ScanTailor-Advanced · pablogventura · Apr 20, 2026 · Apr 27, 2026 · May 22, 2026
diff --git a/README.md b/README.md
@@ -74,7 +74,7 @@ Go to [this repository](https://github.com/ScanTailor-Advanced/scantailor-libs-b
 
 **Windows – supported OS versions (issue #101):** Release builds follow upstream **Qt** and **toolchain** support policies; **legacy Windows** (for example Windows 7) is **not** exercised in this project’s CI and is **best-effort only**. You may need an **older tagged release** or a **self-built** binary against an older Qt/MSVC stack. Community reports (including compatibility tips) are welcome in the issue tracker.
 
-**Linux – Wayland (issue #97):** If you see rendering issues (blank or corrupted windows) when running under Wayland, try starting the application with `QT_QPA_PLATFORM=xcb` to use the X11 compatibility layer.
+**Linux – Wayland (issue #97):** On Qt5 builds, if `XDG_SESSION_TYPE` is `wayland` and `QT_QPA_PLATFORM` is not set, the application defaults to the X11 (`xcb`) platform plugin to avoid broken dialogs and painting. Set **`SCANTAILOR_NO_XCB_FALLBACK=1`** in the environment to keep native Wayland and, if needed, set `QT_QPA_PLATFORM=wayland` or `QT_QPA_PLATFORM=xcb` yourself.
 
 **Linux – Flatpak / Flathub ([issue #105](https://github.com/ScanTailor-Advanced/scantailor-advanced/issues/105)):**
 

diff --git a/src/app/MainWindow.cpp b/src/app/MainWindow.cpp
@@ -10,6 +10,7 @@
 #include <QDir>
 #include <QFileDialog>
 #include <QFileSystemModel>
+#include <QMenu>
 #include <QMessageBox>
 #include <QResource>
 #include <QScrollBar>
@@ -301,6 +302,7 @@ MainWindow::MainWindow()
   });
 
   connect(actionFixDpi, SIGNAL(triggered(bool)), SLOT(fixDpiDialogRequested()));
+  connect(actionReverseTwoPageOrder, SIGNAL(triggered(bool)), SLOT(toggleTwoPageSpreadReadingOrder()));
   connect(actionRelinking, SIGNAL(triggered(bool)), SLOT(showRelinkingDialog()));
 #ifdef ENABLE_DEBUG_FEATURES
   connect(actionDebug, SIGNAL(toggled(bool)), SLOT(debugToggled(bool)));
@@ -1016,7 +1018,8 @@ void MainWindow::pageContextMenuRequested(const PageInfo& pageInfo_, const QPoin
     goToPage(pageInfo.id());
   }
 
-  QMenu menu;
+  // Parent widget helps correct multi-monitor placement (issue #75).
+  QMenu menu(thumbView);
 
   auto& iconProvider = IconProvider::getInstance();
   QAction* insBefore = menu.addAction(iconProvider.getIcon("insert-before"), tr("Insert before ..."));
@@ -1036,12 +1039,24 @@ void MainWindow::pageContextMenuRequested(const PageInfo& pageInfo_, const QPoin
   }
 }  // MainWindow::pageContextMenuRequested
 
+void MainWindow::toggleTwoPageSpreadReadingOrder() {
+  if (!isProjectLoaded() || !m_pages) {
+    return;
+  }
+  const Qt::LayoutDirection nextDir
+      = (m_pages->layoutDirection() == Qt::LeftToRight) ? Qt::RightToLeft : Qt::LeftToRight;
+  m_pages->setLayoutDirection(nextDir);
+  m_outFileNameGen.setLayoutDirection(nextDir);
+  resetThumbSequence(currentPageOrderProvider(), ThumbnailSequence::KEEP_SELECTION);
+  invalidateAllThumbnails();
+}
+
 void MainWindow::pastLastPageContextMenuRequested(const QPoint& screenPos) {
   if (!isProjectLoaded()) {
     return;
   }
 
-  QMenu menu;
+  QMenu menu(thumbView);
   menu.addAction(IconProvider::getInstance().getIcon("insert-here"), tr("Insert here ..."));
 
   if (menu.exec(screenPos)) {
@@ -1579,6 +1594,7 @@ void MainWindow::updateProjectActions() {
   actionSaveProjectAs->setEnabled(loaded);
   actionFixDpi->setEnabled(loaded);
   actionRelinking->setEnabled(loaded);
+  actionReverseTwoPageOrder->setEnabled(loaded);
 }
 
 bool MainWindow::isBatchProcessingInProgress() const {

diff --git a/src/app/MainWindow.h b/src/app/MainWindow.h
@@ -118,6 +118,8 @@ class MainWindow : public QMainWindow, private FilterUiInterface, private Ui::Ma
 
   void pastLastPageContextMenuRequested(const QPoint& screenPos);
 
+  void toggleTwoPageSpreadReadingOrder();
+
   void thumbViewFocusToggled(bool checked);
 
   void thumbViewScrolled();

diff --git a/src/app/MainWindow.ui b/src/app/MainWindow.ui
@@ -75,6 +75,7 @@
     </widget>
     <addaction name="actionFixDpi"/>
     <addaction name="actionRelinking"/>
+    <addaction name="actionReverseTwoPageOrder"/>
     <addaction name="separator"/>
     <addaction name="actionDebug"/>
     <addaction name="separator"/>
@@ -1214,6 +1215,20 @@ QToolButton:pressed {
     <bool>false</bool>
    </property>
   </action>
+  <action name="actionReverseTwoPageOrder">
+   <property name="text">
+    <string>Reverse two-page spread order</string>
+   </property>
+   <property name="toolTip">
+    <string>Swap left/right page order for two-page scans (e.g. Japanese book reading order).</string>
+   </property>
+   <property name="shortcut">
+    <string notr="true"/>
+   </property>
+   <property name="autoRepeat">
+    <bool>false</bool>
+   </property>
+  </action>
   <action name="actionSwitchFilter1">
    <property name="text">
     <string>Switch filter to orientation</string>

diff --git a/src/app/main.cpp b/src/app/main.cpp
@@ -18,6 +18,12 @@
 
 int main(int argc, char* argv[]) {
 #if QT_VERSION_MAJOR == 5
+  // Issue #97: Qt5 on Wayland can corrupt dialogs; use X11 unless opted out.
+  if (!qEnvironmentVariableIsSet("SCANTAILOR_NO_XCB_FALLBACK")) {
+    if (qgetenv("XDG_SESSION_TYPE") == "wayland" && qEnvironmentVariableIsEmpty("QT_QPA_PLATFORM")) {
+      qputenv("QT_QPA_PLATFORM", QByteArrayLiteral("xcb"));
+    }
+  }
   QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
   QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
 #if QT_VERSION >= QT_VERSION_CHECK(5, 14, 0)

diff --git a/src/core/OutputFileNameGenerator.h b/src/core/OutputFileNameGenerator.h
@@ -24,6 +24,8 @@ class OutputFileNameGenerator {
 
   void performRelinking(const AbstractRelinker& relinker);
 
+  void setLayoutDirection(Qt::LayoutDirection dir) { m_layoutDirection = dir; }
+
   Qt::LayoutDirection layoutDirection() const { return m_layoutDirection; }
 
   const QString& outDir() const { return m_outDir; }

diff --git a/src/core/ProjectPages.cpp b/src/core/ProjectPages.cpp
@@ -72,6 +72,14 @@ Qt::LayoutDirection ProjectPages::layoutDirection() const {
   }
 }
 
+void ProjectPages::setLayoutDirection(const Qt::LayoutDirection dir) {
+  {
+    QMutexLocker locker(&m_mutex);
+    initSubPagesInOrder(dir);
+  }
+  emit modified();
+}
+
 void ProjectPages::initSubPagesInOrder(const Qt::LayoutDirection layoutDirection) {
   if (layoutDirection == Qt::LeftToRight) {
     m_subPagesInOrder[0] = PageId::LEFT_PAGE;

diff --git a/src/core/ProjectPages.h b/src/core/ProjectPages.h
@@ -48,6 +48,11 @@ class ProjectPages : public QObject {
 
   Qt::LayoutDirection layoutDirection() const;
 
+  /**
+   * \brief Swap logical order of left/right sub-pages for two-page layouts (issue #62).
+   */
+  void setLayoutDirection(Qt::LayoutDirection dir);
+
   PageSequence toPageSequence(PageView view) const;
 
   void listRelinkablePaths(const VirtualFunction<void, const RelinkablePath&>& sink) const;

diff --git a/src/core/filters/deskew/ApplyDialog.cpp b/src/core/filters/deskew/ApplyDialog.cpp
@@ -33,25 +33,28 @@ ApplyDialog::ApplyDialog(QWidget* parent, const PageId& curPage, const PageSelec
 ApplyDialog::~ApplyDialog() = default;
 
 void ApplyDialog::onSubmit() {
+  const bool applyDeskew = applyDeskewCheckBox->isChecked();
+  const bool applyOblique = applyObliqueCheckBox->isChecked();
+
   std::set<PageId> pages;
   // thisPageRB is intentionally not handled.
   if (allPagesRB->isChecked()) {
     m_pages.selectAll().swap(pages);
-    emit appliedToAllPages(pages);
+    emit appliedToAllPages(pages, applyDeskew, applyOblique);
   } else if (thisPageAndFollowersRB->isChecked()) {
     m_pages.selectPagePlusFollowers(m_curPage).swap(pages);
-    emit appliedTo(pages);
+    emit appliedTo(pages, applyDeskew, applyOblique);
   } else if (selectedPagesRB->isChecked()) {
-    emit appliedTo(m_selectedPages);
+    emit appliedTo(m_selectedPages, applyDeskew, applyOblique);
   } else if (everyOtherRB->isChecked()) {
     m_pages.selectEveryOther(m_curPage).swap(pages);
-    emit appliedTo(pages);
+    emit appliedTo(pages, applyDeskew, applyOblique);
   } else if (thisEveryOtherRB->isChecked()) {
     m_pages.selectThisPageAndFollowingEveryOther(m_curPage).swap(pages);
-    emit appliedTo(pages);
+    emit appliedTo(pages, applyDeskew, applyOblique);
   } else if (everyOtherSelectedRB->isChecked()) {
     m_pages.selectEveryOtherInSubsetFromPage(m_curPage, m_selectedPages).swap(pages);
-    emit appliedTo(pages);
+    emit appliedTo(pages, applyDeskew, applyOblique);
   }
   accept();
 }  // ApplyDialog::onSubmit

diff --git a/src/core/filters/deskew/ApplyDialog.h b/src/core/filters/deskew/ApplyDialog.h
@@ -25,9 +25,9 @@ class ApplyDialog : public QDialog, private Ui::ApplyDialog {
 
  signals:
 
-  void appliedTo(const std::set<PageId>& pages);
+  void appliedTo(const std::set<PageId>& pages, bool applyDeskew, bool applyOblique);
 
-  void appliedToAllPages(const std::set<PageId>& pages);
+  void appliedToAllPages(const std::set<PageId>& pages, bool applyDeskew, bool applyOblique);
 
  private slots:
 

diff --git a/src/core/filters/deskew/ApplyDialog.ui b/src/core/filters/deskew/ApplyDialog.ui
@@ -139,6 +139,35 @@
      </layout>
     </widget>
    </item>
+   <item>
+    <widget class="QGroupBox" name="applyPartsGroupBox">
+     <property name="title">
+      <string>Apply parameters</string>
+     </property>
+     <layout class="QVBoxLayout" name="verticalLayout_apply_parts">
+      <item>
+       <widget class="QCheckBox" name="applyDeskewCheckBox">
+        <property name="text">
+         <string>Deskew angle and mode</string>
+        </property>
+        <property name="checked">
+         <bool>true</bool>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QCheckBox" name="applyObliqueCheckBox">
+        <property name="text">
+         <string>Oblique angle and mode</string>
+        </property>
+        <property name="checked">
+         <bool>true</bool>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
    <item>
     <spacer name="verticalSpacer">
      <property name="orientation">

diff --git a/src/core/filters/deskew/CacheDrivenTask.cpp b/src/core/filters/deskew/CacheDrivenTask.cpp
@@ -27,7 +27,9 @@ void CacheDrivenTask::process(const PageInfo& pageInfo,
                               const ImageTransformation& xform) {
   const Dependencies deps(xform.preCropArea(), xform.preRotation());
   std::unique_ptr<Params> params(m_settings->getPageParams(pageInfo.id()));
-  if (!params || (!deps.matches(params->dependencies()) && (params->mode() == MODE_AUTO))) {
+  if (!params
+      || (!deps.matches(params->dependencies())
+          && ((params->mode() == MODE_AUTO) || (params->obliqueMode() == MODE_AUTO)))) {
     if (auto* thumbCol = dynamic_cast<ThumbnailCollector*>(collector)) {
       thumbCol->processThumbnail(std::unique_ptr<QGraphicsItem>(new IncompleteThumbnail(
           thumbCol->thumbnailCache(), thumbCol->maxLogicalThumbSize(), pageInfo.imageId(), xform)));