feat: remove checkerboard icon and change bottom toolbar

- "auto" is not essential for our hard fork, so i simply remove it.
- remove all useless code after removing it.
- enlarge the min size of window because previous may trigger bad layout when showing navigation view.

CMakeLists.txt

@@ -39,7 +39,6 @@ endif ()
 
 set (PPIC_CPP_FILES
     app/main.cpp
-    app/framelesswindow.cpp
     app/mainwindow.cpp
     app/actionmanager.cpp
     app/graphicsview.cpp
@@ -54,10 +53,12 @@ set (PPIC_CPP_FILES
     app/exiv2wrapper.cpp
     app/playlistmanager.cpp
     app/fileopeneventhandler.cpp
+    app/playlistscout.cpp
+    app/playlistscouts/qtscout.cpp
+    app/playlistscouts/explorerscout.cpp
 )
 
 set (PPIC_HEADER_FILES
-    app/framelesswindow.h
     app/mainwindow.h
     app/actionmanager.h
     app/graphicsview.h
@@ -72,12 +73,16 @@ set (PPIC_HEADER_FILES
     app/exiv2wrapper.h
     app/playlistmanager.h
     app/fileopeneventhandler.h
+    app/playlistscout.h
+    app/playlistscouts/qtscout.h
+    app/playlistscouts/explorerscout.h
 )
 
 set (PPIC_UI_FILES
     app/settingsdialog.ui
     app/aboutdialog.ui
     app/metadatadialog.ui
+    app/mainwindow.ui
 )
 
 set (PPIC_QRC_FILES
@@ -119,6 +124,11 @@ else()
     qt_add_translations(${EXE_NAME} ${ADD_TRANSLATIONS_ADDITIONAL_ARGS} TS_FILES ${PPIC_TS_FILES} QM_FILES_OUTPUT_VARIABLE PPIC_QM_FILES)
 endif()
 
+# YYC MARK:
+# This is essential, otherwise Qt UIC generated UI header file
+# can not find our header files if there are custom widgets inside UI file.
+target_include_directories(${EXE_NAME} PRIVATE app/)
+
 target_sources(${EXE_NAME} PRIVATE ${PPIC_QM_FILES})
 
 target_link_libraries (${EXE_NAME} Qt${QT_VERSION_MAJOR}::Widgets Qt${QT_VERSION_MAJOR}::Svg Qt${QT_VERSION_MAJOR}::SvgWidgets)

app/actionmanager.cpp

@@ -55,7 +55,7 @@ void ActionManager::setupAction(MainWindow *mainWindow)
     // TODO: We may replace all Qt theme icons to our custom icon for visual consistency.
     // TODO: Some icons are invalid.
 
-    CREATE_NEW_THEMEICON_ACTION(mainWindow, actionCopyPixmap, edit-copy);
+    CREATE_NEW_ACTION(mainWindow, actionCopyPixmap);
     CREATE_NEW_ACTION(mainWindow, actionCopyFilePath);
 
     CREATE_NEW_ICON_ACTION(mainWindow, actionPrevPicture, go-previous);
@@ -74,7 +74,7 @@ void ActionManager::setupAction(MainWindow *mainWindow)
     CREATE_NEW_ICON_ACTION(mainWindow, actionRotateCounterClockwise, app-icon);
 
     CREATE_NEW_ACTION(mainWindow, actionToggleAvoidResetTransform);
-    CREATE_NEW_ICON_ACTION(mainWindow, actionToggleCheckerboard, view-background-checkerboard);
+    CREATE_NEW_ACTION(mainWindow, actionToggleCheckerboard);
     CREATE_NEW_ACTION(mainWindow, actionTogglePauseAnimation);
     CREATE_NEW_ACTION(mainWindow, actionAnimationNextFrame);
 

app/bottombuttongroup.cpp

@@ -8,7 +8,7 @@
 #include <QVBoxLayout>
 #include <QDebug>
 
-BottomButtonGroup::BottomButtonGroup(const std::vector<QAction *> &actionList, QWidget *parent)
+BottomButtonGroup::BottomButtonGroup(QWidget *parent)
     : QGroupBox (parent)
 {
     QHBoxLayout * mainLayout = new QHBoxLayout(this);
@@ -25,7 +25,9 @@ QToolButton {
     border-style: none;
 }
 )#");
+}
 
+void BottomButtonGroup::addActions(const std::vector<QAction *> & actionList) {
     for (QAction * action : actionList) {
         // Create button
         QToolButton * btn = new QToolButton(this);
@@ -37,3 +39,7 @@ QToolButton {
     }
     updateGeometry();
 }
+
+void BottomButtonGroup::addAction(QAction* action) {
+    addActions({action});
+}

app/bottombuttongroup.h

@@ -14,7 +14,10 @@ class BottomButtonGroup : public QGroupBox
 {
     Q_OBJECT
 public:
-    explicit BottomButtonGroup(const std::vector<QAction *> & actionList, QWidget *parent = nullptr);
+    explicit BottomButtonGroup(QWidget *parent = nullptr);
+
+    void addActions(const std::vector<QAction *> & actionList);
+    void addAction(QAction* action);
 };
 
 #endif // BOTTOMBUTTONGROUP_H

app/framelesswindow.cpp

@@ -1,36 +0,0 @@
-// SPDX-FileCopyrightText: 2022 Gary Wang <wzc782970009@gmail.com>
-// SPDX-FileCopyrightText: 2023 Tad Young <yyc12321@outlook.com>
-//
-// SPDX-License-Identifier: MIT
-
-#include "framelesswindow.h"
-
-#include <QMouseEvent>
-#include <QHoverEvent>
-#include <QApplication>
-#include <QVBoxLayout>
-#include <QWindow>
-
-FramelessWindow::FramelessWindow(QWidget *parent)
-    : QWidget(parent)
-    , m_centralLayout(new QVBoxLayout(this))
-{
-    this->setWindowFlags(Qt::Window | Qt::WindowTitleHint | Qt::WindowSystemMenuHint | Qt::WindowMinMaxButtonsHint | Qt::WindowCloseButtonHint);
-
-    // YYC MARK:
-    // 72 px is the height of Windows Photo Viewer's bottom line.
-
-    // TODO: This value may be declared as a constant.
-    m_centralLayout->setContentsMargins(QMargins(0, 0, 0, 72));
-}
-
-void FramelessWindow::setCentralWidget(QWidget *widget)
-{
-    if (m_centralWidget) {
-        m_centralLayout->removeWidget(m_centralWidget);
-        m_centralWidget->deleteLater();
-    }
-
-    m_centralLayout->addWidget(widget);
-    m_centralWidget = widget;
-}

app/framelesswindow.h

@@ -1,27 +0,0 @@
-// SPDX-FileCopyrightText: 2022 Gary Wang <wzc782970009@gmail.com>
-//
-// SPDX-License-Identifier: MIT
-
-#ifndef FRAMELESSWINDOW_H
-#define FRAMELESSWINDOW_H
-
-#include <QWidget>
-
-QT_BEGIN_NAMESPACE
-class QVBoxLayout;
-QT_END_NAMESPACE
-
-class FramelessWindow : public QWidget
-{
-    Q_OBJECT
-public:
-    explicit FramelessWindow(QWidget *parent = nullptr);
-
-    void setCentralWidget(QWidget * widget);
-
-private:
-    QVBoxLayout * m_centralLayout = nullptr;
-    QWidget * m_centralWidget = nullptr; // just a pointer, doesn't take the ownership.
-};
-
-#endif // FRAMELESSWINDOW_H

app/graphicsscene.h

@@ -38,7 +38,7 @@ public:
 
     QPixmap renderToPixmap();
 
-public slots:
+private slots:
     void updateStyle(Qt::ColorScheme colorScheme);
 
 private:

app/graphicsview.cpp

@@ -224,7 +224,18 @@ void GraphicsView::fitByOrientation(Qt::Orientation ori, bool scaleDownOnly)
     QRectF originalScene = sceneRect();
     QTransform currentTransform = transform();
     
-    // TODO: May be optimized by matrix arithmetic operation?
+    // TODO: 
+    // I guess following code may be optimized by matrix arithmetic operation.
+    // There is an AI given solution. But I didn't use it.
+    // Because I want to keep the same behavior of upstream.
+
+    // // Horizontal fit: Let the position of top center of viewport, (cx, 0), be inversely mapped to scene.
+    // // And compensate the behavior of `centerOn` which put given point to the center of viewport.
+    // QTransform inv = currentTransform.inverted();
+    // QPointF viewCx = viewport()->rect().center().x();
+    // QPointF viewCy = viewport()->rect().center().y();
+    // // The target is viewport top center. Its y=0, so `centerOn` required scene point is (viewCx, -viewCy).
+    // centerOn(inv.map(QPointF(viewCx, -viewCy)));
 
     if (ori == Qt::Horizontal) {
         // For horizontal fit (fit by width), position at top (for tall images)

app/graphicsview.h

@@ -52,7 +52,7 @@ signals:
     void navigatorViewRequired(bool required, QTransform transform);
     void viewportRectChanged();
 
-public slots:
+private slots:
     void updateStyle(Qt::ColorScheme colorScheme);
 
 private:

app/mainwindow.cpp

@@ -3,6 +3,7 @@
 // SPDX-License-Identifier: MIT
 
 #include "mainwindow.h"
+#include "ui_mainwindow.h"
 
 #include "settings.h"
 #include "bottombuttongroup.h"
@@ -46,51 +47,50 @@
 using namespace Qt::Literals::StringLiterals;
 
 MainWindow::MainWindow(QWidget *parent)
-    : FramelessWindow(parent)
+    : QWidget(parent)
+    , ui(new QT_PREPEND_NAMESPACE(Ui::MainWindow))
     , m_am(new ActionManager)
     , m_pm(new PlaylistManager(this))
     , m_fileSystemWatcher(new QFileSystemWatcher(this))
 {
+    ui->setupUi(this);
+    this->setWindowFlags(Qt::Window | Qt::WindowTitleHint | Qt::WindowSystemMenuHint | Qt::WindowMinMaxButtonsHint | Qt::WindowCloseButtonHint);
+
     // YYC MARK:
     // Blumis set original value is 350 x 330.
     // It is too small for modern device,
-    // so I level it up to standard VGA resolution 640 x 480.
-    this->setMinimumSize(640, 480);
+    // so I level it up to SVGA resolution 800 x 600.
+    this->setMinimumSize(800, 600);
     this->setWindowIcon(QIcon(u":/icons/app-icon.svg"_s));
     this->setAcceptDrops(true);
 
+    // Initialize playlist manager
     m_pm->setAllowedSuffixes(supportedImageFormats());
 
+    // Initialize graphics scene
     GraphicsScene * scene = new GraphicsScene(this);
-
-    m_gv = new GraphicsView(this);
-    m_gv->setScene(scene);
-    this->setCentralWidget(m_gv);
-
-    m_nav = new NavigatorView(this);
-    // YYC MARK:
-    // Blumia set original value is 220 x 160.
-    // So if we set its height to 72 for respecting the height of Windows Photo Viewer,
-    // the width should be set to 99 for keeping aspect ratio.
-    m_nav->setFixedSize(99, 72);
-    m_nav->setScene(scene);
-    m_nav->setMainView(m_gv);
-    m_nav->fitInView(m_nav->sceneRect(), Qt::KeepAspectRatio);
-
-    connect(m_gv, &GraphicsView::navigatorViewRequired,
+    // Setup graphics view (main photo view)
+    ui->m_gv->setScene(scene);
+    // Setup navigator view (right-bottom corner thumbnail view)
+    ui->m_nav->setScene(scene);
+    ui->m_nav->setMainView(ui->m_gv);
+    ui->m_nav->fitInView(ui->m_nav->sceneRect(), Qt::KeepAspectRatio);
+    // Binding graphics and navigator views signals
+    connect(ui->m_gv, &GraphicsView::navigatorViewRequired,
             this, [this](bool required, const QTransform & tf){
-        m_nav->setTransform(GraphicsView::resetScale(tf));
-        m_nav->fitInView(m_nav->sceneRect(), Qt::KeepAspectRatio);
-        m_nav->setVisible(required);
-        m_nav->updateMainViewportRegion();
+        ui->m_nav->setTransform(GraphicsView::resetScale(tf));
+        ui->m_nav->fitInView(ui->m_nav->sceneRect(), Qt::KeepAspectRatio);
+        ui->m_nav->setVisible(required);
+        ui->m_navPH->setVisible(required);
+        ui->m_nav->updateMainViewportRegion();
     });
+    connect(ui->m_gv, &GraphicsView::viewportRectChanged,
+            ui->m_nav, &NavigatorView::updateMainViewportRegion);
 
-    connect(m_gv, &GraphicsView::viewportRectChanged,
-            m_nav, &NavigatorView::updateMainViewportRegion);
-
+    // Setup action manager
     m_am->setupAction(this);
-
-    m_bottomButtonGroup = new BottomButtonGroup({
+    // Setup bottom button group
+    ui->m_bottomButtonGroup->addActions({
         m_am->actionActualSize,
         m_am->actionFitToScreen,
         m_am->actionZoomIn,
@@ -101,55 +101,60 @@ MainWindow::MainWindow(QWidget *parent)
         m_am->actionRotateCounterClockwise,
         m_am->actionRotateClockwise,
         m_am->actionFlipHorizontal,
-        m_am->actionToggleCheckerboard,
-    }, this);
-
-    m_menu = new QMenu(this);
-
+        m_am->actionFlipVertical,
+    });
+    // Setup right click menus
     {
-        m_menu->addAction(m_am->actionCopyPixmap);
-        m_menu->addAction(m_am->actionCopyFilePath);
+        ui->m_subMenuCopy->addAction(m_am->actionCopyPixmap);
+        ui->m_subMenuCopy->addAction(m_am->actionCopyFilePath);
+    }
+    {
+        ui->m_subMenuTransform->addAction(m_am->actionActualSize);
+        ui->m_subMenuTransform->addAction(m_am->actionFitToScreen);
+        ui->m_subMenuTransform->addAction(m_am->actionFitByWidth);
+        ui->m_subMenuTransform->addAction(m_am->actionFitByHeight);
+        ui->m_subMenuTransform->addAction(m_am->actionZoomIn);
+        ui->m_subMenuTransform->addAction(m_am->actionZoomOut);
 
-        m_menu->addSeparator();
+        ui->m_subMenuTransform->addSeparator();
 
-        m_menu->addAction(m_am->actionPrevPicture);
-        m_menu->addAction(m_am->actionNextPicture);
+        ui->m_subMenuTransform->addAction(m_am->actionFlipHorizontal);
+        ui->m_subMenuTransform->addAction(m_am->actionFlipVertical);
+        ui->m_subMenuTransform->addAction(m_am->actionRotateClockwise);
+        ui->m_subMenuTransform->addAction(m_am->actionRotateCounterClockwise);
+    }
+    {
+        ui->m_menu->addMenu(ui->m_subMenuCopy);
 
-        m_menu->addSeparator();
+        ui->m_menu->addSeparator();
 
-        m_menu->addAction(m_am->actionActualSize);
-        m_menu->addAction(m_am->actionFitToScreen);
-        m_menu->addAction(m_am->actionFitByWidth);
-        m_menu->addAction(m_am->actionFitByHeight);
-        m_menu->addAction(m_am->actionZoomIn);
-        m_menu->addAction(m_am->actionZoomOut);
+        ui->m_menu->addAction(m_am->actionPrevPicture);
+        ui->m_menu->addAction(m_am->actionNextPicture);
 
-        m_menu->addSeparator();
+        ui->m_menu->addSeparator();
 
-        m_menu->addAction(m_am->actionFlipHorizontal);
-        m_menu->addAction(m_am->actionFlipVertical);
-        m_menu->addAction(m_am->actionRotateClockwise);
-        m_menu->addAction(m_am->actionRotateCounterClockwise);
+        ui->m_menu->addMenu(ui->m_subMenuTransform);
 
-        m_menu->addSeparator();
+        ui->m_menu->addSeparator();
 
-        m_menu->addAction(m_am->actionToggleAvoidResetTransform);
-        m_menu->addAction(m_am->actionToggleCheckerboard);
-        m_menu->addAction(m_am->actionTogglePauseAnimation);
-        m_menu->addAction(m_am->actionAnimationNextFrame);
+        ui->m_menu->addAction(m_am->actionToggleAvoidResetTransform);
+        ui->m_menu->addAction(m_am->actionToggleCheckerboard);
+        ui->m_menu->addAction(m_am->actionTogglePauseAnimation);
+        ui->m_menu->addAction(m_am->actionAnimationNextFrame);
 
-        m_menu->addSeparator();
+        ui->m_menu->addSeparator();
 
-        m_menu->addAction(m_am->actionTrash);
-        m_menu->addAction(m_am->actionLocateInFileManager);
-        m_menu->addAction(m_am->actionProperties);
+        ui->m_menu->addAction(m_am->actionTrash);
+        ui->m_menu->addAction(m_am->actionLocateInFileManager);
+        ui->m_menu->addAction(m_am->actionProperties);
 
-        m_menu->addSeparator();
+        ui->m_menu->addSeparator();
 
-        m_menu->addAction(m_am->actionSettings);
-        m_menu->addAction(m_am->actionHelp);
+        ui->m_menu->addAction(m_am->actionSettings);
+        ui->m_menu->addAction(m_am->actionHelp);
     }
 
+    // Connect playlist manager and file watcher signals for photo browsering.
     connect(m_pm, &PlaylistManager::playlistChanged, this, std::bind(&MainWindow::updateActionState, this));
 
     connect(m_pm, &PlaylistManager::playlistChanged, this, std::bind(&MainWindow::galleryCurrent, this, false));
@@ -159,10 +164,7 @@ MainWindow::MainWindow(QWidget *parent)
         QTimer::singleShot(500, this, std::bind(&MainWindow::galleryCurrent, this, true));
     });
 
-    QShortcut * fullscreenShorucut = new QShortcut(QKeySequence(QKeySequence::FullScreen), this);
-    connect(fullscreenShorucut, &QShortcut::activated,
-            this, &MainWindow::toggleFullscreen);
-
+    // Change window location
     centerWindow();
 
     QTimer::singleShot(0, this, [this](){
@@ -173,66 +175,31 @@ MainWindow::MainWindow(QWidget *parent)
 
 MainWindow::~MainWindow()
 {
-
+    delete ui;
 }
 
 void MainWindow::showFiles(const QStringList &files)
 {
     m_pm->loadPlaylist(files);
-    m_nav->fitInView(m_nav->sceneRect(), Qt::KeepAspectRatio);
+    ui->m_nav->fitInView(ui->m_nav->sceneRect(), Qt::KeepAspectRatio);
 }
 
 void MainWindow::showFiles(const QList<QUrl>& urls)
 {
     m_pm->loadPlaylist(urls);
-    m_nav->fitInView(m_nav->sceneRect(), Qt::KeepAspectRatio);
+    ui->m_nav->fitInView(ui->m_nav->sceneRect(), Qt::KeepAspectRatio);
 }
 
 void MainWindow::initWindowSize()
 {
     switch (Settings::instance()->initWindowSizeBehavior()) {
-    case Settings::WindowSizeBehavior::Auto:
-        adjustWindowSizeBySceneRect();
-        break;
     case Settings::WindowSizeBehavior::Maximized:
         showMaximized();
         break;
     case Settings::WindowSizeBehavior::Windowed:
+    default:
         showNormal();
         break;
-    default:
-        adjustWindowSizeBySceneRect();
-        break;
-    }
-}
-
-void MainWindow::adjustWindowSizeBySceneRect()
-{
-    if (m_pm->totalCount() < 1) return;
-
-    QSize sceneSize = m_gv->sceneRect().toRect().size();
-    QSize sceneSizeWithMargins = sceneSize + QSize(130, 125);
-
-    if (m_gv->scaleFactor() < 1 || size().expandedTo(sceneSizeWithMargins) != size()) {
-        // if it scaled down by the resize policy:
-        QSize screenSize = qApp->screenAt(QCursor::pos())->availableSize();
-        if (screenSize.expandedTo(sceneSize) == screenSize) {
-            // we can show the picture by increase the window size.
-            QSize finalSize = (screenSize.expandedTo(sceneSizeWithMargins) == screenSize) ?
-                              sceneSizeWithMargins : screenSize;
-            // We have a very reasonable sizeHint() value ;P
-            this->resize(finalSize.expandedTo(this->sizeHint()));
-
-            // We're sure the window can display the whole thing with 1:1 scale.
-            // The old window size may cause fitInView call from resize() and the
-            // above resize() call won't reset the scale back to 1:1, so we
-            // just call resetScale() here to ensure the thing is no longer scaled.
-            m_gv->resetScale();
-            centerWindow();
-        } else {
-            // toggle maximum
-            showMaximized();
-        }
     }
 }
 
@@ -268,13 +235,13 @@ void MainWindow::galleryCurrent(bool fromFileWatcher)
     auto index = m_pm->currentIndex();
     if (index.has_value()) {
         QString localFilePath = m_pm->localFileByIndex(*index);
-        m_gv->showFileFromPath(localFilePath);
+        ui->m_gv->showFileFromPath(localFilePath);
         if (!fromFileWatcher) {
             updateFileWatcher(localFilePath);
             setWindowTitle(m_pm->urlByIndex(*index).fileName());
         }
     } else {
-        m_gv->showText(tr("Drag image here"));
+        ui->m_gv->showText(tr("Drag image here"));
         setWindowTitle(QString());
         updateFileWatcher();
     }
@@ -295,53 +262,6 @@ QStringList MainWindow::supportedImageFormats()
     return formatFilters;
 }
 
-void MainWindow::showEvent(QShowEvent *event)
-{
-    updateWidgetsPosition();
-
-    return FramelessWindow::showEvent(event);
-}
-
-void MainWindow::enterEvent(QEnterEvent *event)
-{
-    return FramelessWindow::enterEvent(event);
-}
-
-void MainWindow::leaveEvent(QEvent *event)
-{
-    return FramelessWindow::leaveEvent(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 Settings::DoubleClickBehavior::Close:
-        quitAppAction();
-        event->accept();
-        break;
-    case Settings::DoubleClickBehavior::Maximize:
-        toggleMaximize();
-        event->accept();
-        break;
-    case Settings::DoubleClickBehavior::FullScreen:
-        toggleFullscreen();
-        event->accept();
-        break;
-    case Settings::DoubleClickBehavior::Ignore:
-        break;
-    }
-
-    // blumia: don't call parent constructor here, seems it will cause mouse move
-    //         event get called even if we set event->accept();
-    // return QMainWindow::mouseDoubleClickEvent(event);
-}
-
 void MainWindow::wheelEvent(QWheelEvent *event)
 {
     QPoint numDegrees = event->angleDelta() / 8;
@@ -374,22 +294,15 @@ void MainWindow::wheelEvent(QWheelEvent *event)
         }
         event->accept();
     } else {
-        FramelessWindow::wheelEvent(event);
+        QWidget::wheelEvent(event);
     }
 }
 
-void MainWindow::resizeEvent(QResizeEvent *event)
-{
-    updateWidgetsPosition();
-
-    return FramelessWindow::resizeEvent(event);
-}
-
 void MainWindow::contextMenuEvent(QContextMenuEvent *event)
 {
-    m_menu->exec(mapToGlobal(event->pos()));
+    ui->m_menu->exec(mapToGlobal(event->pos()));
 
-    return FramelessWindow::contextMenuEvent(event);
+    return QWidget::contextMenuEvent(event);
 }
 
 void MainWindow::dragEnterEvent(QDragEnterEvent *event)
@@ -400,7 +313,7 @@ void MainWindow::dragEnterEvent(QDragEnterEvent *event)
         event->ignore();
     }
 
-    return FramelessWindow::dragEnterEvent(event);
+    return QWidget::dragEnterEvent(event);
 }
 
 void MainWindow::dragMoveEvent(QDragMoveEvent *event)
@@ -416,7 +329,7 @@ void MainWindow::dropEvent(QDropEvent *event)
     if (mimeData->hasUrls()) {
         showFiles(mimeData->urls());
     } else {
-        m_gv->showText(tr("Not supported mimedata: %1").arg(mimeData->formats().first()));
+        ui->m_gv->showText(tr("Not supported mimedata: %1").arg(mimeData->formats().first()));
     }
 }
 
@@ -432,25 +345,9 @@ void MainWindow::centerWindow()
     );
 }
 
-void MainWindow::closeWindow()
-{
-}
-
-void MainWindow::updateWidgetsPosition()
-{
-    m_bottomButtonGroup->move((width() - m_bottomButtonGroup->width()) / 2,
-                              (72 - m_bottomButtonGroup->height()) / 2 + (height() - 72));
-    m_nav->move(width() - m_nav->width(), height() - m_nav->height());
-}
-
 void MainWindow::toggleAvoidResetTransform()
 {
-    m_gv->setAvoidResetTransform(!m_gv->isAvoidResetTransform());
-}
-
-void MainWindow::quitAppAction(bool force)
-{
-    closeWindow();
+    ui->m_gv->setAvoidResetTransform(!ui->m_gv->isAvoidResetTransform());
 }
 
 void MainWindow::toggleFullscreen()
@@ -481,7 +378,7 @@ QSize MainWindow::sizeHint() const
 void MainWindow::on_actionCopyPixmap_triggered()
 {
     QClipboard *cb = QApplication::clipboard();
-    cb->setPixmap(m_gv->scene()->renderToPixmap());
+    cb->setPixmap(ui->m_gv->scene()->renderToPixmap());
 }
 
 void MainWindow::on_actionCopyFilePath_triggered()
@@ -505,58 +402,58 @@ void MainWindow::on_actionNextPicture_triggered()
 
 void MainWindow::on_actionActualSize_triggered()
 {
-    m_gv->resetScale();
-    m_gv->setEnableAutoFitToScreen(false);
+    ui->m_gv->resetScale();
+    ui->m_gv->setEnableAutoFitToScreen(false);
 }
 
 void MainWindow::on_actionFitToScreen_triggered()
 {
-    m_gv->fitInView(m_nav->sceneRect(), Qt::KeepAspectRatio);
-    m_gv->setEnableAutoFitToScreen(m_gv->scaleFactor() <= 1);
+    ui->m_gv->fitInView(ui->m_nav->sceneRect(), Qt::KeepAspectRatio);
+    ui->m_gv->setEnableAutoFitToScreen(ui->m_gv->scaleFactor() <= 1);
 }
 
 void MainWindow::on_actionFitByWidth_triggered()
 {
-    m_gv->fitByOrientation(Qt::Orientation::Horizontal);
+    ui->m_gv->fitByOrientation(Qt::Orientation::Horizontal);
 }
 
 void MainWindow::on_actionFitByHeight_triggered()
 {
-    m_gv->fitByOrientation(Qt::Orientation::Vertical);
+    ui->m_gv->fitByOrientation(Qt::Orientation::Vertical);
 }
 
 void MainWindow::on_actionZoomIn_triggered()
 {
-    if (m_gv->scaleFactor() < 1000) {
-        m_gv->zoomView(1.25);
+    if (ui->m_gv->scaleFactor() < 1000) {
+        ui->m_gv->zoomView(1.25);
     }
 }
 
 void MainWindow::on_actionZoomOut_triggered()
 {
-    m_gv->zoomView(0.8);
+    ui->m_gv->zoomView(0.8);
 }
 
 void MainWindow::on_actionFlipHorizontal_triggered()
 {
-    m_gv->flipView(true);
+    ui->m_gv->flipView(true);
 }
 
 void MainWindow::on_actionFlipVertical_triggered()
 {
-    m_gv->flipView(false);
+    ui->m_gv->flipView(false);
 }
 
 void MainWindow::on_actionRotateClockwise_triggered()
 {
-    m_gv->rotateView(true);
-    m_gv->displayScene();
+    ui->m_gv->rotateView(true);
+    ui->m_gv->displayScene();
 }
 
 void MainWindow::on_actionRotateCounterClockwise_triggered()
 {
-    m_gv->rotateView(false);
-    m_gv->displayScene();
+    ui->m_gv->rotateView(false);
+    ui->m_gv->displayScene();
 }
 
 void MainWindow::on_actionToggleAvoidResetTransform_triggered()
@@ -566,17 +463,17 @@ void MainWindow::on_actionToggleAvoidResetTransform_triggered()
 
 void MainWindow::on_actionToggleCheckerboard_triggered()
 {
-    m_gv->toggleCheckerboard(QGuiApplication::queryKeyboardModifiers().testFlag(Qt::ShiftModifier));
+    ui->m_gv->toggleCheckerboard(QGuiApplication::queryKeyboardModifiers().testFlag(Qt::ShiftModifier));
 }
 
 void MainWindow::on_actionTogglePauseAnimation_triggered()
 {
-    m_gv->scene()->togglePauseAnimation();
+    ui->m_gv->scene()->togglePauseAnimation();
 }
 
 void MainWindow::on_actionAnimationNextFrame_triggered()
 {
-    m_gv->scene()->skipAnimationFrame(1);
+    ui->m_gv->scene()->skipAnimationFrame(1);
 }
 
 void MainWindow::on_actionTrash_triggered()
@@ -678,5 +575,5 @@ bool MainWindow::updateFileWatcher(const QString &basePath)
 }
 
 void MainWindow::updateActionState() {
-    m_am->updateActionState(m_pm, m_gv);
+    m_am->updateActionState(m_pm, ui->m_gv);
 }

app/mainwindow.h

@@ -5,24 +5,19 @@
 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H
 
-#include "framelesswindow.h"
-
-#include <QParallelAnimationGroup>
-#include <QPropertyAnimation>
-#include <QPushButton>
+#include <QWidget>
 
 QT_BEGIN_NAMESPACE
-class QMenu;
-class QGraphicsView;
 class QFileSystemWatcher;
+namespace Ui {
+class MainWindow;
+}
 QT_END_NAMESPACE
 
 class ActionManager;
 class PlaylistManager;
-class GraphicsView;
-class NavigatorView;
-class BottomButtonGroup;
-class MainWindow : public FramelessWindow
+
+class MainWindow : public QWidget
 {
     Q_OBJECT
 
@@ -33,7 +28,6 @@ public:
     void showFiles(const QStringList& files);
     void showFiles(const QList<QUrl>& urls);
     void initWindowSize();
-    void adjustWindowSizeBySceneRect();
 
     void clearGallery();
     void galleryPrev();
@@ -43,22 +37,14 @@ public:
     static QStringList supportedImageFormats();
 
 protected slots:
-    void showEvent(QShowEvent *event) override;
-    void enterEvent(QEnterEvent *event) override;
-    void leaveEvent(QEvent *event) override;
-    void mouseDoubleClickEvent(QMouseEvent *event) override;
     void wheelEvent(QWheelEvent *event) override;
-    void resizeEvent(QResizeEvent *event) override;
     void contextMenuEvent(QContextMenuEvent *event) override;
     void dragEnterEvent(QDragEnterEvent *event) override;
     void dragMoveEvent(QDragMoveEvent *event) override;
     void dropEvent(QDropEvent *event) override;
 
     void centerWindow();
-    void closeWindow();
-    void updateWidgetsPosition();
     void toggleAvoidResetTransform();
-    void quitAppAction(bool force = false);
     void toggleFullscreen();
     void toggleMaximize();
 
@@ -101,14 +87,11 @@ private:
     void updateActionState();
 
 private:
+    QT_PREPEND_NAMESPACE(Ui::MainWindow) *ui;
+    
     ActionManager *m_am;
     PlaylistManager *m_pm;
-    GraphicsView *m_gv;
-    NavigatorView *m_nav;
-
-    QMenu *m_menu;
     QFileSystemWatcher *m_fileSystemWatcher;
-    BottomButtonGroup *m_bottomButtonGroup;
 };
 
 #endif // MAINWINDOW_H

app/mainwindow.ui

@@ -0,0 +1,172 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QWidget" name="MainWindow">
+  <property name="windowModality">
+   <enum>Qt::NonModal</enum>
+  </property>
+  <property name="minimumSize">
+   <size>
+    <width>640</width>
+    <height>480</height>
+   </size>
+  </property>
+  <property name="acceptDrops">
+   <bool>true</bool>
+  </property>
+  <layout class="QVBoxLayout" name="m_centralLayout">
+   <property name="spacing">
+    <number>0</number>
+   </property>
+   <property name="leftMargin">
+    <number>0</number>
+   </property>
+   <property name="topMargin">
+    <number>0</number>
+   </property>
+   <property name="rightMargin">
+    <number>0</number>
+   </property>
+   <property name="bottomMargin">
+    <number>0</number>
+   </property>
+   <item>
+    <widget class="GraphicsView" name="m_gv">
+     <property name="frameShape">
+      <enum>QFrame::NoFrame</enum>
+     </property>
+     <property name="verticalScrollBarPolicy">
+      <enum>Qt::ScrollBarAlwaysOff</enum>
+     </property>
+     <property name="horizontalScrollBarPolicy">
+      <enum>Qt::ScrollBarAlwaysOff</enum>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QWidget" name="bottomBar" native="true">
+     <property name="minimumSize">
+      <size>
+       <width>0</width>
+       <height>72</height>
+      </size>
+     </property>
+     <property name="maximumSize">
+      <size>
+       <width>16777215</width>
+       <height>72</height>
+      </size>
+     </property>
+     <layout class="QHBoxLayout" name="bottomBarLayout">
+      <property name="spacing">
+       <number>0</number>
+      </property>
+      <property name="leftMargin">
+       <number>0</number>
+      </property>
+      <property name="topMargin">
+       <number>0</number>
+      </property>
+      <property name="rightMargin">
+       <number>0</number>
+      </property>
+      <property name="bottomMargin">
+       <number>0</number>
+      </property>
+      <item>
+       <widget class="QWidget" name="m_navPH" native="true">
+        <property name="minimumSize">
+         <size>
+          <width>99</width>
+          <height>72</height>
+         </size>
+        </property>
+        <property name="maximumSize">
+         <size>
+          <width>99</width>
+          <height>72</height>
+         </size>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <spacer name="leftSpacer">
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+       </spacer>
+      </item>
+      <item>
+       <widget class="BottomButtonGroup" name="m_bottomButtonGroup"/>
+      </item>
+      <item>
+       <spacer name="rightSpacer">
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+       </spacer>
+      </item>
+      <item>
+       <widget class="NavigatorView" name="m_nav">
+        <property name="minimumSize">
+         <size>
+          <width>99</width>
+          <height>72</height>
+         </size>
+        </property>
+        <property name="maximumSize">
+         <size>
+          <width>99</width>
+          <height>72</height>
+         </size>
+        </property>
+        <property name="frameShape">
+         <enum>QFrame::NoFrame</enum>
+        </property>
+        <property name="verticalScrollBarPolicy">
+         <enum>Qt::ScrollBarAlwaysOff</enum>
+        </property>
+        <property name="horizontalScrollBarPolicy">
+         <enum>Qt::ScrollBarAlwaysOff</enum>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
+  </layout>
+  <widget class="QMenu" name="m_subMenuCopy">
+   <property name="title">
+    <string>&amp;Copy</string>
+   </property>
+   <property name="icon">
+    <iconset theme="edit-copy"/>
+   </property>
+  </widget>
+  <widget class="QMenu" name="m_subMenuTransform">
+   <property name="title">
+    <string>&amp;Transform</string>
+   </property>
+  </widget>
+  <widget class="QMenu" name="m_menu"/>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>GraphicsView</class>
+   <extends>QGraphicsView</extends>
+   <header>graphicsview.h</header>
+  </customwidget>
+  <customwidget>
+   <class>NavigatorView</class>
+   <extends>QGraphicsView</extends>
+   <header>navigatorview.h</header>
+  </customwidget>
+  <customwidget>
+   <class>BottomButtonGroup</class>
+   <extends>QGroupBox</extends>
+   <header>bottombuttongroup.h</header>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

app/navigatorview.h

@@ -18,6 +18,8 @@ public:
 
 public slots:
     void updateMainViewportRegion();
+
+private slots:
     void updateStyle(Qt::ColorScheme colorScheme);
 
 private:

app/playlistmanager.cpp

@@ -3,6 +3,7 @@
 // SPDX-License-Identifier: MIT
 
 #include "playlistmanager.h"
+#include "playlistscout.h"
 
 #include <QCollator>
 #include <QDir>
@@ -71,34 +72,14 @@ bool PlaylistManager::loadSingleFilePlaylist(const QUrl& url) {
     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;
-        }
+    // Scout playlist by given file
+    auto scoutResult = PlaylistScout::scout(url, m_allowedSuffixes);
+    if (!scoutResult.has_value()) {
+        return false;
     }
 
-    setPlaylist(std::move(playlist), idx);
+    // Setup playlist with index
+    setPlaylist(std::move(scoutResult->playlist), scoutResult->indexHint);
     return true;
 }
 

app/playlistscout.cpp

@@ -0,0 +1,25 @@
+// SPDX-FileCopyrightText: 2026 yyc12345 <yyc12321@outlook.com>
+//
+// SPDX-License-Identifier: MIT
+
+#include "playlistscout.h"
+
+#include "playlistscouts/qtscout.h"
+#include "playlistscouts/explorerscout.h"
+
+std::optional<PlaylistScout::ScoutResult> PlaylistScout::scout(
+    const QUrl &url, const QStringList &allowedSuffixes) {
+
+#ifdef Q_OS_WIN
+    // In Windows, Qt approach can not aware Windows Explorer custom sort order.
+    // So we need to try using Win32 functions for fetching it at first.
+    if (auto rv = PlaylistScout::Explorer::scout(url, allowedSuffixes); rv.has_value()) {
+        return rv;
+    }
+#endif // Q_OS_WIN
+
+    // TODO: We may add macOS Finder, KDE Dolphin and etc supports in future.
+
+    // Qt way is the last fallback.
+    return PlaylistScout::Qt::scout(url, allowedSuffixes);
+}

app/playlistscout.h

@@ -0,0 +1,31 @@
+// SPDX-FileCopyrightText: 2026 yyc12345 <yyc12321@outlook.com>
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include <QUrl>
+#include <QStringList>
+#include <QList>
+#include <optional>
+
+namespace PlaylistScout {
+    /// The result of scout
+    struct ScoutResult {
+        /// The final fetched playlist (it can be empty).
+        /// Each item must be a QUrl pointing to a local file.
+        QList<QUrl> playlist;
+        /// The index of given file located in playlist.
+        /// Nullopt if it is not presented in playlist.
+        std::optional<qsizetype> indexHint;
+    };
+
+    /// @brief Scout available image files in given file's parent dir with given allowed suffixes.
+    /// @param[in] url The path to file whose parent dir is our target dir for finding image files.
+    /// @param[in] allowedSuffixes 
+    /// Each items in this list is a wildcard pattern for matching allowed file name, like \c *.png .
+    /// The fetched item will be preserved if its name matching any of them.
+    /// If this list is empty, there is no restrictions for finding files.
+    /// @return Scout result if success, otherwise nullopt.
+    std::optional<ScoutResult> scout(const QUrl &url, const QStringList &allowedSuffixes);
+}

app/playlistscouts/explorerscout.cpp

@@ -0,0 +1,332 @@
+// SPDX-FileCopyrightText: 2026 yyc12345 <yyc12321@outlook.com>
+//
+// SPDX-License-Identifier: MIT
+
+#include "explorerscout.h"
+
+#ifdef Q_OS_WIN
+
+#include <QDir>
+#include <QDebug>
+#include <QFileInfo>
+#include <QRegularExpression>
+
+#include <optional>
+
+#include <exdisp.h>     // IShellWindows, CLSID_ShellWindows
+#include <servprov.h>   // IServiceProvider
+#include <shlguid.h>    // SID_STopLevelBrowser
+#include <shlobj.h>
+
+// YYC MARK:
+// We use custom RAII wrappers instead of existing COM smart pointers because the
+// project may be built with MinGW, which does not have good compatibility with
+// CComPtr and Microsoft's WRL ComPtr (<wrl/client.h>).
+// Furthermore, PIDLs are not COM objects (they are freed via ILFree, not Release),
+// so no standard smart pointer covers them regardless of compiler.
+
+/// RAII wrapper for COM initialization (CoInitialize / CoUninitialize).
+/// Must be declared before any COM objects (e.g., ComPtr, UniquePidl) so that
+/// CoUninitialize runs after all COM objects are released during scope exit.
+class ComGuard {
+public:
+    ComGuard() : m_hr(CoInitialize(nullptr)) {}
+    ~ComGuard() { if (SUCCEEDED(m_hr)) CoUninitialize(); }
+    ComGuard(const ComGuard&) = delete;
+    ComGuard& operator=(const ComGuard&) = delete;
+
+    bool IsInitialized() const { return SUCCEEDED(m_hr); }
+
+private:
+    HRESULT m_hr;
+};
+
+/// RAII wrapper for COM interface pointers.
+template <typename T>
+class ComPtr {
+public:
+    ComPtr() = default;
+    ComPtr(std::nullptr_t) {}
+    ~ComPtr() { Reset(); }
+    ComPtr(const ComPtr&) = delete;
+    ComPtr& operator=(const ComPtr&) = delete;
+    ComPtr(ComPtr&& other) noexcept : m_ptr(other.m_ptr) { other.m_ptr = nullptr; }
+    ComPtr& operator=(ComPtr&& other) noexcept {
+        if (this != &other) {
+            Reset();
+            m_ptr = other.m_ptr;
+            other.m_ptr = nullptr;
+        }
+        return *this;
+    }
+
+    T* operator->() const { return m_ptr; }
+    T* Get() const { return m_ptr; }
+    T** GetAddressOf() { return &m_ptr; }
+    explicit operator bool() const { return m_ptr != nullptr; }
+    void Reset() { if (m_ptr) { m_ptr->Release(); m_ptr = nullptr; } }
+
+private:
+    T* m_ptr = nullptr;
+};
+
+/// RAII wrapper for PIDL (Item ID List).
+class UniquePidl {
+public:
+    UniquePidl() = default;
+    explicit UniquePidl(LPITEMIDLIST pidl) : m_pidl(pidl) {}
+    ~UniquePidl() { Reset(); }
+    UniquePidl(const UniquePidl&) = delete;
+    UniquePidl& operator=(const UniquePidl&) = delete;
+    UniquePidl(UniquePidl&& other) noexcept : m_pidl(other.m_pidl) { other.m_pidl = nullptr; }
+    UniquePidl& operator=(UniquePidl&& other) noexcept {
+        if (this != &other) {
+            Reset();
+            m_pidl = other.m_pidl;
+            other.m_pidl = nullptr;
+        }
+        return *this;
+    }
+
+    LPCITEMIDLIST Get() const { return m_pidl; }
+    LPITEMIDLIST* GetAddressOf() { return &m_pidl; }
+    explicit operator bool() const { return m_pidl != nullptr; }
+    void Reset() { if (m_pidl) { ILFree(m_pidl); m_pidl = nullptr; } }
+
+private:
+    LPITEMIDLIST m_pidl = nullptr;
+};
+
+/// Outputs a diagnostic warning for debugging Windows Explorer integration failures.
+static void ReportError(const QString& detail)
+{
+    qWarning("Windows Explorer file list fetch error: %s",
+             qPrintable(detail));
+}
+
+/// Normalizes a Windows directory path for case-insensitive comparison:
+/// converts to native separators, lowercases, and ensures a trailing backslash.
+static QString NormalizePath(const QString& path)
+{
+    QString result = QDir::toNativeSeparators(path).toLower();
+    if (!result.endsWith(QChar('\\'))) {
+        result += QChar('\\');
+    }
+    return result;
+}
+
+/// Checks whether the Explorer window represented by the given IDispatch is
+/// displaying the target folder. Returns its IFolderView2 on match, or null.
+static ComPtr<IFolderView2> TryMatchWindow(IDispatch* dispatch, const QString& normalizedTarget)
+{
+    // Navigate: IDispatch -> IServiceProvider -> IShellBrowser.
+    ComPtr<IServiceProvider> serviceProvider;
+    if (FAILED(dispatch->QueryInterface(IID_PPV_ARGS(serviceProvider.GetAddressOf())))) {
+        return nullptr;
+    }
+
+    ComPtr<IShellBrowser> shellBrowser;
+    if (FAILED(serviceProvider->QueryService(SID_STopLevelBrowser,
+            IID_PPV_ARGS(shellBrowser.GetAddressOf())))) {
+        return nullptr;
+    }
+
+    // IShellBrowser -> active IShellView.
+    ComPtr<IShellView> shellView;
+    if (FAILED(shellBrowser->QueryActiveShellView(shellView.GetAddressOf()))) {
+        return nullptr;
+    }
+
+    // Retrieve the folder's path via IPersistIDList.
+    ComPtr<IPersistIDList> persistIdList;
+    if (FAILED(shellView->QueryInterface(IID_PPV_ARGS(persistIdList.GetAddressOf())))) {
+        return nullptr;
+    }
+
+    UniquePidl folderPidl;
+    if (FAILED(persistIdList->GetIDList(folderPidl.GetAddressOf()))) {
+        return nullptr;
+    }
+
+    PWSTR pathStr = nullptr;
+    if (FAILED(SHGetNameFromIDList(folderPidl.Get(), SIGDN_DESKTOPABSOLUTEPARSING, &pathStr))) {
+        return nullptr;
+    }
+
+    QString windowPath = NormalizePath(QString::fromWCharArray(pathStr));
+    CoTaskMemFree(pathStr);
+
+    if (windowPath != normalizedTarget) {
+        return nullptr;
+    }
+
+    // Path matches — query IFolderView2 from the ShellView.
+    ComPtr<IFolderView2> folderView2;
+    if (FAILED(shellView->QueryInterface(IID_PPV_ARGS(folderView2.GetAddressOf())))) {
+        return nullptr;
+    }
+    return folderView2;
+}
+
+/// Tries to find a live Explorer window that is currently displaying the given
+/// folder path. Returns the IFolderView2 from that window, or an empty ComPtr.
+///
+/// Explorer's sort order is stored only in the running Explorer process's memory.
+/// Creating a new shell view via IShellFolder::CreateViewObject yields a default
+/// sort (always by name), so we must find the actual live IFolderView2 instead.
+///
+/// Reference:
+/// - https://www.stephenli.ca/getting-windows-explorers-current-directory-sort-order
+/// - https://github.com/d2phap/ImageGlass/blob/75a296287f338edcf409eee3917531b25ff5d927/v9/Components/ImageGlass.Base/FileSystem/FileFinder.cs
+/// - NuGet Package: D2Phap.EggShell
+static ComPtr<IFolderView2> FindLiveFolderView(const QString& targetFolderPath)
+{
+    // Create the Shell windows collection (all open Explorer windows).
+    ComPtr<IShellWindows> shellWindows;
+    if (FAILED(CoCreateInstance(CLSID_ShellWindows, nullptr, CLSCTX_ALL,
+            IID_PPV_ARGS(shellWindows.GetAddressOf())))) {
+        ReportError("Failed to create IShellWindows instance");
+        return nullptr;
+    }
+
+    QString normalizedTarget = NormalizePath(targetFolderPath);
+
+    // 1. Try the Desktop window first — it may contain the file the user opened.
+    {
+        VARIANT varLoc;
+        VariantInit(&varLoc);
+        varLoc.vt = VT_I4;
+        varLoc.lVal = 0;
+
+        VARIANT varLocRoot;
+        VariantInit(&varLocRoot);
+
+        long desktopHwnd = 0;
+        ComPtr<IDispatch> desktopDispatch;
+        HRESULT findHr = shellWindows->FindWindowSW(
+            &varLoc, &varLocRoot, SWC_DESKTOP,
+            &desktopHwnd, SWFO_NEEDDISPATCH,
+            desktopDispatch.GetAddressOf());
+
+        VariantClear(&varLoc);
+        VariantClear(&varLocRoot);
+
+        if (SUCCEEDED(findHr) && desktopDispatch) {
+            ComPtr<IFolderView2> result = TryMatchWindow(desktopDispatch.Get(), normalizedTarget);
+            if (result) return result;
+        }
+    }
+
+    // 2. Iterate regular Explorer windows.
+    LONG count = 0;
+    shellWindows->get_Count(&count);
+
+    for (LONG i = 0; i < count; i++) {
+        VARIANT varIndex;
+        VariantInit(&varIndex);
+        varIndex.vt = VT_I4;
+        varIndex.lVal = i;
+
+        ComPtr<IDispatch> dispatch;
+        HRESULT itemHr = shellWindows->Item(varIndex, dispatch.GetAddressOf());
+        VariantClear(&varIndex);
+
+        if (FAILED(itemHr) || !dispatch) {
+            continue;
+        }
+
+        ComPtr<IFolderView2> result = TryMatchWindow(dispatch.Get(), normalizedTarget);
+        if (result) return result;
+    }
+
+    return nullptr;
+}
+
+std::optional<PlaylistScout::ScoutResult> PlaylistScout::Explorer::scout(
+    const QUrl &url, const QStringList &allowedSuffixes) {
+    PlaylistScout::ScoutResult rv;
+
+    QFileInfo info(url.toLocalFile());
+    QString folderPath = info.path();
+    QString currentFileName = info.fileName();
+
+    // Pre-compile wildcard suffix filters into regular expressions for performance.
+    QList<QRegularExpression> nameRegexps;
+    for (const QString &pattern : allowedSuffixes) {
+        nameRegexps.append(QRegularExpression(
+            QRegularExpression::wildcardToRegularExpression(pattern),
+            QRegularExpression::CaseInsensitiveOption));
+    }
+
+    // Initialize COM. The ComGuard must be declared before any COM objects
+    // below so that CoUninitialize runs after all of them are released.
+    ComGuard comGuard;
+    if (!comGuard.IsInitialized()) {
+        ReportError("COM initialization failed");
+        return std::nullopt;
+    }
+
+    // Find a live Explorer window that is currently displaying the target folder.
+    ComPtr<IFolderView2> folderView2 = FindLiveFolderView(folderPath);
+    if (!folderView2) {
+        ReportError("No open Explorer window matches the folder: " + folderPath);
+        return std::nullopt;
+    }
+
+    // Get items already sorted in Explorer's view order, as an IShellItemArray.
+    // SVGIO_ALLVIEW returns all items; SVGIO_FLAG_VIEWORDER respects the view's sort.
+    ComPtr<IShellItemArray> itemArray;
+    if (FAILED(folderView2->Items(SVGIO_ALLVIEW | SVGIO_FLAG_VIEWORDER,
+            IID_PPV_ARGS(itemArray.GetAddressOf())))) {
+        ReportError("IFolderView2::Items(SVGIO_ALLVIEW | SVGIO_FLAG_VIEWORDER) failed");
+        return std::nullopt;
+    }
+
+    DWORD itemCount = 0;
+    itemArray->GetCount(&itemCount);
+
+    // Enumerate sorted items, filter by pattern, and build the playlist.
+    for (DWORD i = 0; i < itemCount; i++) {
+        ComPtr<IShellItem> shellItem;
+        if (FAILED(itemArray->GetItemAt(i, shellItem.GetAddressOf()))) {
+            continue;
+        }
+
+        // Get the full parsing path of the item.
+        PWSTR pathStr = nullptr;
+        if (FAILED(shellItem->GetDisplayName(SIGDN_DESKTOPABSOLUTEPARSING, &pathStr)) || !pathStr) {
+            continue;
+        }
+        QString filePath = QString::fromWCharArray(pathStr);
+        CoTaskMemFree(pathStr);
+
+        // Skip directories — the view may include folders alongside files.
+        QFileInfo fileInfo(filePath);
+        if (!fileInfo.isFile()) {
+            continue;
+        }
+
+        QString fileName = fileInfo.fileName();
+
+        // Match against compiled wildcard patterns.
+        bool matches = nameRegexps.isEmpty();
+        for (const QRegularExpression &re : std::as_const(nameRegexps)) {
+            if (re.match(fileName).hasMatch()) {
+                matches = true;
+                break;
+            }
+        }
+        if (!matches) {
+            continue;
+        }
+
+        rv.playlist.append(QUrl::fromLocalFile(filePath));
+        if (fileName == currentFileName) {
+            rv.indexHint = rv.playlist.size() - 1;
+        }
+    }
+
+    return rv;
+}
+
+#endif // Q_OS_WIN

app/playlistscouts/explorerscout.h

@@ -0,0 +1,16 @@
+// SPDX-FileCopyrightText: 2026 yyc12345 <yyc12321@outlook.com>
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include "../playlistscout.h"
+#include <QtSystemDetection>
+
+#ifdef Q_OS_WIN
+
+namespace PlaylistScout::Explorer {
+    std::optional<ScoutResult> scout(const QUrl &url, const QStringList &allowedSuffixes);
+}
+
+#endif // Q_OS_WIN

app/playlistscouts/qtscout.cpp

@@ -0,0 +1,40 @@
+// SPDX-FileCopyrightText: 2025 Gary Wang <git@blumia.net>
+// SPDX-FileCopyrightText: 2026 yyc12345 <yyc12321@outlook.com>
+//
+// SPDX-License-Identifier: MIT
+
+#include "qtscout.h"
+
+#include <QFileInfo>
+#include <QDir>
+#include <QCollator>
+
+std::optional<PlaylistScout::ScoutResult> PlaylistScout::Qt::scout(
+    const QUrl &url, const QStringList &allowedSuffixes) {
+    PlaylistScout::ScoutResult rv;
+
+    QFileInfo info(url.toLocalFile());
+    QDir dir(info.path());
+    QString currentFileName = info.fileName();
+
+    QStringList entryList = dir.entryList(
+        allowedSuffixes, QDir::Files | QDir::NoSymLinks, QDir::NoSort);
+
+    QCollator collator;
+    collator.setNumericMode(true);
+
+    std::sort(entryList.begin(), entryList.end(), collator);
+
+    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);
+
+        rv.playlist.append(url);
+        if (fileName == currentFileName) {
+            rv.indexHint = i;
+        }
+    }
+
+    return rv;
+}

app/playlistscouts/qtscout.h

@@ -0,0 +1,11 @@
+// SPDX-FileCopyrightText: 2026 yyc12345 <yyc12321@outlook.com>
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include "../playlistscout.h"
+
+namespace PlaylistScout::Qt {
+    std::optional<ScoutResult> scout(const QUrl &url, const QStringList &allowedSuffixes);
+}

app/settings.cpp

@@ -65,12 +65,6 @@ bool Settings::svgTiny12Only() const
 #endif // QT_VERSION < QT_VERSION_CHECK(6, 9, 3)
 }
 
-Settings::DoubleClickBehavior Settings::doubleClickBehavior() const
-{
-    QString result = m_qsettings->value("double_click_behavior", "").toString();
-    return QEnumHelper::fromString<DoubleClickBehavior>(result, DoubleClickBehavior::Ignore);
-}
-
 Settings::MouseWheelBehavior Settings::mouseWheelBehavior() const
 {
     QString result = m_qsettings->value("mouse_wheel_behavior", "").toString();
@@ -107,12 +101,6 @@ void Settings::setSvgTiny12Only(bool on)
     m_qsettings->sync();
 }
 
-void Settings::setDoubleClickBehavior(DoubleClickBehavior dcb)
-{
-    m_qsettings->setValue("double_click_behavior", QEnumHelper::toString(dcb));
-    m_qsettings->sync();
-}
-
 void Settings::setMouseWheelBehavior(MouseWheelBehavior mwb)
 {
     m_qsettings->setValue("mouse_wheel_behavior", QEnumHelper::toString(mwb));

app/settings.h

@@ -11,23 +11,13 @@ class Settings : public QObject
 {
     Q_OBJECT
 public:
-    enum DoubleClickBehavior {
-        Ignore,
-        Close,
-        Maximize,
-        FullScreen,
-    };
-    Q_ENUM(DoubleClickBehavior)
-
     enum MouseWheelBehavior {
         Zoom,
         Switch,
     };
     Q_ENUM(MouseWheelBehavior)
 
-    // TODO: I want to remove Auto behavior in future.
     enum WindowSizeBehavior {
-        Auto,
         Maximized,
         Windowed,
     };
@@ -38,7 +28,6 @@ public:
     bool useLightCheckerboard() const;
     bool loopGallery() const;
     bool svgTiny12Only() const;
-    DoubleClickBehavior doubleClickBehavior() const;
     MouseWheelBehavior mouseWheelBehavior() const;
     WindowSizeBehavior initWindowSizeBehavior() const;
     Qt::HighDpiScaleFactorRoundingPolicy hiDpiScaleFactorBehavior() const;
@@ -46,7 +35,6 @@ public:
     void setUseLightCheckerboard(bool light);
     void setLoopGallery(bool on);
     void setSvgTiny12Only(bool on);
-    void setDoubleClickBehavior(DoubleClickBehavior dcb);
     void setMouseWheelBehavior(MouseWheelBehavior mwb);
     void setInitWindowSizeBehavior(WindowSizeBehavior wsb);
     void setHiDpiScaleFactorBehavior(Qt::HighDpiScaleFactorRoundingPolicy hidpi);

app/settingsdialog.cpp

@@ -49,15 +49,6 @@ private:
     Pairs pairs;
 };
 
-static EnumComboBoxTransformer<Settings::DoubleClickBehavior> DC_OPTIONS {
-    {
-        {Settings::DoubleClickBehavior::Ignore, QCoreApplication::translate("SettingsDialog", "Do nothing")},
-        {Settings::DoubleClickBehavior::Close, QCoreApplication::translate("SettingsDialog", "Close the window")},
-        {Settings::DoubleClickBehavior::Maximize, QCoreApplication::translate("SettingsDialog", "Toggle maximize")},
-        {Settings::DoubleClickBehavior::FullScreen, QCoreApplication::translate("SettingsDialog", "Toggle fullscreen")}
-    }
-};
-
 static EnumComboBoxTransformer<Settings::MouseWheelBehavior, QString> MW_OPTIONS {
     {
         { Settings::MouseWheelBehavior::Zoom, QCoreApplication::translate("SettingsDialog", "Zoom in and out") },
@@ -67,7 +58,6 @@ static EnumComboBoxTransformer<Settings::MouseWheelBehavior, QString> MW_OPTIONS
 
 static EnumComboBoxTransformer<Settings::WindowSizeBehavior, QString> IWS_OPTIONS {
     {
-        { Settings::WindowSizeBehavior::Auto, QCoreApplication::translate("SettingsDialog", "Auto size") },
         { Settings::WindowSizeBehavior::Maximized, QCoreApplication::translate("SettingsDialog", "Maximized") },
         { Settings::WindowSizeBehavior::Windowed, QCoreApplication::translate("SettingsDialog", "Windowed") }
     }
@@ -92,9 +82,6 @@ SettingsDialog::SettingsDialog(QWidget *parent)
     ui->m_useLightCheckerboard->setChecked(settings->useLightCheckerboard());
     ui->m_loopGallery->setChecked(settings->loopGallery());
     ui->m_svgTiny12Only->setChecked(settings->svgTiny12Only());
-    ui->m_doubleClickBehavior->setModel(DC_OPTIONS.buildComboBoxModel(this));
-    Settings::DoubleClickBehavior dcb = settings->doubleClickBehavior();
-    ui->m_doubleClickBehavior->setCurrentIndex(DC_OPTIONS.to_index(dcb));
     ui->m_mouseWheelBehavior->setModel(MW_OPTIONS.buildComboBoxModel(this));
     Settings::MouseWheelBehavior mwb = settings->mouseWheelBehavior();
     ui->m_mouseWheelBehavior->setCurrentIndex(MW_OPTIONS.to_index(mwb));
@@ -125,10 +112,6 @@ SettingsDialog::SettingsDialog(QWidget *parent)
         Settings::instance()->setSvgTiny12Only(state == Qt::Checked);
     });
 
-    connect(ui->m_doubleClickBehavior, QOverload<int>::of(&QComboBox::currentIndexChanged), this, [ = ](int index){
-        Settings::instance()->setDoubleClickBehavior(DC_OPTIONS.to_value(index));
-    });
-
     connect(ui->m_mouseWheelBehavior, QOverload<int>::of(&QComboBox::currentIndexChanged), this, [ = ](int index){
         Settings::instance()->setMouseWheelBehavior(MW_OPTIONS.to_value(index));
     });

app/settingsdialog.ui

@@ -41,43 +41,33 @@
          </widget>
         </item>
        <item row="3" column="0">
-         <widget class="QLabel" name="m_doubleClickBehaviorLabel">
-         <property name="text">
-          <string>Double-click behavior</string>
-         </property>
-        </widget>
-       </item>
-       <item row="3" column="1">
-        <widget class="QComboBox" name="m_doubleClickBehavior"/>
-       </item>
-       <item row="4" column="0">
          <widget class="QLabel" name="m_mouseWheelBehaviorLabel">
          <property name="text">
           <string>Mouse wheel behavior</string>
          </property>
         </widget>
        </item>
-       <item row="4" column="1">
+       <item row="3" column="1">
         <widget class="QComboBox" name="m_mouseWheelBehavior"/>
        </item>
-       <item row="5" column="0">
+       <item row="4" column="0">
          <widget class="QLabel" name="m_initWindowSizeBehaviorLabel">
          <property name="text">
           <string>Default window size</string>
          </property>
         </widget>
        </item>
-       <item row="5" column="1">
+       <item row="4" column="1">
         <widget class="QComboBox" name="m_initWindowSizeBehavior"/>
        </item>
-       <item row="6" column="0">
+       <item row="5" column="0">
          <widget class="QLabel" name="m_hiDpiRoundingPolicyBehaviorLabel">
          <property name="text">
           <string>HiDPI scale factor rounding policy</string>
          </property>
         </widget>
        </item>
-       <item row="6" column="1">
+       <item row="5" column="1">
         <widget class="QComboBox" name="m_hiDpiRoundingPolicyBehavior"/>
        </item>
       </layout>