Added animation demo

Cargo.toml

@@ -31,4 +31,5 @@ objc = "0.2.7"
 
 [dev-dependencies]
 winit = "0.26.1"
-image = "0.23.14"
+image = "0.23.14"
+rayon = "1.5.1"

examples/animation.rs

@@ -0,0 +1,70 @@
+use std::f64::consts::PI;
+use std::time::Instant;
+use rayon::prelude::*;
+use softbuffer::GraphicsContext;
+use winit::event::{Event, WindowEvent};
+use winit::event_loop::{ControlFlow, EventLoop};
+use winit::window::WindowBuilder;
+
+fn main() {
+    let event_loop = EventLoop::new();
+    let window = WindowBuilder::new().build(&event_loop).unwrap();
+    let mut graphics_context = unsafe { GraphicsContext::new(window) }.unwrap();
+
+    let mut old_size = (0, 0);
+    let mut frames = pre_render_frames(0, 0);
+
+    let start = Instant::now();
+    event_loop.run(move |event, _, control_flow| {
+        *control_flow = ControlFlow::Poll;
+
+        match event {
+            Event::RedrawRequested(window_id) if window_id == graphics_context.window().id() => {
+                let elapsed = start.elapsed().as_secs_f64() % 1.0;
+                let (width, height) = {
+                    let size = graphics_context.window().inner_size();
+                    (size.width, size.height)
+                };
+
+                if (width, height) != old_size{
+                    old_size = (width, height);
+                    frames = pre_render_frames(width as usize, height as usize);
+                };
+
+                let buffer = &frames[((elapsed*60.0).round() as usize).clamp(0, 59)];
+                graphics_context.set_buffer(buffer.as_slice(), width as u16, height as u16);
+            }
+            Event::MainEventsCleared => {
+                graphics_context.window().request_redraw();
+            }
+            Event::WindowEvent {
+                event: WindowEvent::CloseRequested,
+                window_id,
+            } if window_id == graphics_context.window().id() => {
+                *control_flow = ControlFlow::Exit;
+            }
+            _ => {}
+        }
+    });
+}
+
+fn pre_render_frames(width: usize, height: usize) -> Vec<Vec<u32>>{
+    (0..60).into_par_iter().map(|frame_id|{
+        let elapsed = ((frame_id as f64)/(60.0))*2.0*PI;
+        let buffer = (0..((width * height) as usize))
+            .map(|index| {
+                let y = ((index / (width as usize)) as f64)/(height as f64);
+                let x = ((index % (width as usize)) as f64)/(width as f64);
+                let red = ((((y + elapsed).sin()*0.5+0.5)*255.0).round() as u32).clamp(0, 255);
+                let green = ((((x + elapsed).sin()*0.5+0.5)*255.0).round() as u32).clamp(0, 255);
+                let blue = ((((y - elapsed).cos()*0.5+0.5)*255.0).round() as u32).clamp(0, 255);
+
+                let color = blue | (green << 8) | (red << 16);
+
+                color
+            })
+            .collect::<Vec<_>>();
+
+        buffer
+    }).collect()
+}