How to change Gtk::Image after object creation when PixBuf is given

Question

I am attempting to change Gtk::Image-derived object by giving it pixbuf, but i cannot figure out how to approach that.

The simple setup can be mimicked as:

#include <gtkmm.h>
#include <iostream>

class MyImage : public Gtk::Image
{
public:
    void setPixBuf(Glib::RefPtr<Gdk::Pixbuf> pixbuf);
};

void MyImage::setPixBuf(Glib::RefPtr<Gdk::Pixbuf> pixbuf)
{
    // How can i override the existing pixbuf here?
}

void freeImagePixelData(const guint8* data)
{
    delete[] data;
}
Glib::RefPtr<Gdk::Pixbuf> generateTestImage()
{
    guint8 *data = new guint8[40*40*4];
    for(int i=0; i<40*40*4; )
    {
        data[i++] = (guint8)255;    // R
        data[i++] = (guint8)255;    // G
        data[i++] = (guint8)0;      // B
        data[i++] = (guint8)255;    // A
    }

    Glib::RefPtr<Gdk::Pixbuf> pixbuf = Gdk::Pixbuf::create_from_data(
        data, Gdk::Colorspace::COLORSPACE_RGB, true, 8, 40, 40,  40*4, sigc::ptr_fun(&freeImagePixelData));
    return pixbuf;
}

int main(int argc, char** argv)
{
    Glib::RefPtr<Gtk::Application> app = Gtk::Application::create(argc, argv, "com.almost-university.gtkmm.image.pixbuf");

    Gtk::Window window;

    MyImage im1;
    im1.setPixBuf(generateTestImage());
    window.add(im1);

    window.show_all_children();

    app->run(window);

    return 0;
}

(Please note that this is an oversimplified version of what i am trying to figure out, i do know that i should be using Gtk::manage and not add things directly to the window without another container, this is just a mock-up).

I know that if i were to generate the image using a constructor as so:

    Gtk::Image im2(generateTestImage());
    window.add(im2);

then i would in fact be getting a yellow square.

Somehow i refuse to believe that one can only use pixbuf at the time of object creation. There must be a way to set the image data somehow, and i just cannot find the needed function.

Answer 1

To set Pixbuf in an Gtk::Image you can use Gtk::Image::set(const Glib::RefPtr< Gdk::Pixbuf >& pixbuf) method:

void MyImage::setPixBuf(Glib::RefPtr<Gdk::Pixbuf> pixbuf)
{
    set(pixbuf);
}