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actor: Add pivot point

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The pivot point is a point in normalized coordinates space around which
all transformations revolve.

It supercedes the anchor point and the per-transformation center points
as well as the gravity settings, and tries to sort out the mess that
is the modelview matrix set up in ClutterActor.

https://bugzilla.gnome.org/show_bug.cgi?id=677853
This commit is contained in:
Emmanuele Bassi 2012-07-06 10:35:13 +01:00
parent b20e9b78e5
commit 1fd0f4b9a5
4 changed files with 170 additions and 6 deletions
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3
clutter/clutter-actor-private.h
View File

@ -201,6 +201,9 @@ struct _ClutterTransformInfo
/* z_position */
gfloat z_position;
/* transformation center */
ClutterPoint pivot;
};
const ClutterTransformInfo * _clutter_actor_get_transform_info_or_defaults (ClutterActor *self);

153
clutter/clutter-actor.c
View File

@ -870,6 +870,8 @@ enum
PROP_REALIZED,
PROP_REACTIVE,
PROP_PIVOT_POINT,
PROP_SCALE_X,
PROP_SCALE_Y,
PROP_SCALE_CENTER_X,
@ -2946,9 +2948,18 @@ clutter_actor_real_apply_transform (ClutterActor *self,
{
CoglMatrix *transform = &priv->transform;
const ClutterTransformInfo *info;
float pivot_x = 0.f, pivot_y = 0.f;
info = _clutter_actor_get_transform_info_or_defaults (self);
if (!clutter_point_equals (&info->pivot, clutter_point_zero ()))
{
pivot_x = (priv->allocation.x2 - priv->allocation.x1)
* info->pivot.x;
pivot_y = (priv->allocation.y2 - priv->allocation.y1)
* info->pivot.y;
}
cogl_matrix_init_identity (transform);
cogl_matrix_translate (transform,
@ -2959,6 +2970,10 @@ clutter_actor_real_apply_transform (ClutterActor *self,
if (info->z_position != 0.f)
cogl_matrix_translate (transform, 0, 0, info->z_position);
/* pivot point, used as the transformation center */
if (pivot_x != 0.f || pivot_y != 0.f)
cogl_matrix_translate (transform, pivot_x, pivot_y, 0.f);
/*
* because the rotation involves translations, we must scale
* before applying the rotations (if we apply the scale after
@ -3005,6 +3020,10 @@ clutter_actor_real_apply_transform (ClutterActor *self,
cogl_matrix_translate (transform, -x, -y, -z);
}
/* roll back the pivot translation */
if (pivot_x != 0.f || pivot_y != 0.f)
cogl_matrix_translate (transform, -pivot_x, -pivot_y, 0.f);
priv->transform_valid = TRUE;
}
@ -4074,7 +4093,9 @@ static const ClutterTransformInfo default_transform_info = {
{ 0, }, /* anchor */
0.0, /* depth */
0.0, /* z-position */
CLUTTER_POINT_INIT_ZERO, /* pivot */
};
/*< private >
@ -4146,6 +4167,22 @@ _clutter_actor_get_transform_info (ClutterActor *self)
return info;
}
static inline void
clutter_actor_set_pivot_point_internal (ClutterActor *self,
const ClutterPoint *pivot)
{
ClutterTransformInfo *info;
info = _clutter_actor_get_transform_info (self);
info->pivot = *pivot;
self->priv->transform_valid = FALSE;
g_object_notify_by_pspec (G_OBJECT (self), obj_props[PROP_PIVOT_POINT]);
clutter_actor_queue_redraw (self);
}
/*< private >
* clutter_actor_set_rotation_angle_internal:
* @self: a #ClutterActor
@ -4593,6 +4630,17 @@ clutter_actor_set_property (GObject *object,
clutter_actor_hide (actor);
break;
case PROP_PIVOT_POINT:
{
const ClutterPoint *pivot = g_value_get_boxed (value);
if (pivot == NULL)
pivot = clutter_point_zero ();
clutter_actor_set_pivot_point (actor, pivot->x, pivot->y);
}
break;
case PROP_SCALE_X:
clutter_actor_set_scale_factor (actor, CLUTTER_X_AXIS,
g_value_get_double (value));
@ -4970,6 +5018,15 @@ clutter_actor_get_property (GObject *object,
g_value_set_boolean (value, priv->clip_to_allocation);
break;
case PROP_PIVOT_POINT:
{
const ClutterTransformInfo *info;
info = _clutter_actor_get_transform_info_or_defaults (actor);
g_value_set_boxed (value, &info->pivot);
}
break;
case PROP_SCALE_X:
{
const ClutterTransformInfo *info;
@ -6219,6 +6276,28 @@ clutter_actor_class_init (ClutterActorClass *klass)
NULL,
CLUTTER_PARAM_READWRITE);
/**
* ClutterActor:pivot-point:
*
* The point around which the scaling and rotation transformations occur.
*
* The pivot point is expressed in normalized coordinates space, with (0, 0)
* being the top left corner of the actor and (1, 1) the bottom right corner
* of the actor.
*
* The #ClutterActor:pivot property is animatable.
*
* Since: 1.12
*/
obj_props[PROP_PIVOT_POINT] =
g_param_spec_boxed ("pivot-point",
P_("Pivot Point"),
P_("The point around which the scaling and rotation occur"),
CLUTTER_TYPE_POINT,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
CLUTTER_PARAM_ANIMATABLE);
/**
* ClutterActor:scale-x:
*
@ -10935,6 +11014,74 @@ clutter_actor_get_z_position (ClutterActor *self)
return _clutter_actor_get_transform_info_or_defaults (self)->z_position;
}
/**
* clutter_actor_set_pivot_point:
* @self: a #ClutterActor
* @pivot_x: the normalized X coordinate of the pivot point
* @pivot_y: the normalized Y coordinate of the pivot point
*
* Sets the position of the #ClutterActor:pivot-point around which the
* scaling and rotation transformations occur.
*
* The pivot point's coordinates are in normalized space, with the (0, 0)
* point being the top left corner of the actor, and the (1, 1) point being
* the bottom right corner.
*
* Since: 1.12
*/
void
clutter_actor_set_pivot_point (ClutterActor *self,
gfloat pivot_x,
gfloat pivot_y)
{
ClutterPoint pivot = CLUTTER_POINT_INIT (pivot_x, pivot_y);
g_return_if_fail (CLUTTER_IS_ACTOR (self));
if (_clutter_actor_get_transition (self, obj_props[PROP_PIVOT_POINT]) == NULL)
{
const ClutterTransformInfo *info;
info = _clutter_actor_get_transform_info_or_defaults (self);
_clutter_actor_create_transition (self, obj_props[PROP_PIVOT_POINT],
&info->pivot,
&pivot);
}
else
_clutter_actor_update_transition (self, obj_props[PROP_PIVOT_POINT], &pivot);
}
/**
* clutter_actor_get_pivot_point:
* @self: a #ClutterActor
* @pivot_x: (out) (allow-none): return location for the normalized X
* coordinate of the pivot point, or %NULL
* @pivot_y: (out) (allow-none): return location for the normalized Y
* coordinate of the pivot point, or %NULL
*
* Retrieves the coordinates of the #ClutterActor:pivot-point.
*
* Since: 1.12
*/
void
clutter_actor_get_pivot_point (ClutterActor *self,
gfloat *pivot_x,
gfloat *pivot_y)
{
const ClutterTransformInfo *info;
g_return_if_fail (CLUTTER_IS_ACTOR (self));
info = _clutter_actor_get_transform_info_or_defaults (self);
if (pivot_x != NULL)
*pivot_y = info->pivot.x;
if (pivot_y != NULL)
*pivot_y = info->pivot.y;
}
/**
* clutter_actor_set_depth:
* @self: a #ClutterActor
@ -13764,6 +13911,10 @@ clutter_actor_set_animatable_property (ClutterActor *actor,
clutter_actor_set_background_color_internal (actor, clutter_value_get_color (value));
break;
case PROP_PIVOT_POINT:
clutter_actor_set_pivot_point_internal (actor, g_value_get_boxed (value));
break;
case PROP_SCALE_X:
clutter_actor_set_scale_factor_internal (actor,
g_value_get_double (value),

8
clutter/clutter-actor.h
View File

@ -625,6 +625,14 @@ gboolean clutter_actor_iter_is_valid
/* Transformations */
gboolean clutter_actor_is_rotated (ClutterActor *self);
gboolean clutter_actor_is_scaled (ClutterActor *self);
CLUTTER_AVAILABLE_IN_1_12
void clutter_actor_set_pivot_point (ClutterActor *self,
gfloat pivot_x,
gfloat pivot_y);
CLUTTER_AVAILABLE_IN_1_12
void clutter_actor_get_pivot_point (ClutterActor *self,
gfloat *pivot_x,
gfloat *pivot_y);
void clutter_actor_set_rotation (ClutterActor *self,
ClutterRotateAxis axis,
gdouble angle,

2
clutter/clutter.symbols
View File

@ -130,6 +130,7 @@ clutter_actor_get_paint_visibility
clutter_actor_get_paint_volume
clutter_actor_get_pango_context
clutter_actor_get_parent
clutter_actor_get_pivot_point
clutter_actor_get_position
clutter_actor_get_preferred_height
clutter_actor_get_preferred_size
@ -252,6 +253,7 @@ clutter_actor_set_name
clutter_actor_set_offscreen_redirect
clutter_actor_set_opacity
clutter_actor_set_parent
clutter_actor_set_pivot_point
clutter_actor_set_position
clutter_actor_set_reactive
clutter_actor_set_request_mode