Add destination path preview label to batch queue panel.

Label initially says "Destination path for the first selected image appears here"
so the feature is discoverable. Select a file and it shows the destination path
that would be used if it is the first file to be processed and the file does
not already exist. Label is updated as the template is edited, so you can see the
effect of the edits. If "Save to folder" is selected, the previewed path uses
that folder.

rtdata/languages/default

@@ -2101,6 +2101,8 @@ QINFO_PIXELSHIFT;Pixel Shift / %2 frame(s)
 QUEUE_AUTOSTART;Auto-start
 QUEUE_AUTOSTART_TOOLTIP;Start processing automatically when a new job arrives.
 QUEUE_DESTFILENAME;Path and file name
+QUEUE_DESTPREVIEW_TITLE;Select a thumbnail to preview its destination path here
+QUEUE_DESTPREVIEW_TOOLTIP;Destination path for the first selected image appears here
 QUEUE_FORMAT_TITLE;File Format
 QUEUE_LOCATION_FOLDER;Save to folder
 QUEUE_LOCATION_TEMPLATE;Use template

rtgui/batchqueue.cc

@@ -567,6 +567,41 @@ void BatchQueue::openLastSelectedItemInEditor()
     }
 }
 
+void BatchQueue::updateDestinationPathPreview()
+{
+    MYWRITERLOCK(l, entryRW);
+
+    if (selected.size())
+    {
+        auto &entry = *selected.at(0);
+        int sequence = 0;   // Sequence during subsequent queue processing can't be determined here
+        Glib::ustring baseDestination;
+        if (options.saveUsePathTemplate)
+        {
+            baseDestination = calcAutoFileNameBase(entry.filename, sequence);
+        }
+        else
+        {
+            Glib::ustring baseFilename;
+            int extpos = entry.filename.size() - 1;
+            for (; extpos >= 0 && entry.filename[extpos] != '.'; extpos--)
+            {
+            }
+            for (int k = extpos - 1; k >= 0 && entry.filename[k] != '/' && entry.filename[k] != '\\'; k--)
+            {
+                baseFilename = entry.filename[k] + baseFilename;
+            }
+            baseDestination = options.savePathFolder + '/' + baseFilename;
+        }
+        Glib::ustring destination = Glib::ustring::compose ("%1.%2", baseDestination, options.saveFormatBatch.format);
+
+        if (listener)
+        {
+            listener->setDestinationPreviewText(destination);
+        }
+    }
+}
+
 void BatchQueue::openItemInEditor(ThumbBrowserEntryBase* item)
 {
     if (item) {
@@ -1021,3 +1056,8 @@ void BatchQueue::redrawNeeded (LWButton* button)
     GThreadLock lock;
     queue_draw ();
 }
+
+void BatchQueue::selectionChanged()
+{
+    updateDestinationPathPreview();
+}

rtgui/batchqueue.h

@@ -38,6 +38,7 @@ public:
     virtual ~BatchQueueListener() = default;
     virtual void queueSizeChanged(int qsize, bool queueRunning, bool queueError, const Glib::ustring& queueErrorMessage) = 0;
     virtual bool canStartNext() = 0;
+    virtual void setDestinationPreviewText(const Glib::ustring& destinationPath) = 0;
 };
 
 class FileCatalog;
@@ -59,6 +60,7 @@ public:
     void selectAll ();
     void openItemInEditor(ThumbBrowserEntryBase* item);
     void openLastSelectedItemInEditor();
+    void updateDestinationPathPreview();
 
     void startProcessing ();
 
@@ -79,6 +81,7 @@ public:
     bool keyPressed (GdkEventKey* event) override;
     void buttonPressed (LWButton* button, int actionCode, void* actionData) override;
     void redrawNeeded  (LWButton* button) override;
+    void selectionChanged () override;
 
     void setBatchQueueListener (BatchQueueListener* l)
     {

rtgui/batchqueuepanel.cc

@@ -108,6 +108,9 @@ BatchQueuePanel::BatchQueuePanel (FileCatalog* aFileCatalog) : parent(nullptr)
 #endif
 
     odvb->pack_start (*hb3, Gtk::PACK_SHRINK, 4);
+    destinationPreviewLabel = Gtk::manage (new Gtk::Label ());
+    destinationPreviewLabel->set_tooltip_markup(M("QUEUE_DESTPREVIEW_TOOLTIP"));
+    odvb->pack_start (*destinationPreviewLabel);
     Gtk::RadioButton::Group g = useTemplate->get_group();
     useFolder->set_group (g);
     fdir->add (*odvb);
@@ -122,6 +125,7 @@ BatchQueuePanel::BatchQueuePanel (FileCatalog* aFileCatalog) : parent(nullptr)
     outdirTemplate->set_text (options.savePathTemplate);
     useTemplate->set_active (options.saveUsePathTemplate);
     useFolder->set_active (!options.saveUsePathTemplate);
+    destinationPreviewLabel->set_text (M("QUEUE_DESTPREVIEW_TITLE"));
 
     // setup signal handlers
     outdirTemplate->signal_changed().connect (sigc::mem_fun(*this, &BatchQueuePanel::saveOptions));
@@ -329,6 +333,7 @@ void BatchQueuePanel::saveOptions ()
     options.savePathTemplate    = outdirTemplate->get_text();
     options.saveUsePathTemplate = useTemplate->get_active();
     options.procQueueEnabled    = qAutoStart->get_active();
+    batchQueue->updateDestinationPathPreview();
 }
 
 bool BatchQueuePanel::handleShortcutKey (GdkEventKey* event)
@@ -358,6 +363,11 @@ bool BatchQueuePanel::canStartNext ()
     return queueShouldRun;
 }
 
+void BatchQueuePanel::setDestinationPreviewText(const Glib::ustring &destinationPath)
+{
+    destinationPreviewLabel->set_text(destinationPath);
+}
+
 void BatchQueuePanel::pathFolderButtonPressed ()
 {
 
@@ -381,6 +391,7 @@ void BatchQueuePanel::pathFolderButtonPressed ()
 void BatchQueuePanel::pathFolderChanged ()
 {
     options.savePathFolder = outdirFolder->get_filename();
+    batchQueue->updateDestinationPathPreview();
 }
 
 void BatchQueuePanel::formatChanged(const Glib::ustring& format)

rtgui/batchqueuepanel.h

@@ -42,6 +42,7 @@ class BatchQueuePanel : public Gtk::Box,
     Gtk::CheckButton* qAutoStart;
 
     Gtk::Entry* outdirTemplate;
+    Gtk::Label* destinationPreviewLabel;
     MyFileChooserButton* outdirFolder;
     Gtk::Button* outdirFolderButton;
     Gtk::RadioButton* useTemplate;
@@ -72,6 +73,7 @@ public:
     // batchqueuelistener interface
     void queueSizeChanged(int qsize, bool queueRunning, bool queueError, const Glib::ustring& queueErrorMessage) override;
     bool canStartNext() override;
+    void setDestinationPreviewText(const Glib::ustring& destinationPath) override;
 
 private:
     void startBatchProc ();