Adds update interval config for FpsOverlayPlugin (#17489)

# Objective
Fixes #17487 

- Adds a new field `refresh_interval` to `FpsOverlayConfig` to allow the
user setting a minimum time before each refresh of the FPS display

## Solution

- Add `refresh_interval` to `FpsOverlayConfig`
- When updating the on screen text, check a duration of
`refresh_interval` has passed, if not, don't update the FPS counter

## Testing

- Created a new bevy project
- Included the `FpsOverlayPlugin` with the default `refresh_interval`
(100 ms)
- Included the `FpsOverlayPlugin` with an obnoxious `refresh_interval`
(2 seconds)
---

---------

Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>

crates/bevy_dev_tools/src/fps_overlay.rs

@@ -8,6 +8,7 @@ use bevy_ecs::{
     change_detection::DetectChangesMut,
     component::Component,
     entity::Entity,
+    prelude::Local,
     query::With,
     resource::Resource,
     schedule::{common_conditions::resource_changed, IntoSystemConfigs},
@@ -15,10 +16,12 @@ use bevy_ecs::{
 };
 use bevy_render::view::Visibility;
 use bevy_text::{Font, TextColor, TextFont, TextSpan};
+use bevy_time::Time;
 use bevy_ui::{
     widget::{Text, TextUiWriter},
     GlobalZIndex, Node, PositionType,
 };
+use core::time::Duration;
 
 /// [`GlobalZIndex`] used to render the fps overlay.
 ///
@@ -65,6 +68,10 @@ pub struct FpsOverlayConfig {
     pub text_color: Color,
     /// Displays the FPS overlay if true.
     pub enabled: bool,
+    /// The period after which the FPS overlay re-renders.
+    ///
+    /// Defaults to once every 100 ms.
+    pub refresh_interval: Duration,
 }
 
 impl Default for FpsOverlayConfig {
@@ -77,6 +84,7 @@ impl Default for FpsOverlayConfig {
             },
             text_color: Color::WHITE,
             enabled: true,
+            refresh_interval: Duration::from_millis(100),
         }
     }
 }
@@ -110,11 +118,18 @@ fn update_text(
     diagnostic: Res<DiagnosticsStore>,
     query: Query<Entity, With<FpsText>>,
     mut writer: TextUiWriter,
+    time: Res<Time>,
+    config: Res<FpsOverlayConfig>,
+    mut time_since_rerender: Local<Duration>,
 ) {
-    for entity in &query {
-        if let Some(fps) = diagnostic.get(&FrameTimeDiagnosticsPlugin::FPS) {
-            if let Some(value) = fps.smoothed() {
-                *writer.text(entity, 1) = format!("{value:.2}");
+    *time_since_rerender += time.delta();
+    if *time_since_rerender >= config.refresh_interval {
+        *time_since_rerender = Duration::ZERO;
+        for entity in &query {
+            if let Some(fps) = diagnostic.get(&FrameTimeDiagnosticsPlugin::FPS) {
+                if let Some(value) = fps.smoothed() {
+                    *writer.text(entity, 1) = format!("{value:.2}");
+                }
             }
         }
     }

examples/dev_tools/fps_overlay.rs

@@ -30,6 +30,8 @@ fn main() {
                     },
                     // We can also change color of the overlay
                     text_color: OverlayColor::GREEN,
+                    // We can also set the refresh interval for the FPS counter
+                    refresh_interval: core::time::Duration::from_millis(100),
                     enabled: true,
                 },
             },