Plot pdf: fix issue when a 0 sized text is plotted (files are broken): now 0...

Plot pdf: fix issue when a 0 sized text is plotted (files are broken): now 0 sized texts are ignored.
pcbnew: remove a false error message when undoing a change on a text, or some other board items (graphic items for instance)

common/common_plotPDF_functions.cpp

@@ -167,7 +167,8 @@ void PDF_PLOTTER::Circle( const wxPoint& pos, int diametre, FILL_T aFill, int wi
     /* OK. Here's a trick. PDF doesn't support circles or circular angles, that's
        a fact. You'll have to do with cubic beziers. These *can't* represent
        circular arcs (NURBS can, beziers don't). But there is a widely known
-       approximation which is really good */
+       approximation which is really good
+    */
 
     SetCurrentLineWidth( width );
     double magic = radius * 0.551784; // You don't want to know where this come from
@@ -747,6 +748,10 @@ void PDF_PLOTTER::Text( const wxPoint&              aPos,
                         bool                        aBold,
                         bool                        aMultilineAllowed )
 {
+    // PDF files do not like 0 sized texts which create broken files.
+    if( aSize.x == 0 || aSize.y == 0 )
+        return;
+
     // Fix me: see how to use PDF text mode for multiline texts
     if( aMultilineAllowed && !aText.Contains( wxT( "\n" ) ) )
         aMultilineAllowed = false;  // the text has only one line.

pcbnew/board_undo_redo.cpp

@@ -183,12 +183,17 @@ static bool TestForExistingItem( BOARD* aPcb, BOARD_ITEM* aItem )
 void BOARD_ITEM::SwapData( BOARD_ITEM* aImage )
 {
     if( aImage == NULL )
-    {
         return;
-    }
+
+    // Remark: to create images of edited items to undo, we are using Clone method
+    // which can duplication of items foe copy, but does not clone all members
+    // mainly pointers in chain and time stamp, which is set to new, unique value.
+    // So we have to use the current values of these parameters.
 
     EDA_ITEM * pnext = Next();
     EDA_ITEM * pback = Back();
+    DHEAD* mylist    = m_List;
+    time_t timestamp = GetTimeStamp();
 
     switch( Type() )
     {
@@ -286,15 +291,11 @@ void BOARD_ITEM::SwapData( BOARD_ITEM* aImage )
         break;
     }
 
-    if( pnext != Next() || pback != Back() )
-    {
-        Pnext = pnext;
-        Pback = pback;
-#ifdef DEBUG
-        wxLogMessage( wxT( "SwapData Error: %s Pnext or Pback pointers modified" ),
-                      GetClass().GetData() );
-#endif
-    }
+    // Restore pointers and time stamp, to be sure they are not broken
+    Pnext = pnext;
+    Pback = pback;
+    m_List = mylist;
+    SetTimeStamp( timestamp );
 }