Max FPS setting, and repaint at least once per second

src/settings.rs

@@ -12,6 +12,7 @@ pub const DEFAULT_VIEW_POSTS_REFERRING_TO: bool = false;
 pub const DEFAULT_VIEW_THREADED: bool = true;
 pub const DEFAULT_NUM_RELAYS_PER_PERSON: u8 = 2;
 pub const DEFAULT_MAX_RELAYS: u8 = 15;
+pub const DEFAULT_MAX_FPS: u32 = 60;
 
 #[derive(Clone, Debug, Deserialize, Serialize)]
 pub struct Settings {
@@ -25,6 +26,7 @@ pub struct Settings {
     pub max_relays: u8,
     pub public_key: Option<PublicKey>,
     pub encrypted_private_key: Option<EncryptedPrivateKey>,
+    pub max_fps: u32,
 }
 
 impl Default for Settings {
@@ -40,6 +42,7 @@ impl Default for Settings {
             max_relays: DEFAULT_MAX_RELAYS,
             public_key: None,
             encrypted_private_key: None,
+            max_fps: DEFAULT_MAX_FPS,
         }
     }
 }
@@ -89,6 +92,7 @@ impl Settings {
                         }
                     }
                 }
+                "max_fps" => settings.max_fps = row.1.parse::<u32>().unwrap_or(DEFAULT_MAX_FPS),
                 _ => {}
             }
         }
@@ -105,7 +109,7 @@ impl Settings {
                                    ('feed_chunk', ?),('overlap', ?),('autofollow', ?),\
                                    ('view_posts_referred_to', ?),('view_posts_referring_to', ?),\
                                    ('view_threaded', ?),('num_relays_per_person', ?), \
-                                   ('max_relays', ?)",
+                                   ('max_relays', ?),('max_fps', ?)",
         )?;
         stmt.execute((
             self.feed_chunk,
@@ -124,6 +128,7 @@ impl Settings {
             if self.view_threaded { "1" } else { "0" },
             self.num_relays_per_person,
             self.max_relays,
+            self.max_fps,
         ))?;
 
         // Save private key identity

src/ui/mod.rs

@@ -15,6 +15,7 @@ use crate::settings::Settings;
 use eframe::{egui, IconData, Theme};
 use egui::{ColorImage, Context, ImageData, TextureHandle, TextureOptions};
 use nostr_types::{PublicKey, PublicKeyHex};
+use std::time::{Duration, Instant};
 use zeroize::Zeroize;
 
 pub fn run() -> Result<(), Error> {
@@ -59,6 +60,7 @@ enum Page {
 }
 
 struct GossipUi {
+    next_frame: Instant,
     page: Page,
     about: About,
     icon: TextureHandle,
@@ -123,6 +125,7 @@ impl GossipUi {
         let settings = GLOBALS.settings.blocking_read().clone();
 
         GossipUi {
+            next_frame: Instant::now(),
             page: Page::Feed,
             about: crate::about::about(),
             icon: icon_texture_handle,
@@ -142,6 +145,13 @@ impl GossipUi {
 
 impl eframe::App for GossipUi {
     fn update(&mut self, ctx: &Context, frame: &mut eframe::Frame) {
+        // Wait until the next frame
+        std::thread::sleep(self.next_frame - Instant::now());
+        self.next_frame += Duration::from_secs_f32(1.0 / self.settings.max_fps as f32);
+
+        // Redraw at least once per second
+        ctx.request_repaint_after(Duration::from_secs(1));
+
         if GLOBALS
             .shutting_down
             .load(std::sync::atomic::Ordering::Relaxed)

src/ui/settings.rs

@@ -77,7 +77,7 @@ pub(super) fn update(
     .on_hover_text("Definately not recommended. In fact we may remove this soon.");
 
     ui.add_space(24.0);
-    ui.heading("Style");
+    ui.heading("User Interface");
 
     ui.horizontal(|ui| {
         ui.label("Switch to");
@@ -102,6 +102,15 @@ pub(super) fn update(
         }
     });
 
+    ui.add_space(24.0);
+    ui.horizontal(|ui| {
+        ui.label("Maximum FPS: ")
+            .on_hover_text(
+                "The UI redraws every frame. By limiting the maximum FPS you can reduce load on your CPU. Takes effect immediately.",
+            );
+        ui.add(Slider::new(&mut app.settings.max_fps, 10..=60).text("Frames per second"));
+    });
+
     ui.add_space(32.0);
     ui.with_layout(Layout::top_down(Align::Center), |ui| {
         if ui.button("SAVE CHANGES").clicked() {