Hello,
is there some sample code to capture screen to memory (raw image). This codes should work on Gnome (Wayland) so cannot use any XWindow APIs. e.g. Firefox captures screen after asking user for permission.
earlier code :
auto y=g_dbus_connection_call_sync (connection,
“org.gnome.Shell.Screenshot”,
“/org/gnome/Shell/Screenshot”,
“org.gnome.Shell.Screenshot”,
“Screenshot”, …………
mimics screenshot and drops the content into a file….
You can use the XDG Desktop Portal API:
I did google that part:
auto y=g_dbus_connection_call_sync (connection,
"org.freedesktop.portal.Screenshot",
"/org/freedesktop/portal/Screenshot",
"org.freedesktop.portal.Screenshot",
"screenshot",
g_variant_new ("parent_window"), //no idea what to pass here
NULL,
G_DBUS_CALL_FLAGS_NONE,
-1,
NULL,
&error);
is there any sample code for me to refer to…
GIMP uses the portal for screenshots for example:
There must be a signal for me to connect to which gives me the raw data:
e.g:
g_signal_connect(G_OBJECT(p), “ScreenShotReady”, G_CALLBACK(MyCallback), NULL);
There is a Response signal that contains a uri with the URI to an image file in its results. There is no raw data.
Thanks, this worked for me…now I want raw data …like what firefox gets when we give it screen recording access….
There is no API to get raw screenshot data.
how does firefox do this
Are you asking about screencasts (as in video) or screenshots (as in one static image)?
screen cast I guess: https://screen-recorder.com/
Also I will place the code here in the forum for others to follow.
Thanks, I will check, in the mean time, the below code I am using for future reference (it works fine on my Ubuntu 25.04 system)
//sudo apt install libgtk-4-dev
//gcc $(pkg-config --cflags gtk4) Wayland_screenShot.cpp $(pkg-config --libs gtk4) -lstdc++
//https://gitlab.gnome.org/GNOME/gimp/-/blob/2865aa7f039ee585e3c80d28d5ac75d0f8fef4e4/plug-ins/screenshot/screenshot-freedesktop.c
#include <bits/stdc++.h>
using namespace std;
#include <gtk/gtk.h>
GtkApplication *app=nullptr;
GMainLoop *main_loop=nullptr;
bool quitflag=false;
static void
screenshot_freedesktop_dbus_signal (GDBusProxy *proxy,
gchar *sender_name,
gchar *signal_name,
GVariant *parameters,
void *image)
{
cout<<“inside screenshot_freedesktop_dbus_signal (1)”<<endl;
if (g_strcmp0 (signal_name, "Response") == 0)
{
//got the screen shot
cout<<"inside screenshot_freedesktop_dbus_signal (2)"<<endl;
GVariant *results;
guint32 response;
g_variant_get (parameters, "(u@a{sv})",
&response,
&results);
gchar *uri=nullptr;
if (g_variant_lookup (results, "uri", "s", &uri))
{
cout<<uri<<endl;
}
g_free (uri);
g_variant_unref (results);
}
g_main_loop_quit(main_loop);
//quitflag=true;
}
static void
activate (GtkApplication *app,
gpointer user_data)
{
GDBusConnection \*connection;
g_autoptr(GError) error = NULL;
connection = g_application_get_dbus_connection (g_application_get_default ());
GDBusProxy *proxy = g_dbus_proxy_new_for_bus_sync (G_BUS_TYPE_SESSION,
G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START,
NULL,
"org.freedesktop.portal.Desktop",
"/org/freedesktop/portal/desktop",
"org.freedesktop.portal.Screenshot",
NULL, NULL);
{
GVariant *retval1 = g_dbus_proxy_call_sync (proxy, "org.freedesktop.DBus.Peer.Ping",
NULL,
G_DBUS_CALL_FLAGS_NONE,
-1, NULL, &error);
g_variant_unref (retval1);
}
GVariantBuilder *options = g_variant_builder_new (G_VARIANT_TYPE ("a{sv}"));
g_variant_builder_add (options, "{sv}", "interactive", g_variant_new_boolean (TRUE));
GVariant *retval=g_dbus_proxy_call_sync (proxy, "Screenshot", //this will trigger the screen shot
g_variant_new ("(sa{sv})",
"",
options, NULL),
G_DBUS_CALL_FLAGS_NONE,
-1, NULL, &error);
if (retval)
{
//now to get the request
gchar *opath = NULL;
g_variant_get (retval, "(o)", &opath);
auto proxy2 = g_dbus_proxy_new_for_bus_sync (G_BUS_TYPE_SESSION,
G_DBUS_PROXY_FLAGS_NONE,
NULL,
"org.freedesktop.portal.Desktop",
opath,
"org.freedesktop.portal.Request",
NULL, NULL);
g_signal_connect (proxy2, "g-signal",
G_CALLBACK (screenshot_freedesktop_dbus_signal),
nullptr);
if(nullptr == main_loop)
main_loop = g_main_loop_new (g_main_context_default(), TRUE);
g_main_loop_run(main_loop);
//while(false==quitflag)
// g_main_context_iteration (g_main_context_default(), TRUE);
g_object_unref (proxy2);
g_free (opath);
}
g_variant_unref (retval);
g_variant_builder_unref(options);
g_object_unref (proxy);
g_object_unref (connection);
}
int
main (int argc,
char **argv)
{
int status;
app = gtk_application_new ("org.gnome.Screenshot", G_APPLICATION_DEFAULT_FLAGS);
g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
status = g_application_run (G_APPLICATION (app), argc, argv);
g_main_loop_unref(main_loop);
g_object_unref (app);
return status;
}
Looking at Disable a dbus (the screenshot one) - #8 by wjt
I hope the screen shot application is now disabled in the newer versions of gnome.
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