refactor: fully refactor playlist manager

- refactor playlist manager. remove useless qt model design.
- update action updator function.

app/actionmanager.cpp

@@ -179,6 +179,11 @@ void ActionManager::updateActionState(PlaylistManager* pm, GraphicsView* gv)
     const auto* gs = gv->scene();
     const auto* settings = Settings::instance();
 
+    // Update copy actions
+    bool canCopy = pm->currentIndex().has_value();
+    actionCopyPixmap->setEnabled(canCopy);
+    actionCopyFilePath->setEnabled(canCopy);
+
     // Update Prev/Next Picture State
     const int galleryFileCount = pm->totalCount();
     const bool loopGallery = settings->loopGallery();
@@ -186,11 +191,9 @@ void ActionManager::updateActionState(PlaylistManager* pm, GraphicsView* gv)
     actionNextPicture->setEnabled(galleryFileCount > 1 && (loopGallery || !pm->isLastIndex()));
 
     // Update Avoid Reset Transform
-    actionToggleAvoidResetTransform->setCheckable(gv->avoidResetTransform());
-
+    actionToggleAvoidResetTransform->setChecked(gv->isAvoidResetTransform());
     // Update Checkerboard
-    actionToggleCheckerboard->setChecked(gv->checkerboard());
-
+    actionToggleCheckerboard->setChecked(gv->isCheckerboard());
     // Update Animation Graphics Action
     bool canPauseAnimation = gs->canPauseAnimation();
     actionTogglePauseAnimation->setEnabled(canPauseAnimation);
@@ -202,7 +205,10 @@ void ActionManager::updateActionState(PlaylistManager* pm, GraphicsView* gv)
     bool canSkipAnimation = gs->canSkipAnimationFrame();
     actionAnimationNextFrame->setEnabled(canSkipAnimation);
 
-    // TODO: Add more...
-
+    // Update trash, located in explorer and properties.
+    bool hasLoadedFile = pm->currentIndex().has_value();
+    actionTrash->setEnabled(hasLoadedFile);
+    actionLocateInFileManager->setEnabled(hasLoadedFile);
+    actionProperties->setEnabled(hasLoadedFile);
 }
 

app/graphicsscene.cpp

@@ -129,7 +129,7 @@ private:
 GraphicsScene::GraphicsScene(QObject *parent)
     : QGraphicsScene(parent)
 {
-    showText(tr("Drag image here"));
+    showText(tr("Drag image here", "The same meaning of MainWindow's hint."));
     connect(qGuiApp->styleHints(), &QStyleHints::colorSchemeChanged, this, &GraphicsScene::updateStyle);
 }
 

app/graphicsview.cpp

@@ -320,7 +320,7 @@ void GraphicsView::setEnableAutoFitToScreen(bool enable)
     m_enableFitToScreen = enable;
 }
 
-bool GraphicsView::avoidResetTransform() const
+bool GraphicsView::isAvoidResetTransform() const
 {
     return m_avoidResetTransform;
 }
@@ -330,7 +330,7 @@ void GraphicsView::setAvoidResetTransform(bool avoidReset)
     m_avoidResetTransform = avoidReset;
 }
 
-bool GraphicsView::checkerboard() const {
+bool GraphicsView::isCheckerboard() const {
     return m_checkerboardEnabled;
 }
 

app/graphicsview.h

@@ -40,10 +40,10 @@ public:
     bool isSceneBiggerThanView() const;
     void setEnableAutoFitToScreen(bool enable = true);
 
-    bool avoidResetTransform() const;
+    bool isAvoidResetTransform() const;
     void setAvoidResetTransform(bool avoidReset);
 
-    bool checkerboard() const;
+    bool isCheckerboard() const;
     void toggleCheckerboard(bool invertCheckerboardColor = false);
 
     static QTransform resetScale(const QTransform & orig);

app/main.cpp

@@ -4,7 +4,6 @@
 
 #include "mainwindow.h"
 
-#include "playlistmanager.h"
 #include "settings.h"
 
 #ifdef Q_OS_MACOS
@@ -68,21 +67,19 @@ int main(int argc, char *argv[])
     a.installEventFilter(fileOpenEventHandler);
     a.connect(fileOpenEventHandler, &FileOpenEventHandler::fileOpen, [&w](const QUrl & url){
         if (w.isHidden()) {
-            w.setWindowOpacity(1);
             w.showNormal();
         } else {
             w.activateWindow();
         }
-        w.showUrls({url});
+        w.showFiles({url});
         w.initWindowSize();
     });
 
     // Handle dock icon clicks to show hidden window
     a.connect(&a, &QApplication::applicationStateChanged, [&w](Qt::ApplicationState state) {
         if (state == Qt::ApplicationActive && w.isHidden()) {
-            w.showUrls({});
-            w.galleryCurrent(true, true);
-            w.setWindowOpacity(1);
+            w.showFiles({});
+            w.galleryCurrent(false);
             w.showNormal();
             w.raise();
             w.activateWindow();
@@ -90,12 +87,8 @@ int main(int argc, char *argv[])
     });
 #endif // Q_OS_MACOS
 
-    QStringList urlStrList = parser.positionalArguments();
-    QList<QUrl> && urlList = PlaylistManager::convertToUrlList(urlStrList);
-
-    if (!urlList.isEmpty()) {
-        w.showUrls(urlList);
-    }
+    QStringList fileList = parser.positionalArguments();
+    w.showFiles(fileList);
 
     w.initWindowSize();
 

app/mainwindow.cpp

@@ -59,7 +59,7 @@ MainWindow::MainWindow(QWidget *parent)
     this->setWindowIcon(QIcon(u":/icons/app-icon.svg"_s));
     this->setAcceptDrops(true);
 
-    m_pm->setAutoLoadFilterSuffixes(supportedImageFormats());
+    m_pm->setAllowedSuffixes(supportedImageFormats());
 
     GraphicsScene * scene = new GraphicsScene(this);
 
@@ -104,13 +104,13 @@ MainWindow::MainWindow(QWidget *parent)
         m_am->actionToggleCheckerboard,
     }, this);
 
-    connect(m_pm, &PlaylistManager::totalCountChanged, this, &MainWindow::updateGalleryButtonsVisibility);
+    connect(m_pm, &PlaylistManager::playlistChanged, this, std::bind(&MainWindow::updateActionState, this));
 
-    connect(m_pm->model(), &PlaylistModel::modelReset, this, std::bind(&MainWindow::galleryCurrent, this, false, false));
-    connect(m_pm, &PlaylistManager::currentIndexChanged, this, std::bind(&MainWindow::galleryCurrent, this, true, false));
+    connect(m_pm, &PlaylistManager::playlistChanged, this, std::bind(&MainWindow::galleryCurrent, this, false));
+    connect(m_pm, &PlaylistManager::currentIndexChanged, this, std::bind(&MainWindow::galleryCurrent, this, false));
 
     connect(m_fileSystemWatcher, &QFileSystemWatcher::fileChanged, this, [this](){
-        QTimer::singleShot(500, this, std::bind(&MainWindow::galleryCurrent, this, false, true));
+        QTimer::singleShot(500, this, std::bind(&MainWindow::galleryCurrent, this, true));
     });
 
     QShortcut * fullscreenShorucut = new QShortcut(QKeySequence(QKeySequence::FullScreen), this);
@@ -130,26 +130,15 @@ MainWindow::~MainWindow()
 
 }
 
-void MainWindow::showUrls(const QList<QUrl> &urls)
+void MainWindow::showFiles(const QStringList &files)
 {
-    if (!urls.isEmpty()) {
-        const QUrl & firstUrl = urls.first();
-        if (urls.count() == 1) {
-            const QString lowerCaseUrlPath(firstUrl.path().toLower());
-            if (lowerCaseUrlPath.endsWith(".m3u8") || lowerCaseUrlPath.endsWith(".m3u")) {
-                m_pm->loadM3U8Playlist(firstUrl);
-                galleryCurrent(true, true);
-                return;
-            }
-        }
-        m_gv->showFileFromPath(firstUrl.toLocalFile());
-        m_pm->loadPlaylist(urls);
-    } else {
-        m_gv->showText(tr("File url list is empty"));
-        m_pm->setPlaylist(urls);
-        return;
-    }
+    m_pm->loadPlaylist(files);
+    m_nav->fitInView(m_nav->sceneRect(), Qt::KeepAspectRatio);
+}
 
+void MainWindow::showFiles(const QList<QUrl>& urls)
+{
+    m_pm->loadPlaylist(urls);
     m_nav->fitInView(m_nav->sceneRect(), Qt::KeepAspectRatio);
 }
 
@@ -201,15 +190,9 @@ void MainWindow::adjustWindowSizeBySceneRect()
     }
 }
 
-// can be empty if it is NOT from a local file.
-QUrl MainWindow::currentImageFileUrl() const
-{
-    return m_pm->urlByIndex(m_pm->curIndex());
-}
-
 void MainWindow::clearGallery()
 {
-    m_pm->setPlaylist({});
+    m_pm->clearPlaylist();
 }
 
 void MainWindow::galleryPrev()
@@ -217,10 +200,9 @@ void MainWindow::galleryPrev()
     const bool loopGallery = Settings::instance()->loopGallery();
     if (!loopGallery && m_pm->isFirstIndex()) return;
 
-    QModelIndex index = m_pm->previousIndex();
-    if (index.isValid()) {
-        m_pm->setCurrentIndex(index);
-        m_gv->showFileFromPath(m_pm->localFileByIndex(index));
+    auto index = m_pm->previousIndex();
+    if (index.has_value()) {
+        m_pm->setCurrentIndex(*index);
     }
 }
 
@@ -229,31 +211,29 @@ void MainWindow::galleryNext()
     const bool loopGallery = Settings::instance()->loopGallery();
     if (!loopGallery && m_pm->isLastIndex()) return;
 
-    QModelIndex index = m_pm->nextIndex();
-    if (index.isValid()) {
-        m_pm->setCurrentIndex(index);
-        m_gv->showFileFromPath(m_pm->localFileByIndex(index));
+    auto index = m_pm->nextIndex();
+    if (index.has_value()) {
+        m_pm->setCurrentIndex(*index);
     }
 }
 
-// Only use this to update minor information.
-void MainWindow::galleryCurrent(bool showLoadImageHintWhenEmpty, bool reloadImage)
+void MainWindow::galleryCurrent(bool fromFileWatcher)
 {
-    QModelIndex index = m_pm->curIndex();
-    bool shouldResetfileWatcher = true;
-    if (index.isValid()) {
-        const QString & localFilePath(m_pm->localFileByIndex(index));
-        if (reloadImage) m_gv->showFileFromPath(localFilePath);
-        shouldResetfileWatcher = !updateFileWatcher(localFilePath);
-        setWindowTitle(m_pm->urlByIndex(index).fileName());
-    } else if (showLoadImageHintWhenEmpty && m_pm->totalCount() <= 0) {
-        m_gv->showText(QCoreApplication::translate("GraphicsScene", "Drag image here"));
+    auto index = m_pm->currentIndex();
+    if (index.has_value()) {
+        QString localFilePath = m_pm->localFileByIndex(*index);
+        m_gv->showFileFromPath(localFilePath);
+        if (!fromFileWatcher) {
+            updateFileWatcher(localFilePath);
+            setWindowTitle(m_pm->urlByIndex(*index).fileName());
+        }
+    } else {
+        m_gv->showText(tr("Drag image here"));
         setWindowTitle(QString());
+        updateFileWatcher();
     }
 
-    updateGalleryButtonsVisibility();
-
-    if (shouldResetfileWatcher) updateFileWatcher();
+    updateActionState();
 }
 
 QStringList MainWindow::supportedImageFormats()
@@ -361,23 +341,10 @@ void MainWindow::resizeEvent(QResizeEvent *event)
 
 void MainWindow::contextMenuEvent(QContextMenuEvent *event)
 {
-    // TODO: Update this function.
     QMenu * menu = new QMenu;
 
-    // TODO: currentImageFileUrl() may be redundant.
-    QMenu * copyMenu = new QMenu(tr("&Copy"));
-    QUrl currentFileUrl = currentImageFileUrl();
-
-    copyMenu->setIcon(QIcon::fromTheme(u"edit-copy"_s));
-    copyMenu->addAction(m_am->actionCopyPixmap);
-    if (currentFileUrl.isValid()) {
-        copyMenu->addAction(m_am->actionCopyFilePath);
-    }
-    if (copyMenu->actions().count() == 1) {
-        menu->addActions(copyMenu->actions());
-    } else {
-        menu->addMenu(copyMenu);
-    }
+    menu->addAction(m_am->actionCopyPixmap);
+    menu->addAction(m_am->actionCopyFilePath);
 
     menu->addSeparator();
 
@@ -402,26 +369,16 @@ void MainWindow::contextMenuEvent(QContextMenuEvent *event)
 
     menu->addSeparator();
 
-    // TODO: Move checked update to action manager.
-    QAction * avoidResetTransform = m_am->actionToggleAvoidResetTransform;
-    avoidResetTransform->setCheckable(true);
-    avoidResetTransform->setChecked(m_gv->avoidResetTransform());
-    menu->addAction(avoidResetTransform);
+    menu->addAction(m_am->actionToggleAvoidResetTransform);
     menu->addAction(m_am->actionToggleCheckerboard);
-    QAction * pauseAnimation = m_am->actionTogglePauseAnimation;
-    pauseAnimation->setCheckable(true);
-    pauseAnimation->setChecked(m_gv->scene()->pauseAnimation());
-    menu->addAction(pauseAnimation);
+    menu->addAction(m_am->actionTogglePauseAnimation);
     menu->addAction(m_am->actionAnimationNextFrame);
 
-    if (currentFileUrl.isValid()) {
     menu->addSeparator();
-        if (currentFileUrl.isLocalFile()) {
+
     menu->addAction(m_am->actionTrash);
     menu->addAction(m_am->actionLocateInFileManager);
-        }
     menu->addAction(m_am->actionProperties);
-    }
 
     menu->addSeparator();
 
@@ -430,14 +387,13 @@ void MainWindow::contextMenuEvent(QContextMenuEvent *event)
 
     menu->exec(mapToGlobal(event->pos()));
     menu->deleteLater();
-    copyMenu->deleteLater();
 
     return FramelessWindow::contextMenuEvent(event);
 }
 
 void MainWindow::dragEnterEvent(QDragEnterEvent *event)
 {
-    if (event->mimeData()->hasUrls() || event->mimeData()->hasImage() || event->mimeData()->hasText()) {
+    if (event->mimeData()->hasUrls()) {
         event->acceptProposedAction();
     } else {
         event->ignore();
@@ -456,24 +412,8 @@ void MainWindow::dropEvent(QDropEvent *event)
     event->acceptProposedAction();
 
     const QMimeData * mimeData = event->mimeData();
-
     if (mimeData->hasUrls()) {
-        const QList<QUrl> &urls = mimeData->urls();
-        if (urls.isEmpty()) {
-            m_gv->showText(tr("File url list is empty"));
-        } else {
-            showUrls(urls);
-        }
-    } else if (mimeData->hasImage()) {
-        QImage img = qvariant_cast<QImage>(mimeData->imageData());
-        QPixmap pixmap = QPixmap::fromImage(img);
-        if (pixmap.isNull()) {
-            m_gv->showText(tr("Image data is invalid"));
-        } else {
-            m_gv->showImage(pixmap);
-        }
-    } else if (mimeData->hasText()) {
-        m_gv->showText(mimeData->text());
+        showFiles(mimeData->urls());
     } else {
         m_gv->showText(tr("Not supported mimedata: %1").arg(mimeData->formats().first()));
     }
@@ -504,25 +444,7 @@ void MainWindow::updateWidgetsPosition()
 
 void MainWindow::toggleAvoidResetTransform()
 {
-    m_gv->setAvoidResetTransform(!m_gv->avoidResetTransform());
-}
-
-bool MainWindow::canPaste() const
-{
-    const QMimeData * clipboardData = QApplication::clipboard()->mimeData();
-    if (clipboardData->hasImage()) {
-        return true;
-    } else if (clipboardData->hasText()) {
-        QString clipboardText(clipboardData->text());
-        if (clipboardText.startsWith("PICTURE:")) {
-            QString maybeFilename(clipboardText.mid(8));
-            if (QFile::exists(maybeFilename)) {
-                return true;
-            }
-        }
-    }
-
-    return false;
+    m_gv->setAvoidResetTransform(!m_gv->isAvoidResetTransform());
 }
 
 void MainWindow::quitAppAction(bool force)
@@ -563,11 +485,11 @@ void MainWindow::on_actionCopyPixmap_triggered()
 
 void MainWindow::on_actionCopyFilePath_triggered()
 {
-    QUrl currentFileUrl(currentImageFileUrl());
-    if (currentFileUrl.isValid()) {
+    auto index = m_pm->currentIndex();
+    if (!index.has_value()) return;
+
     QClipboard *cb = QApplication::clipboard();
-        cb->setText(currentFileUrl.toLocalFile());
-    }
+    cb->setText(m_pm->localFileByIndex(*index));
 }
 
 void MainWindow::on_actionPrevPicture_triggered()
@@ -673,15 +595,16 @@ void MainWindow::on_actionTrash_triggered()
             QMessageBox::warning(this, tr("Failed to move file to trash"),
                                  tr("Move to trash failed, it might caused by file permission issue, file system limitation, or platform limitation."));
         } else {
-            m_pm->removeAt(index);
-            galleryCurrent(true, true);
+            m_pm->removeFromPlaylist(*index);
         }
     }
 }
 
 void MainWindow::on_actionLocateInFileManager_triggered()
 {
-    QUrl currentFileUrl = currentImageFileUrl();
+    auto index = m_pm->currentIndex();
+    if (!index.has_value()) return;
+    QUrl currentFileUrl = m_pm->urlByIndex(*index);
     if (!currentFileUrl.isValid()) return;
 
     QFileInfo fileInfo(currentFileUrl.toLocalFile());
@@ -716,7 +639,9 @@ void MainWindow::on_actionLocateInFileManager_triggered()
 
 void MainWindow::on_actionProperties_triggered()
 {
-    QUrl currentFileUrl = currentImageFileUrl();
+    auto index = m_pm->currentIndex();
+    if (!index.has_value()) return;
+    QUrl currentFileUrl = m_pm->urlByIndex(*index);
     if (!currentFileUrl.isValid()) return;
 
     MetadataModel * md = new MetadataModel();
@@ -750,3 +675,7 @@ bool MainWindow::updateFileWatcher(const QString &basePath)
     if (!basePath.isEmpty()) return m_fileSystemWatcher->addPath(basePath);
     return false;
 }
+
+void MainWindow::updateActionState() {
+    m_am->updateActionState(m_pm, m_gv);
+}

app/mainwindow.h

@@ -29,15 +29,15 @@ public:
     explicit MainWindow(QWidget *parent = nullptr);
     ~MainWindow() override;
 
-    void showUrls(const QList<QUrl> &urls);
+    void showFiles(const QStringList& files);
+    void showFiles(const QList<QUrl>& urls);
     void initWindowSize();
     void adjustWindowSizeBySceneRect();
-    QUrl currentImageFileUrl() const;
 
     void clearGallery();
     void galleryPrev();
     void galleryNext();
-    void galleryCurrent(bool showLoadImageHintWhenEmpty, bool reloadImage);
+    void galleryCurrent(bool fromFileWatcher);
 
     static QStringList supportedImageFormats();
 
@@ -57,7 +57,6 @@ protected slots:
     void closeWindow();
     void updateWidgetsPosition();
     void toggleAvoidResetTransform();
-    bool canPaste() const;
     void quitAppAction(bool force = false);
     void toggleFullscreen();
     void toggleMaximize();
@@ -98,6 +97,7 @@ private slots:
 
 private:
     bool updateFileWatcher(const QString & basePath = QString());
+    void updateActionState();
 
 private:
     ActionManager *m_am;

app/playlistmanager.cpp

@@ -9,152 +9,13 @@
 #include <QFileInfo>
 #include <QUrl>
 
-PlaylistModel::PlaylistModel(QObject *parent)
-    : QAbstractListModel(parent)
-{
-
-}
-
-PlaylistModel::~PlaylistModel()
-= default;
-
-void PlaylistModel::setPlaylist(const QList<QUrl> &urls)
-{
-    beginResetModel();
-    m_playlist = urls;
-    endResetModel();
-}
-
-QModelIndex PlaylistModel::loadPlaylist(const QList<QUrl> & urls)
-{
-    if (urls.isEmpty()) return {};
-    if (urls.count() == 1) {
-        return loadPlaylist(urls.constFirst());
-    } else {
-        setPlaylist(urls);
-        return index(0);
-    }
-}
-
-QModelIndex PlaylistModel::loadPlaylist(const QUrl &url)
-{
-    QFileInfo info(url.toLocalFile());
-    QDir dir(info.path());
-    QString && currentFileName = info.fileName();
-
-    if (dir.path() == m_currentDir) {
-        int idx = indexOf(url);
-        return idx == -1 ? appendToPlaylist(url) : index(idx);
-    }
-
-    QStringList entryList = dir.entryList(
-        m_autoLoadSuffixes,
-        QDir::Files | QDir::NoSymLinks, QDir::NoSort);
-
-    QCollator collator;
-    collator.setNumericMode(true);
-
-    std::sort(entryList.begin(), entryList.end(), collator);
-
-    QList<QUrl> playlist;
-
-    int idx = -1;
-    for (int i = 0; i < entryList.count(); i++) {
-        const QString & fileName = entryList.at(i);
-        const QString & oneEntry = dir.absoluteFilePath(fileName);
-        const QUrl & url = QUrl::fromLocalFile(oneEntry);
-        playlist.append(url);
-        if (fileName == currentFileName) {
-            idx = i;
-        }
-    }
-    if (idx == -1) {
-        idx = playlist.count();
-        playlist.append(url);
-    }
-    m_currentDir = dir.path();
-
-    setPlaylist(playlist);
-
-    return index(idx);
-}
-
-QModelIndex PlaylistModel::appendToPlaylist(const QUrl &url)
-{
-    const int lastIndex = rowCount();
-    beginInsertRows(QModelIndex(), lastIndex, lastIndex);
-    m_playlist.append(url);
-    endInsertRows();
-    return index(lastIndex);
-}
-
-bool PlaylistModel::removeAt(int index)
-{
-    if (index < 0 || index >= rowCount()) return false;
-    beginRemoveRows(QModelIndex(), index, index);
-    m_playlist.removeAt(index);
-    endRemoveRows();
-    return true;
-}
-
-int PlaylistModel::indexOf(const QUrl &url) const
-{
-    return m_playlist.indexOf(url);
-}
-
-QUrl PlaylistModel::urlByIndex(int index) const
-{
-    return m_playlist.value(index);
-}
-
-QStringList PlaylistModel::autoLoadFilterSuffixes() const
-{
-    return m_autoLoadSuffixes;
-}
-
-QHash<int, QByteArray> PlaylistModel::roleNames() const
-{
-    QHash<int, QByteArray> result = QAbstractListModel::roleNames();
-    result.insert(UrlRole, "url");
-    return result;
-}
-
-int PlaylistModel::rowCount(const QModelIndex &parent) const
-{
-    return m_playlist.count();
-}
-
-QVariant PlaylistModel::data(const QModelIndex &index, int role) const
-{
-    if (!index.isValid()) return {};
-
-    switch (role) {
-    case Qt::DisplayRole:
-        return m_playlist.at(index.row()).fileName();
-    case UrlRole:
-        return m_playlist.at(index.row());
-    }
-
-    return {};
-}
-
 PlaylistManager::PlaylistManager(QObject *parent)
     : QObject(parent)
+    , m_currentIndex(std::nullopt)
+    , m_playlist()
+    , m_allowedSuffixes()
 {
-    connect(&m_model, &PlaylistModel::rowsRemoved, this,
-            [this](const QModelIndex &, int, int) {
-                if (m_model.rowCount() <= m_currentIndex) {
-                    setProperty("currentIndex", m_currentIndex - 1);
-                }
-            });
 
-    auto onRowCountChanged = [this](){
-        emit totalCountChanged(m_model.rowCount());
-    };
-
-    connect(&m_model, &PlaylistModel::rowsInserted, this, onRowCountChanged);
-    connect(&m_model, &PlaylistModel::rowsRemoved, this, onRowCountChanged);
-    connect(&m_model, &PlaylistModel::modelReset, this, onRowCountChanged);
 }
 
 PlaylistManager::~PlaylistManager()
@@ -162,35 +23,106 @@ PlaylistManager::~PlaylistManager()
 
 }
 
-PlaylistModel *PlaylistManager::model()
-{
-    return &m_model;
+// region: Allowed Suffixes Operations
+
+const QStringList& PlaylistManager::allowedSuffixes() const {
+    return m_allowedSuffixes;
 }
 
-void PlaylistManager::setPlaylist(const QList<QUrl> &urls)
-{
-    m_model.setPlaylist(urls);
+void PlaylistManager::setAllowedSuffixes(const QStringList& nameFilters) {
+    m_allowedSuffixes = nameFilters;
+    emit allowedSuffixesChanged(m_allowedSuffixes);
 }
 
-QModelIndex PlaylistManager::loadPlaylist(const QList<QUrl> &urls)
-{
-    QModelIndex idx = m_model.loadPlaylist(urls);
-    setProperty("currentIndex", idx.row());
-    return idx;
+// endregion
+
+// region: Playlist Loader and Reset
+
+bool PlaylistManager::loadPlaylist(const QStringList& files) {
+    // Convert string list to url list first
+    QList<QUrl> urls;
+    for (const QString & file : std::as_const(files)) {
+        urls.append(urlFromString(file));
+    }
+
+    return loadPlaylist(urls);
 }
 
-QModelIndex PlaylistManager::loadPlaylist(const QUrl &url)
-{
-    QModelIndex idx = m_model.loadPlaylist(url);
-    setProperty("currentIndex", idx.row());
-    return idx;
+bool PlaylistManager::loadPlaylist(const QList<QUrl>& urls) {
+    // Check its count, and check M3U8 playlist for single file case.
+    if (urls.isEmpty()) {
+        clearPlaylist();
+        return true;
+    } else if (urls.count() == 1) {
+        const QUrl& firstUrl = urls.first();
+        const QString lowerCaseUrlPath(firstUrl.path().toLower());
+        if (lowerCaseUrlPath.endsWith(".m3u8") || lowerCaseUrlPath.endsWith(".m3u")) {
+            return loadM3U8Playlist(firstUrl);
+        } else {
+            return loadSingleFilePlaylist(firstUrl);
+        }
+    } else {
+        return loadMultipleFilesPlaylist(std::move(urls));
+    }
 }
 
-QModelIndex PlaylistManager::loadM3U8Playlist(const QUrl &url)
-{
+bool PlaylistManager::loadSingleFilePlaylist(const QUrl& url) {
+    // Check URL at first
+    if (!checkUrl(url))
+        return false;
+
+    QFileInfo info(url.toLocalFile());
+    QDir dir(info.path());
+    QString currentFileName = info.fileName();
+
+    QStringList entryList = dir.entryList(
+        m_allowedSuffixes, QDir::Files | QDir::NoSymLinks, QDir::NoSort);
+
+    QCollator collator;
+    collator.setNumericMode(true);
+
+    std::sort(entryList.begin(), entryList.end(), collator);
+
+    QList<QUrl> playlist;
+    std::optional<qsizetype> idx = std::nullopt;
+    for (qsizetype i = 0; i < entryList.count(); i++) {
+        const QString &fileName = entryList.at(i);
+        const QString &oneEntry = dir.absoluteFilePath(fileName);
+        const QUrl &url = QUrl::fromLocalFile(oneEntry);
+        if (!checkUrl(url)) {
+            return false;
+        }
+        playlist.append(url);
+        if (fileName == currentFileName) {
+            idx = i;
+        }
+    }
+
+    setPlaylist(std::move(playlist), idx);
+    return true;
+}
+
+bool PlaylistManager::loadMultipleFilesPlaylist(const QList<QUrl>&& urls) {
+    // Check all of them are valid
+    for (const auto& url : std::as_const(urls)) {
+        if (!checkUrl(url)) {
+            return false;
+        }
+    }
+
+    // Set playlist and return
+    setPlaylist(std::move(urls));
+    return true;
+}
+
+bool PlaylistManager::loadM3U8Playlist(const QUrl& url) {
+    // Check URL at first
+    if (!checkUrl(url))
+        return false;
+
+    QList<QUrl> urls;
     QFile file(url.toLocalFile());
     if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
-        QList<QUrl> urls;
         while (!file.atEnd()) {
             QString line = file.readLine();
             if (line.startsWith('#')) {
@@ -198,86 +130,185 @@ QModelIndex PlaylistManager::loadM3U8Playlist(const QUrl &url)
             }
             QFileInfo fileInfo(file);
             QUrl item = QUrl::fromUserInput(line, fileInfo.absolutePath());
+            if (!checkUrl(item)) {
+                return false;
+            }
             urls.append(item);
         }
-        return loadPlaylist(urls);
     } else {
-        return {};
+        return false;
+    }
+
+    setPlaylist(std::move(urls));
+    return true;
+}
+
+void PlaylistManager::setPlaylist(const QList<QUrl>&& urls, std::optional<qsizetype> indexHint) {
+    // Setup playlist
+    m_playlist = std::move(urls);
+
+    // Set index with hint
+    if (indexHint.has_value()) {
+        m_currentIndex = *indexHint;
+    }
+    sanitizeIndex();
+
+    // Raise signal
+    emit playlistChanged(totalCount());
+}
+
+void PlaylistManager::clearPlaylist() {
+    m_playlist.clear();
+    sanitizeIndex();
+    emit playlistChanged(this->totalCount());
+}
+
+// endregion
+
+// region: Playlist Operations
+
+void PlaylistManager::appendToPlaylist(const QString &file)
+{
+    return appendToPlaylist(urlFromString(file));
+}
+
+void PlaylistManager::appendToPlaylist(const QUrl &url)
+{
+    m_playlist.append(url);
+    sanitizeIndex();
+    emit playlistChanged(totalCount());
+}
+
+bool PlaylistManager::insertIntoPlaylist(qsizetype index, const QString &file)
+{
+    return insertIntoPlaylist(index, urlFromString(file));
+}
+
+bool PlaylistManager::insertIntoPlaylist(qsizetype index, const QUrl &url)
+{
+    if (index < 0 || index > totalCount()) {
+        return false;
+    } else {
+        m_playlist.insert(index, url);
+        sanitizeIndex();
+        emit playlistChanged(totalCount());
+        return true;
     }
 }
 
-int PlaylistManager::totalCount() const
+bool PlaylistManager::removeFromPlaylist(qsizetype index)
 {
-    return m_model.rowCount();
+    if (index < 0 || index >= totalCount()) {
+        return false;
+    } else {
+        m_playlist.removeAt(index);
+        sanitizeIndex();
+        emit playlistChanged(totalCount());
+        return true;
+    }
 }
 
-QModelIndex PlaylistManager::previousIndex() const
-{
-    int count = totalCount();
-    if (count == 0) return {};
+// endregion
 
-    return m_model.index(isFirstIndex() ? count - 1 : m_currentIndex - 1);
+// region: Index Operations
+
+qsizetype PlaylistManager::totalCount() const
+{
+    return m_playlist.count();
 }
 
-QModelIndex PlaylistManager::nextIndex() const
+std::optional<qsizetype> PlaylistManager::previousIndex() const
 {
-    int count = totalCount();
-    if (count == 0) return {};
-
-    return m_model.index(isLastIndex() ? 0 : m_currentIndex + 1);
+    if (!m_currentIndex.has_value() || totalCount() <= 0) return std::nullopt;
+    return (isFirstIndex() ? totalCount() - 1 : *m_currentIndex - 1);
 }
 
-QModelIndex PlaylistManager::curIndex() const
+std::optional<qsizetype> PlaylistManager::nextIndex() const
 {
-    return m_model.index(m_currentIndex);
+    if (!m_currentIndex.has_value() || totalCount() <= 0) return std::nullopt;
+    return (isLastIndex() ? 0 : *m_currentIndex + 1);
 }
 
 bool PlaylistManager::isFirstIndex() const
 {
-    return m_currentIndex == 0;
+    return m_currentIndex.has_value() && *m_currentIndex == 0;
 }
 
 bool PlaylistManager::isLastIndex() const
 {
-    return m_currentIndex + 1 == totalCount();
+    return m_currentIndex.has_value() && *m_currentIndex + 1 == totalCount();
 }
 
-void PlaylistManager::setCurrentIndex(const QModelIndex &index)
+std::optional<qsizetype> PlaylistManager::currentIndex() const
 {
-    if (index.isValid() && index.row() >= 0 && index.row() < totalCount()) {
-        setProperty("currentIndex", index.row());
+    return m_currentIndex;
+}
+
+bool PlaylistManager::setCurrentIndex(qsizetype index)
+{
+    if (!m_currentIndex.has_value()) {
+        return false;
     }
+    if (index < 0 || index >= totalCount()) {
+        return false;
+    }
+    if (*m_currentIndex == index) {
+        return true;
+    }
+
+    m_currentIndex = index;
+    emit currentIndexChanged(index);
+    return true;
 }
 
-QUrl PlaylistManager::urlByIndex(const QModelIndex &index)
+QUrl PlaylistManager::urlByIndex(qsizetype index) const
 {
-    return m_model.urlByIndex(index.row());
+    return m_playlist.value(index);
 }
 
-QString PlaylistManager::localFileByIndex(const QModelIndex &index)
+QString PlaylistManager::localFileByIndex(qsizetype index) const
 {
     return urlByIndex(index).toLocalFile();
 }
 
-bool PlaylistManager::removeAt(const QModelIndex &index)
-{
-    return m_model.removeAt(index.row());
-}
+// endregion
 
-void PlaylistManager::setAutoLoadFilterSuffixes(const QStringList &nameFilters)
-{
-    m_model.setProperty("autoLoadFilterSuffixes", nameFilters);
-}
+// region: Misc
 
-QList<QUrl> PlaylistManager::convertToUrlList(const QStringList &files)
+void PlaylistManager::sanitizeIndex()
 {
-    QList<QUrl> urlList;
-    for (const QString & str : std::as_const(files)) {
-        QUrl url = QUrl::fromLocalFile(str);
-        if (url.isValid()) {
-            urlList.append(url);
+    auto cnt = totalCount();
+    if (cnt == 0) {
+        // If playlist is empty, current index should be invalid.
+        m_currentIndex = std::nullopt;
+    } else {
+        if (m_currentIndex.has_value()) {
+            // Clamp current index in playlist range.
+            // If it is already in range, not change was done.
+            auto currentIndex = *m_currentIndex;
+            if (currentIndex < 0) {
+                m_currentIndex = 0;
+            } else if (currentIndex >= cnt) {
+                m_currentIndex = cnt - 1;
+            } else {
+                ; // No change.
+            }
+        } else {
+            // If there is no set value for current index,
+            // set it at the beginning of playlist.
+            m_currentIndex = 0;
         }
     }
-
-    return urlList;
 }
+
+bool PlaylistManager::checkUrl(const QUrl& url)
+{
+    return url.isValid() && url.isLocalFile();
+}
+
+QUrl PlaylistManager::urlFromString(const QString& file)
+{
+    return QUrl::fromLocalFile(file);
+}
+
+// endregion

app/playlistmanager.h

@@ -5,84 +5,126 @@
 #pragma once
 
 #include <QUrl>
-#include <QAbstractListModel>
-
-class PlaylistModel : public QAbstractListModel
-{
-    Q_OBJECT
-public:
-    enum PlaylistRole {
-        UrlRole = Qt::UserRole
-    };
-    Q_ENUM(PlaylistRole)
-    Q_PROPERTY(QStringList autoLoadFilterSuffixes MEMBER m_autoLoadSuffixes NOTIFY autoLoadFilterSuffixesChanged)
-
-    explicit PlaylistModel(QObject *parent = nullptr);
-    ~PlaylistModel() override;
-
-    void setPlaylist(const QList<QUrl> & urls);
-    QModelIndex loadPlaylist(const QList<QUrl> & urls);
-    QModelIndex loadPlaylist(const QUrl & url);
-    QModelIndex appendToPlaylist(const QUrl & url);
-    bool removeAt(int index);
-    int indexOf(const QUrl & url) const;
-    QUrl urlByIndex(int index) const;
-    QStringList autoLoadFilterSuffixes() const;
-
-    QHash<int, QByteArray> roleNames() const override;
-    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
-    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
-
-signals:
-    void autoLoadFilterSuffixesChanged(QStringList suffixes);
-
-private:
-    // model data
-    QList<QUrl> m_playlist;
-    // properties
-    QStringList m_autoLoadSuffixes = {};
-    // internal
-    QString m_currentDir;
-};
+#include <QObject>
+#include <optional>
 
+/// The manager of playlist.
 class PlaylistManager : public QObject
 {
     Q_OBJECT
 public:
-    Q_PROPERTY(int currentIndex MEMBER m_currentIndex NOTIFY currentIndexChanged)
-    Q_PROPERTY(QStringList autoLoadFilterSuffixes WRITE setAutoLoadFilterSuffixes)
-    Q_PROPERTY(PlaylistModel * model READ model CONSTANT)
-
-    explicit PlaylistManager(QObject *parent = nullptr);
+    /// Constructs a PlaylistManager with an optional parent QObject.
+    explicit PlaylistManager(QObject* parent = nullptr);
+    /// Destructor.
     ~PlaylistManager();
 
-    PlaylistModel * model();
+    /// Get the allowed file suffixes of this playlist.
+    /// @return The current list of allowed suffixes.
+    const QStringList& allowedSuffixes() const;
+    /// Set the allowed file suffixes of this playlist.
+    /// @remark This only works for "load the whole directory by one file" case.
+    /// @param[in] nameFilters The new list of allowed suffixes.
+    void setAllowedSuffixes(const QStringList& nameFilters);
 
-    void setPlaylist(const QList<QUrl> & url);
-    Q_INVOKABLE QModelIndex loadPlaylist(const QList<QUrl> & urls);
-    Q_INVOKABLE QModelIndex loadPlaylist(const QUrl & url);
-    Q_INVOKABLE QModelIndex loadM3U8Playlist(const QUrl & url);
+    /// Load user specified files as playlist.
+    /// @remark The wrapper for another overload.
+    /// @return True for successful load, otherwise false.
+    bool loadPlaylist(const QStringList& files);
+    /// Load user specified URLs as playlist.
+    /// @remark This function automatically dispatch these files into correct sub-load functions.
+    /// @return True for successful load, otherwise false.
+    bool loadPlaylist(const QList<QUrl>& urls);
+    /// Clear the entire playlist and reset current index.
+    void clearPlaylist();
 
-    int totalCount() const;
-    QModelIndex previousIndex() const;
-    QModelIndex nextIndex() const;
-    QModelIndex curIndex() const;
+    /// Append a local file path to the playlist.
+    void appendToPlaylist(const QString& file);
+    /// Append a URL to the playlist.
+    void appendToPlaylist(const QUrl& url);
+    /// Insert a local file path at the given index.
+    /// @return True if inserted successfully, false if index is out of range.
+    bool insertIntoPlaylist(qsizetype index, const QString& file);
+    /// Insert a URL at the given index.
+    /// @return True if inserted successfully, false if index is out of range.
+    bool insertIntoPlaylist(qsizetype index, const QUrl& url);
+    /// Remove the entry at the given index.
+    /// @return True if removed successfully, false if index is out of range.
+    bool removeFromPlaylist(qsizetype index);
+
+    /// Returns the total number of items in the playlist.
+    /// @return Total count of entries in the playlist.
+    qsizetype totalCount() const;
+    /// Try fetching previous index.
+    /// @details This previous index is gallery-loop-aware.
+    /// @return std::nullopt if playlist is empty, otherwise the previous index considering gallery loop.
+    std::optional<qsizetype> previousIndex() const;
+    /// Try fetching next index.
+    /// @details This next index is gallery-loop-aware.
+    /// @return std::nullopt if playlist is empty, otherwise the next index considering gallery loop.
+    std::optional<qsizetype> nextIndex() const;
+    /// Check whether current index is the first index.
+    /// @return False if current index is not the first index or playlist is empty, otherwise true.
     bool isFirstIndex() const;
+    /// Check whether current index is the last index.
+    /// @return False if current index is not the last index or playlist is empty, otherwise true.
     bool isLastIndex() const;
-    void setCurrentIndex(const QModelIndex & index);
-    QUrl urlByIndex(const QModelIndex & index);
-    QString localFileByIndex(const QModelIndex & index);
-    bool removeAt(const QModelIndex & index);
-
-    void setAutoLoadFilterSuffixes(const QStringList &nameFilters);
-
-    static QList<QUrl> convertToUrlList(const QStringList & files);
+    /// Returns the current index.
+    /// @return std::nullopt if the playlist is empty, otherwise the current index.
+    std::optional<qsizetype> currentIndex() const;
+    /// Set the current index.
+    /// @remark Index only can be set when playlist is not empty.
+    /// @return True if successful set, including "not changed" set, otherwise false.
+    /// This return value only indicates whether we can set index and given index is valid for setting.
+    /// If "no changed" set occurs, this function returns true, but doesn't raise current index changed signal.
+    bool setCurrentIndex(qsizetype index);
+    /// Returns the URL at the given index.
+    /// @return The URL if index is valid.
+    /// This class guarantee that this QUrl is pointing to a local file.
+    QUrl urlByIndex(qsizetype index) const;
+    /// Returns the local file path at the given index.
+    /// @return The local file path if index is valid.
+    /// This class guarantee that local file path always is valid.
+    QString localFileByIndex(qsizetype index) const;
 
 signals:
-    void currentIndexChanged(int index);
-    void totalCountChanged(int count);
+    void allowedSuffixesChanged(const QStringList& suffixes);
+    /// Raised when index was changed bu setter.
+    /// The argument holds the new current index.
+    /// Please note that this signal will NOT be raised by the whole playlist change caused index change.
+    void currentIndexChanged(qsizetype index);
+    /// The whole playlist was changed, involving loading, editing and deleting some or full entries.
+    /// The argument holds the total count of new play list.
+    void playlistChanged(qsizetype count);
 
 private:
-    int m_currentIndex = -1;
-    PlaylistModel m_model;
+    /// The fundamental playlist setter.
+    /// @details All playlist load functions will call this function to set playlist at last.
+    /// @param[in] urls ALl urls in this list should be checked by checkUrl() function.
+    /// @param[in] indexHint Try to set current index to this index if possible.
+    void setPlaylist(const QList<QUrl>&& urls, std::optional<qsizetype> indexHint = std::nullopt);
+    /// Load playlist from a single file.
+    /// @details This function scans the same directory for siblings matching allowed suffixes, sorted naturally.
+    /// @return True if the playlist was loaded successfully, false otherwise.
+    bool loadSingleFilePlaylist(const QUrl& url);
+    /// Load playlist from multiple URLs directly.
+    /// @return True if all URLs are valid, false otherwise.
+    bool loadMultipleFilesPlaylist(const QList<QUrl>&& urls);
+    /// Load playlist from an M3U/M3U8 playlist file.
+    /// @return True if loaded successfully, false otherwise.
+    bool loadM3U8Playlist(const QUrl& url);
+
+    /// Make sure that current index is valid.
+    /// @details This function usually is used by those functions manipulating playlist.
+    void sanitizeIndex();
+
+    /// Check whether given QUrl is proper to be put into playlist.
+    /// @details Only the url pointing to local file can be put into playlist.
+    static bool checkUrl(const QUrl& url);
+    /// Convert a string to local file into a QUrl.
+    /// @param[in] file The string pointing to local file.
+    static QUrl urlFromString(const QString& file);
+
+    std::optional<qsizetype> m_currentIndex;
+    QList<QUrl> m_playlist;
+    QStringList m_allowedSuffixes;
 };