Implement get_fps and get_delta_time

* implement get fps

* fix wasm

* add doc get fps

* rename from get_rate to get_delta_time

Author: Luca00casati

src/lib.rs

@@ -631,6 +631,24 @@ impl Window {
         }
     }
 
+    /// Returns the current fps of the window
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// # use minifb::*;
+    /// # let mut window = Window::new("Test", 640, 400, WindowOptions::default()).unwrap();
+    /// let fps = window.get_fps();
+    /// println!("fps {}", fps);
+    /// ```
+    #[inline]
+    pub fn get_fps(&mut self) -> usize {
+        match self.0.get_delta_time() {
+            Some(rate) => (1.0 / rate.as_secs_f32()) as usize,
+            _ => 0,
+        }
+    }
+
     /// Returns the current size of the window
     ///
     /// # Examples

src/os/macos/mod.rs

@@ -344,6 +344,11 @@ impl Window {
         self.update_rate.set_rate(rate);
     }
 
+    #[inline]
+    pub fn get_delta_time(&self) -> Option<Duration> {
+        self.update_rate.get_delta_time()
+    }
+
     #[inline]
     pub fn update_rate(&mut self) {
         self.update_rate.update();

src/os/posix/mod.rs

@@ -225,6 +225,15 @@ impl Window {
         }
     }
 
+    pub fn get_delta_time(&self) -> Option<Duration> {
+        match self {
+            #[cfg(feature = "x11")]
+            Window::X11(w) => w.get_delta_time(),
+            #[cfg(feature = "wayland")]
+            Window::Wayland(w) => w.get_delta_time(),
+        }
+    }
+
     pub fn update_rate(&mut self) {
         match self {
             #[cfg(feature = "x11")]

src/os/posix/wayland.rs

@@ -672,6 +672,11 @@ impl Window {
         self.update_rate.set_rate(rate);
     }
 
+    #[inline]
+    pub fn get_delta_time(&self) -> Option<Duration> {
+        self.update_rate.get_delta_time()
+    }
+
     #[inline]
     pub fn set_key_repeat_rate(&mut self, rate: f32) {
         self.key_handler.set_key_repeat_delay(rate);

src/os/posix/x11.rs

@@ -769,6 +769,11 @@ impl Window {
         self.update_rate.set_rate(rate);
     }
 
+    #[inline]
+    pub fn get_delta_time(&self) -> Option<Duration> {
+        self.update_rate.get_delta_time()
+    }
+
     #[inline]
     pub fn update_rate(&mut self) {
         self.update_rate.update();

src/os/wasm/mod.rs

@@ -228,6 +228,11 @@ impl Window {
     #[inline]
     pub fn set_rate(&mut self, _rate: Option<Duration>) {}
 
+    #[inline]
+    pub fn get_delta_time(&self) -> Option<Duration> {
+        None
+    }
+
     #[inline]
     pub fn update_rate(&mut self) {}
 

src/os/windows/mod.rs

@@ -870,6 +870,11 @@ impl Window {
         self.update_rate.set_rate(rate);
     }
 
+    #[inline]
+    pub fn get_delta_time(&self) -> Option<Duration> {
+        self.update_rate.get_delta_time()
+    }
+
     #[inline]
     pub fn update_rate(&mut self) {
         self.update_rate.update();

src/rate.rs

@@ -9,34 +9,45 @@ use std::time::{Duration, Instant};
 pub struct UpdateRate {
     target_rate: Option<Duration>,
     prev_time: Instant,
+    delta: Option<Duration>,
 }
 
 #[cfg_attr(target_arch = "wasm32", allow(unused))]
 impl UpdateRate {
-    pub fn new() -> UpdateRate {
-        UpdateRate {
-            // Default limit to 4 ms
+    pub fn new() -> Self {
+        Self {
+            // Default target rate: 4 ms per frame (~250 FPS)
             target_rate: Some(Duration::from_millis(4)),
             prev_time: Instant::now(),
+            delta: None,
         }
     }
 
     #[inline]
     pub fn set_rate(&mut self, rate: Option<Duration>) {
-        self.target_rate = rate
+        self.target_rate = rate;
     }
 
     pub fn update(&mut self) {
-        if let Some(target_rate) = self.target_rate {
-            let delta = self.prev_time.elapsed();
+        let now = Instant::now();
+        let elapsed = now.duration_since(self.prev_time);
 
-            if delta < target_rate {
-                let sleep_time = target_rate - delta;
-                //eprintln!("sleeping {} ms", sleep_time.as_secs_f64() * 1000.);
+        // If a target rate is set, sleep to match it
+        if let Some(target_rate) = self.target_rate {
+            if elapsed < target_rate {
+                let sleep_time = target_rate - elapsed;
                 std::thread::sleep(sleep_time);
             }
-
-            self.prev_time = Instant::now();
         }
+
+        // Now mark the new frame time and compute total delta (including sleep)
+        let now = Instant::now();
+        self.delta = Some(now.duration_since(self.prev_time));
+        self.prev_time = now;
+    }
+
+    #[inline]
+    pub fn get_delta_time(&self) -> Option<Duration> {
+        self.delta
     }
 }