Class
GtkGLArea
since: 3.16
Description [src]
class Gtk.GLArea : Gtk.Widget
implements Atk.ImplementorIface, Gtk.Buildable {
/* No available fields */
}GtkGLArea is a widget that allows drawing with OpenGL.
GtkGLArea sets up its own GdkGLContext for the window it creates, and
creates a custom GL framebuffer that the widget will do GL rendering onto.
It also ensures that this framebuffer is the default GL rendering target
when rendering.
In order to draw, you have to connect to the GtkGLArea::render signal,
or subclass GtkGLArea and override the GtkGLAreaClass.render() virtual function.
The GtkGLArea widget ensures that the GdkGLContext is associated with
the widget’s drawing area, and it is kept updated when the size and
position of the drawing area changes.
Drawing with GtkGLArea
The simplest way to draw using OpenGL commands in a GtkGLArea is to
create a widget instance and connect to the GtkGLArea::render signal:
// create a GtkGLArea instance
GtkWidget *gl_area = gtk_gl_area_new ();
// connect to the "render" signal
g_signal_connect (gl_area, "render", G_CALLBACK (render), NULL);
The render() function will be called when the GtkGLArea is ready
for you to draw its content:
static gboolean
render (GtkGLArea *area, GdkGLContext *context)
{
// inside this function it's safe to use GL; the given
// `GdkGLContext` has been made current to the drawable
// surface used by the `GtkGLArea` and the viewport has
// already been set to be the size of the allocation
// we can start by clearing the buffer
glClearColor (0, 0, 0, 0);
glClear (GL_COLOR_BUFFER_BIT);
// draw your object
draw_an_object ();
// we completed our drawing; the draw commands will be
// flushed at the end of the signal emission chain, and
// the buffers will be drawn on the window
return TRUE;
}
If you need to initialize OpenGL state, e.g. buffer objects or
shaders, you should use the GtkWidget::realize signal; you
can use the GtkWidget::unrealize signal to clean up. Since the
GdkGLContext creation and initialization may fail, you will
need to check for errors, using gtk_gl_area_get_error(). An example
of how to safely initialize the GL state is:
static void
on_realize (GtkGLarea *area)
{
// We need to make the context current if we want to
// call GL API
gtk_gl_area_make_current (area);
// If there were errors during the initialization or
// when trying to make the context current, this
// function will return a `GError` for you to catch
if (gtk_gl_area_get_error (area) != NULL)
return;
// You can also use `gtk_gl_area_set_error()` in order
// to show eventual initialization errors on the
// GtkGLArea widget itself
GError *internal_error = NULL;
init_buffer_objects (&error);
if (error != NULL)
{
gtk_gl_area_set_error (area, error);
g_error_free (error);
return;
}
init_shaders (&error);
if (error != NULL)
{
gtk_gl_area_set_error (area, error);
g_error_free (error);
return;
}
}
If you need to change the options for creating the GdkGLContext
you should use the GtkGLArea::create-context signal.
Available since: 3.16
Instance methods
gtk_gl_area_attach_buffers
Ensures that the area framebuffer object is made the current draw
and read target, and that all the required buffers for the area
are created and bound to the frambuffer.
since: 3.16
gtk_gl_area_get_required_version
Retrieves the required version of OpenGL set using gtk_gl_area_set_required_version().
since: 3.16
gtk_gl_area_make_current
Ensures that the GdkGLContext used by area is associated with
the GtkGLArea.
since: 3.16
gtk_gl_area_queue_render
Marks the currently rendered data (if any) as invalid, and queues
a redraw of the widget, ensuring that the GtkGLArea::render signal
is emitted during the draw.
since: 3.16
gtk_gl_area_set_auto_render
If auto_render is TRUE the GtkGLArea::render signal will be
emitted every time the widget draws. This is the default and is
useful if drawing the widget is faster.
since: 3.16
gtk_gl_area_set_error
Sets an error on the area which will be shown instead of the
GL rendering. This is useful in the GtkGLArea::create-context
signal if GL context creation fails.
since: 3.16
gtk_gl_area_set_has_alpha
If has_alpha is TRUE the buffer allocated by the widget will have
an alpha channel component, and when rendering to the window the
result will be composited over whatever is below the widget.
since: 3.16
gtk_gl_area_set_has_depth_buffer
If has_depth_buffer is TRUE the widget will allocate and
enable a depth buffer for the target framebuffer. Otherwise
there will be none.
since: 3.16
gtk_gl_area_set_has_stencil_buffer
If has_stencil_buffer is TRUE the widget will allocate and
enable a stencil buffer for the target framebuffer. Otherwise
there will be none.
since: 3.16
gtk_gl_area_set_required_version
Sets the required version of OpenGL to be used when creating the context for the widget.
since: 3.16
gtk_gl_area_set_use_es
Sets whether the area should create an OpenGL or an OpenGL ES context.
since: 3.22
Methods inherited from GtkBuildable (10)
gtk_buildable_add_child
Adds a child to buildable. type is an optional string
describing how the child should be added.
since: 2.12
gtk_buildable_construct_child
Constructs a child of buildable with the name name.
since: 2.12
gtk_buildable_custom_finished
This is similar to gtk_buildable_parser_finished() but is
called once for each custom tag handled by the buildable.
since: 2.12
gtk_buildable_custom_tag_end
This is called at the end of each custom element handled by the buildable.
since: 2.12
gtk_buildable_custom_tag_start
This is called for each unknown element under <child>.
since: 2.12
gtk_buildable_get_internal_child
Get the internal child called childname of the buildable object.
since: 2.12
gtk_buildable_get_name
Gets the name of the buildable object.
since: 2.12
gtk_buildable_parser_finished
Called when the builder finishes the parsing of a
[GtkBuilder UI definition][BUILDER-UI].
Note that this will be called once for each time
gtk_builder_add_from_file() or gtk_builder_add_from_string()
is called on a builder.
since: 2.12
gtk_buildable_set_buildable_property
Sets the property name name to value on the buildable object.
since: 2.12
gtk_buildable_set_name
Sets the name of the buildable object.
since: 2.12
Properties
Gtk.GLArea:auto-render
If set to TRUE the GtkGLArea::render signal will be emitted every time
the widget draws. This is the default and is useful if drawing the widget
is faster.
since: 3.16
Gtk.GLArea:has-alpha
If set to TRUE the buffer allocated by the widget will have an alpha channel
component, and when rendering to the window the result will be composited over
whatever is below the widget.
since: 3.16
Gtk.GLArea:has-depth-buffer
If set to TRUE the widget will allocate and enable a depth buffer for the
target framebuffer.
since: 3.16
Gtk.GLArea:has-stencil-buffer
If set to TRUE the widget will allocate and enable a stencil buffer for the
target framebuffer.
since: 3.16
Gtk.GLArea:use-es
If set to TRUE the widget will try to create a GdkGLContext using
OpenGL ES instead of OpenGL.
since: 3.22
Properties inherited from GtkWidget (39)
Gtk.Widget:app-paintable
Gtk.Widget:can-default
Gtk.Widget:can-focus
Gtk.Widget:composite-child
Gtk.Widget:double-buffered
Whether the widget is double buffered.
deprecated: 3.14 since: 2.18
Gtk.Widget:events
Gtk.Widget:expand
Whether to expand in both directions. Setting this sets both GtkWidget:hexpand and GtkWidget:vexpand.
since: 3.0
Gtk.Widget:focus-on-click
Whether the widget should grab focus when it is clicked with the mouse.
since: 3.20
Gtk.Widget:halign
How to distribute horizontal space if widget gets extra space, see GtkAlign.
since: 3.0
Gtk.Widget:has-default
Gtk.Widget:has-focus
Gtk.Widget:has-tooltip
Enables or disables the emission of GtkWidget::query-tooltip on widget.
A value of TRUE indicates that widget can have a tooltip, in this case
the widget will be queried using GtkWidget::query-tooltip to determine
whether it will provide a tooltip or not.
since: 2.12
Gtk.Widget:height-request
Gtk.Widget:hexpand
Whether to expand horizontally. See gtk_widget_set_hexpand().
since: 3.0
Gtk.Widget:hexpand-set
Whether to use the GtkWidget:hexpand property. See gtk_widget_get_hexpand_set().
since: 3.0
Gtk.Widget:is-focus
Gtk.Widget:margin
Sets all four sides’ margin at once. If read, returns max margin on any side.
since: 3.0
Gtk.Widget:margin-bottom
Margin on bottom side of widget.
since: 3.0
Gtk.Widget:margin-end
Margin on end of widget, horizontally. This property supports left-to-right and right-to-left text directions.
since: 3.12
Gtk.Widget:margin-left
Margin on left side of widget.
deprecated: 3.12 since: 3.0
Gtk.Widget:margin-right
Margin on right side of widget.
deprecated: 3.12 since: 3.0
Gtk.Widget:margin-start
Margin on start of widget, horizontally. This property supports left-to-right and right-to-left text directions.
since: 3.12
Gtk.Widget:margin-top
Margin on top side of widget.
since: 3.0
Gtk.Widget:name
Gtk.Widget:no-show-all
Gtk.Widget:opacity
The requested opacity of the widget. See gtk_widget_set_opacity() for
more details about window opacity.
since: 3.8
Gtk.Widget:parent
Gtk.Widget:receives-default
Gtk.Widget:scale-factor
The scale factor of the widget. See gtk_widget_get_scale_factor() for
more details about widget scaling.
since: 3.10
Gtk.Widget:sensitive
Gtk.Widget:style
The style of the widget, which contains information about how it will look (colors, etc).
deprecated: Unknown
Gtk.Widget:tooltip-markup
Sets the text of tooltip to be the given string, which is marked up with the [Pango text markup language][PangoMarkupFormat]. Also see gtk_tooltip_set_markup().
since: 2.12
Gtk.Widget:tooltip-text
Sets the text of tooltip to be the given string.
since: 2.12
Gtk.Widget:valign
How to distribute vertical space if widget gets extra space, see GtkAlign.
since: 3.0
Gtk.Widget:vexpand
Whether to expand vertically. See gtk_widget_set_vexpand().
since: 3.0
Gtk.Widget:vexpand-set
Whether to use the GtkWidget:vexpand property. See gtk_widget_get_vexpand_set().
since: 3.0
Gtk.Widget:visible
Gtk.Widget:width-request
Gtk.Widget:window
The widget’s window if it is realized, NULL otherwise.
since: 2.14
Signals
Gtk.GLArea::create-context
The ::create-context signal is emitted when the widget is being realized, and allows you to override how the GL context is created. This is useful when you want to reuse an existing GL context, or if you want to try creating different kinds of GL options.
since: 3.16
Gtk.GLArea::render
The ::render signal is emitted every time the contents
of the GtkGLArea should be redrawn.
since: 3.16
Gtk.GLArea::resize
The ::resize signal is emitted once when the widget is realized, and then each time the widget is changed while realized. This is useful in order to keep GL state up to date with the widget size, like for instance camera properties which may depend on the width/height ratio.
since: 3.16
Signals inherited from GtkWidget (69)
GtkWidget::accel-closures-changed
GtkWidget::button-press-event
The ::button-press-event signal will be emitted when a button (typically from a mouse) is pressed.
GtkWidget::button-release-event
The ::button-release-event signal will be emitted when a button (typically from a mouse) is released.
GtkWidget::can-activate-accel
Determines whether an accelerator that activates the signal
identified by signal_id can currently be activated.
This signal is present to allow applications and derived
widgets to override the default GtkWidget handling
for determining whether an accelerator can be activated.
GtkWidget::child-notify
The ::child-notify signal is emitted for each [child property][child-properties] that has changed on an object. The signal’s detail holds the property name.
GtkWidget::composited-changed
The ::composited-changed signal is emitted when the composited
status of widgets screen changes.
See gdk_screen_is_composited().
deprecated: 3.22
GtkWidget::configure-event
The ::configure-event signal will be emitted when the size, position or
stacking of the widget‘s window has changed.
GtkWidget::damage-event
Emitted when a redirected window belonging to widget gets drawn into.
The region/area members of the event shows what area of the redirected
drawable was drawn into.
since: 2.14
GtkWidget::delete-event
The ::delete-event signal is emitted if a user requests that
a toplevel window is closed. The default handler for this signal
destroys the window. Connecting gtk_widget_hide_on_delete() to
this signal will cause the window to be hidden instead, so that
it can later be shown again without reconstructing it.
GtkWidget::destroy
Signals that all holders of a reference to the widget should release the reference that they hold. May result in finalization of the widget if all references are released.
GtkWidget::destroy-event
The ::destroy-event signal is emitted when a GdkWindow is destroyed.
You rarely get this signal, because most widgets disconnect themselves
from their window before they destroy it, so no widget owns the
window at destroy time.
GtkWidget::direction-changed
The ::direction-changed signal is emitted when the text direction of a widget changes.
GtkWidget::drag-begin
The ::drag-begin signal is emitted on the drag source when a drag is started. A typical reason to connect to this signal is to set up a custom drag icon with e.g. gtk_drag_source_set_icon_pixbuf().
GtkWidget::drag-data-delete
The ::drag-data-delete signal is emitted on the drag source when a drag
with the action GDK_ACTION_MOVE is successfully completed. The signal
handler is responsible for deleting the data that has been dropped. What
“delete” means depends on the context of the drag operation.
GtkWidget::drag-data-get
The ::drag-data-get signal is emitted on the drag source when the drop
site requests the data which is dragged. It is the responsibility of
the signal handler to fill data with the data in the format which
is indicated by info. See gtk_selection_data_set() and gtk_selection_data_set_text().
GtkWidget::drag-data-received
The ::drag-data-received signal is emitted on the drop site when the
dragged data has been received. If the data was received in order to
determine whether the drop will be accepted, the handler is expected
to call gdk_drag_status() and not finish the drag.
If the data was received in response to a GtkWidget::drag-drop signal
(and this is the last target to be received), the handler for this
signal is expected to process the received data and then call
gtk_drag_finish(), setting the success parameter depending on
whether the data was processed successfully.
GtkWidget::drag-drop
The ::drag-drop signal is emitted on the drop site when the user drops
the data onto the widget. The signal handler must determine whether
the cursor position is in a drop zone or not. If it is not in a drop
zone, it returns FALSE and no further processing is necessary.
Otherwise, the handler returns TRUE. In this case, the handler must
ensure that gtk_drag_finish() is called to let the source know that
the drop is done. The call to gtk_drag_finish() can be done either
directly or in a GtkWidget::drag-data-received handler which gets
triggered by calling gtk_drag_get_data() to receive the data for one
or more of the supported targets.
GtkWidget::drag-end
The ::drag-end signal is emitted on the drag source when a drag is
finished. A typical reason to connect to this signal is to undo
things done in GtkWidget::drag-begin.
GtkWidget::drag-failed
The ::drag-failed signal is emitted on the drag source when a drag has
failed. The signal handler may hook custom code to handle a failed DnD
operation based on the type of error, it returns TRUE is the failure has
been already handled (not showing the default “drag operation failed”
animation), otherwise it returns FALSE.
since: 2.12
GtkWidget::drag-leave
The ::drag-leave signal is emitted on the drop site when the cursor
leaves the widget. A typical reason to connect to this signal is to
undo things done in GtkWidget::drag-motion, e.g. undo highlighting
with gtk_drag_unhighlight().
GtkWidget::drag-motion
The ::drag-motion signal is emitted on the drop site when the user
moves the cursor over the widget during a drag. The signal handler
must determine whether the cursor position is in a drop zone or not.
If it is not in a drop zone, it returns FALSE and no further processing
is necessary. Otherwise, the handler returns TRUE. In this case, the
handler is responsible for providing the necessary information for
displaying feedback to the user, by calling gdk_drag_status().
GtkWidget::draw
This signal is emitted when a widget is supposed to render itself.
The widget‘s top left corner must be painted at the origin of
the passed in context and be sized to the values returned by
gtk_widget_get_allocated_width() and gtk_widget_get_allocated_height().
since: 3.0
GtkWidget::enter-notify-event
The ::enter-notify-event will be emitted when the pointer enters
the widget‘s window.
GtkWidget::event
The GTK+ main loop will emit three signals for each GDK event delivered
to a widget: one generic ::event signal, another, more specific,
signal that matches the type of event delivered (e.g.
GtkWidget::key-press-event) and finally a generic
GtkWidget::event-after signal.
GtkWidget::event-after
After the emission of the GtkWidget::event signal and (optionally)
the second more specific signal, ::event-after will be emitted
regardless of the previous two signals handlers return values.
GtkWidget::focus
GtkWidget::focus-in-event
The ::focus-in-event signal will be emitted when the keyboard focus
enters the widget‘s window.
GtkWidget::focus-out-event
The ::focus-out-event signal will be emitted when the keyboard focus
leaves the widget‘s window.
GtkWidget::grab-broken-event
Emitted when a pointer or keyboard grab on a window belonging
to widget gets broken.
since: 2.8
GtkWidget::grab-focus
GtkWidget::grab-notify
The ::grab-notify signal is emitted when a widget becomes shadowed by a GTK+ grab (not a pointer or keyboard grab) on another widget, or when it becomes unshadowed due to a grab being removed.
GtkWidget::hide
The ::hide signal is emitted when widget is hidden, for example with gtk_widget_hide().
GtkWidget::hierarchy-changed
The ::hierarchy-changed signal is emitted when the
anchored state of a widget changes. A widget is
“anchored” when its toplevel
ancestor is a GtkWindow. This signal is emitted when
a widget changes from un-anchored to anchored or vice-versa.
GtkWidget::key-press-event
The ::key-press-event signal is emitted when a key is pressed. The signal emission will reoccur at the key-repeat rate when the key is kept pressed.
GtkWidget::key-release-event
The ::key-release-event signal is emitted when a key is released.
GtkWidget::keynav-failed
Gets emitted if keyboard navigation fails.
See gtk_widget_keynav_failed() for details.
since: 2.12
GtkWidget::leave-notify-event
The ::leave-notify-event will be emitted when the pointer leaves
the widget‘s window.
GtkWidget::map
The ::map signal is emitted when widget is going to be mapped, that is
when the widget is visible (which is controlled with
gtk_widget_set_visible()) and all its parents up to the toplevel widget
are also visible. Once the map has occurred, GtkWidget::map-event will
be emitted.
GtkWidget::map-event
The ::map-event signal will be emitted when the widget‘s window is
mapped. A window is mapped when it becomes visible on the screen.
GtkWidget::mnemonic-activate
The default handler for this signal activates widget if group_cycling
is FALSE, or just makes widget grab focus if group_cycling is TRUE.
GtkWidget::motion-notify-event
The ::motion-notify-event signal is emitted when the pointer moves
over the widget’s GdkWindow.
GtkWidget::move-focus
GtkWidget::parent-set
The ::parent-set signal is emitted when a new parent has been set on a widget.
GtkWidget::popup-menu
This signal gets emitted whenever a widget should pop up a context
menu. This usually happens through the standard key binding mechanism;
by pressing a certain key while a widget is focused, the user can cause
the widget to pop up a menu. For example, the GtkEntry widget creates
a menu with clipboard commands. See the
[Popup Menu Migration Checklist][checklist-popup-menu]
for an example of how to use this signal.
GtkWidget::property-notify-event
The ::property-notify-event signal will be emitted when a property on
the widget‘s window has been changed or deleted.
GtkWidget::proximity-in-event
To receive this signal the GdkWindow associated to the widget needs
to enable the #GDK_PROXIMITY_IN_MASK mask.
GtkWidget::proximity-out-event
To receive this signal the GdkWindow associated to the widget needs
to enable the #GDK_PROXIMITY_OUT_MASK mask.
GtkWidget::query-tooltip
Emitted when GtkWidget:has-tooltip is TRUE and the hover timeout
has expired with the cursor hovering “above” widget; or emitted when widget got
focus in keyboard mode.
since: 2.12
GtkWidget::realize
The ::realize signal is emitted when widget is associated with a
GdkWindow, which means that gtk_widget_realize() has been called or the
widget has been mapped (that is, it is going to be drawn).
GtkWidget::screen-changed
The ::screen-changed signal gets emitted when the screen of a widget has changed.
GtkWidget::scroll-event
The ::scroll-event signal is emitted when a button in the 4 to 7 range is pressed. Wheel mice are usually configured to generate button press events for buttons 4 and 5 when the wheel is turned.
GtkWidget::selection-clear-event
The ::selection-clear-event signal will be emitted when the
the widget‘s window has lost ownership of a selection.
GtkWidget::selection-get
GtkWidget::selection-notify-event
GtkWidget::selection-received
GtkWidget::selection-request-event
The ::selection-request-event signal will be emitted when
another client requests ownership of the selection owned by
the widget‘s window.
GtkWidget::show
The ::show signal is emitted when widget is shown, for example with gtk_widget_show().
GtkWidget::show-help
GtkWidget::size-allocate
GtkWidget::state-changed
The ::state-changed signal is emitted when the widget state changes. See gtk_widget_get_state().
deprecated: 3.0
GtkWidget::state-flags-changed
The ::state-flags-changed signal is emitted when the widget state changes, see gtk_widget_get_state_flags().
since: 3.0
GtkWidget::style-set
The ::style-set signal is emitted when a new style has been set
on a widget. Note that style-modifying functions like
gtk_widget_modify_base() also cause this signal to be emitted.
deprecated: 3.0
GtkWidget::style-updated
The ::style-updated signal is a convenience signal that is emitted when the
GtkStyleContext::changed signal is emitted on the widget‘s associated
GtkStyleContext as returned by gtk_widget_get_style_context().
since: 3.0
GtkWidget::touch-event
GtkWidget::unmap
The ::unmap signal is emitted when widget is going to be unmapped, which
means that either it or any of its parents up to the toplevel widget have
been set as hidden.
GtkWidget::unmap-event
The ::unmap-event signal will be emitted when the widget‘s window is
unmapped. A window is unmapped when it becomes invisible on the screen.
GtkWidget::unrealize
The ::unrealize signal is emitted when the GdkWindow associated with
widget is destroyed, which means that gtk_widget_unrealize() has been
called or the widget has been unmapped (that is, it is going to be hidden).
GtkWidget::visibility-notify-event
The ::visibility-notify-event will be emitted when the widget‘s
window is obscured or unobscured.
deprecated: 3.12
GtkWidget::window-state-event
The ::window-state-event will be emitted when the state of the
toplevel window associated to the widget changes.
Signals inherited from GObject (1)
GObject::notify
The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.
Class structure
struct GtkGLAreaClass {
gboolean (* render) (
GtkGLArea* area,
GdkGLContext* context
);
void (* resize) (
GtkGLArea* area,
int width,
int height
);
GdkGLContext* (* create_context) (
GtkGLArea* area
);
}The GtkGLAreaClass structure contains only private data.
Class members
render: gboolean (* render) ( GtkGLArea* area, GdkGLContext* context )Class closure for the
GtkGLArea::rendersignal.resize: void (* resize) ( GtkGLArea* area, int width, int height )Class closeure for the
GtkGLArea::resizesignal.create_context: GdkGLContext* (* create_context) ( GtkGLArea* area )Class closure for the
GtkGLArea::create-contextsignal.