Class

GtkGLArea

Description [src]

class Gtk.GLArea : Gtk.Widget {
  /* No available fields */
}

GtkGLArea is a widget that allows drawing with OpenGL.

An example GtkGLArea

GtkGLArea sets up its own GdkGLContext, 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:

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;
}

void setup_glarea (void)
{
  // 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);
}

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.

Hierarchy

hierarchy this GtkGLArea implements_0 GtkAccessible this--implements_0 implements_1 GtkBuildable this--implements_1 implements_2 GtkConstraintTarget this--implements_2 ancestor_0 GtkWidget ancestor_0--this ancestor_1 GInitiallyUnowned ancestor_1--ancestor_0 ancestor_2 GObject ancestor_2--ancestor_1

Ancestors

Constructors

gtk_gl_area_new

Creates a new GtkGLArea widget.

Instance methods

gtk_gl_area_attach_buffers

Binds buffers to the framebuffer.

gtk_gl_area_get_auto_render

Returns whether the area is in auto render mode or not.

gtk_gl_area_get_context

Retrieves the GdkGLContext used by area.

gtk_gl_area_get_error

Gets the current error set on the area.

gtk_gl_area_get_has_depth_buffer

Returns whether the area has a depth buffer.

gtk_gl_area_get_has_stencil_buffer

Returns whether the area has a stencil buffer.

gtk_gl_area_get_required_version

Retrieves the required version of OpenGL.

gtk_gl_area_get_use_es

Returns whether the GtkGLArea should use OpenGL ES.

gtk_gl_area_make_current

Ensures that the GdkGLContext used by area is associated with the GtkGLArea.

gtk_gl_area_queue_render

Marks the currently rendered data (if any) as invalid, and queues a redraw of the widget.

gtk_gl_area_set_auto_render

Sets whether the GtkGLArea is in auto render mode.

gtk_gl_area_set_error

Sets an error on the area which will be shown instead of the GL rendering.

gtk_gl_area_set_has_depth_buffer

Sets whether the GtkGLArea should use a depth buffer.

gtk_gl_area_set_has_stencil_buffer

Sets whether the GtkGLArea should use a stencil buffer.

gtk_gl_area_set_required_version

Sets the required version of OpenGL to be used when creating the context for the widget.

gtk_gl_area_set_use_es

Sets whether the area should create an OpenGL or an OpenGL ES context.

Methods inherited from GtkWidget (159)
gtk_widget_action_set_enabled

Enable or disable an action installed with gtk_widget_class_install_action().

gtk_widget_activate

For widgets that can be “activated” (buttons, menu items, etc.), this function activates them.

gtk_widget_activate_action

Looks up the action in the action groups associated with widget and its ancestors, and activates it.

gtk_widget_activate_action_variant

Looks up the action in the action groups associated with widget and its ancestors, and activates it.

gtk_widget_activate_default

Activates the default.activate action from widget.

gtk_widget_add_controller

Adds controller to widget so that it will receive events.

gtk_widget_add_css_class

Adds a style class to widget.

gtk_widget_add_mnemonic_label

Adds a widget to the list of mnemonic labels for this widget.

gtk_widget_add_tick_callback

Queues an animation frame update and adds a callback to be called before each frame.

gtk_widget_allocate

This function is only used by GtkWidget subclasses, to assign a size, position and (optionally) baseline to their child widgets.

gtk_widget_child_focus

Called by widgets as the user moves around the window using keyboard shortcuts.

gtk_widget_compute_bounds

Computes the bounds for widget in the coordinate space of target.

gtk_widget_compute_expand

Computes whether a container should give this widget extra space when possible.

gtk_widget_compute_point

Translates the given point in widgets coordinates to coordinates relative to target’s coordinate system.

gtk_widget_compute_transform

Computes a matrix suitable to describe a transformation from widgets coordinate system into targets coordinate system.

gtk_widget_contains

Tests if the point at (x, y) is contained in widget.

gtk_widget_create_pango_context

Creates a new PangoContext with the appropriate font map, font options, font description, and base direction for drawing text for this widget.

gtk_widget_create_pango_layout

Creates a new PangoLayout with the appropriate font map, font description, and base direction for drawing text for this widget.

gtk_drag_check_threshold

Checks to see if a drag movement has passed the GTK drag threshold.

gtk_widget_error_bell

Notifies the user about an input-related error on this widget.

gtk_widget_get_allocated_baseline

Returns the baseline that has currently been allocated to widget.

gtk_widget_get_allocated_height

Returns the height that has currently been allocated to widget.

gtk_widget_get_allocated_width

Returns the width that has currently been allocated to widget.

Methods inherited from GtkAccessible (10)
gtk_accessible_get_accessible_role

Retrieves the GtkAccessibleRole for the given GtkAccessible.

gtk_accessible_reset_property

Resets the accessible property to its default value.

gtk_accessible_reset_relation

Resets the accessible relation to its default value.

gtk_accessible_reset_state

Resets the accessible state to its default value.

gtk_accessible_update_property

Updates a list of accessible properties.

gtk_accessible_update_property_value

Updates an array of accessible properties.

gtk_accessible_update_relation

Updates a list of accessible relations.

gtk_accessible_update_relation_value

Updates an array of accessible relations.

gtk_accessible_update_state

Updates a list of accessible states. See the GtkAccessibleState documentation for the value types of accessible states.

gtk_accessible_update_state_value

Updates an array of accessible states.

Methods inherited from GtkBuildable (1)
gtk_buildable_get_buildable_id

Gets the ID of the buildable object.

Properties

Gtk.GLArea:auto-render

If set to TRUE the ::render signal will be emitted every time the widget draws.

Gtk.GLArea:context

The GdkGLContext used by the GtkGLArea widget.

Gtk.GLArea:has-depth-buffer

If set to TRUE the widget will allocate and enable a depth buffer for the target framebuffer.

Gtk.GLArea:has-stencil-buffer

If set to TRUE the widget will allocate and enable a stencil buffer for the target framebuffer.

Gtk.GLArea:use-es

If set to TRUE the widget will try to create a GdkGLContext using OpenGL ES instead of OpenGL.

Properties inherited from GtkWidget (34)
Gtk.Widget:can-focus

Whether the widget or any of its descendents can accept the input focus.

Gtk.Widget:can-target

Whether the widget can receive pointer events.

Gtk.Widget:css-classes

A list of css classes applied to this widget.

Gtk.Widget:css-name

The name of this widget in the CSS tree.

Gtk.Widget:cursor

The cursor used by widget.

Gtk.Widget:focus-on-click

Whether the widget should grab focus when it is clicked with the mouse.

Gtk.Widget:focusable

Whether this widget itself will accept the input focus.

Gtk.Widget:halign

How to distribute horizontal space if widget gets extra space.

Gtk.Widget:has-default

Whether the widget is the default widget.

Gtk.Widget:has-focus

Whether the widget has the input focus.

Gtk.Widget:has-tooltip

Enables or disables the emission of the ::query-tooltip signal on widget.

Gtk.Widget:height-request

Override for height request of the widget.

Gtk.Widget:hexpand

Whether to expand horizontally.

Gtk.Widget:hexpand-set

Whether to use the hexpand property.

Gtk.Widget:layout-manager

The GtkLayoutManager instance to use to compute the preferred size of the widget, and allocate its children.

Gtk.Widget:margin-bottom

Margin on bottom side of widget.

Gtk.Widget:margin-end

Margin on end of widget, horizontally.

Gtk.Widget:margin-start

Margin on start of widget, horizontally.

Gtk.Widget:margin-top

Margin on top side of widget.

Gtk.Widget:name

The name of the widget.

Gtk.Widget:opacity

The requested opacity of the widget.

Gtk.Widget:overflow

How content outside the widget’s content area is treated.

Gtk.Widget:parent

The parent widget of this widget.

Gtk.Widget:receives-default

Whether the widget will receive the default action when it is focused.

Gtk.Widget:root

The GtkRoot widget of the widget tree containing this widget.

Gtk.Widget:scale-factor

The scale factor of the widget.

Gtk.Widget:sensitive

Whether the widget responds to input.

Gtk.Widget:tooltip-markup

Sets the text of tooltip to be the given string, which is marked up with Pango markup.

Gtk.Widget:tooltip-text

Sets the text of tooltip to be the given string.

Gtk.Widget:valign

How to distribute vertical space if widget gets extra space.

Gtk.Widget:vexpand

Whether to expand vertically.

Gtk.Widget:vexpand-set

Whether to use the vexpand property.

Gtk.Widget:visible

Whether the widget is visible.

Gtk.Widget:width-request

Override for width request of the widget.

Properties inherited from GtkAccessible (1)
Gtk.Accessible:accessible-role

The accessible role of the given GtkAccessible implementation.

Signals

Gtk.GLArea::create-context

Emitted when the widget is being realized.

Gtk.GLArea::render

Emitted every time the contents of the GtkGLArea should be redrawn.

Gtk.GLArea::resize

Emitted once when the widget is realized, and then each time the widget is changed while realized.

Signals inherited from GtkWidget (13)
Gtk.Widget::destroy

Signals that all holders of a reference to the widget should release the reference that they hold.

Gtk.Widget::direction-changed

Emitted when the text direction of a widget changes.

Gtk.Widget::hide

Emitted when widget is hidden.

Gtk.Widget::keynav-failed

Emitted if keyboard navigation fails.

Gtk.Widget::map

Emitted when widget is going to be mapped.

Gtk.Widget::mnemonic-activate

Emitted when a widget is activated via a mnemonic.

Gtk.Widget::move-focus

Emitted when the focus is moved.

Gtk.Widget::query-tooltip

Emitted when the widgets tooltip is about to be shown.

Gtk.Widget::realize

Emitted when widget is associated with a GdkSurface.

Gtk.Widget::show

Emitted when widget is shown.

Gtk.Widget::state-flags-changed

Emitted when the widget state changes.

Gtk.Widget::unmap

Emitted when widget is going to be unmapped.

Gtk.Widget::unrealize

Emitted when the GdkSurface associated with widget is destroyed.

Class structure

struct GtkGLAreaClass {
  gboolean (* render) (
    GtkGLArea* area,
    GdkGLContext* context
  );
  void (* resize) (
    GtkGLArea* area,
    int width,
    int height
  );
  GdkGLContext* (* create_context) (
    GtkGLArea* area
  );
  
}
Class members
render
gboolean (* render) (
    GtkGLArea* area,
    GdkGLContext* context
  )
  No description available.
resize
void (* resize) (
    GtkGLArea* area,
    int width,
    int height
  )
  No description available.
create_context
GdkGLContext* (* create_context) (
    GtkGLArea* area
  )
  No description available.

Virtual methods

Gtk.GLAreaClass.create_context
No description available.
Gtk.GLAreaClass.render
No description available.
Gtk.GLAreaClass.resize
No description available.