add --fps parameter to output fps

uw8-window/src/lib.rs

@@ -4,31 +4,64 @@ use std::time::Instant;
 mod cpu;
 mod gpu;
 
-pub struct Window(Box<dyn WindowImpl>);
+pub struct Window {
+    inner: Box<dyn WindowImpl>,
+    fps_counter: Option<FpsCounter>,
+}
+
+struct FpsCounter {
+    start: Instant,
+    num_frames: u32,
+}
 
 impl Window {
     pub fn new(config: WindowConfig) -> Result<Window> {
+        let fps_counter = if config.fps_counter {
+            Some(FpsCounter {
+                start: Instant::now(),
+                num_frames: 0,
+            })
+        } else {
+            None
+        };
         if config.enable_gpu {
             match gpu::Window::new(config) {
-                Ok(window) => return Ok(Window(Box::new(window))),
+                Ok(window) => {
+                    return Ok(Window {
+                        inner: Box::new(window),
+                        fps_counter,
+                    })
+                }
                 Err(err) => eprintln!(
                     "Failed to create gpu window: {}\nFalling back tp cpu window",
                     err
                 ),
             }
         }
-        cpu::Window::new().map(|window| Window(Box::new(window)))
+        cpu::Window::new().map(|window| Window {
+            inner: Box::new(window),
+            fps_counter,
+        })
     }
 
     pub fn begin_frame(&mut self) -> Input {
-        self.0.begin_frame()
+        self.inner.begin_frame()
     }
     pub fn end_frame(&mut self, framebuffer: &[u8], palette: &[u8], next_frame: Instant) {
-        self.0.end_frame(framebuffer, palette, next_frame)
+        self.inner.end_frame(framebuffer, palette, next_frame);
+        if let Some(ref mut fps_counter) = self.fps_counter {
+            fps_counter.num_frames += 1;
+            let elapsed = fps_counter.start.elapsed().as_secs_f32();
+            if elapsed >= 1.0 {
+                println!("fps: {:.1}", fps_counter.num_frames as f32 / elapsed);
+                fps_counter.num_frames = 0;
+                fps_counter.start = Instant::now();
+            }
+        }
     }
 
     pub fn is_open(&self) -> bool {
-        self.0.is_open()
+        self.inner.is_open()
     }
 }
 
@@ -37,6 +70,7 @@ pub struct WindowConfig {
     enable_gpu: bool,
     filter: u32,
     fullscreen: bool,
+    fps_counter: bool,
 }
 
 impl Default for WindowConfig {
@@ -45,6 +79,7 @@ impl Default for WindowConfig {
             enable_gpu: true,
             filter: 5,
             fullscreen: false,
+            fps_counter: false,
         }
     }
 }
@@ -66,6 +101,7 @@ impl WindowConfig {
             }
         }
         self.fullscreen = args.contains("--fullscreen");
+        self.fps_counter = args.contains("--fps");
     }
 }