Viewport frame-rate readout (Preferences ▸ Graphics) (#1580)

Thanks @sthifen.

crates/ui-egui/src/lib.rs

@@ -44,6 +44,7 @@ pub mod drag_snap;
 pub mod edit_clipboard;
 pub mod fonts;
 pub mod frame;
+pub mod frame_rate;
 pub mod gizmo;
 pub mod gpu;
 pub mod help;
@@ -353,6 +354,8 @@ pub struct SolveApp {
     /// [`SolveApp::set_wgpu`].
     pub cpu_meshing: bool,
     pub frame_ms: f64,
+    /// The viewport's frame-rate readout ([`frame_rate`]).
+    pub frame_rate: frame_rate::FrameRate,
     pub synthetic: Vec<egui::Event>,
     /// The modifiers of the synthetic press in progress (a Ctrl-drag keeps Ctrl while it moves).
     pub synthetic_mods: egui::Modifiers,
@@ -446,6 +449,7 @@ impl SolveApp {
             integrated_titlebar: false,
             cpu_meshing: false,
             frame_ms: 0.0,
+            frame_rate: frame_rate::FrameRate::default(),
             synthetic: Vec::new(),
             synthetic_mods: egui::Modifiers::default(),
             control_rx: None,