We continue to flesh out the functionality of our application. For now, we add search. gtkmm supports this with Gtk::SearchEntry and Gtk::SearchBar. The search bar is a widget that can slide in from the top to present a search entry.

We add a toggle button to the header bar, which can be used to slide out the search bar below the header bar. The new widgets are added in the window.ui file.

Implementing the search needs quite a few code changes that we are not going to completely go over here. The central piece of the search implementation is a signal handler that listens for text changes in the search entry, shown here without error handling.

void ExampleAppWindow::on_search_text_changed()
{
  const auto text = m_searchentry->get_text();
  auto tab = dynamic_cast<Gtk::ScrolledWindow*>(m_stack->get_visible_child());
  auto view = dynamic_cast<Gtk::TextView*>(tab->get_child());

  // Very simple-minded search implementation.
  auto buffer = view->get_buffer();
  Gtk::TextIter match_start;
  Gtk::TextIter match_end;
  if (buffer->begin().forward_search(text, Gtk::TEXT_SEARCH_CASE_INSENSITIVE,
      match_start, match_end))
  {
    buffer->select_range(match_start, match_end);
    view->scroll_to(match_start);
  }
}

With the search bar, our application now looks like this:

Source Code

File: exampleappwindow.h (For use with gtkmm 3, not gtkmm 2)

#ifndef GTKMM_EXAMPLEAPPWINDOW_H_
#define GTKMM_EXAMPLEAPPWINDOW_H_

#include <gtkmm.h>

class ExampleAppWindow : public Gtk::ApplicationWindow
{
public:
  ExampleAppWindow(BaseObjectType* cobject,
    const Glib::RefPtr<Gtk::Builder>& refBuilder);

  static ExampleAppWindow* create();

  void open_file_view(const Glib::RefPtr<Gio::File>& file);

protected:
  // Signal handlers
  void on_search_text_changed();
  void on_visible_child_changed();

  Glib::RefPtr<Gtk::Builder> m_refBuilder;
  Glib::RefPtr<Gio::Settings> m_settings;
  Gtk::Stack* m_stack;
  Gtk::ToggleButton* m_search;
  Gtk::SearchBar* m_searchbar;
  Gtk::SearchEntry* m_searchentry;
  Glib::RefPtr<Glib::Binding> m_prop_binding;
};

#endif /* GTKMM_EXAMPLEAPPWINDOW_H */

File: exampleappprefs.h (For use with gtkmm 3, not gtkmm 2)

#include "../step5/exampleappprefs.h"
// Equal to the corresponding file in step5

File: exampleapplication.h (For use with gtkmm 3, not gtkmm 2)

#include "../step4/exampleapplication.h"
// Equal to the corresponding file in step4

File: exampleapplication.cc (For use with gtkmm 3, not gtkmm 2)

#include "../step5/exampleapplication.cc"
// Equal to the corresponding file in step5

File: main.cc (For use with gtkmm 3, not gtkmm 2)

#include "../step5/main.cc"
// Equal to the corresponding file in step5

File: exampleappwindow.cc (For use with gtkmm 3, not gtkmm 2)

#include "exampleappwindow.h"
#include <iostream>
#include <stdexcept>

ExampleAppWindow::ExampleAppWindow(BaseObjectType* cobject,
  const Glib::RefPtr<Gtk::Builder>& refBuilder)
: Gtk::ApplicationWindow(cobject),
  m_refBuilder(refBuilder),
  m_settings(),
  m_stack(nullptr),
  m_search(nullptr),
  m_searchbar(nullptr),
  m_searchentry(nullptr),
  m_prop_binding()
{
  m_refBuilder->get_widget("stack", m_stack);
  if (!m_stack)
    throw std::runtime_error("No \"stack\" object in window.ui");

  m_refBuilder->get_widget("search", m_search);
  if (!m_search)
    throw std::runtime_error("No \"search\" object in window.ui");

  m_refBuilder->get_widget("searchbar", m_searchbar);
  if (!m_searchbar)
    throw std::runtime_error("No \"searchbar\" object in window.ui");

  m_refBuilder->get_widget("searchentry", m_searchentry);
  if (!m_searchentry)
    throw std::runtime_error("No \"searchentry\" object in window.ui");

  m_settings = Gio::Settings::create("org.gtkmm.exampleapp");
  m_settings->bind("transition", m_stack->property_transition_type());

  m_prop_binding = Glib::Binding::bind_property(m_search->property_active(),
    m_searchbar->property_search_mode_enabled(), Glib::BINDING_BIDIRECTIONAL);

  // Connect signal handlers.
  m_searchentry->signal_search_changed().connect(
    sigc::mem_fun(*this, &ExampleAppWindow::on_search_text_changed));
  m_stack->property_visible_child().signal_changed().connect(
    sigc::mem_fun(*this, &ExampleAppWindow::on_visible_child_changed));
}

//static
ExampleAppWindow* ExampleAppWindow::create()
{
  // Load the Builder file and instantiate its widgets.
  auto refBuilder = Gtk::Builder::create_from_resource("/org/gtkmm/exampleapp/window.ui");

  ExampleAppWindow* window = nullptr;
  refBuilder->get_widget_derived("app_window", window);
  if (!window)
    throw std::runtime_error("No \"app_window\" object in window.ui");

  return window;
}

void ExampleAppWindow::open_file_view(const Glib::RefPtr<Gio::File>& file)
{
  const auto basename = file->get_basename();

  auto scrolled = Gtk::make_managed<Gtk::ScrolledWindow>();
  scrolled->set_hexpand(true);
  scrolled->set_vexpand(true);
  scrolled->show();
  auto view = Gtk::make_managed<Gtk::TextView>();
  view->set_editable(false);
  view->set_cursor_visible(false);
  view->show();
  scrolled->add(*view);
  m_stack->add(*scrolled, basename, basename);

  auto buffer = view->get_buffer();
  try
  {
    char* contents = nullptr;
    gsize length = 0;
    
    file->load_contents(contents, length);
    buffer->set_text(contents, contents+length);
    g_free(contents);
  }
  catch (const Glib::Error& ex)
  {
    std::cout << "ExampleAppWindow::open_file_view(\"" << file->get_parse_name()
      << "\"):\n  " << ex.what() << std::endl;
    return;
  }

  auto tag = buffer->create_tag();
  m_settings->bind("font", tag->property_font());
  buffer->apply_tag(tag, buffer->begin(), buffer->end());

  m_search->set_sensitive(true);
}

void ExampleAppWindow::on_search_text_changed()
{
  const auto text = m_searchentry->get_text();
  if (text.empty())
    return;

  auto tab = dynamic_cast<Gtk::ScrolledWindow*>(m_stack->get_visible_child());
  if (!tab)
  {
    std::cout << "ExampleAppWindow::on_search_text_changed(): No visible child." << std::endl;
    return;
  }

  auto view = dynamic_cast<Gtk::TextView*>(tab->get_child());
  if (!view)
  {
    std::cout << "ExampleAppWindow::on_search_text_changed(): No visible text view." << std::endl;
    return;
  }

  // Very simple-minded search implementation.
  auto buffer = view->get_buffer();
  Gtk::TextIter match_start;
  Gtk::TextIter match_end;
  if (buffer->begin().forward_search(text, Gtk::TEXT_SEARCH_CASE_INSENSITIVE,
      match_start, match_end))
  {
    buffer->select_range(match_start, match_end);
    view->scroll_to(match_start);
  }
}

void ExampleAppWindow::on_visible_child_changed()
{
  m_searchbar->set_search_mode(false);
}

File: exampleappprefs.cc (For use with gtkmm 3, not gtkmm 2)

#include "../step5/exampleappprefs.cc"
// Equal to the corresponding file in step5

File: window.ui (For use with gtkmm 3, not gtkmm 2)

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <!-- interface-requires gtk+ 3.8 -->
  <object class="GtkApplicationWindow" id="app_window">
    <property name="title" translatable="yes">Example Application</property>
    <property name="default-width">600</property>
    <property name="default-height">400</property>
    <child>
      <object class="GtkBox" id="content_box">
        <property name="visible">True</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkHeaderBar" id="header">
            <property name="visible">True</property>
            <child type="title">
              <object class="GtkStackSwitcher" id="tabs">
                <property name="visible">True</property>
                <property name="stack">stack</property>
              </object>
            </child>
            <child>
              <object class="GtkToggleButton" id="search">
                <property name="visible">True</property>
                <property name="sensitive">False</property>
                <style>
                  <class name="image-button"/>
                </style>
                <child>
                  <object class="GtkImage" id="search-icon">
                    <property name="visible">True</property>
                    <property name="icon-name">edit-find-symbolic</property>
                    <property name="icon-size">1</property>
                  </object>
                </child>
              </object>
              <packing>
                <property name="pack-type">end</property>
              </packing>
            </child>
          </object>
        </child>
        <child>
          <object class="GtkSearchBar" id="searchbar">
            <property name="visible">True</property>
            <child>
              <object class="GtkSearchEntry" id="searchentry">
                <property name="visible">True</property>
              </object>
            </child>
          </object>
        </child>
        <child>
          <object class="GtkStack" id="stack">
            <property name="visible">True</property>
            <property name="transition-duration">500</property>
          </object>
        </child>
      </object>
    </child>
  </object>
</interface>