2008-02-15 Emmanuele Bassi <ebassi@openedhand.com>

* clutter-animation.sgml: Fix the animations documentation.
This commit is contained in:
Emmanuele Bassi 2008-02-15 15:50:21 +00:00
parent 94f884f2ef
commit f14837a6d1
2 changed files with 208 additions and 107 deletions

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@ -1,8 +1,10 @@
2008-02-15 Emmanuele Bassi <ebassi@openedhand.com>
* clutter-animation.sgml: Fix the animations documentation.
2008-02-15 Chris Lord <chris@openedhand.com>
reviewed by: <delete if not using a buddy>
* clutter-docs.sgml:
* clutter-docs.sgml: Fix documentation.
2008-02-15 Matthew Allum <mallum@openedhand.com>

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@ -87,89 +87,109 @@ rotate_actor (gpointer data)
<section id="clutter-animation-timelines">
<title>Timelines</title>
<para>
Clutter Timelines abstract a set period of time with a set rate at
which to call a provided call back function.
#ClutterTimeline<!-- -->s abstract a set period of time with a set frame
rate at which to call a provided callback.
</para>
<para>
They essentially extend g_timeout like functionality further by;
#ClutterTimeline<!-- -->s also extend the timeout sources functionality
further by:
</para>
<orderedlist>
<listitem><para>Having a set duration (in milliseconds) and a set 'frame rate'. Essentially the rate at which the callback is called.</para></listitem>
<listitem><para>Passing current position information to the callback.</para></listitem>
<listitem><para>Handling 'dropped frames' in guarenteeing the set duration and skipping over frames if Clutter cannot keep up with set rates.</para></listitem>
<listitem><para>Query the number of milliseconds elapsed between current and previous callback.</para></listitem>
<listitem><para>Allowing the timeline to be modified on the fly as well as being stoped, started, looped, rewound, reversed.</para></listitem>
<listitem><para>Using the ClutterTimeoutPool to more efficiently schedule multiple timeout istances.</para></listitem>
<listitem><para>Having a set duration (in milliseconds) and a set
'frame rate' - that is, the rate at which the callback is
called</para></listitem>
<listitem><para>Passing current progress information to the
callback</para></listitem>
<listitem><para>Handling 'dropped frames' and guarenteeing the set
duration by skipping over frames if the callback cannot keep up with
the set frame rate</para></listitem>
<listitem><para>Querying the number of milliseconds elapsed between
the current and previous callback.</para></listitem>
<listitem><para>Allowing the timeline to be modified on the fly as
well as being stopped, started, looped, rewound and
reversed</para></listitem>
<listitem><para>Using a #ClutterTimeoutPool to more efficiently
schedule multiple timeout sources without incurring in potential
starvation of the main loop slices</para></listitem>
</orderedlist>
<para>
A Timeline is created with;
</para>
<programlisting>
clutter_timeline_new (guint n_frames, guint fps);
clutter_timeline_new (n_frames, frames_per_seconds);
</programlisting>
<para>
Taking a number of frames and a frames per second, or by;
</para>
<programlisting>
clutter_timeline_new_for_duration (guint msecs);
clutter_timeline_new_for_duration (msecs);
</programlisting>
<para>
Which takes the duration of the timeline in milliseconds with a
default frame rate (See #clutter_get_default_frame_rate())
default frame rate (See clutter_get_default_frame_rate()).
</para>
<para>
The speed, duration and number of frames of the timeline then be
modifed via the objects properties and API calls. The timeline can
be made to loop by settings it "loop" property to TRUE.
be made to loop by settings it "loop" property to %TRUE.
</para>
<para>
The timelines is started via #clutter_timeline_start () and its
playback further manipulated by the #clutter_timeline_pause (),
#clutter_timeline_stop (), #clutter_timeline_rewind () ,
#clutter_timeline_skip () calls.
The timelines is started via clutter_timeline_start() and its
playback further manipulated by the clutter_timeline_pause(),
clutter_timeline_stop(), clutter_timeline_rewind() and
clutter_timeline_skip() calls.
</para>
<para>
By attaching a handler to the timelines "new-frame" signal a timeline
can then be used to drive an animation by altering actors visual
properties in this callback. The callback looks like;
By attaching a handler to the timeline's ClutterTimeline::new-frame
signal a timeline can then be used to drive an animation by altering
an actor's visual properties in this callback. The callback looks like:
</para>
<programlisting>
void
on_new_frame (ClutterTimeline *timeline,
gint frame_num,
gpointer user_data)
{
void on_new_frame (ClutterTimeline *timeline,
gint frame_num,
gpointer user_data)
}
</programlisting>
<para>
The new-frame signals 'frame_num' parameter is set to the timelines
current frame number this is between 0 and the "num-frames"
property. This value can be used to compute the state of a
particular animation that is dependant on the current timeline
position. The function #clutter_timeline_get_progress () can also be
used to get a normalised value of the timelines current position.
The <literal>frame_num</literal> parameter is set to the timeline's
current frame number (which is between 0 and the "num-frames" property).
This value can be used to compute the state of a particular animation
that is dependant on the frame numer. The clutter_timeline_get_progress()
function can also be used to get a normalised value of the timeline's
current position between 0 and 1.
</para>
<para>
Timelines can also be played in reverse
#clutter_timeline_set_direction() and a one-time delay set before
they begin playing #clutter_timeline_set_delay ().
Timelines can also be played in reverse by setting the direction using
clutter_timeline_set_direction(), and can also have a one-time delay set
before they begin playing by using clutter_timeline_set_delay().
</para>
<para>
When using a timeline to control a physical simulation using
#clutter_timeline_get_delta() allows retrieving the number of frames
and milliseconds since the previous callback to ensure the physics
simulation to be able to take the actual time elapsed between
Timelines can also control a pyshical simulation; the
clutter_timeline_get_delta() function allows retrieving the number of
frames and milliseconds elapsed since the previous callback to ensure
the physics engine to be able to take the actual time elapsed between
iterations into account.
</para>
@ -188,9 +208,11 @@ on_new_frame (ClutterTimeline *timeline,
{
ClutterActor *actor = CLUTTER_ACTOR(data);
clutter_actor_set_rotation (actor, (gdouble)frame_num,
clutter_actor_get_width (actor)/2,
clutter_actor_get_height (actor)/2);
clutter_actor_set_rotation (actor, CLUTTER_Z_AXIS,
(gdouble) frame_num,
clutter_actor_get_width (actor) / 2,
clutter_actor_get_height (actor) / 2,
0);
}
int
@ -213,8 +235,8 @@ main (int argc, char *argv[])
clutter_actor_set_position (actor, 100, 100);
timeline = clutter_timeline_new (360, 60); /* num frames, fps */
g_object_set(timeline, "loop", TRUE, NULL); /* have it loop */
timeline = clutter_timeline_new_for (360, 60); /* a degree per frame */
clutter_timeline_set_loop (timeline, TRUE);
g_signal_connect (timeline, "new-frame", G_CALLBACK (on_new_frame), actor);
@ -266,19 +288,58 @@ main (int argc, char *argv[])
</para>
<para>
%CLUTTER_ALPHA_RAMP_INC
%CLUTTER_ALPHA_RAMP_DEC
%CLUTTER_ALPHA_RAMP
%CLUTTER_ALPHA_SINE
%CLUTTER_ALPHA_SINE_INC
%CLUTTER_ALPHA_SINE_DEC
%CLUTTER_ALPHA_SINE_HALF
%CLUTTER_ALPHA_SQUARE
%CLUTTER_ALPHA_SMOOTHSTEP_INC
%CLUTTER_ALPHA_SMOOTHSTEP_DEC
%CLUTTER_ALPHA_EXP_INC
%CLUTTER_ALPHA_EXP_DEC
<variablelist>
<varlistentry>
<term>%CLUTTER_ALPHA_RAMP_INC</term>
<listitem><simpara>Increasing ramp function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_RAMP_DEC</term>
<listitem><simpara>Decreasing ramp function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_RAMP</term>
<listitem><simpara>Full ramp function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_SINE_INC</term>
<listitem><simpara>Increasing sine function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_SINE_DEC</term>
<listitem><simpara>Decreasing sine function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_SINE_HALF</term>
<listitem><simpara>Half sine function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_SINE</term>
<listitem><simpara>Full sine function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_SQUARE</term>
<listitem><simpara>Square waveform ("step") function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_SMOOTHSTEP_INC</term>
<listitem><simpara>Increasing smooth transition step
function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_SMOOTHSTEP_DEC</term>
<listitem><simpara>Decreasing smooth transition step
function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_EXP_INC</term>
<listitem><simpara>Increasing exponential function</simpara></listitem>
</varlistentry>
<varlistentry>
<term>%CLUTTER_ALPHA_EXP_DEC</term>
<listitem><simpara>Decreasing exponential function</simpara></listitem>
</varlistentry>
</variablelist>
</para>
<para>
@ -331,18 +392,42 @@ main (int argc, char *argv[])
</para>
<para>
The behaviours included with clutter are
The behaviours included in Clutter are
</para>
<para>
#ClutterBehaviourBspline
#ClutterBehaviourDepth
#ClutterBehaviourEllipse
#ClutterBehaviourOpacity
#ClutterBehaviourPath
#ClutterBehaviourRotate
#ClutterBehaviourScale
<variablelist>
<varlistentry>
<term>#ClutterBehaviourBspline</term>
<listitem><simpara>Moves actors along a B-spline path</simpara></listitem>
</varlistentry>
<varlistentry>
<term>#ClutterBehaviourDepth</term>
<listitem><simpara>Changes the depth of actors</simpara></listitem>
</varlistentry>
<varlistentry>
<term>#ClutterBehaviourEllipse</term>
<listitem><simpara>Moves actors along an ellipsis</simpara></listitem>
</varlistentry>
<varlistentry>
<term>#ClutterBehaviourOpacity</term>
<listitem><simpara>Changes the opacity of actors</simpara></listitem>
</varlistentry>
<varlistentry>
<term>#ClutterBehaviourPath</term>
<listitem><simpara>Moves actors along a path</simpara></listitem>
</varlistentry>
<varlistentry>
<term>#ClutterBehaviourRotate</term>
<listitem><simpara>Rotates actors along an axis</simpara></listitem>
</varlistentry>
<varlistentry>
<term>#ClutterBehaviourScale</term>
<listitem><simpara>Changes the scaling factors of
actors</simpara></listitem>
</varlistentry>
</variablelist>
</para>
@ -372,22 +457,22 @@ main (int argc, char *argv[])
clutter_container_add_actor (CLUTTER_CONTAINER (stage), actor);
timeline = clutter_timeline_new (100, 26); /* num frames, fps */
g_object_set(timeline, "loop", TRUE, NULL); /* have it loop */
timeline = clutter_timeline_new_for_duration (4000); /* milliseconds */
clutter_timeline_set_loop (timeline, TRUE);
/* Set an alpha func to power behaviour */
/* Set an alpha func to power the behaviour */
alpha = clutter_alpha_new_full (timeline,
CLUTTER_ALPHA_SINE,
NULL, NULL);
behave = clutter_behaviour_ellipse_new (alpha,
200, /* center x */
200, /* center y */
400, /* width */
300, /* height */
200, /* center x */
200, /* center y */
400, /* width */
300, /* height */
CLUTTER_ROTATE_CW, /* direction */
0.0, /* angle begin */
360.0); /* angle end */
0.0, /* initial angle */
360.0); /* final angle */
clutter_behaviour_apply (behave, actor);
@ -397,6 +482,10 @@ main (int argc, char *argv[])
clutter_main();
/* clean up */
g_object_unref (behave);
g_object_unref (timeline);
return 0;
}
@ -405,20 +494,22 @@ main (int argc, char *argv[])
<note>Behaviour parameters can be changed whilst a animation is running</note>
<para>
There can be many ClutterAlpha's attached to a single timeline. There can be
many Behaviours for a ClutterAlpha There can be many Behaviours applied to an
actor. A ClutterScore can be used to chain many behaviour togeather
<para>
There can be many #ClutterAlpha's attached to a single timeline. There
can be many behaviours for a #ClutterAlpha. There can be many behaviours
applied to an actor. A #ClutterScore can be used to chain many behaviour
together.
</para>
<warn>combining behaviours that effect the same actor properties
(i.e two seperate paths) will cause unexpected results. The values
will not be merged in any way with essentially a the last applied
behaviour taking precedence.</warn>
<warn><para>Combining behaviours that effect the same actor properties
(i.e two separate paths) will cause unexpected results. The values
will not be merged in any way with essentially a the last applied
behaviour taking precedence.</para></warn>
<para>
FIXME: actually move subclassing behaviours here?
</para>
<para>
Tips for implementing a new behaviour can be found <link
linkend="creating-your-own-behaviours">here</link>.
</para>
</section>
<section id="clutter-animation-effects">
@ -426,55 +517,60 @@ behaviour taking precedence.</warn>
<para>
ClutterEffect's provide a simplified abstraction for firing simple
transitions from code. ClutterEffects are created from
ClutterEffectTemplate s which are an abstraction of a timeline and
an alpha. An effect template can be created with:
Clutter effects API provide a simplified abstraction for firing simple
transitions from code. Clutter effects are created from a
#ClutterEffectTemplate which is an abstraction of a timeline and
an alpha function. An effect template can be created with:
</para>
<programlisting>
ClutterEffectTemplate *etemplate;
etemplate = clutter_effect_template_new_for_duration (
2000, CLUTTER_ALPHA_RAMP_INC);
ClutterEffectTemplate *etemplate =
clutter_effect_template_new_for_duration (2000, CLUTTER_ALPHA_RAMP_INC);
</programlisting>
<para>
This will create an effect template lasting 2000 milliseconds (2
seconds) and use an alpha function of CLUTTER_ALPHA_RAMP_INC, there
seconds) and use an alpha function of %CLUTTER_ALPHA_RAMP_INC, there
are other more advanced forms for creating effect templates from
existing timelines, as well as attaching a callback to be called
with user_data when the effecttemplate is destroyed.
with user_data when the effect template is destroyed.
</para>
<para>
When we have an effect-template we can create a temporary behaviour
When we have an effect template we can create a temporary behaviour
animating an actor simply by issuing:
</para>
<programlisting>
clutter_actor_move (etemplate, actor, 23, 42, NULL, NULL);
clutter_effect_move (etemplate, actor, 23, 42, NULL, NULL);
</programlisting>
<para>
and the actor will move to the coordintes 23, 42 in 2 seconds, if we at the
same time issued:
and the actor will move from its current position to the coordinates
(23, 42) in 2 seconds. Effects can also be stacked, so calling:
</para>
<programlisting>
clutter_actor_fade (etemplate, actor, 0x0, NULL, NULL);
clutter_effect_move (etemplate, actor, 23, 42, NULL, NULL);
clutter_effect_fade (etemplate, actor, 0, NULL, NULL);
</programlisting>
<para>
The actor would fade out at the same time.
The actor will move and fade out at the same time.
</para>
<para>
Clutter effects return a timeline, you can stop an effect from
Since effects return a #ClutterTimeline, you can stop an effect from
immediatly happening by calling clutter_timeline_stop () on the
returned timeline. This returned timeline can also be used to then
use effects in the ClutterScore etc.
returned timeline.
</para>
<para>
The timeline and all the effect infrastructure is unreferenced as soon
as the timeline emits the ClutterTimeline::completed signal.
</para>
</section>
<section id="clutter-animation-conclusion">
<title>Conclusion</title>
<para>
@ -493,7 +589,10 @@ The actor would fade out at the same time.
</para>
<para>
The animation functionality in clutter is primarily suited to building animations with a set or finite running time - i.e transitions and the like. For animations involving variable input (such as touchscreen handling) physical simulations may be more suited.
The animation functionality in Clutter is primarily suited to
building animations with a set or finite running time - i.e transitions
and the like. For animations involving variable input (such as touchscreen
handling) physical simulations may be more suited.
</para>