- 一个 toolkit/scenegraph/canvas 库，使用 OpenGL/OpenGL ES 渲染
- 依赖于 GOject, Glib, GDKPixbuf 和 Pango；
- 目的是创建速度快、支持动画效果、视觉丰富的图形界面；
- 原始 (raw) 但是灵活 (flexible) 的 API
- 不是一个通用的 OpenGL 接口，是一个带有 3D 效果的 2D (2D with 3D effects).
- 基于 C 开发，基于 LGPL 发布
Why clutter
- 让使用者摆脱了 OpenGL API 和相关数学知识带来的复杂性；
- 简洁的 面向对象的类似 GTK+ 的 API，并提供了窗口和事件抽象；
- 3D 桌面硬件和 3D 嵌入式硬件越来越流行；
- Media boxes，如 Microsoft Media Center, Apple's Front Row;
- 桌面应用特效，如 iTunes 的 Coverflow, 图片浏览器的 slideshow;
- 嵌入式设备：Zune, iPhone 等
Internals
- All fixed point math (fixed and float API entry points);
- ClutterUnits
- Timeline Pool
- Custome Pango render - efficient text rendering
Backends
- Clutter backend essentially abstracted into 2 parts:
- 'Cogl' layer abstracts over regular GL and GL ES;
- Features allows easy runtime detection of missing features (eg YUV textures, texture reads).
Bindings
General concepts
- Actors (Widgets): 可视界面元素；
- Stage (Window)：actors 加入到 Stage 中；
- Actors 可以有父亲元素，也可以有孩子元素；
- 通过事件和动画直接操作 actors.
Actors
- All Actors can be tranformed in various ways：
- Position ed in 3D space (via pixels or ClutterUnits)；
- Rotated around 3 Axis;
- Sized;
- Scaled;
- Have Opacity set;
- Clipped;
- Transforms also apply to children;
- Position relative to parent;
A simple Actor example
#include <clutter/clutter.h>
int main (int argc, char* argv[])
{
ClutterActor *stage, *actor;
GdkPixbuf * pixbuf;
clutter_init (&argc, &argv);
stage = clutter_stage_get_default ();
pixbuf = gdk_pixbuf_new_from_file ("superoh,png", NULL);
actor = clutter_texture_new_from_pixbuf (pixbuf);
clutter_container_add_actor (CLUTTER_CONTAINER (stage), actor);
clutter_actor_set_position (actor, 100, 100);
clutter_actor_rotate_z (actor, 180.0,
clutter_actor_get_width (actor)/2,
cluter_actor_get_height (actor)/2);
clutter_actor_show_all (stage);
clutter_main ();
return 0;
}
Simple Actor Example II
pixbuf = gdk_pixbuf_new_from_file ("redhand,png", NULL);
group = clutter_group_new ();
actor1 = clutter_texture_new_from_pixbuf (pixbuf);
actor2 = clutter_texture_new_from_pixbuf (pixbuf);
clutter_container_add (CLUTTER_CONTAINER (group), actor1, actor2,
NULL);
clutter_actor_set_position (actor1, 0, 0);
clutter_actor_set_position (actor2, 200, 0);
clutter_container_add_actor (CLUTTER_CONTAINER (stage), group);
clutter_actor_set_position (group, 100, 100);
clutter_actor_rotate_z (group, 45.0,
clutter_actor_get_width (group)/2,
cluter_actor_get_height (group)/2);
clutter_actor_show_all (group);
clutter_actor_show_all (stage);
clutter_main ();
Included Actors
- ClutterTexture, ClutterAnimationTexture, ClutterCloneTexture
- ClutterRectangle
- ClutterLabel
- ClutterEntry
- ClutterContainer, ClutterStage, ClutterGroup, ClutterVBox, ClutterHBox
- ClutterCairo, ClutterGstVideo (Via Add ons)
- Easy to subclass and make your own
Events
- Simple processed input events (keyboard, mouse)
- All signals from stage
- clutter_stage_actor_at_pos ()
- Reasoning: performance, focus model;
- Plans to improve RSN;
ClutterTimelines
- 动画的基础；
- 指定总帧数和每秒钟对应的帧；
- Callback on a new frame
- Skips 'dropped' frames
- Delay, Stop, start, pause, loop
Timeline Example:
void on_new_frame (ClutterTimeline* timeline, gint frame_num,
gpointer data)
{
ClutterActor *actor = CLUTTER_ACTOR (data);
clutter_actor_rotate_z (actor, (gdouble)frame_num,
clutter_actor_get_width (actor)/2,
cluter_actor_get_height (actor)/2);
}
int main (int argc, char* argv[])
{
ClutterTimeline* timeline;
...
timeline = clutter_timeline_new (360, 60); /*num frames, fps*/
g_object_set (timeline, "loop", TRUE, NULL); /* have it loop */
/* fire a callback for frame change */
g_signal_connect (timeline, "new-frame",
G_CALLBACK (on_new_frame), actor);
clutter_timeline_start (timeline);
...
}
ClutterAlphas
- A function of time - not pixel alpha;
- Takes a timeline as parameter and a function;
- Produces a value between 0 and CLUTTER_ALPHA_MAX;
- Various prebuilt functions included: ramps, sinewaves, smoothstep,
exponential, etc
- In a word, A clutterAlpha binds a Timeline to a progress function
which translates the time T into an adimensional factor alpha. The
factor can then be used to drive a Behaviour, which translates the
value into something meaningful for an Actor.
ClutterBehaviours
- Manipultates actors properties in various ways driven by Alphas;
- Makes complex animations easy.
- Opacity, Rotation, Depth. Paths, BSplines Paths, Ellipse Paths;
- Mix, Stack, Easy to roll your own.
Behaviour example
timeline = clutter_timeline_new (100, 26); /* num frames, fps */
/**/
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 */
0.0, /* angle begin */
360.0, /* angle end */
0.0 /* title */ );
clutter_behaviour_apply (behave, actor);
/* start the timeline and thus the animations */
clutter_timeline_start (timeline);
ClutterEffects
- 'One shot' effects
- Utility wrapper around timelines+alphas+behaviours
- More limited, but easy
ClutterEffectTemplate* template;
effect_template = clutter_effect_template_new(
clutter_time_line_new (60, 60),
CLUTTER_ALPHA_RAMP_INC);
clutter_effect_scale (effect_template, actor, 1.0, 4.0,
CLUTTER_GRAVITY_CENTER,
on_completion_callback,
on_completion_callback_data);
ClutterCairo
- A cairo Canvas Actor, 2 API calls
- not accelerated (yet)
actor = clutter_cairo_new (width, height);
cr = clutter_cairo_create (CLUTTER_CAIRO(actor));
... cairo rendering calls...
cairo_destroy (cr);
ClutterGst
- Video Texture Actor - simple video file playback
- Clutter Texture Sink - for custom pipelines
- Simpel audio playback also
ClutterGTK
- GTK Clutter Canvas widget
- Allows clutter to be embedded into GTK apps
SeeAlso
http://www.clutter-project.org/presentations/clutter-foo/slide-01.html
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