Don't try to print something with invalid sizes

Unfortunately as we can't add new strings to stable versions it'd say "unwnown error" if that happens
Don't think it's too bad since this shouldn't be happening much

BUGS: 329562

core/generator.h

@@ -358,7 +358,8 @@ class OKULAR_EXPORT Generator : public QObject
             InvalidPrinterStatePrintError,
             UnableToFindFilePrintError,
             NoFileToPrintError,
-            NoBinaryToPrintError
+            NoBinaryToPrintError,
+            InvalidPageSizePrintError ///< @since 0.18.2 (KDE 4.12.2)
         };
         
         /**

generators/poppler/generator_pdf.cpp

@@ -1116,6 +1116,13 @@ bool PDFGenerator::print( QPrinter& printer )
     int width = printer.width();
     int height = printer.height();
 #endif
+
+    if (width <= 0 || height <= 0)
+    {
+        lastPrintError = InvalidPageSizePrintError;
+        return false;
+    }
+
     // Create the tempfile to send to FilePrinter, which will manage the deletion
     KTemporaryFile tf;
     tf.setSuffix( ".ps" );