[glom] Print Layout: Print Preview: Avoid warnings when there are no records yet.

[Murray Cumming <murrayc src gnome org>]

commit 7791d0230eefdc5192e76162e31af8bdd69974ee
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Feb 9 09:28:34 2012 +0100

    Print Layout: Print Preview: Avoid warnings when there are no records yet.
    
    * glom/print_layout/canvas_print_layout.cc: fill_with_data(): Do nothing,
    and hint on stdout, if there are no records yet. This avoids several
    real warnings later.

 ChangeLog                                |    8 ++++++++
 glom/frame_glom.cc                       |    5 ++++-
 glom/print_layout/canvas_print_layout.cc |    8 ++++++++
 3 files changed, 20 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 15ae1d0..2efcaae 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2012-02-09  Murray Cumming  <murrayc murrayc com>
+
+	Print Layout: Print Preview: Avoid warnings when there are no records yet.
+
+	* glom/print_layout/canvas_print_layout.cc: fill_with_data(): Do nothing,
+	and hint on stdout, if there are no records yet. This avoids several 
+	real warnings later.
+
 2012-02-08  Murray Cumming  <murrayc murrayc com>
 
 	Print Layout: Avoid sometimes over-scaled images.
diff --git a/glom/frame_glom.cc b/glom/frame_glom.cc
index d027d1c..a48b767 100644
--- a/glom/frame_glom.cc
+++ b/glom/frame_glom.cc
@@ -2330,9 +2330,12 @@ void Frame_Glom::do_print_layout(const Glib::ustring& print_layout_name, bool pr
     return;
   }
   
-  //TODO: When expandingt items, avoid the page gaps that the print layout's designed
+  //TODO: When expanding items, avoid the page gaps that the print layout's design
   //has added.  
   const FoundSet found_set = m_Notebook_Data.get_found_set_details();
+  //Note that found_set.m_where_clause could be empty if there are no records yet,
+  //and that is acceptable if this is for a print preview while designing the print layout. 
+  
   PrintLayoutUtils::do_print_layout(print_layout, found_set, 
     preview, document, false /* do not avoid print margins */, transient_for);
 }
diff --git a/glom/print_layout/canvas_print_layout.cc b/glom/print_layout/canvas_print_layout.cc
index a2df454..79b8856 100644
--- a/glom/print_layout/canvas_print_layout.cc
+++ b/glom/print_layout/canvas_print_layout.cc
@@ -717,6 +717,14 @@ guint Canvas_PrintLayout::get_page_count() const
 
 void Canvas_PrintLayout::fill_with_data(const FoundSet& found_set, bool avoid_page_margins)
 {
+  if(found_set.m_where_clause.empty())
+  {
+    //This might help a developer/debugger:
+    //This is not an error.
+    std::cout << G_STRFUNC << ": Not attempting to show real data because the where_clause is empty, maybe because there are no records in the database yet." << std::endl;
+    return;
+  }
+  
   fill_with_data(m_items_group, found_set, avoid_page_margins);
 }