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mutter/clutter/clutter-alpha.c
Emmanuele Bassi 82860b5d5a Use the right argument naming for alpha functions 
The name of the argument in the header must match the name in the
function implementation, for gtk-doc to work properly.
2007-07-04 12:29:44 +00:00

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/*
* Clutter.
*
* An OpenGL based 'interactive canvas' library.
*
* Authored By Matthew Allum <mallum@openedhand.com>
* Jorn Baayen <jorn@openedhand.com>
* Emmanuele Bassi <ebassi@openedhand.com>
* Tomas Frydrych <tf@openedhand.com>
*
* Copyright (C) 2006, 2007 OpenedHand
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* SECTION:clutter-alpha
* @short_description: A class for calculating an alpha value as a function
* of time.
*
* #ClutterAlpha is a class for calculating an integer value between
* 0 and %CLUTTER_ALPHA_MAX_ALPHA as a function of time. You should
* provide a #ClutterTimeline and bind it to the #ClutterAlpha object;
* you should also provide a function returning the alpha value depending
* on the position inside the timeline; this function will be executed
* each time a new frame in the #ClutterTimeline is reached. Since the
* alpha function is controlled by the timeline instance, you can pause
* or stop the #ClutterAlpha from calling the alpha function by controlling
* the #ClutterTimeline object.
*
* #ClutterAlpha is used to "drive" a #ClutterBehaviour instance.
*
* Since: 0.2
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <math.h>
#include "clutter-alpha.h"
#include "clutter-main.h"
#include "clutter-marshal.h"
#include "clutter-private.h"
#include "clutter-debug.h"
G_DEFINE_TYPE (ClutterAlpha, clutter_alpha, G_TYPE_OBJECT);
struct _ClutterAlphaPrivate
{
ClutterTimeline *timeline;
guint timeline_new_frame_id;
guint32 alpha;
ClutterAlphaFunc func;
gpointer data;
GDestroyNotify destroy;
};
enum
{
PROP_0,
PROP_TIMELINE,
PROP_ALPHA
};
static void
timeline_new_frame_cb (ClutterTimeline *timeline,
guint current_frame_num,
ClutterAlpha *alpha)
{
ClutterAlphaPrivate *priv = alpha->priv;
/* Update alpha value and notify */
if (priv->func)
{
g_object_ref (alpha);
priv->alpha = priv->func (alpha, priv->data);
g_object_notify (G_OBJECT (alpha), "alpha");
g_object_unref (alpha);
}
}
static void
clutter_alpha_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
ClutterAlpha *alpha;
ClutterAlphaPrivate *priv;
alpha = CLUTTER_ALPHA (object);
priv = alpha->priv;
switch (prop_id)
{
case PROP_TIMELINE:
clutter_alpha_set_timeline (alpha, g_value_get_object (value));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
clutter_alpha_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
ClutterAlpha *alpha;
ClutterAlphaPrivate *priv;
alpha = CLUTTER_ALPHA (object);
priv = alpha->priv;
switch (prop_id)
{
case PROP_TIMELINE:
g_value_set_object (value, priv->timeline);
break;
case PROP_ALPHA:
g_value_set_uint (value, priv->alpha);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
clutter_alpha_finalize (GObject *object)
{
ClutterAlphaPrivate *priv = CLUTTER_ALPHA (object)->priv;
if (priv->destroy)
{
priv->destroy (priv->data);
priv->destroy = NULL;
priv->data = NULL;
priv->func = NULL;
}
G_OBJECT_CLASS (clutter_alpha_parent_class)->finalize (object);
}
static void
clutter_alpha_dispose (GObject *object)
{
ClutterAlpha *self = CLUTTER_ALPHA(object);
clutter_alpha_set_timeline (self, NULL);
G_OBJECT_CLASS (clutter_alpha_parent_class)->dispose (object);
}
static void
clutter_alpha_class_init (ClutterAlphaClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
object_class->set_property = clutter_alpha_set_property;
object_class->get_property = clutter_alpha_get_property;
object_class->finalize = clutter_alpha_finalize;
object_class->dispose = clutter_alpha_dispose;
g_type_class_add_private (klass, sizeof (ClutterAlphaPrivate));
/**
* ClutterAlpha:timeline:
*
* A #ClutterTimeline instance used to drive the alpha function.
*
* Since: 0.2
*/
g_object_class_install_property (object_class,
PROP_TIMELINE,
g_param_spec_object ("timeline",
"Timeline",
"Timeline",
CLUTTER_TYPE_TIMELINE,
CLUTTER_PARAM_READWRITE));
/**
* ClutterAlpha:alpha:
*
* The alpha value as computed by the alpha function.
*
* Since: 0.2
*/
g_object_class_install_property (object_class,
PROP_ALPHA,
g_param_spec_uint ("alpha",
"Alpha value",
"Alpha value",
0,
CLUTTER_ALPHA_MAX_ALPHA,
0,
CLUTTER_PARAM_READABLE));
}
static void
clutter_alpha_init (ClutterAlpha *self)
{
self->priv = G_TYPE_INSTANCE_GET_PRIVATE (self,
CLUTTER_TYPE_ALPHA,
ClutterAlphaPrivate);
}
/**
* clutter_alpha_get_alpha:
* @alpha: A #ClutterAlpha
*
* Query the current alpha value.
*
* Return Value: The current alpha value for the alpha
*
* Since: 0.2
*/
guint32
clutter_alpha_get_alpha (ClutterAlpha *alpha)
{
g_return_val_if_fail (CLUTTER_IS_ALPHA (alpha), FALSE);
return alpha->priv->alpha;
}
/**
* clutter_alpha_set_func:
* @alpha: A #ClutterAlpha
* @func: A #ClutterAlphaAlphaFunc
* @data: user data to be passed to the alpha function, or %NULL
* @destroy: notify function used when disposing the alpha function
*
* Sets the #ClutterAlphaFunc function used to compute
* the alpha value at each frame of the #ClutterTimeline
* bound to @alpha.
*
* Since: 0.2
*/
void
clutter_alpha_set_func (ClutterAlpha *alpha,
ClutterAlphaFunc func,
gpointer data,
GDestroyNotify destroy)
{
ClutterAlphaPrivate *priv;
g_return_if_fail (CLUTTER_IS_ALPHA (alpha));
priv = alpha->priv;
if (priv->destroy)
{
priv->destroy (priv->data);
priv->func = NULL;
priv->data = NULL;
priv->destroy = NULL;
}
priv->func = func;
priv->data = data;
priv->destroy = destroy;
}
/**
* clutter_alpha_set_timeline:
* @alpha: A #ClutterAlpha
* @timeline: A #ClutterTimeline
*
* Binds @alpha to @timeline.
*
* Since: 0.2
*/
void
clutter_alpha_set_timeline (ClutterAlpha *alpha,
ClutterTimeline *timeline)
{
ClutterAlphaPrivate *priv;
g_return_if_fail (CLUTTER_IS_ALPHA (alpha));
g_return_if_fail (timeline == NULL || CLUTTER_IS_TIMELINE (timeline));
priv = alpha->priv;
if (priv->timeline)
{
g_signal_handlers_disconnect_by_func (priv->timeline,
timeline_new_frame_cb,
alpha);
g_object_unref (priv->timeline);
priv->timeline = NULL;
}
if (timeline)
{
priv->timeline = g_object_ref (timeline);
g_signal_connect (priv->timeline, "new-frame",
G_CALLBACK (timeline_new_frame_cb),
alpha);
}
}
/**
* clutter_alpha_get_timeline:
* @alpha: A #ClutterAlpha
*
* Gets the #ClutterTimeline bound to @alpha.
*
* Return value: a #ClutterTimeline instance
*
* Since: 0.2
*/
ClutterTimeline *
clutter_alpha_get_timeline (ClutterAlpha *alpha)
{
g_return_val_if_fail (CLUTTER_IS_ALPHA (alpha), NULL);
return alpha->priv->timeline;
}
/**
* clutter_alpha_new:
*
* Creates a new #ClutterAlpha instance. You must set a function
* to compute the alpha value using clutter_alpha_set_func() and
* bind a #ClutterTimeline object to the #ClutterAlpha instance
* using clutter_alpha_set_timeline().
*
* You should use the newly created #ClutterAlpha instance inside
* a #ClutterBehaviour object.
*
* Return value: the newly created empty #ClutterAlpha instance.
*
* Since: 0.2
*/
ClutterAlpha *
clutter_alpha_new (void)
{
return g_object_new (CLUTTER_TYPE_ALPHA, NULL);
}
/**
* clutter_alpha_new_full:
* @timeline: #ClutterTimeline timeline
* @func: #ClutterAlphaFunc alpha function
* @data: data to be passed to the alpha function
* @destroy: notify to be called when removing the alpha function
*
* Creates a new #ClutterAlpha instance and sets the timeline
* and alpha function.
*
* Return Value: the newly created #ClutterAlpha
*
* Since: 0.2
*/
ClutterAlpha *
clutter_alpha_new_full (ClutterTimeline *timeline,
ClutterAlphaFunc func,
gpointer data,
GDestroyNotify destroy)
{
ClutterAlpha *retval;
g_return_val_if_fail (CLUTTER_IS_TIMELINE (timeline), NULL);
g_return_val_if_fail (func != NULL, NULL);
retval = clutter_alpha_new ();
clutter_alpha_set_timeline (retval, timeline);
clutter_alpha_set_func (retval, func, data, destroy);
return retval;
}
/**
* clutter_ramp_inc_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a monotonic increasing ramp. You
* can use this function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.2
*/
guint32
clutter_ramp_inc_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline *timeline;
gint current_frame_num, n_frames;
timeline = clutter_alpha_get_timeline (alpha);
current_frame_num = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
return (current_frame_num * CLUTTER_ALPHA_MAX_ALPHA) / n_frames;
}
/**
* clutter_ramp_dec_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a monotonic decreasing ramp. You
* can use this function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.2
*/
guint32
clutter_ramp_dec_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline *timeline;
gint current_frame_num, n_frames;
timeline = clutter_alpha_get_timeline (alpha);
current_frame_num = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
return (n_frames - current_frame_num)
* CLUTTER_ALPHA_MAX_ALPHA
/ n_frames;
}
/**
* clutter_ramp_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a full ramp function (increase for
* half the time, decrease for the remaining half). You can use this
* function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.2
*/
guint32
clutter_ramp_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline *timeline;
gint current_frame_num, n_frames;
timeline = clutter_alpha_get_timeline (alpha);
current_frame_num = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
if (current_frame_num > (n_frames / 2))
{
return (n_frames - current_frame_num)
* CLUTTER_ALPHA_MAX_ALPHA
/ (n_frames / 2);
}
else
{
return current_frame_num
* CLUTTER_ALPHA_MAX_ALPHA
/ (n_frames / 2);
}
}
static guint32
sincx1024_func (ClutterAlpha *alpha,
ClutterAngle angle,
ClutterFixed offset)
{
ClutterTimeline *timeline;
gint current_frame_num, n_frames;
ClutterAngle x;
unsigned int sine;
timeline = clutter_alpha_get_timeline (alpha);
current_frame_num = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
x = angle * current_frame_num / n_frames;
x -= (512 * 512 / angle);
sine = ((clutter_sini (x) + offset)/2) * CLUTTER_ALPHA_MAX_ALPHA;
sine = sine >> CFX_Q;
return sine;
}
#if 0
/*
* The following two functions are left in place for reference
* purposes.
*/
static guint32
sincx_func (ClutterAlpha *alpha,
ClutterFixed angle,
ClutterFixed offset)
{
ClutterTimeline *timeline;
gint current_frame_num, n_frames;
ClutterFixed x, sine;
timeline = clutter_alpha_get_timeline (alpha);
current_frame_num = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
x = angle * current_frame_num / n_frames;
x = CLUTTER_FIXED_MUL (x, CFX_PI) - CLUTTER_FIXED_DIV (CFX_PI, angle);
sine = (clutter_fixed_sin (x) + offset)/2;
CLUTTER_NOTE (ALPHA, "sine: %2f\n", CLUTTER_FIXED_TO_DOUBLE (sine));
return CLUTTER_FIXED_INT (sine * CLUTTER_ALPHA_MAX_ALPHA);
}
/* NB: angle is not in radians but in muliples of PI, i.e., 2.0
* represents full circle.
*/
static guint32
sinc_func (ClutterAlpha *alpha,
float angle,
float offset)
{
ClutterTimeline *timeline;
gint current_frame_num, n_frames;
gdouble x, sine;
timeline = clutter_alpha_get_timeline (alpha);
current_frame_num = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
/* FIXME: fixed point, and fixed point sine() */
x = (gdouble) (current_frame_num * angle * M_PI) / n_frames ;
sine = (sin (x - (M_PI / angle)) + offset) * 0.5f;
CLUTTER_NOTE (ALPHA, "sine: %2f\n",sine);
return CLUTTER_FLOAT_TO_INT ((sine * (gdouble) CLUTTER_ALPHA_MAX_ALPHA));
}
#endif
/**
* clutter_sine_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a sine wave. You can use this
* function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.2
*/
guint32
clutter_sine_func (ClutterAlpha *alpha,
gpointer dummy)
{
#if 0
return sinc_func (alpha, 2.0, 1.0);
#else
/* 2.0 above represents full circle */
return sincx1024_func (alpha, 1024, CFX_ONE);
#endif
}
/**
* clutter_sine_inc_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a sine wave over interval [0, pi / 2].
* You can use this function as the alpha function for
* clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.2
*/
guint32
clutter_sine_inc_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline * timeline;
gint frame;
gint n_frames;
ClutterAngle x;
ClutterFixed sine;
timeline = clutter_alpha_get_timeline (alpha);
frame = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
x = 256 * frame / n_frames;
sine = clutter_sini (x) * CLUTTER_ALPHA_MAX_ALPHA;
return ((guint32)sine) >> CFX_Q;
}
/**
* clutter_sine_dec_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a sine wave over interval [pi / 2, pi].
* You can use this function as the alpha function for
* clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.4
*/
guint32
clutter_sine_dec_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline * timeline;
gint frame;
gint n_frames;
ClutterAngle x;
ClutterFixed sine;
timeline = clutter_alpha_get_timeline (alpha);
frame = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
x = 256 * frame / n_frames + 256;
sine = clutter_sini (x) * CLUTTER_ALPHA_MAX_ALPHA;
return ((guint32)sine) >> CFX_Q;
}
/**
* clutter_sine_half_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a sine wave over interval [0, pi].
* You can use this function as the alpha function for
* clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.4
*/
guint32
clutter_sine_half_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline * timeline;
gint frame;
gint n_frames;
ClutterAngle x;
ClutterFixed sine;
timeline = clutter_alpha_get_timeline (alpha);
frame = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
x = 512 * frame / n_frames;
sine = clutter_sini (x) * CLUTTER_ALPHA_MAX_ALPHA;
return ((guint32)sine) >> CFX_Q;
}
/**
* clutter_square_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a square wave. You can use this
* function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value
*
* Since: 0.4
*/
guint32
clutter_square_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline *timeline;
gint current_frame_num, n_frames;
timeline = clutter_alpha_get_timeline (alpha);
current_frame_num = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
return (current_frame_num > (n_frames / 2)) ? CLUTTER_ALPHA_MAX_ALPHA
: 0;
}
/**
* clutter_smoothstep_inc_func:
* @alpha: a #ClutterAlpha
* @dummy: unused
*
* Convenience alpha function for a smoothstep curve. You can use this
* function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value
*
* Since: 0.4
*/
guint32
clutter_smoothstep_inc_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline *timeline;
gint frame;
gint n_frames;
gint32 r;
gint32 x;
/*
* The smoothstep function uses f(x) = -2x^3 + 3x^2 where x is from <0,1>,
* and precission is critical -- we use 8.24 fixed format for this operation.
* The earlier operations involve division, which we cannot do in 8.24 for
* numbers in <0,1> we use ClutterFixed.
*/
timeline = clutter_alpha_get_timeline (alpha);
frame = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
/*
* Convert x to 8.24 for next step.
*/
x = CFX_DIV (frame, n_frames) << 8;
/*
* f(x) = -2x^3 + 3x^2
*
* Convert result to ClutterFixed to avoid overflow in next step.
*/
r = ((x >> 12) * (x >> 12) * 3 - (x >> 15) * (x >> 16) * (x >> 16)) >> 8;
return CFX_INT (r * CLUTTER_ALPHA_MAX_ALPHA);
}
/**
* clutter_smoothstep_dec_func:
* @alpha: a #ClutterAlpha
* @dummy: unused
*
* Convenience alpha function for a downward smoothstep curve. You can use
* this function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value
*
* Since: 0.4
*/
guint32
clutter_smoothstep_dec_func (ClutterAlpha *alpha,
gpointer dummy)
{
return CLUTTER_ALPHA_MAX_ALPHA - clutter_smoothstep_inc_func (alpha, dummy);
}
/**
* clutter_exp_inc_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a 2^x curve. You can use this function as the
* alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.4
*/
guint32
clutter_exp_inc_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline * timeline;
gint frame;
gint n_frames;
ClutterFixed x;
ClutterFixed x_alpha_max = 0x100000;
guint32 result;
/*
* Choose x_alpha_max such that
*
* (2^x_alpha_max) - 1 == CLUTTER_ALPHA_MAX_ALPHA
*/
#if CLUTTER_ALPHA_MAX_ALPHA != 0xffff
#error Adjust x_alpha_max to match CLUTTER_ALPHA_MAX_ALPHA
#endif
timeline = clutter_alpha_get_timeline (alpha);
frame = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
x = x_alpha_max * frame / n_frames;
result = clutter_pow2x (x) - 1;
return result;
}
/**
* clutter_exp_dec_func:
* @alpha: a #ClutterAlpha
* @dummy: unused argument
*
* Convenience alpha function for a decreasing 2^x curve. You can use this
* function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value.
*
* Since: 0.4
*/
guint32
clutter_exp_dec_func (ClutterAlpha *alpha,
gpointer dummy)
{
ClutterTimeline * timeline;
gint frame;
gint n_frames;
ClutterFixed x;
ClutterFixed x_alpha_max = 0x100000;
guint32 result;
/*
* Choose x_alpha_max such that
*
* (2^x_alpha_max) - 1 == CLUTTER_ALPHA_MAX_ALPHA
*/
#if CLUTTER_ALPHA_MAX_ALPHA != 0xffff
#error Adjust x_alpha_max to match CLUTTER_ALPHA_MAX_ALPHA
#endif
timeline = clutter_alpha_get_timeline (alpha);
frame = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
x = (x_alpha_max * (n_frames - frame)) / n_frames;
result = clutter_pow2x (x) - 1;
return result;
}
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