Detect click on Gtk::Image? - events

Question

I've been trying to detect click on a Gtk::Image with gtkmm for over 2 hours, but I couldn't get it to work. It does compile and execute fine, but the event is never triggered.
Some stuff I tried, that compiles, does not crash, but doesn't work:
m_image = manage(new Gtk::Image(Gtk::Stock::APPLY, Gtk::ICON_SIZE_BUTTON));
m_image->add_events(Gdk::ALL_EVENTS_MASK);
m_hbox->pack_start(*m_image, Gtk::PACK_SHRINK);
m_image->signal_button_release_event()
.connect(sigc::hide(sigc::mem_fun(*this, &Todo::switchStatus)));
m_image->show();
or
#include <gtkmm/main.h>
#include <gtkmm/window.h>
#include <gtkmm/button.h>
#include <gtkmm/stock.h>
#include <gtkmm/image.h>
#include <iostream>
using namespace std;
class Win : public Gtk::Window
{
public:
Win();
bool link(GdkEventButton* e);
private:
Gtk::Image image;
};
Win::Win()
: image(Gtk::Stock::APPLY, Gtk::ICON_SIZE_BUTTON)
{
cerr << "created" << endl;
image.add_events(Gdk::BUTTON_PRESS_MASK | Gdk::BUTTON_RELEASE_MASK);
image.signal_button_release_event().connect(sigc::mem_fun(*this, &Win::link));
image.show();
add(image);
}
bool Win::link(GdkEventButton* e)
{
cerr << "kuh" << endl;
}
int main(int argc, char *argv[])
{
Gtk::Main app(argc, argv);
Gtk::Window window;
window.resize(300, 500);
Win win;
Gtk::Main::run(win);
return 0;
}

Answer 1

From http://developer.gnome.org/gtkmm/unstable/classGtk_1_1Image.html:
Gtk::Image is a "no window" widget (has no Gdk::Window of its own), so by default does not receive events. If you want to receive events on the image, such as button clicks, place the image inside a Gtk::EventBox, then connect to the event signals on the event box
So I guess try to put a signal on an eventbox after wrapping the image with the EventBox.

Answer 2

I like to put a button overtop of the image with an opacity of 0. Then you can use the click event from it instead.

Answer 3

This thread is quite old but still popular. I came across the same problem and I coded this code, maybe it can help someone save tim. My code detects the click ONLY if the pointer is hovering the image.
#include <gtk/gtk.h>
//compile with cc `pkg-config --cflags gtk+-3.0` text.c `pkg-config --libs gtk+-3.0` -o text
static void click_callback(GtkWidget *widget, GdkEventButton *event, gpointer );
static gboolean inRange(gint value, gint min, gint max);
static gboolean pointInRect(gint mouseX, gint mouseY, gint wx, gint wy, gint width, gint height);
GtkWidget *image;
GtkWidget *image2;
int main (int argc, char *argv[])
{
GtkWidget *event_box;
GtkWidget *window;
GtkWidget *box;
gtk_init(&argc, &argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
box = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0);
/* GTK_ALIGN_CENTER is necessary otherwise
* the callback triggers from the space on
* the top and the bottom of the image */
gtk_widget_set_valign(box, GTK_ALIGN_CENTER);
image = gtk_image_new_from_file("image1.png");
image2 = gtk_image_new_from_file("image2.png");
gtk_box_pack_start(GTK_BOX(box), image, TRUE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(box), image2, TRUE, FALSE, 0);
event_box = gtk_event_box_new ();
gtk_container_add (GTK_CONTAINER (event_box), box);
gtk_container_add (GTK_CONTAINER (window), event_box);
g_signal_connect(window, "destroy",
G_CALLBACK(gtk_main_quit), NULL);
g_signal_connect( event_box, "button_press_event", G_CALLBACK( click_callback ), image);
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_window_set_title(GTK_WINDOW(window), "Image click event");
gtk_widget_show_all(window);
gtk_main();
return 0;
}
static void click_callback(GtkWidget *widget, GdkEventButton *event, gpointer data)
{
GtkAllocation alloc;
GtkAllocation alloc2;
gtk_widget_get_allocation(image, &alloc);
gtk_widget_get_allocation(image2, &alloc2);
if (pointInRect(event->x, event->y, alloc.x, alloc.y, alloc.width, alloc.height))
g_print("You clicked from image\n");
if (pointInRect(event->x, event->y, alloc2.x, alloc2.y, alloc2.width, alloc2.height))
g_print("You clicked from image2\n");
}
static gboolean pointInRect(gint mouseX, gint mouseY, gint wx, gint wy, gint width, gint height)
{
return inRange(mouseX, wx, wx + width) &&
inRange(mouseY, wy, wy + height);
}
static gboolean inRange(gint value, gint min, gint max)
{
return (value >= min && value <= max);
}