Eeschema: don't stat files when updating title bar text.

The tests for file existence and write status perform two file stats
which cause performance issues on slow network shares.  Now the file
state is determined at load time and stored in the SCH_SCREEN object
so file access is no longer required.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/9343

eeschema/sch_edit_frame.cpp

@@ -1231,16 +1231,20 @@ void SCH_EDIT_FRAME::AddItemToScreenAndUndoList( SCH_SCREEN* aScreen, SCH_ITEM*
 
 void SCH_EDIT_FRAME::UpdateTitle()
 {
+    SCH_SCREEN* screen = GetScreen();
+
+    wxCHECK( screen, /* void */ );
+
     wxString title;
 
-    if( !GetScreen()->GetFileName().IsEmpty() )
+    if( !screen->GetFileName().IsEmpty() )
     {
-        wxFileName fn( Prj().AbsolutePath( GetScreen()->GetFileName() ) );
+        wxFileName fn( Prj().AbsolutePath( screen->GetFileName() ) );
         bool       readOnly = false;
         bool       unsaved = false;
 
-        if( fn.IsOk() && fn.FileExists() )
+        if( fn.IsOk() && screen->FileExists() )
-            readOnly = !fn.IsFileWritable();
+            readOnly = screen->IsReadOnly();
         else
             unsaved = true;
 

eeschema/sch_plugins/kicad/sch_sexpr_plugin.cpp

@@ -519,6 +519,9 @@ void SCH_SEXPR_PLUGIN::loadHierarchy( SCH_SHEET* aSheet )
                 m_error += ioe.What();
             }
 
+            aSheet->GetScreen()->SetFileReadOnly( !fileName.IsFileWritable() );
+            aSheet->GetScreen()->SetFileExists( true );
+
             // This was moved out of the try{} block so that any sheets definitionsthat
             // the plugin fully parsed before the exception was raised will be loaded.
             for( SCH_ITEM* aItem : aSheet->GetScreen()->Items().OfType( SCH_SHEET_T ) )
@@ -594,6 +597,8 @@ void SCH_SEXPR_PLUGIN::Save( const wxString& aFileName, SCH_SHEET* aSheet, SCHEM
     m_out = &formatter;     // no ownership
 
     Format( aSheet );
+
+    aSheet->GetScreen()->SetFileExists( true );
 }
 
 

eeschema/sch_plugins/legacy/sch_legacy_plugin.cpp

@@ -744,6 +744,9 @@ void SCH_LEGACY_PLUGIN::loadHierarchy( SCH_SHEET* aSheet )
                 m_error += ioe.What();
             }
 
+            aSheet->GetScreen()->SetFileReadOnly( !fileName.IsFileWritable() );
+            aSheet->GetScreen()->SetFileExists( true );
+
             for( auto aItem : aSheet->GetScreen()->Items().OfType( SCH_SHEET_T ) )
             {
                 wxCHECK2( aItem->Type() == SCH_SHEET_T, continue );
@@ -1864,6 +1867,7 @@ std::shared_ptr<BUS_ALIAS> SCH_LEGACY_PLUGIN::loadBusAlias( LINE_READER& aReader
     {
         buf.clear();
         parseUnquotedString( buf, aReader, line, &line, true );
+
         if( buf.Len() > 0 )
         {
             busAlias->AddMember( buf );
@@ -1895,6 +1899,8 @@ void SCH_LEGACY_PLUGIN::Save( const wxString& aFileName, SCH_SHEET* aSheet, SCHE
     m_out = &formatter;     // no ownership
 
     Format( aSheet );
+
+    aSheet->GetScreen()->SetFileExists( true );
 }
 
 

eeschema/sch_screen.cpp

@@ -66,7 +66,9 @@
 SCH_SCREEN::SCH_SCREEN( EDA_ITEM* aParent ) :
     BASE_SCREEN( aParent, SCH_SCREEN_T ),
     m_fileFormatVersionAtLoad( 0 ),
-    m_paper( wxT( "A4" ) )
+    m_paper( wxT( "A4" ) ),
+    m_isReadOnly( false ),
+    m_fileExists( false )
 {
     m_modification_sync = 0;
     m_refCount = 0;

eeschema/sch_screen.h

@@ -144,6 +144,12 @@ public:
 
     const wxString& GetFileName() const                     { return m_fileName; }
 
+    void SetFileReadOnly( bool aIsReadOnly )                { m_isReadOnly = aIsReadOnly; }
+    bool IsReadOnly() const                                 { return m_isReadOnly; }
+
+    void SetFileExists( bool aFileExists )                  { m_fileExists = aFileExists; }
+    bool FileExists() const                                 { return m_fileExists; }
+
     const wxPoint& GetAuxOrigin() const                     { return m_aux_origin; }
     void SetAuxOrigin( const wxPoint& aPosition )           { m_aux_origin = aPosition; }
 
@@ -512,6 +518,11 @@ private:
     bool        m_zoomInitialized;          // Set to true once the zoom value is initialized with
                                             // `InitZoom()`.
 
+    bool        m_isReadOnly;               ///< Read only status of the screen file.
+
+    ///< Flag to indicate the file associated with this screen has been created.
+    bool        m_fileExists;
+
     /// List of bus aliases stored in this screen.
     std::unordered_set< std::shared_ptr< BUS_ALIAS > > m_aliases;