GTKmm - How to put a pixbuf in a treeview

Question

I'm learning how to use GTKmm and I'm having a really hard time figuring out how to put an image into a treeview. I used Glade to create a treestore with 3 columns, one of which is a GdkPixbuf called store_pixbuf. I also created a treeview in glade, with a column that has both a pixbuf cell renderer called int_col_pict and a char array cell renderer. In my code, I have the usual MyColumns definition for the treestore like:

class MyModelColumns : public Gtk::TreeModel::ColumnRecord
{
   public:
   Gtk::TreeModelColumn<Glib::ustring> store_hostname;
   Gtk::TreeModelColumn<Glib::ustring> store_intname;
   Gtk::TreeModelColumn<Glib::RefPtr<Gdk::Pixbuf> > store_pict;

   MyModelColumns   () { add(store_hostname); add(store_intname); add(store_pict);}
};

and use the following bit of code to populate it.

//Get a pointer to the treestore
Glib::RefPtr<Gtk::TreeStore> treestore = Glib::RefPtr<Gtk::TreeStore>::cast_static(builder->get_object("routerTreeStore"));

//make sure the pointer isn't bad
if(treestore){
MyModelColumns columns;

    //populate the first column
    Gtk::TreeRow row= *(treestore->append());
    row[columns.store_hostname] = router->hostname;

    //populate all children
    for(int i=0; i<router->interfaces.size(); i++)
    {   
        //append child row
        Gtk::TreeRow child = *(treestore->append(row.children()));

        //insert data into the row
        child[columns.store_pict] = Gdk::Pixbuf::create_from_file("red_dot.png");
        child[columns.store_intname] = router->interfaces[i].interfaceName;
    }
}//if

I initially tried to use a stock image, but I could not figure out what function I was supposed to use, so then I tried to use Gdk::Pixbuf::create_from_file() (as you can see above), but at run time I get the following error:

Gtk-WARNING **: gtktreestore.c:765: Unable to convert from GdkPixbuf to gtkmm__GdkPixbuf

Click here to see what it looks like running. The image is supposed to go on the same line as the "FastEthernet..." lines

Does anyone know how I can solve this? Am I going about it completely wrong? Thanks for looking, every little bit of help is appreciated!

Answer 1

Looks like it's necessary to explicitly set CellRenderer for pixbuf cells. This code snippet displays CANCEL icon on each data row.

Gtk::CellRendererPixbuf *cross = Gtk::manage(new Gtk::CellRendererPixbuf());
cross->property_stock_id() = Gtk::StockID(Gtk::Stock::CANCEL).get_string();
cross->property_stock_size() = Gtk::ICON_SIZE_BUTTON;
[...]
int cols_count = m_TreeView.append_column("icons", *cross);

For displaying custom images you need to remove two lines setting stock_id add something like this below:

Gtk::TreeViewColumn* pColumn = m_TreeView.get_column(cols_count - 1);
if(pColumn) {
  pColumn->add_attribute(cell->property_value(), columns.store_pict);
}

Answer 2

If all you want is a potentially different stock icon for each row, you can do it by setting an pixbuf renderer attribute. The idea is that the column contains a string stock-id, which the renderer displays as an icon.

// in your class declaration

struct columnsRecord : public Gtk::TreeModel::ColumnRecord {
    ...
    Gtk::TreeModelColumn<std::string>    stockID;   // stock id name
    ...
} treeColumns;

Gtk::CellRendererPixBuf     pixBufRenderer;
... 
// setting up columns
int numcols = treeView.append_column("Icon Column", pixBufRenderer);  // returns # cols after append
treeView.get_column(numcols-1)->add_attribute(pixBufRenderer,"stock-id",treeColumns.stockID)
...
// setting a row
std::string id = good_val ? Gtk::Stock::YES.id : Gtk::Stock::NO.id;
rowiter->set_value(columns.stockID,id);

Answer 3

Your code looks correct. I just coded up a quick example and with gtkmm-2.4, I have no problems creating a column for a Glib::RefPtr

I couple of questions: what version of gtkmm are you using? Are you adding a column in the treeview for the Pixbuf?

I won't post my complete example but the relevant bits are:

in example.h

  //Tree model columns:
  class ModelColumns : public Gtk::TreeModel::ColumnRecord
  {
  public:

    ModelColumns()
    { add(m_col_store_pict);}
    Gtk::TreeModelColumn<Glib::RefPtr<Gdk::Pixbuf> > m_col_store_pict;

  };

  ModelColumns m_Columns;

in example.cpp

  //Create the Tree model:
  m_refTreeModel = Gtk::ListStore::create(m_Columns);
  m_TreeView.set_model(m_refTreeModel);

  //Fill the TreeView's model
  Gtk::TreeModel::Row row = *(m_refTreeModel->append());
  row[m_Columns.m_col_store_pict] = Gdk::Pixbuf::create_from_file("/usr/share/icons/gnome/22x22/apps/arts.png");

  row = *(m_refTreeModel->append());
  row[m_Columns.m_col_store_pict] = Gdk::Pixbuf::create_from_file("/usr/share/icons/gnome/22x22/apps/fonts.png");

  row = *(m_refTreeModel->append());
  row[m_Columns.m_col_store_pict] = Gdk::Pixbuf::create_from_file("/usr/share/icons/gnome/22x22/apps/access.png");

  //Add the TreeView's view columns:
  m_TreeView.append_column("Some Picture", m_Columns.m_col_store_pict);

Is that any help?