Class WaylandGLContext

Calling this function begins a drawing operation using context on the surface that context was created from. The actual requirements and guarantees for the drawing operation vary for different implementations of drawing, so a [classGdk.CairoContext] and a [classGdk.GLContext] need to be treated differently.

A call to this function is a requirement for drawing and must be followed by a call to [methodGdk.DrawContext.end_frame], which will complete the drawing operation and ensure the contents become visible on screen.

Note that the region passed to this function is the minimum region that needs to be drawn and depending on implementation, windowing system and hardware in use, it might be necessary to draw a larger region. Drawing implementation must use [methodGdk.DrawContext.get_frame_region] to query the region that must be drawn.

When using GTK, the widget system automatically places calls to gdk_draw_context_begin_frame() and gdk_draw_context_end_frame() via the use of [classGsk.Renderer]s, so application code does not need to call these functions explicitly.

Whenever the source_property is changed the target_property is updated using the same value. For instance:

  g_object_bind_property (action, "active", widget, "sensitive", 0);

Will result in the "sensitive" property of the widget #GObject instance to be updated with the same value of the "active" property of the action #GObject instance.

If flags contains %G_BINDING_BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well.

The binding will automatically be removed when either the source or the target instances are finalized. To remove the binding without affecting the source and the target you can just call g_object_unref() on the returned #GBinding instance.

Removing the binding by calling g_object_unref() on it must only be done if the binding, source and target are only used from a single thread and it is clear that both source and target outlive the binding. Especially it is not safe to rely on this if the binding, source or target can be finalized from different threads. Keep another reference to the binding and use g_binding_unbind() instead to be on the safe side.

A #GObject can have multiple bindings.

This function is the language bindings friendly version of g_object_bind_property_full(), using #GClosures instead of function pointers.

This makes the drawing available on screen. See [methodGdk.DrawContext.begin_frame] for more details about drawing.

When using a [classGdk.GLContext], this function may call glFlush() implicitly before returning; it is not recommended to call glFlush() explicitly before calling this function.

This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.

If the renderer has not been realized yet, 0 is returned.

See [methodGdk.GLContext.set_debug_enabled].

See [methodGdk.GLContext.set_forward_compatible].

After a call to [methodGdk.DrawContext.begin_frame] this function will return a union of the region passed to that function and the area of the surface that the context determined needs to be repainted.

If context is not in between calls to [methodGdk.DrawContext.begin_frame] and [methodGdk.DrawContext.end_frame], %NULL will be returned.

The value can be:

• an empty #GValue initialized by %G_VALUE_INIT, which will be automatically initialized with the expected type of the property (since GLib 2.60)
• a #GValue initialized with the expected type of the property
• a #GValue initialized with a type to which the expected type of the property can be transformed

In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling g_value_unset().

Note that g_object_get_property() is really intended for language bindings, g_object_get() is much more convenient for C programming.

See [methodGdk.GLContext.set_required_version].

As many contexts can share data now and no single shared context exists anymore, this function has been deprecated and now always returns %NULL.

The context must be realized prior to calling this function.

This is the case between calls to [methodGdk.DrawContext.begin_frame] and [methodGdk.DrawContext.end_frame]. In this situation, drawing commands may be effecting the contents of the context's surface.

The GdkGLContext must be realized before calling this function.

When realizing a GL context, GDK will try to use the OpenGL 3.2 core profile; this profile removes all the OpenGL API that was deprecated prior to the 3.2 version of the specification. If the realization is successful, this function will return %FALSE.

If the underlying OpenGL implementation does not support core profiles, GDK will fall back to a pre-3.2 compatibility profile, and this function will return %TRUE.

You can use the value returned by this function to decide which kind of OpenGL API to use, or whether to do extension discovery, or what kind of shader programs to load.

When they can, the texture IDs from other can be used in self. This is particularly useful when passing GdkGLTexture objects between different contexts.

Contexts created for the same display with the same properties will always be compatible, even if they are created for different surfaces. For other contexts it depends on the GL backend.

Both contexts must be realized for this check to succeed. If either one is not, this function will return %FALSE.

When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

This function omits the property name lookup, hence it is faster than g_object_notify().

One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with g_object_class_install_property() inside a static array, e.g.:

  enum
  {
    PROP_0,
    PROP_FOO,
    PROP_LAST
  };

  static GParamSpec *properties[PROP_LAST];

  static void
  my_object_class_init (MyObjectClass *klass)
  {
    properties[PROP_FOO] = g_param_spec_int ("foo", "Foo", "The foo",
                                             0, 100,
                                             50,
                                             G_PARAM_READWRITE);
    g_object_class_install_property (gobject_class,
                                     PROP_FOO,
                                     properties[PROP_FOO]);
  }

and then notify a change on the "foo" property with:

  g_object_notify_by_pspec (self, properties[PROP_FOO]);

It is safe to call this function on a realized GdkGLContext.

Since GLib 2.56, if GLIB_VERSION_MAX_ALLOWED is 2.56 or greater, the type of object will be propagated to the return type (using the GCC typeof() extension), so any casting the caller needs to do on the return type must be explicit.

In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.

Since GLib 2.56, the type of object will be propagated to the return type under the same conditions as for g_object_ref().

This function should only be called from object system implementations.

If you set it on a realized context, the property will not have any effect. It is only relevant during gdk_gl_context_realize().

By default, all APIs are allowed.

If the object already had an association with that name, the old association will be destroyed.

Internally, the key is converted to a #GQuark using g_quark_from_string(). This means a copy of key is kept permanently (even after object has been finalized) — so it is recommended to only use a small, bounded set of values for key in your program, to avoid the #GQuark storage growing unbounded.

This is useful during development, but has additional overhead.

The GdkGLContext must not be realized or made current prior to calling this function.

Forward-compatible contexts must not support OpenGL functionality that has been marked as deprecated in the requested version; non-forward compatible contexts, on the other hand, must support both deprecated and non deprecated functionality.

The GdkGLContext must not be realized or made current prior to calling this function.

Setting major and minor to zero will use the default values.

The GdkGLContext must not be realized or made current prior to calling this function.

Not all platforms support OpenGL ES.

The context must not have been realized.

By default, GDK will attempt to automatically detect whether the underlying GL implementation is OpenGL or OpenGL ES once the context is realized.

You should check the return value of [methodGdk.GLContext.get_use_es] after calling [methodGdk.GLContext.realize] to decide whether to use the OpenGL or OpenGL ES API, extensions, or shaders.

void
object_add_to_user_list (GObject     *object,
                         const gchar *new_string)
{
  // the quark, naming the object data
  GQuark quark_string_list = g_quark_from_static_string ("my-string-list");
  // retrieve the old string list
  GList *list = g_object_steal_qdata (object, quark_string_list);

  // prepend new string
  list = g_list_prepend (list, g_strdup (new_string));
  // this changed 'list', so we need to set it again
  g_object_set_qdata_full (object, quark_string_list, list, free_string_list);
}
static void
free_string_list (gpointer data)
{
  GList *node, *list = data;

  for (node = list; node; node = node->next)
    g_free (node->data);
  g_list_free (list);
}

Using g_object_get_qdata() in the above example, instead of g_object_steal_qdata() would have left the destroy function set, and thus the partial string list would have been freed upon g_object_set_qdata_full().

Duplicate notifications for each property are squashed so that at most one #GObject::notify signal is emitted for each property, in the reverse order in which they have been queued.

It is an error to call this function when the freeze count is zero.

If the pointer to the #GObject may be reused in future (for example, if it is an instance variable of another object), it is recommended to clear the pointer to %NULL rather than retain a dangling pointer to a potentially invalid #GObject instance. Use g_clear_object() for this.