be able to trigger a loading screen anywhere

editor/src/abtest/setup.rs

@@ -1,7 +1,6 @@
 use crate::abtest::{ABTestMode, State};
 use crate::game::{GameState, Mode};
 use crate::ui::{Flags, PerMapUI, UI};
-use abstutil::Timer;
 use ezgui::{EventCtx, GfxCtx, Key, LogScroller, ModalMenu, Wizard, WrappedWizard};
 use map_model::Map;
 use sim::{ABTest, SimFlags};
@@ -103,35 +102,37 @@ fn launch_test(test: &ABTest, ui: &mut UI, ctx: &mut EventCtx) -> Mode {
 
     // TODO Cheaper to load the edits for the map and then instantiate the scenario for the
     // primary.
-    let mut timer = Timer::new("setup A/B test");
-    let primary = PerMapUI::new(
-        Flags {
-            sim_flags: SimFlags {
-                load: load.clone(),
-                rng_seed,
-                run_name: format!("{} with {}", test.test_name, test.edits1_name),
-                edits_name: test.edits1_name.clone(),
+    let (primary, secondary) = ctx.loading_screen(|ctx, timer| {
+        let primary = PerMapUI::new(
+            Flags {
+                sim_flags: SimFlags {
+                    load: load.clone(),
+                    rng_seed,
+                    run_name: format!("{} with {}", test.test_name, test.edits1_name),
+                    edits_name: test.edits1_name.clone(),
+                },
+                ..current_flags.clone()
             },
-            ..current_flags.clone()
-        },
-        &ui.cs,
-        ctx.prerender,
-        &mut timer,
-    );
-    let secondary = PerMapUI::new(
-        Flags {
-            sim_flags: SimFlags {
-                load,
-                rng_seed,
-                run_name: format!("{} with {}", test.test_name, test.edits2_name),
-                edits_name: test.edits2_name.clone(),
+            &ui.cs,
+            ctx.prerender,
+            timer,
+        );
+        let secondary = PerMapUI::new(
+            Flags {
+                sim_flags: SimFlags {
+                    load,
+                    rng_seed,
+                    run_name: format!("{} with {}", test.test_name, test.edits2_name),
+                    edits_name: test.edits2_name.clone(),
+                },
+                ..current_flags.clone()
             },
-            ..current_flags.clone()
-        },
-        &ui.cs,
-        ctx.prerender,
-        &mut timer,
-    );
+            &ui.cs,
+            ctx.prerender,
+            timer,
+        );
+        (primary, secondary)
+    });
 
     ui.primary = primary;
     let mut mode = ABTestMode::new(ctx);

editor/src/game.rs

@@ -246,8 +246,9 @@ fn splash_screen(
                     // This retains no state, but that's probably fine.
                     let mut flags = ui.primary.current_flags.clone();
                     flags.sim_flags.load = PathBuf::from(format!("../data/maps/{}.abst", name));
-                    let mut timer = Timer::new(&format!("load {}", name));
-                    *ui = UI::new(flags, ctx.prerender, ctx.canvas, &mut timer);
+                    *ui = ctx.loading_screen(|ctx, timer| {
+                        UI::new(flags, ctx.prerender, ctx.canvas, timer)
+                    });
                     break Some(Mode::Sandbox(SandboxMode::new(ctx.canvas)));
                 } else if wizard.aborted() {
                     break Some(Mode::SplashScreen(Wizard::new(), maybe_screensaver.take()));

editor/src/mission/scenario.rs

@@ -2,7 +2,7 @@ use crate::game::Mode;
 use crate::mission::MissionEditMode;
 use crate::sandbox::SandboxMode;
 use crate::ui::UI;
-use abstutil::{Timer, WeightedUsizeChoice};
+use abstutil::WeightedUsizeChoice;
 use ezgui::{
     Color, Drawable, EventCtx, GfxCtx, Key, LogScroller, ModalMenu, Wizard, WrappedWizard,
 };
@@ -58,12 +58,14 @@ impl ScenarioEditor {
                 } else if menu.action("edit") {
                     *self = ScenarioEditor::EditScenario(scenario.clone(), Wizard::new());
                 } else if menu.action("instantiate") {
-                    scenario.instantiate(
-                        &mut ui.primary.sim,
-                        &ui.primary.map,
-                        &mut ui.primary.current_flags.sim_flags.make_rng(),
-                        &mut Timer::new("instantiate scenario"),
-                    );
+                    ctx.loading_screen(|_, timer| {
+                        scenario.instantiate(
+                            &mut ui.primary.sim,
+                            &ui.primary.map,
+                            &mut ui.primary.current_flags.sim_flags.make_rng(),
+                            timer,
+                        );
+                    });
                     return Some(Mode::Sandbox(SandboxMode::new(ctx.canvas)));
                 } else if menu.action("visualize") {
                     let neighborhoods = Neighborhood::load_all(

editor/src/sandbox/spawner.rs

@@ -91,13 +91,18 @@ impl AgentSpawner {
             None => {
                 if ui.primary.sim.is_empty() {
                     if sandbox_menu.action("seed the sim with agents") {
-                        Scenario::scaled_run(map, ui.primary.current_flags.num_agents).instantiate(
-                            &mut ui.primary.sim,
-                            map,
-                            &mut ui.primary.current_flags.sim_flags.make_rng(),
-                            &mut Timer::new("seed sim"),
-                        );
-                        ui.primary.sim.step(map);
+                        // TODO This covers up the map. :\
+                        ctx.loading_screen(|_, timer| {
+                            let map = &ui.primary.map;
+                            Scenario::scaled_run(map, ui.primary.current_flags.num_agents)
+                                .instantiate(
+                                    &mut ui.primary.sim,
+                                    map,
+                                    &mut ui.primary.current_flags.sim_flags.make_rng(),
+                                    timer,
+                                );
+                            ui.primary.sim.step(map);
+                        });
                     }
                 }
             }

ezgui/src/event_ctx.rs

@@ -1,4 +1,6 @@
+use crate::runner::LoadingScreen;
 use crate::{Canvas, Color, UserInput};
+use abstutil::Timer;
 use geom::Polygon;
 use glium::implement_vertex;
 use std::cell::Cell;
@@ -112,6 +114,23 @@ pub struct EventCtx<'a> {
     // TODO These two probably shouldn't be public
     pub canvas: &'a mut Canvas,
     pub prerender: &'a Prerender<'a>,
+
+    pub(crate) program: &'a glium::Program,
+}
+
+impl<'a> EventCtx<'a> {
+    pub fn loading_screen<O, F: FnOnce(&mut EventCtx, &mut Timer) -> O>(&mut self, f: F) -> O {
+        let mut timer = Timer::new_with_sink(
+            "Loading...",
+            Box::new(LoadingScreen::new(
+                self.prerender,
+                self.program,
+                self.canvas.window_width,
+                self.canvas.window_height,
+            )),
+        );
+        f(self, &mut timer)
+    }
 }
 
 fn f32_to_u8(x: f32) -> u8 {

ezgui/src/runner.rs

@@ -48,7 +48,12 @@ pub(crate) struct State<G: GUI> {
 
 impl<G: GUI> State<G> {
     // The bool indicates if the input was actually used.
-    fn event(mut self, ev: Event, prerender: &Prerender) -> (State<G>, EventLoopMode, bool) {
+    fn event(
+        mut self,
+        ev: Event,
+        prerender: &Prerender,
+        program: &glium::Program,
+    ) -> (State<G>, EventLoopMode, bool) {
         // Clear out the possible keys
         match self.context_menu {
             ContextMenu::Inactive(_) => {
@@ -67,6 +72,7 @@ impl<G: GUI> State<G> {
                 input: &mut input,
                 canvas: &mut canvas,
                 prerender,
+                program,
             })
         })) {
             Ok(pair) => pair,
@@ -195,7 +201,6 @@ pub fn run<G: GUI, F: FnOnce(&mut Canvas, &Prerender, &mut Timer) -> G>(
         let mut timer = Timer::new_with_sink(
             "Loading application...",
             Box::new(LoadingScreen::new(
-                &display,
                 &prerender,
                 &program,
                 initial_width,
@@ -261,7 +266,7 @@ fn loop_forever<G: GUI>(
         let mut any_input_used = false;
 
         for event in new_events {
-            let (new_state, mode, input_used) = state.event(event, &prerender);
+            let (new_state, mode, input_used) = state.event(event, &prerender, &program);
             if input_used {
                 any_input_used = true;
             }
@@ -313,8 +318,7 @@ fn loop_forever<G: GUI>(
     }
 }
 
-struct LoadingScreen<'a> {
-    display: &'a glium::Display,
+pub struct LoadingScreen<'a> {
     canvas: Canvas,
     prerender: &'a Prerender<'a>,
     program: &'a glium::Program,
@@ -322,8 +326,7 @@ struct LoadingScreen<'a> {
 }
 
 impl<'a> LoadingScreen<'a> {
-    fn new(
-        display: &'a glium::Display,
+    pub fn new(
         prerender: &'a Prerender<'a>,
         program: &'a glium::Program,
         initial_width: f64,
@@ -331,11 +334,10 @@ impl<'a> LoadingScreen<'a> {
     ) -> LoadingScreen<'a> {
         // TODO Ew! Expensive and wacky. Fix by not storing GlyphBrush in Canvas at all.
         let dejavu: &[u8] = include_bytes!("assets/DejaVuSans.ttf");
-        let glyphs = GlyphBrush::new(display, vec![Font::from_bytes(dejavu).unwrap()]);
+        let glyphs = GlyphBrush::new(prerender.display, vec![Font::from_bytes(dejavu).unwrap()]);
         let canvas = Canvas::new(initial_width, initial_height, glyphs);
 
         LoadingScreen {
-            display,
             canvas,
             prerender,
             program,
@@ -344,12 +346,12 @@ impl<'a> LoadingScreen<'a> {
     }
 
     fn redraw(&self, text: Text) {
-        let mut target = self.display.draw();
+        let mut target = self.prerender.display.draw();
         let context_menu = ContextMenu::new();
         let mut g = GfxCtx::new(
             &self.canvas,
             self.prerender,
-            self.display,
+            self.prerender.display,
             &mut target,
             self.program,
             &context_menu,