ClutterCairoTexture

ClutterCairoTexture — Texture with Cairo integration

Synopsis

struct              ClutterCairoTexture;
struct              ClutterCairoTextureClass;
ClutterActor *      clutter_cairo_texture_new           (guint width,
                                                         guint height);
void                clutter_cairo_texture_set_surface_size
                                                        (ClutterCairoTexture *self,
                                                         guint width,
                                                         guint height);
void                clutter_cairo_texture_get_surface_size
                                                        (ClutterCairoTexture *self,
                                                         guint *width,
                                                         guint *height);
void                clutter_cairo_texture_set_auto_resize
                                                        (ClutterCairoTexture *self,
                                                         gboolean value);
gboolean            clutter_cairo_texture_get_auto_resize
                                                        (ClutterCairoTexture *self);

cairo_t *           clutter_cairo_texture_create        (ClutterCairoTexture *self);
cairo_t *           clutter_cairo_texture_create_region (ClutterCairoTexture *self,
                                                         gint x_offset,
                                                         gint y_offset,
                                                         gint width,
                                                         gint height);

void                clutter_cairo_texture_invalidate_rectangle
                                                        (ClutterCairoTexture *self,
                                                         cairo_rectangle_int_t *rect);
void                clutter_cairo_texture_invalidate    (ClutterCairoTexture *self);
void                clutter_cairo_texture_clear         (ClutterCairoTexture *self);

Object Hierarchy

  GObject
   +----GInitiallyUnowned
         +----ClutterActor
               +----ClutterTexture
                     +----ClutterCairoTexture

Implemented Interfaces

ClutterCairoTexture implements ClutterContainer, ClutterScriptable, ClutterAnimatable and AtkImplementorIface.

Properties

  "auto-resize"              gboolean              : Read / Write
  "surface-height"           guint                 : Read / Write
  "surface-width"            guint                 : Read / Write

Signals

  "create-surface"                                 : No Recursion
  "draw"                                           : No Recursion

Description

ClutterCairoTexture is a ClutterTexture that displays the contents of a Cairo context. The ClutterCairoTexture actor will create a Cairo image surface which will then be uploaded to a GL texture when needed.

Note

Since ClutterCairoTexture uses a Cairo image surface internally all the drawing operations will be performed in software and not using hardware acceleration. This can lead to performance degradation if the contents of the texture change frequently.

In order to use a ClutterCairoTexture you should connect to the "draw" signal; the signal is emitted each time the ClutterCairoTexture has been told to invalidate its contents, by using clutter_cairo_texture_invalidate_rectangle() or its sister function, clutter_cairo_texture_invalidate().

Each callback to the "draw" signal will receive a cairo_t context which can be used for drawing; the Cairo context is owned by the ClutterCairoTexture and should not be destroyed explicitly.

Example 24. A simple ClutterCairoTexture canvas

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#include <stdlib.h>
#include <math.h>
#include <cairo.h>
#include <clutter/clutter.h>

static gboolean
draw_clock (ClutterCairoTexture *canvas,
            cairo_t             *cr)
{
  guint width, height;
  GDateTime *now;
  float hours, minutes, seconds;

  /* get the current time and compute the angles */
  now = g_date_time_new_now_local ();
  seconds = g_date_time_get_second (now) * G_PI / 30;
  minutes = g_date_time_get_minute (now) * G_PI / 30;
  hours = g_date_time_get_hour (now) * G_PI / 6;

  /* clear the contents of the canvas, to avoid painting
   * over the previous frame
   */
  clutter_cairo_texture_clear (canvas);

  /* scale the modelview to the size of the surface */
  clutter_cairo_texture_get_surface_size (canvas, &width, &height);
  cairo_scale (cr, width, height);

  cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
  cairo_set_line_width (cr, 0.1);

  /* the black rail that holds the seconds indicator */
  clutter_cairo_set_source_color (cr, CLUTTER_COLOR_Black);
  cairo_translate (cr, 0.5, 0.5);
  cairo_arc (cr, 0, 0, 0.4, 0, G_PI * 2);
  cairo_stroke (cr);

  /* the seconds indicator */
  clutter_cairo_set_source_color (cr, CLUTTER_COLOR_White);
  cairo_move_to (cr, 0, 0);
  cairo_arc (cr, sinf (seconds) * 0.4, - cosf (seconds) * 0.4, 0.05, 0, G_PI * 2);
  cairo_fill (cr);

  /* the minutes hand */
  clutter_cairo_set_source_color (cr, CLUTTER_COLOR_DarkChameleon);
  cairo_move_to (cr, 0, 0);
  cairo_line_to (cr, sinf (minutes) * 0.4, -cosf (minutes) * 0.4);
  cairo_stroke (cr);

  /* the hours hand */
  cairo_move_to (cr, 0, 0);
  cairo_line_to (cr, sinf (hours) * 0.2, -cosf (hours) * 0.2);
  cairo_stroke (cr);

  g_date_time_unref (now);

  /* we're done drawing */
  return TRUE;
}

static gboolean
invalidate_clock (gpointer data_)
{
  /* invalidate the contents of the canvas */
  clutter_cairo_texture_invalidate (data_);

  /* keep the timeout source */
  return TRUE;
}

G_MODULE_EXPORT int
test_cairo_clock_main (int argc, char *argv[])
{
  ClutterActor *stage, *canvas;

  /* initialize Clutter */
  if (clutter_init (&argc, &argv) != CLUTTER_INIT_SUCCESS)
    return EXIT_FAILURE;

  /* create a resizable stage */
  stage = clutter_stage_new ();
  clutter_stage_set_title (CLUTTER_STAGE (stage), "2D Clock");
  clutter_stage_set_user_resizable (CLUTTER_STAGE (stage), TRUE);
  clutter_actor_set_background_color (stage, CLUTTER_COLOR_LightSkyBlue);
  clutter_actor_set_size (stage, 300, 300);
  clutter_actor_show (stage);

  /* our 2D canvas, courtesy of Cairo */
  canvas = clutter_cairo_texture_new (300, 300);
  clutter_container_add_actor (CLUTTER_CONTAINER (stage), canvas);

  /* bind the size of the canvas to that of the stage */
  clutter_actor_add_constraint (canvas, clutter_bind_constraint_new (stage, CLUTTER_BIND_SIZE, 0));

  /* make sure to match allocation to canvas size */
  clutter_cairo_texture_set_auto_resize (CLUTTER_CAIRO_TEXTURE (canvas), TRUE);

  /* quit on destroy */
  g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);

  /* connect our drawing code */
  g_signal_connect (canvas, "draw", G_CALLBACK (draw_clock), NULL);

  /* invalidate the canvas, so that we can draw before the main loop starts */
  clutter_cairo_texture_invalidate (CLUTTER_CAIRO_TEXTURE (canvas));

  /* set up a timer that invalidates the canvas every second */
  clutter_threads_add_timeout (1000, invalidate_clock, canvas);

  clutter_main ();

  return EXIT_SUCCESS;
}

G_MODULE_EXPORT const char *
test_cairo_clock_describe (void)
{
  return "Simple 2D canvas using a Cairo texture actor";
}


ClutterCairoTexture is available since Clutter 1.0.

ClutterCairoTexture is deprecated since Clutter 1.12.

Details

struct ClutterCairoTexture

struct ClutterCairoTexture;

Warning

ClutterCairoTexture has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

The ClutterCairoTexture struct contains only private data.

Since 1.0

struct ClutterCairoTextureClass

struct ClutterCairoTextureClass {
  cairo_surface_t *(* create_surface) (ClutterCairoTexture *texture,
                                       guint                width,
                                       guint                height);

  gboolean         (* draw)           (ClutterCairoTexture *texture,
                                       cairo_t             *cr);
};

Warning

ClutterCairoTextureClass has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

The ClutterCairoTextureClass struct contains only private data.

create_surface ()

 class handler for the "create-surface" signal

draw ()

 class handler for the "draw" signal

Since 1.0

clutter_cairo_texture_new ()

ClutterActor *      clutter_cairo_texture_new           (guint width,
                                                         guint height);

Warning

clutter_cairo_texture_new has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Creates a new ClutterCairoTexture actor, with a surface of width by height pixels.

width :

 the width of the surface

height :

 the height of the surface

Returns :

 the newly created ClutterCairoTexture actor

Since 1.0

clutter_cairo_texture_set_surface_size ()

void                clutter_cairo_texture_set_surface_size
                                                        (ClutterCairoTexture *self,
                                                         guint width,
                                                         guint height);

Warning

clutter_cairo_texture_set_surface_size has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Resizes the Cairo surface used by self to width and height.

This function will not invalidate the contents of the Cairo texture: you will have to explicitly call either clutter_cairo_texture_invalidate_rectangle() or clutter_cairo_texture_invalidate().

self :

 a ClutterCairoTexture

width :

 the new width of the surface

height :

 the new height of the surface

Since 1.0

clutter_cairo_texture_get_surface_size ()

void                clutter_cairo_texture_get_surface_size
                                                        (ClutterCairoTexture *self,
                                                         guint *width,
                                                         guint *height);

Warning

clutter_cairo_texture_get_surface_size has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Retrieves the surface width and height for self.

self :

 a ClutterCairoTexture

width :

 return location for the surface width, or NULL. [out]

height :

 return location for the surface height, or NULL. [out]

Since 1.0

clutter_cairo_texture_set_auto_resize ()

void                clutter_cairo_texture_set_auto_resize
                                                        (ClutterCairoTexture *self,
                                                         gboolean value);

Warning

clutter_cairo_texture_set_auto_resize has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Sets whether the ClutterCairoTexture should ensure that the backing Cairo surface used matches the allocation assigned to the actor. If the allocation changes, the contents of the ClutterCairoTexture will also be invalidated automatically.

self :

 a ClutterCairoTexture

value :

 TRUE if the ClutterCairoTexture should bind the surface size to the allocation

Since 1.8

clutter_cairo_texture_get_auto_resize ()

gboolean            clutter_cairo_texture_get_auto_resize
                                                        (ClutterCairoTexture *self);

Warning

clutter_cairo_texture_get_auto_resize has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Retrieves the value set using clutter_cairo_texture_set_auto_resize().

self :

 a ClutterCairoTexture

Returns :

 TRUE if the ClutterCairoTexture should track the allocation, and FALSE otherwise

Since 1.8

clutter_cairo_texture_create ()

cairo_t *           clutter_cairo_texture_create        (ClutterCairoTexture *self);

Warning

clutter_cairo_texture_create has been deprecated since version 1.8 and should not be used in newly-written code. Use the "draw" signal and the clutter_cairo_texture_invalidate() function to obtain a Cairo context for 2D drawing.

Creates a new Cairo context for the cairo texture. It is similar to using clutter_cairo_texture_create_region() with x_offset and y_offset of 0, width equal to the cairo texture surface width and height equal to the cairo texture surface height.

Warning

Do not call this function within the paint virtual function or from a callback to the "paint" signal.

self :

 a ClutterCairoTexture

Returns :

 a newly created Cairo context. Use cairo_destroy() to upload the contents of the context when done drawing

Since 1.0

clutter_cairo_texture_create_region ()

cairo_t *           clutter_cairo_texture_create_region (ClutterCairoTexture *self,
                                                         gint x_offset,
                                                         gint y_offset,
                                                         gint width,
                                                         gint height);

Warning

clutter_cairo_texture_create_region has been deprecated since version 1.8 and should not be used in newly-written code. Use the "draw" signal and clutter_cairo_texture_invalidate_rectangle() to obtain a clipped Cairo context for 2D drawing.

Creates a new Cairo context that will updat the region defined by x_offset, y_offset, width and height.

Warning

Do not call this function within the paint virtual function or from a callback to the "paint" signal.

self :

 a ClutterCairoTexture

x_offset :

 offset of the region on the X axis

y_offset :

 offset of the region on the Y axis

width :

 width of the region, or -1 for the full surface width

height :

 height of the region, or -1 for the full surface height

Returns :

 a newly created Cairo context. Use cairo_destroy() to upload the contents of the context when done drawing

Since 1.0

clutter_cairo_texture_invalidate_rectangle ()

void                clutter_cairo_texture_invalidate_rectangle
                                                        (ClutterCairoTexture *self,
                                                         cairo_rectangle_int_t *rect);

Warning

clutter_cairo_texture_invalidate_rectangle has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Invalidates a rectangular region of a ClutterCairoTexture.

The invalidation will cause the "draw" signal to be emitted.

See also: clutter_cairo_texture_invalidate()

self :

 a ClutterCairoTexture

rect :

 a rectangle with the area to invalida, or NULL to perform an unbounded invalidation. [allow-none]

Since 1.8

clutter_cairo_texture_invalidate ()

void                clutter_cairo_texture_invalidate    (ClutterCairoTexture *self);

Warning

clutter_cairo_texture_invalidate has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Invalidates the whole surface of a ClutterCairoTexture.

This function will cause the "draw" signal to be emitted.

See also: clutter_cairo_texture_invalidate_rectangle()

self :

 a ClutterCairoTexture

Since 1.8

clutter_cairo_texture_clear ()

void                clutter_cairo_texture_clear         (ClutterCairoTexture *self);

Warning

clutter_cairo_texture_clear has been deprecated since version 1.12 and should not be used in newly-written code. Use ClutterCanvas instead

Clears self's internal drawing surface, so that the next upload will replace the previous contents of the ClutterCairoTexture rather than adding to it.

Calling this function from within a "draw" signal handler will clear the invalidated area.

self :

 a ClutterCairoTexture

Since 1.0

Property Details

The "auto-resize" property

  "auto-resize"              gboolean              : Read / Write

Warning

ClutterCairoTexture:auto-resize is deprecated and should not be used in newly-written code. 1.12

Controls whether the ClutterCairoTexture should automatically resize the Cairo surface whenever the actor's allocation changes. If :auto-resize is set to TRUE the surface contents will also be invalidated automatically.

Default value: FALSE

Since 1.8

The "surface-height" property

  "surface-height"           guint                 : Read / Write

Warning

ClutterCairoTexture:surface-height is deprecated and should not be used in newly-written code. 1.12

The height of the Cairo surface used by the ClutterCairoTexture actor, in pixels.

Default value: 0

Since 1.0

The "surface-width" property

  "surface-width"            guint                 : Read / Write

Warning

ClutterCairoTexture:surface-width is deprecated and should not be used in newly-written code. 1.12

The width of the Cairo surface used by the ClutterCairoTexture actor, in pixels.

Default value: 0

Since 1.0

Signal Details

The "create-surface" signal

CairoSurface*       user_function                      (ClutterCairoTexture *texture,
                                                        guint                width,
                                                        guint                height,
                                                        gpointer             user_data)      : No Recursion

Warning

ClutterCairoTexture::create-surface is deprecated and should not be used in newly-written code. 1.12

The ::create-surface signal is emitted when a ClutterCairoTexture news its surface (re)created, which happens either when the Cairo context is created with clutter_cairo_texture_create() or clutter_cairo_texture_create_region(), or when the surface is resized through clutter_cairo_texture_set_surface_size().

The first signal handler that returns a non-NULL, valid surface will stop any further signal emission, and the returned surface will be the one used.

texture :

 the ClutterCairoTexture that emitted the signal

width :

 the width of the surface to create

height :

 the height of the surface to create

user_data :

 user data set when the signal handler was connected.

Returns :

 the newly created cairo_surface_t for the texture

Since 1.6

The "draw" signal

gboolean            user_function                      (ClutterCairoTexture *texture,
                                                        CairoContext        *cr,
                                                        gpointer             user_data)      : No Recursion

Warning

ClutterCairoTexture::draw is deprecated and should not be used in newly-written code. 1.12

The ::draw signal is emitted each time a ClutterCairoTexture has been invalidated.

The passed Cairo context passed will be clipped to the invalidated area.

It is safe to connect multiple callbacks to this signals; the state of the Cairo context passed to each callback is automatically saved and restored, so it's not necessary to call cairo_save() and cairo_restore().

texture :

 the ClutterCairoTexture that emitted the signal

cr :

 the Cairo context to use to draw

user_data :

 user data set when the signal handler was connected.

Returns :

 TRUE if the signal emission should stop, and FALSE to continue

Since 1.8

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