     QAction *actionToggleMaximize;

app/mainwindow.cpp

@@ -38,7 +38,6 @@
 #include <QProcess>
 #include <QDesktopServices>
 #include <QMessageBox>
-#include <QImageWriter>
 
 #ifdef HAVE_QTDBUS
 #include <QDBusInterface>
@@ -506,12 +505,6 @@ void MainWindow::contextMenuEvent(QContextMenuEvent *event)
         menu->addAction(paste);
     }
 
-#if 0
-    if (currentFileUrl.isValid()) {
-        menu->addAction(m_am->actionSaveAs);
-    }
-#endif // 0
-
     menu->addSeparator();
 
     menu->addAction(m_am->actionHorizontalFlip);
@@ -704,70 +697,6 @@ void MainWindow::on_actionOpen_triggered()
     }
 }
 
-void MainWindow::on_actionSaveAs_triggered()
-{
-    QUrl currentFileUrl = currentImageFileUrl();
-    if (!currentFileUrl.isValid()) {
-        QMessageBox::warning(this, tr("Save As"), tr("No image is currently open."));
-        return;
-    }
-
-    QStringList supportedFormats;
-    QStringList nameFilters;
-
-    const QList<QByteArray> imageFormats = QImageWriter::supportedImageFormats();
-    for (const QByteArray &format : imageFormats) {
-        QString formatStr = QString::fromLatin1(format).toLower();
-        if (!formatStr.isEmpty()) {
-            supportedFormats << formatStr;
-            nameFilters << tr("%1 Image (*.%2)").arg(formatStr.toUpper(), formatStr);
-        }
-    }
-
-    if (imageFormats.isEmpty()) {
-        QMessageBox::warning(this, tr("Save As"),
-                            tr("No supported image formats are available."));
-        return;
-    }
-
-    QString selectedFilter;
-    QString saveFilePath = QFileDialog::getSaveFileName(this,
-        tr("Save As"),
-        QStandardPaths::writableLocation(QStandardPaths::PicturesLocation),
-        nameFilters.join(";;"),
-        &selectedFilter);
-
-    if (saveFilePath.isEmpty()) {
-        return; // User cancelled
-    }
-
-    // Ensure the file has the correct extension
-    QString expectedExtension;
-
-    const int filterIndex = nameFilters.indexOf(selectedFilter);
-    if (filterIndex != -1) {
-        expectedExtension = supportedFormats.at(filterIndex);
-    }
-
-    if (!expectedExtension.isEmpty() && !saveFilePath.endsWith('.' + expectedExtension, Qt::CaseInsensitive)) {
-        saveFilePath += '.' + expectedExtension;
-    }
-
-    // Save the image
-    QImageReader imageReader(currentFileUrl.toLocalFile());
-    imageReader.setAutoTransform(true);
-    imageReader.setDecideFormatFromContent(true);
-    imageReader.setAllocationLimit(0);
-    QImage img(imageReader.read());
-    QImageWriter writer(saveFilePath);
-    writer.setFormat(expectedExtension.toLatin1());
-    if (!writer.write(img)) {
-        QMessageBox::warning(this, tr("Save As"),
-                            tr("Failed to save image: %1").arg(writer.errorString()));
-        return;
-    }
-}
-
 void MainWindow::on_actionActualSize_triggered()
 {
     m_graphicsView->resetScale();

app/mainwindow.h

@@ -75,7 +75,6 @@ protected:
 
 private slots:
     void on_actionOpen_triggered();
-    void on_actionSaveAs_triggered();
 
     void on_actionActualSize_triggered();
     void on_actionToggleMaximize_triggered();