Refactor Animation Handling in Rust Animation

- Extracted animation logic from Actor into a separate Animation struct.
- Replaced direct animation methods in Actor with set_animation() to use the new Animation struct.
- Updated examples (ani.rs, easing_functions.rs, flex_ui.rs, picture_viewer.rs) to use the new Animation struct instead of direct animation methods in Actor.
- Removed animation-related fields and methods from Actor, simplifying its implementation.
- Added a new animation module to encapsulate animation functionalities.

examples/ani.rs

@@ -7,9 +7,10 @@ extern crate glfw;
 use glfw::{Action, Context, Key};
 
 use rust_animation::actor::Actor;
-use rust_animation::actor::EasingFunction;
 use rust_animation::actor::LayoutMode;
 use rust_animation::play::Play;
+use rust_animation::animation::Animation;
+use rust_animation::animation::EasingFunction;
 use std::sync::mpsc::Receiver;
 
 fn main() {
@@ -45,12 +46,15 @@ fn main() {
   actor_1.y = 100;
   actor_1.set_image("examples/splash.png".to_string());
 
+  let mut animation_1 = Animation::new();
+
   // 1X -> 2X for 5 sec.
   let time = 5.0;
-  actor_1.apply_scale_animation(1.0, 2.0, time, EasingFunction::Linear);
-  actor_1.apply_translation_x_animation(100, 1000, time, EasingFunction::EaseInOut);
-  actor_1.apply_translation_y_animation(100, 300, time, EasingFunction::EaseInOut);
-  actor_1.apply_rotation_animation(0, 360, time, EasingFunction::EaseInOut);
+  animation_1.apply_scale(1.0, 2.0, time, EasingFunction::Linear);
+  animation_1.apply_translation_x(100, 1000, time, EasingFunction::EaseInOut);
+  animation_1.apply_translation_y(100, 300, time, EasingFunction::EaseInOut);
+  animation_1.apply_rotation(0, 360, time, EasingFunction::EaseInOut);
+  actor_1.set_animation(Some(animation_1));
 
   let mut actor_2 = Play::new_actor("actor_2".to_string(), 120, 120, None);
   actor_2.x = 100;
@@ -59,7 +63,10 @@ fn main() {
   actor_2.scale_y = 1.5;
   actor_2.set_color(0.0, 0.0, 1.0);
   // 0 degree -> 360 degree for 5 sec
-  actor_2.apply_rotation_animation(0, 360, 5.0, EasingFunction::EaseInOut);
+
+  let mut animation_2 = Animation::new();
+  animation_2.apply_rotation(0, 360, 5.0, EasingFunction::EaseInOut);
+  actor_2.set_animation(Some(animation_2));
 
   let mut actor_3 = Play::new_actor("actor_3".to_string(), 50, 50, None);
   actor_3.x = 10;

examples/easing_functions.rs

@@ -7,7 +7,8 @@ extern crate glfw;
 use glfw::{Action, Context, Key};
 
 use rust_animation::actor::Actor;
-use rust_animation::actor::EasingFunction;
+use rust_animation::animation::Animation;
+use rust_animation::animation::EasingFunction;
 use rust_animation::actor::LayoutMode;
 use rust_animation::play::Play;
 use std::sync::mpsc::Receiver;
@@ -75,8 +76,11 @@ fn main() {
     actor.y = y;
     y += height as i32;
     actor.set_color(i as f32 / 18.0, i as f32 / 18.0, i as f32 / 18.0);
-    actor.apply_translation_x_animation(0, (1920 - width) as i32, time, easing_functions[i]);
-    actor.apply_rotation_animation(0, 360, time, EasingFunction::Linear);
+
+    let mut animation = Animation::new();
+    animation.apply_translation_x(0, (1920 - width) as i32, time, easing_functions[i]);
+    animation.apply_rotation(0, 360, time, EasingFunction::Linear);
+    actor.set_animation(Some(animation));
     stage.add_sub_actor(actor);
   }
   play.add_stage(stage);

examples/flex_ui.rs

@@ -8,7 +8,6 @@ use glfw::{Action, Context, Key};
 use stretch::{geometry::Rect, geometry::Size, node::Stretch, style::*};
 
 use rust_animation::actor::Actor;
-
 use rust_animation::actor::Layout;
 use rust_animation::actor::LayoutMode;
 use rust_animation::play::Play;

examples/picture_viewer.rs

@@ -17,7 +17,8 @@ use std::sync::mpsc;
 use std::thread;
 
 use rust_animation::actor::Actor;
-use rust_animation::actor::EasingFunction;
+use rust_animation::animation::Animation;
+use rust_animation::animation::EasingFunction;
 use rust_animation::actor::EventHandler;
 use rust_animation::actor::Layout;
 use rust_animation::actor::LayoutMode;
@@ -93,7 +94,9 @@ impl ActorEvent {
 impl EventHandler for ActorEvent {
   fn key_focus_in(&mut self, actor: &mut Actor) {
     println!("key_focus_in: {} {}", self.name, actor.name);
-    actor.apply_scale_animation(1.0, 1.1, 0.3, EasingFunction::EaseInOut);
+    let mut animation = Animation::new();
+    animation.apply_scale(1.0, 1.1, 0.3, EasingFunction::EaseInOut);
+    actor.set_animation(Some(animation));
   }
 
   fn key_focus_out(&mut self, actor: &mut Actor) {