## ClutterStage

ClutterStage — Top level visual element to which actors are placed.

## Synopsis

                        ClutterStage;
                        ClutterStageClass;
    #define             CLUTTER_STAGE_WIDTH                 ()
    #define             CLUTTER_STAGE_HEIGHT                ()
    ClutterActor *      clutter_stage_get_default           (void);
    ClutterActor *      clutter_stage_new                   (void);
    gboolean            clutter_stage_is_default            (ClutterStage *stage);

    void                clutter_stage_set_color             (ClutterStage *stage,
                                                             const ClutterColor *color);
    void                clutter_stage_get_color             (ClutterStage *stage,
                                                             ClutterColor *color);
    void                clutter_stage_fullscreen            (ClutterStage *stage);
    void                clutter_stage_unfullscreen          (ClutterStage *stage);
    void                clutter_stage_show_cursor           (ClutterStage *stage);
    void                clutter_stage_hide_cursor           (ClutterStage *stage);
    ClutterActor *      clutter_stage_get_actor_at_pos      (ClutterStage *stage,
                                                             gint x,
                                                             gint y);
    void                clutter_stage_ensure_current        (ClutterStage *stage);
    void                clutter_stage_queue_redraw          (ClutterStage *stage);
    gboolean            clutter_stage_event                 (ClutterStage *stage,
                                                             ClutterEvent *event);
    void                clutter_stage_set_key_focus         (ClutterStage *stage,
                                                             ClutterActor *actor);
    ClutterActor *      clutter_stage_get_key_focus         (ClutterStage *stage);
    gdouble             clutter_stage_get_resolution        (ClutterStage *stage);
    ClutterFixed        clutter_stage_get_resolutionx       (ClutterStage *stage);
    guchar *            clutter_stage_read_pixels           (ClutterStage *stage,
                                                             gint x,
                                                             gint y,
                                                             gint width,
                                                             gint height);

                        ClutterPerspective;
    void                clutter_stage_set_perspective       (ClutterStage *stage,
                                                             gfloat fovy,
                                                             gfloat aspect,
                                                             gfloat z_near,
                                                             gfloat z_far);
    void                clutter_stage_set_perspectivex      (ClutterStage *stage,
                                                             ClutterPerspective *perspective);
    void                clutter_stage_get_perspective       (ClutterStage *stage,
                                                             gfloat *fovy,
                                                             gfloat *aspect,
                                                             gfloat *z_near,
                                                             gfloat *z_far);
    void                clutter_stage_get_perspectivex      (ClutterStage *stage,
                                                             ClutterPerspective *perspective);

    void                clutter_stage_set_title             (ClutterStage *stage,
                                                             const gchar *title);
    const gchar *       clutter_stage_get_title             (ClutterStage *stage);
    void                clutter_stage_set_user_resizable    (ClutterStage *stage,
                                                             gboolean resizable);
    gboolean            clutter_stage_get_user_resizable    (ClutterStage *stage);

                        ClutterFog;
    void                clutter_stage_set_use_fog           (ClutterStage *stage,
                                                             gboolean fog);
    gboolean            clutter_stage_get_use_fog           (ClutterStage *stage);
    void                clutter_stage_set_fog               (ClutterStage *stage,
                                                             gdouble density,
                                                             gdouble z_near,
                                                             gdouble z_far);
    void                clutter_stage_get_fog               (ClutterStage *stage,
                                                             gdouble *density,
                                                             gdouble *z_near,
                                                             gdouble *z_far);
    void                clutter_stage_set_fogx              (ClutterStage *stage,
                                                             ClutterFog *fog);
    void                clutter_stage_get_fogx              (ClutterStage *stage,
                                                             ClutterFog *fog);

## Object Hierarchy

      GObject
       +----GInitiallyUnowned
             +----ClutterActor
                   +----ClutterGroup
                         +----ClutterStage

## Implemented Interfaces

ClutterStage implements ClutterContainer.

## Properties

      "color"                    ClutterColor*         : Read / Write
      "cursor-visible"           gboolean              : Read / Write / Construct
      "fullscreen"               gboolean              : Read / Write / Construct
      "offscreen"                gboolean              : Read / Write / Construct
      "perspective"              ClutterPerspective*   : Read / Write
      "title"                    gchar*                : Read / Write
      "use-fog"                  gboolean              : Read / Write
      "user-resizable"           gboolean              : Read / Write / Construct

## Signals

      "activate"                                       : Run Last
      "deactivate"                                     : Run Last
      "fullscreen"                                     : Run First
      "unfullscreen"                                   : Run Last

## Description

ClutterStage is a top level 'window' on which child actors are placed and manipulated.

Clutter creates a default stage upon initialization, which can be retrieved using `clutter_stage_get_default()`. Clutter always provides the default stage, unless the backend is unable to create one. The stage returned by `clutter_stage_get_default()` is guaranteed to always be the same.

Backends might provide support for multiple stages. The support for this feature can be checked at run-time using the `clutter_feature_available()` function and the `CLUTTER_FEATURE_STAGE_MULTIPLE` flag. If the backend used supports multiple stages, new ClutterStage instances can be created using `clutter_stage_new()`. These stages must be managed by the developer using `clutter_actor_destroy()`, which will take care of destroying all the actors contained inside them.

ClutterStage is a proxy actor, wrapping the backend-specific implementation of the windowing system. It is possible to subclass ClutterStage, as long as every overridden virtual function chains up to the parent class corresponding function.

## Details

### ClutterStage

    typedef struct _ClutterStage ClutterStage;

### ClutterStageClass

    typedef struct {
      /* signals */
      void (* fullscreen)   (ClutterStage *stage);
      void (* unfullscreen) (ClutterStage *stage);
      void (* activate)     (ClutterStage *stage);
      void (* deactivate)   (ClutterStage *stage);
    } ClutterStageClass;

### CLUTTER_STAGE_WIDTH()

    #define             CLUTTER_STAGE_WIDTH()

Macro that evaluates to the current stage width

Since 0.2

### CLUTTER_STAGE_HEIGHT()

    #define             CLUTTER_STAGE_HEIGHT()

Macro that evaluates to the current stage height

Since 0.2

### clutter_stage_get_default ()

    ClutterActor *      clutter_stage_get_default           (void);

Returns the main stage. The default ClutterStage is a singleton, so the stage will be created the first time this function is called (typically, inside `clutter_init()`); all the subsequent calls to `clutter_stage_get_default()` will return the same instance.

Clutter guarantess the existence of the default stage.

Returns : | the main ClutterStage. You should never destroy or unref the returned actor.

### clutter_stage_new ()

    ClutterActor *      clutter_stage_new                   (void);

Creates a new, non-default stage. A non-default stage is a new top-level actor which can be used as another container. It works exactly like the default stage, but while `clutter_stage_get_default()` will always return the same instance, you will have to keep a pointer to any ClutterStage returned by `clutter_stage_create()`.

The ability to support multiple stages depends on the current backend. Use `clutter_feature_available()` and `CLUTTER_FEATURE_STAGE_MULTIPLE` to check at runtime whether a backend supports multiple stages.

Returns : | a new stage, or `NULL` if the default backend does not support multiple stages. Use `clutter_actor_destroy()` to programmatically close the returned stage.

Since 0.8

### clutter_stage_is_default ()

    gboolean            clutter_stage_is_default            (ClutterStage *stage);

Checks if `stage` is the default stage, or an instance created using `clutter_stage_new()` but internally using the same implementation.

`stage` : | a ClutterStage
Returns : | `TRUE` if the passed stage is the default one

Since 0.8

### clutter_stage_set_color ()

    void                clutter_stage_set_color             (ClutterStage *stage,
                                                             const ClutterColor *color);

Set the stage color.

`stage` : | A ClutterStage
`color` : | A ClutterColor

### clutter_stage_get_color ()

    void                clutter_stage_get_color             (ClutterStage *stage,
                                                             ClutterColor *color);

Retrieves the stage color.

`stage` : | A ClutterStage
`color` : | return location for a ClutterColor

### clutter_stage_fullscreen ()

    void                clutter_stage_fullscreen            (ClutterStage *stage);

Asks to place the stage window in the fullscreen state. Note that you shouldn't assume the window is definitely full screen afterward, because other entities (e.g. the user or window manager) could unfullscreen it again, and not all window managers honor requests to fullscreen windows.

`stage` : | a ClutterStage

### clutter_stage_unfullscreen ()

    void                clutter_stage_unfullscreen          (ClutterStage *stage);

Asks to toggle off the fullscreen state for the stage window. Note that you shouldn't assume the window is definitely not full screen afterward, because other entities (e.g. the user or window manager) could fullscreen it again, and not all window managers honor requests to unfullscreen windows.

`stage` : | a ClutterStage

### clutter_stage_show_cursor ()

    void                clutter_stage_show_cursor           (ClutterStage *stage);

Shows the cursor on the stage window

`stage` : | a ClutterStage

### clutter_stage_hide_cursor ()

    void                clutter_stage_hide_cursor           (ClutterStage *stage);

Makes the cursor invisible on the stage window

`stage` : | a ClutterStage

Since 0.4

### clutter_stage_get_actor_at_pos ()

    ClutterActor *      clutter_stage_get_actor_at_pos      (ClutterStage *stage,
                                                             gint x,
                                                             gint y);

Checks the scene at the coordinates `x` and `y` and returns a pointer to the ClutterActor at those coordinates.

`stage` : | a ClutterStage
`x` : | X coordinate to check
`y` : | Y coordinate to check
Returns : | the actor at the specified coordinates, if any

### clutter_stage_ensure_current ()

    void                clutter_stage_ensure_current        (ClutterStage *stage);

This function essentially makes sure the right GL context is current for the passed stage. It is not intended to be used by applications.

`stage` : | the ClutterStage

Since 0.8

### clutter_stage_queue_redraw ()

    void                clutter_stage_queue_redraw          (ClutterStage *stage);

Queues a redraw for the passed stage.

### Note

Applications should call `clutter_actor_queue_redraw()` and not this function.

`stage` : | the ClutterStage

Since 0.8

### clutter_stage_event ()

    gboolean            clutter_stage_event                 (ClutterStage *stage,
                                                             ClutterEvent *event);

This function is used to emit an event on the main stage.

You should rarely need to use this function, except for synthetised events.

`stage` : | a ClutterStage
`event` : | a ClutterEvent
Returns : | the return value from the signal emission

Since 0.4

### clutter_stage_set_key_focus ()

    void                clutter_stage_set_key_focus         (ClutterStage *stage,
                                                             ClutterActor *actor);

Sets the key focus on `actor`. An actor with key focus will receive all the key events. If `actor` is `NULL`, the stage will receive focus.

`stage` : | the ClutterStage
`actor` : | the actor to set key focus to, or `NULL`

Since 0.6

### clutter_stage_get_key_focus ()

    ClutterActor *      clutter_stage_get_key_focus         (ClutterStage *stage);

Retrieves the actor that is currently under key focus.

`stage` : | the ClutterStage
Returns : | the actor with key focus, or the stage

Since 0.6

### clutter_stage_get_resolution ()

    gdouble             clutter_stage_get_resolution        (ClutterStage *stage);

Retrieves the resolution (in DPI) of the stage from the default backend.

`stage` : | the ClutterStage
Returns : | the resolution of the stage

Since 0.6

### clutter_stage_get_resolutionx ()

    ClutterFixed        clutter_stage_get_resolutionx       (ClutterStage *stage);

Fixed point version of `clutter_stage_get_resolution()`.

`stage` : | the ClutterStage
Returns : | the resolution of the stage

Since 0.6

### clutter_stage_read_pixels ()

    guchar *            clutter_stage_read_pixels           (ClutterStage *stage,
                                                             gint x,
                                                             gint y,
                                                             gint width,
                                                             gint height);

Makes a screenshot of the stage in RGBA 8bit data, returns a linear buffer with `width` * 4 as rowstride.

The alpha data contained in the returned buffer is driver-dependent, and not guaranteed to hold any sensible value.

`stage` : | A ClutterStage
`x` : | x coordinate of the first pixel that is read from stage
`y` : | y coordinate of the first pixel that is read from stage
`width` : | Width dimention of pixels to be read, or -1 for the entire stage width
`height` : | Height dimention of pixels to be read, or -1 for the entire stage height
Returns : | a pointer to newly allocated memory with the buffer or `NULL` if the read failed. Use `g_free()` on the returned data to release the resources it has allocated.

### ClutterPerspective

    typedef struct {
      ClutterFixed fovy;
      ClutterFixed aspect;
      ClutterFixed z_near;
      ClutterFixed z_far;
    } ClutterPerspective;

Stage perspective definition. ClutterPerspective is only used by the fixed point version of `clutter_stage_set_perspective()`.

ClutterFixed `fovy`; | the field of view angle, in degrees, in the y direction
ClutterFixed `aspect`; | the aspect ratio that determines the field of view in the x direction. The aspect ratio is the ratio of x (width) to y (height)
ClutterFixed `z_near`; | the distance from the viewer to the near clipping plane (always positive)
ClutterFixed `z_far`; | the distance from the viewer to the far clipping plane (always positive)

Since 0.4

### clutter_stage_set_perspective ()

    void                clutter_stage_set_perspective       (ClutterStage *stage,
                                                             gfloat fovy,
                                                             gfloat aspect,
                                                             gfloat z_near,
                                                             gfloat z_far);

Sets the stage perspective.

`stage` : | A ClutterStage
`fovy` : | the field of view angle, in degrees, in the y direction
`aspect` : | the aspect ratio that determines the field of view in the x direction. The aspect ratio is the ratio of x (width) to y (height)
`z_near` : | the distance from the viewer to the near clipping plane (always positive)
`z_far` : | the distance from the viewer to the far clipping plane (always positive)

Since 0.4

### clutter_stage_set_perspectivex ()

    void                clutter_stage_set_perspectivex      (ClutterStage *stage,
                                                             ClutterPerspective *perspective);

Set the stage perspective. This is the fixed point version of `clutter_stage_set_perspective()`.

`stage` : | A ClutterStage
`perspective` : | A ClutterPerspective

### clutter_stage_get_perspective ()

    void                clutter_stage_get_perspective       (ClutterStage *stage,
                                                             gfloat *fovy,
                                                             gfloat *aspect,
                                                             gfloat *z_near,
                                                             gfloat *z_far);

Retrieves the stage perspective.

`stage` : | A ClutterStage
`fovy` : | return location for the field of view, in degrees, or `NULL`
`aspect` : | return location for the aspect ratio, or `NULL`
`z_near` : | return location for the distance of the viewer from the near clipping plane, or `NULL`
`z_far` : | return location for the distance of the viewer from the far clipping plane, or `NULL`

Since 0.4

### clutter_stage_get_perspectivex ()

    void                clutter_stage_get_perspectivex      (ClutterStage *stage,
                                                             ClutterPerspective *perspective);

Retrieves the stage perspective. This is the fixed point version of `clutter_stage_get_perspective()`.

`stage` : | A ClutterStage
`perspective` : | return location for a ClutterPerspective

### clutter_stage_set_title ()

    void                clutter_stage_set_title             (ClutterStage *stage,
                                                             const gchar *title);

Sets the stage title.

Since 0.4

`stage` : | A ClutterStage
`title` : | A utf8 string for the stage windows title.

### clutter_stage_get_title ()

    const gchar *       clutter_stage_get_title             (ClutterStage *stage);

Gets the stage title.

`stage` : | A ClutterStage
Returns : | pointer to the title string for the stage. The returned string is owned by the actor and should not be modified or freed.

Since 0.4

### clutter_stage_set_user_resizable ()

    void                clutter_stage_set_user_resizable    (ClutterStage *stage,
                                                             gboolean resizable);

Sets if the stage is resizable by user interaction (e.g. via window manager controls)

`stage` : | a ClutterStage
`resizable` : | whether the stage should be user resizable.

Since 0.4

### clutter_stage_get_user_resizable ()

    gboolean            clutter_stage_get_user_resizable    (ClutterStage *stage);

Retrieves the value set with `clutter_stage_set_user_resizable()`.

`stage` : | a ClutterStage
Returns : | `TRUE` if the stage is resizable by the user.

Since 0.4

### ClutterFog

    typedef struct {
      ClutterFixed density;
      ClutterFixed z_near;
      ClutterFixed z_far;
    } ClutterFog;

Fog settings used to create the depth cueing effect. ClutterFog is useful only when using the fixed point API.

ClutterFixed `density`; | density of the fog
ClutterFixed `z_near`; | starting distance from the viewer to the near clipping plane (always positive)
ClutterFixed `z_far`; | final distance from the viewer to the far clipping plane (always positive)

Since 0.6

### clutter_stage_set_use_fog ()

    void                clutter_stage_set_use_fog           (ClutterStage *stage,
                                                             gboolean fog);

Sets whether the depth cueing effect on the stage should be enabled or not.

Depth cueing is a 3D effect that makes actors farther away from the viewing point less opaque, by fading them with the stage color.

The parameters of the GL fog used can be changed using the `clutter_stage_set_fog()` function.

`stage` : | the ClutterStage
`fog` : | `TRUE` for enabling the depth cueing effect

Since 0.6

### clutter_stage_get_use_fog ()

    gboolean            clutter_stage_get_use_fog           (ClutterStage *stage);

Gets whether the depth cueing effect is enabled on `stage`.

`stage` : | the ClutterStage
Returns : | `TRUE` if the the depth cueing effect is enabled

Since 0.6

### clutter_stage_set_fog ()

    void                clutter_stage_set_fog               (ClutterStage *stage,
                                                             gdouble density,
                                                             gdouble z_near,
                                                             gdouble z_far);

Sets the GL fog settings used to create the depth cueing effect on the `stage`.

If the actors are all near the view point you will need a higher `density` and a smaller interval between `z_near` and `z_far`. On the other hand, if actors are placed far away from the view point you will need a lower `density` but a bigger interval between `z_near` and `z_far`.

`stage` : | the ClutterStage
`density` : | density of the intensity dampening
`z_near` : | starting point of the depth cueing
`z_far` : | ending point of the depth cueing

Since 0.6

### clutter_stage_get_fog ()

    void                clutter_stage_get_fog               (ClutterStage *stage,
                                                             gdouble *density,
                                                             gdouble *z_near,
                                                             gdouble *z_far);

Retrieves the settings used by the GL fog to create the depth cueing effect on the `stage`.

`stage` : | a ClutterStage
`density` : | return location for the intensity dampening
`z_near` : | return location for the starting point of the depth cueing
`z_far` : | return location for the ending point of the depth cueing

Since 0.6

### clutter_stage_set_fogx ()

    void                clutter_stage_set_fogx              (ClutterStage *stage,
                                                             ClutterFog *fog);

Sets the depth cueing settings for the `stage`. This is the fixed point version of `clutter_stage_set_fog()`.

`stage` : | the ClutterStage
`fog` : | a ClutterFog structure

Since 0.6

### clutter_stage_get_fogx ()

    void                clutter_stage_get_fogx              (ClutterStage *stage,
                                                             ClutterFog *fog);

Retrieves the current depth cueing settings from the stage. This is the fixed point version of `clutter_stage_get_fog()`.

`stage` : | the ClutterStage
`fog` : | return location for a ClutterFog structure

Since 0.6

## Property Details

### The `"color"` property

      "color"                    ClutterColor*         : Read / Write

The color of the main stage.

### The `"cursor-visible"` property

      "cursor-visible"           gboolean              : Read / Write / Construct

Whether the mouse pointer should be visible

Default value: TRUE

### The `"fullscreen"` property

      "fullscreen"               gboolean              : Read / Write / Construct

Whether the stage should be fullscreen or not.

Default value: FALSE

### The `"offscreen"` property

      "offscreen"                gboolean              : Read / Write / Construct

Whether the stage should be rendered in an offscreen buffer.

Default value: FALSE

### The `"perspective"` property

      "perspective"              ClutterPerspective*   : Read / Write

The parameters used for the perspective projection from 3D coordinates to 2D

Since 0.8.2

### The `"title"` property

      "title"                    gchar*                : Read / Write

The stage's title - usually displayed in stage windows title decorations.

Default value: NULL

Since 0.4

### The `"use-fog"` property

      "use-fog"                  gboolean              : Read / Write

Whether the stage should use a linear GL "fog" in creating the depth-cueing effect, to enhance the perception of depth by fading actors farther from the viewpoint.

Default value: FALSE

Since 0.6

### The `"user-resizable"` property

      "user-resizable"           gboolean              : Read / Write / Construct

Whether the stage is resizable via user interaction.

Default value: FALSE

Since 0.4

## Signal Details

### The `"activate"` signal

    void                user_function                      (ClutterStage *stage,
                                                            gpointer      user_data)      : Run Last

The ::activate signal is emitted when the stage receives key focus from the underlying window system.

`stage` : | the stage which was activated
`user_data` : | user data set when the signal handler was connected.

Since 0.6

### The `"deactivate"` signal

    void                user_function                      (ClutterStage *stage,
                                                            gpointer      user_data)      : Run Last

The ::activate signal is emitted when the stage loses key focus from the underlying window system.

`stage` : | the stage which was deactivated
`user_data` : | user data set when the signal handler was connected.

Since 0.6

### The `"fullscreen"` signal

    void                user_function                      (ClutterStage *stage,
                                                            gpointer      user_data)      : Run First

The ::fullscreen signal is emitted when the stage is made fullscreen.

`stage` : | the stage which was fullscreened
`user_data` : | user data set when the signal handler was connected.

Since 0.6

### The `"unfullscreen"` signal

    void                user_function                      (ClutterStage *stage,
                                                            gpointer      user_data)      : Run Last

The ::unfullscreen signal is emitted when the stage leaves a fullscreen state.

`stage` : | the stage which has left a fullscreen state.
`user_data` : | user data set when the signal handler was connected.

Since 0.6