Flatten create structure

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

advotracker_client/examples/sdl2_demo.rs

@@ -0,0 +1,45 @@
+extern crate sdl2;
+
+use sdl2::event::Event;
+use sdl2::keyboard::Keycode;
+use sdl2::pixels::Color;
+use std::time::Duration;
+
+pub fn main() -> Result<(), String> {
+    let sdl_context = sdl2::init()?;
+    let video_subsystem = sdl_context.video()?;
+
+    let window = video_subsystem
+        .window("rust-sdl2 demo: Video", 800, 600)
+        .position_centered()
+        .opengl()
+        .build()
+        .map_err(|e| e.to_string())?;
+
+    let mut canvas = window.into_canvas().build().map_err(|e| e.to_string())?;
+
+    canvas.set_draw_color(Color::RGB(255, 0, 0));
+    canvas.clear();
+    canvas.present();
+    let mut event_pump = sdl_context.event_pump()?;
+
+    'running: loop {
+        for event in event_pump.poll_iter() {
+            match event {
+                Event::Quit { .. }
+                | Event::KeyDown {
+                    keycode: Some(Keycode::Escape),
+                    ..
+                } => break 'running,
+                _ => {}
+            }
+        }
+
+        canvas.clear();
+        canvas.present();
+        ::std::thread::sleep(Duration::new(0, 1_000_000_000u32 / 30));
+        // The rest of the game loop goes here...
+    }
+
+    Ok(())
+}