Improve fps_overlay example (#15739)

This PR improves the `fps_overlay` example by adding:

1. The ability to increase the overlay font size (previously, only
decreasing the size was supported).
2. A toggle for overlay color between red and green (previously, it only
changed from green to red without toggling back).

examples/dev_tools/fps_overlay.rs

@@ -5,6 +5,13 @@ use bevy::{
  prelude::*,
 };
 
+struct OverlayColor;
+
+impl OverlayColor {
+ const RED: Color = Color::srgb(1.0, 0.0, 0.0);
+ const GREEN: Color = Color::srgb(0.0, 1.0, 0.0);
+}
+
 fn main() {
  App::new()
  .add_plugins((
@@ -15,7 +22,7 @@ fn main() {
  // Here we define size of our overlay
  font_size: 42.0,
  // We can also change color of the overlay
- color: Color::srgb(0.0, 1.0, 0.0),
+ color: OverlayColor::GREEN,
  // If we want, we can use a custom font
  font: default(),
  },
@@ -47,9 +54,10 @@ fn setup(mut commands: Commands) {
  .with_children(|c| {
  c.spawn(TextBundle::from_section(
  concat!(
- "Press 1 to change color of the overlay.\n",
- "Press 2 to change size of the overlay.\n",
- "Press 3 to toggle the overlay."
+ "Press 1 to toggle the overlay color.\n",
+ "Press 2 to decrease the overlay size.\n",
+ "Press 3 to increase the overlay size.\n",
+ "Press 4 to toggle the overlay visibility."
  ),
  TextStyle::default(),
  ));
@@ -59,12 +67,19 @@ fn setup(mut commands: Commands) {
 fn customize_config(input: Res<ButtonInput<KeyCode>>, mut overlay: ResMut<FpsOverlayConfig>) {
  if input.just_pressed(KeyCode::Digit1) {
  // Changing resource will affect overlay
- overlay.text_config.color = Color::srgb(1.0, 0.0, 0.0);
+ if overlay.text_config.color == OverlayColor::GREEN {
+ overlay.text_config.color = OverlayColor::RED;
+ } else {
+ overlay.text_config.color = OverlayColor::GREEN;
+ }
  }
  if input.just_pressed(KeyCode::Digit2) {
  overlay.text_config.font_size -= 2.0;
  }
  if input.just_pressed(KeyCode::Digit3) {
+ overlay.text_config.font_size += 2.0;
+ }
+ if input.just_pressed(KeyCode::Digit4) {
  overlay.enabled = !overlay.enabled;
  }
 }