Examples
19.4.1. Simple
This example allows copy and pasting of application-specific data, using the standard text target. Although this is simple, it's not ideal because it does not identify the Clipboard data as being of a particular type.
File: examplewindow.h (For use with gtkmm 3, not gtkmm 2)
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H
#include <gtkmm.h>
class ExampleWindow : public Gtk::Window
{
public:
ExampleWindow();
virtual ~ExampleWindow();
protected:
//Signal handlers:
void on_button_copy();
void on_button_paste();
void on_clipboard_text_received(const Glib::ustring& text);
//Child widgets:
Gtk::Box m_VBox;
Gtk::Label m_Label;
Gtk::Grid m_Grid;
Gtk::ToggleButton m_ButtonA1, m_ButtonA2, m_ButtonB1, m_ButtonB2;
Gtk::ButtonBox m_ButtonBox;
Gtk::Button m_Button_Copy, m_Button_Paste;
};
#endif //GTKMM_EXAMPLEWINDOW_H
File: examplewindow.cc (For use with gtkmm 3, not gtkmm 2)
#include "examplewindow.h"
ExampleWindow::ExampleWindow()
: m_VBox(Gtk::ORIENTATION_VERTICAL),
m_Label("Select cells in the grid, click Copy, then open a second "
"instance of this example to try pasting the copied data."),
m_ButtonA1("A1"), m_ButtonA2("A2"), m_ButtonB1("B1"), m_ButtonB2("B2"),
m_Button_Copy("_Copy", /* mnemonic= */ true), m_Button_Paste("_Paste", true)
{
set_title("Gtk::Clipboard example");
set_border_width(12);
add(m_VBox);
m_VBox.pack_start(m_Label, Gtk::PACK_SHRINK);
//Fill Grid:
m_VBox.pack_start(m_Grid);
m_Grid.set_row_homogeneous(true);
m_Grid.set_column_homogeneous(true);
m_Grid.attach(m_ButtonA1, 0, 0, 1, 1);
m_Grid.attach(m_ButtonA2, 1, 0, 1, 1);
m_Grid.attach(m_ButtonB1, 0, 1, 1, 1);
m_Grid.attach(m_ButtonB2, 1, 1, 1, 1);
//Add ButtonBox to bottom:
m_VBox.pack_start(m_ButtonBox, Gtk::PACK_SHRINK);
m_VBox.set_spacing(6);
//Fill ButtonBox:
m_ButtonBox.set_layout(Gtk::BUTTONBOX_END);
m_ButtonBox.pack_start(m_Button_Copy, Gtk::PACK_SHRINK);
m_Button_Copy.signal_clicked().connect(sigc::mem_fun(*this,
&ExampleWindow::on_button_copy) );
m_ButtonBox.pack_start(m_Button_Paste, Gtk::PACK_SHRINK);
m_Button_Paste.signal_clicked().connect(sigc::mem_fun(*this,
&ExampleWindow::on_button_paste) );
show_all_children();
}
ExampleWindow::~ExampleWindow()
{
}
void ExampleWindow::on_button_copy()
{
//Build a string representation of the stuff to be copied:
//Ideally you would use XML, with an XML parser here:
Glib::ustring strData;
strData += m_ButtonA1.get_active() ? "1" : "0";
strData += m_ButtonA2.get_active() ? "1" : "0";
strData += m_ButtonB1.get_active() ? "1" : "0";
strData += m_ButtonB2.get_active() ? "1" : "0";
Glib::RefPtr<Gtk::Clipboard> refClipboard = Gtk::Clipboard::get();
refClipboard->set_text(strData);
}
void ExampleWindow::on_button_paste()
{
//Tell the clipboard to call our method when it is ready:
Glib::RefPtr<Gtk::Clipboard> refClipboard = Gtk::Clipboard::get();
refClipboard->request_text(sigc::mem_fun(*this,
&ExampleWindow::on_clipboard_text_received) );
}
void ExampleWindow::on_clipboard_text_received(const Glib::ustring& text)
{
//See comment in on_button_copy() about this silly clipboard format.
if(text.size() >= 4)
{
m_ButtonA1.set_active( text[0] == '1' );
m_ButtonA2.set_active( text[1] == '1' );
m_ButtonB1.set_active( text[2] == '1' );
m_ButtonB2.set_active( text[3] == '1' );
}
}
File: main.cc (For use with gtkmm 3, not gtkmm 2)
#include "examplewindow.h"
#include <gtkmm/application.h>
int main(int argc, char *argv[])
{
//APPLICATION_NON_UNIQUE because it shall be possible to run several
//instances of this application simultaneously.
Glib::RefPtr<Gtk::Application> app = Gtk::Application::create(
argc, argv, "org.gtkmm.example", Gio::APPLICATION_NON_UNIQUE);
ExampleWindow window;
//Shows the window and returns when it is closed.
return app->run(window);
}
19.4.2. Ideal
This is like the simple example, but it
Defines a custom clipboard target, though the format of that target is still text.
It supports pasting of 2 targets - both the custom one and a text one that creates an arbitrary text representation of the custom data.
It uses request_targets() and the owner_change signal and disables the Paste button if it can't use anything on the clipboard.
File: examplewindow.h (For use with gtkmm 3, not gtkmm 2)
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H
#include <gtkmm.h>
class ExampleWindow : public Gtk::Window
{
public:
ExampleWindow();
virtual ~ExampleWindow();
protected:
//Signal handlers:
void on_button_copy();
void on_button_paste();
void on_clipboard_owner_change(GdkEventOwnerChange* event);
void on_clipboard_get(Gtk::SelectionData& selection_data, guint info);
void on_clipboard_clear();
void on_clipboard_received(const Gtk::SelectionData& selection_data);
void on_clipboard_received_targets(const std::vector<Glib::ustring>& targets);
virtual void update_paste_status(); //Disable the paste button if there is nothing to paste.
//Child widgets:
Gtk::Box m_VBox;
Gtk::Label m_Label;
Gtk::Grid m_Grid;
Gtk::ToggleButton m_ButtonA1, m_ButtonA2, m_ButtonB1, m_ButtonB2;
Gtk::ButtonBox m_ButtonBox;
Gtk::Button m_Button_Copy, m_Button_Paste;
Glib::ustring m_ClipboardStore; //Keep copied stuff here, until it is pasted. This could be a big complex data structure.
};
#endif //GTKMM_EXAMPLEWINDOW_H
File: examplewindow.cc (For use with gtkmm 3, not gtkmm 2)
#include "examplewindow.h"
#include <algorithm>
namespace
{
//These should usually be MIME types.
const char example_target_custom[] = "gtkmmclipboardexample";
const char example_target_text[] = "UTF8_STRING";
} // anonymous namespace
ExampleWindow::ExampleWindow()
: m_VBox(Gtk::ORIENTATION_VERTICAL),
m_Label("Select cells in the grid, click Copy, then open a second instance "
"of this example to try pasting the copied data.\nOr try pasting the "
"text representation into gedit."),
m_ButtonA1("A1"), m_ButtonA2("A2"), m_ButtonB1("B1"), m_ButtonB2("B2"),
m_Button_Copy("_Copy", /* mnemonic= */ true), m_Button_Paste("_Paste", true)
{
set_title("Gtk::Clipboard example");
set_border_width(12);
add(m_VBox);
m_VBox.pack_start(m_Label, Gtk::PACK_SHRINK);
//Fill Grid:
m_VBox.pack_start(m_Grid);
m_Grid.set_row_homogeneous(true);
m_Grid.set_column_homogeneous(true);
m_Grid.attach(m_ButtonA1, 0, 0, 1, 1);
m_Grid.attach(m_ButtonA2, 1, 0, 1, 1);
m_Grid.attach(m_ButtonB1, 0, 1, 1, 1);
m_Grid.attach(m_ButtonB2, 1, 1, 1, 1);
//Add ButtonBox to bottom:
m_VBox.pack_start(m_ButtonBox, Gtk::PACK_SHRINK);
m_VBox.set_spacing(6);
//Fill ButtonBox:
m_ButtonBox.set_layout(Gtk::BUTTONBOX_END);
m_ButtonBox.pack_start(m_Button_Copy, Gtk::PACK_SHRINK);
m_Button_Copy.signal_clicked().connect(sigc::mem_fun(*this,
&ExampleWindow::on_button_copy) );
m_ButtonBox.pack_start(m_Button_Paste, Gtk::PACK_SHRINK);
m_Button_Paste.signal_clicked().connect(sigc::mem_fun(*this,
&ExampleWindow::on_button_paste) );
//Connect a signal handler that will be called when the contents of
//the clipboard change.
Gtk::Clipboard::get()->signal_owner_change().connect(sigc::mem_fun(*this,
&ExampleWindow::on_clipboard_owner_change) );
show_all_children();
update_paste_status();
}
ExampleWindow::~ExampleWindow()
{
}
void ExampleWindow::on_button_copy()
{
//Build a string representation of the stuff to be copied:
//Ideally you would use XML, with an XML parser here:
Glib::ustring strData;
strData += m_ButtonA1.get_active() ? "1" : "0";
strData += m_ButtonA2.get_active() ? "1" : "0";
strData += m_ButtonB1.get_active() ? "1" : "0";
strData += m_ButtonB2.get_active() ? "1" : "0";
Glib::RefPtr<Gtk::Clipboard> refClipboard = Gtk::Clipboard::get();
//Targets:
std::vector<Gtk::TargetEntry> targets;
targets.push_back( Gtk::TargetEntry(example_target_custom) );
targets.push_back( Gtk::TargetEntry(example_target_text) );
refClipboard->set(targets,
sigc::mem_fun(*this, &ExampleWindow::on_clipboard_get),
sigc::mem_fun(*this, &ExampleWindow::on_clipboard_clear) );
//Store the copied data until it is pasted:
//(Must be done after the call to refClipboard->set(), because that call
//may trigger a call to on_clipboard_clear.)
m_ClipboardStore = strData;
update_paste_status();
}
void ExampleWindow::on_button_paste()
{
//Tell the clipboard to call our method when it is ready:
Glib::RefPtr<Gtk::Clipboard> refClipboard = Gtk::Clipboard::get();
refClipboard->request_contents(example_target_custom,
sigc::mem_fun(*this, &ExampleWindow::on_clipboard_received) );
update_paste_status();
}
void ExampleWindow::on_clipboard_owner_change(GdkEventOwnerChange*)
{
update_paste_status();
}
void ExampleWindow::on_clipboard_get(Gtk::SelectionData& selection_data,
guint /* info */)
{
// info corresponds to the optional info parameter in Gtk::TargetEntry's
// constructor. We don't use that, so we use selection_data's target instead.
const std::string target = selection_data.get_target();
if(target == example_target_custom)
{
// This set() override uses an 8-bit text format for the data.
selection_data.set(example_target_custom, m_ClipboardStore);
}
else if(target == example_target_text)
{
//Build some arbitrary text representation of the data,
//so that people see something when they paste into a text editor:
Glib::ustring text_representation;
text_representation += m_ButtonA1.get_active() ? "A1, " : "";
text_representation += m_ButtonA2.get_active() ? "A2, " : "";
text_representation += m_ButtonB1.get_active() ? "B1, " : "";
text_representation += m_ButtonB2.get_active() ? "B2, " : "";
selection_data.set_text(text_representation);
}
else
{
g_warning("ExampleWindow::on_clipboard_get(): "
"Unexpected clipboard target format.");
}
}
void ExampleWindow::on_clipboard_clear()
{
//This isn't really necessary. I guess it might save memory.
m_ClipboardStore.clear();
}
void ExampleWindow::on_clipboard_received(
const Gtk::SelectionData& selection_data)
{
const std::string target = selection_data.get_target();
//It should always be this, because that's what we asked for when calling
//request_contents().
if(target == example_target_custom)
{
Glib::ustring clipboard_data = selection_data.get_data_as_string();
//See comment in on_button_copy() about this silly clipboard format.
if(clipboard_data.size() >= 4)
{
m_ButtonA1.set_active( clipboard_data[0] == '1' );
m_ButtonA2.set_active( clipboard_data[1] == '1' );
m_ButtonB1.set_active( clipboard_data[2] == '1' );
m_ButtonB2.set_active( clipboard_data[3] == '1' );
}
}
}
void ExampleWindow::update_paste_status()
{
//Disable the paste button if there is nothing to paste.
Glib::RefPtr<Gtk::Clipboard> refClipboard = Gtk::Clipboard::get();
//Discover what targets are available:
refClipboard->request_targets(sigc::mem_fun(*this,
&ExampleWindow::on_clipboard_received_targets) );
}
void ExampleWindow::on_clipboard_received_targets(
const std::vector<Glib::ustring>& targets)
{
const bool bPasteIsPossible =
std::find(targets.begin(), targets.end(),
example_target_custom) != targets.end();
// Enable/Disable the Paste button appropriately:
m_Button_Paste.set_sensitive(bPasteIsPossible);
}
File: main.cc (For use with gtkmm 3, not gtkmm 2)
#include "examplewindow.h"
#include <gtkmm/application.h>
int main(int argc, char *argv[])
{
//APPLICATION_NON_UNIQUE because it shall be possible to run several
//instances of this application simultaneously.
Glib::RefPtr<Gtk::Application> app = Gtk::Application::create(
argc, argv, "org.gtkmm.example", Gio::APPLICATION_NON_UNIQUE);
ExampleWindow window;
//Shows the window and returns when it is closed.
return app->run(window);
}