Den 2014-09-02 01:23, Phil Wolff skrev:
Can anybody tell me why this code returns a properly sized Pixbuf with
no image data?
When Gtk::OffscreenWindow::get_pixbuf() is called in Test::Test, the
OffscreenWindow has not yet been drawn. Try my modified version of your
code. When it's started, the window is empty. If you press a mouse
button in the window, Test::on_button_press_event() is called, and the
label's text is shown.
Kjell
#include <gtkmm.h>
#include <iostream>
class Test : public Gtk::Window
{
public:
Test ();
private:
// Override virtual function
virtual bool on_button_press_event(GdkEventButton* event);
Gtk::OffscreenWindow m_pw;
Gtk::Image* m_pi;
};
Test::Test ()
{
set_size_request ( 160, 90 );
set_position ( Gtk::WIN_POS_CENTER );
try {
// Put something offscreen
Gtk::Label* pl = new Gtk::Label ( "Test OffscreenWindow" );
m_pw.add ( *pl );
m_pw.show_all ();
// Retrieve it
Glib::RefPtr<Gdk::Pixbuf > refPixbuf = m_pw.get_pixbuf ();
// Show pixbuf dimensions
set_title ( Glib::ustring::format ( refPixbuf->get_width (), " x ",
refPixbuf->get_height () ) );
// Show pixbuf contents onscreen
m_pi = new Gtk::Image ( refPixbuf );
add ( *m_pi );
//refPixbuf->save ( "pixbuf.png", "png" );
//system ( "eog pixbuf.png" );
show_all_children ();
}
catch ( const Glib::FileError& ex ) {
std::cerr << "File error: " << ex.what () << std::endl;
}
catch ( const Gdk::PixbufError& ex ) {
std::cerr << "Pixbuf error: " << ex.what () << std::endl;
}
}
bool Test::on_button_press_event(GdkEventButton*)
{
Glib::RefPtr<Gdk::Pixbuf> refPixbuf = m_pw.get_pixbuf();
m_pi->set(refPixbuf);
return false;
}
int main ( int argc, char *argv[] )
{
Glib::RefPtr<Gtk::Application> refApp = Gtk::Application::create ( argc,
argv, "org.gtkmm.example" );
Test window;
return refApp->run ( window );
}
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