implement scrolling using arrow keys

Cargo.lock

@@ -1072,7 +1072,7 @@ checksum = "c7d73b3f436185384286bd8098d17ec07c9a7d2388a6599f824d8502b529702a"
 [[package]]
 name = "libosu"
 version = "0.0.15"
-source = "git+https://github.com/iptq/libosu?rev=7f5e8fd6bdf2798dd40df9595ce630ebc27ac13e#7f5e8fd6bdf2798dd40df9595ce630ebc27ac13e"
+source = "git+https://github.com/iptq/libosu?rev=7fbe7afbad55b25398062719ebaccbff0387d139#7fbe7afbad55b25398062719ebaccbff0387d139"
 dependencies = [
  "anyhow",
  "bitflags",

Cargo.toml

@@ -4,6 +4,9 @@ version = "0.1.0"
 authors = ["Michael Zhang <mail@mzhang.io>"]
 edition = "2018"
 
+[profile.release]
+debug = true
+
 [workspace]
 members = [
     "bass-sys",
@@ -21,4 +24,4 @@ structopt = "0.3.21"
 
 [dependencies.libosu]
 git = "https://github.com/iptq/libosu"
-rev = "7f5e8fd6bdf2798dd40df9595ce630ebc27ac13e"
+rev = "7fbe7afbad55b25398062719ebaccbff0387d139"

src/game/mod.rs

@@ -19,6 +19,7 @@ use libosu::{
     hitobject::{HitObjectKind, SpinnerInfo},
     math::Point,
     spline::Spline,
+    timing::TimingPointKind,
 };
 
 use crate::audio::{AudioEngine, Sound};
@@ -26,7 +27,7 @@ use crate::beatmap::{BeatmapExt, STACK_DISTANCE};
 use crate::hitobject::HitObjectExt;
 use crate::skin::Skin;
 
-pub const PLAYFIELD_BOUNDS: Rect = Rect::new(112.0, 112.0, 800.0, 600.0);
+pub const PLAYFIELD_BOUNDS: Rect = Rect::new(112.0, 122.0, 800.0, 600.0);
 
 pub type SliderCache = HashMap<Vec<Point<i32>>, Spline>;
 
@@ -274,6 +275,32 @@ impl Game {
         self.frame += 1;
         Ok(())
     }
+
+    fn seek_by_steps(&self, n: i32) -> Result<()> {
+        if let Some(song) = &self.song {
+            let pos = song.position()?;
+            let mut delta = None;
+            for timing_point in self.beatmap.inner.timing_points.iter() {
+                if let TimingPointKind::Uninherited(info) = &timing_point.kind {
+                    if pos > timing_point.time.as_seconds() {
+                        let diff = pos - timing_point.time.as_seconds();
+                        let tick = info.mpb / 1000.0 / info.meter as f64;
+                        if (diff / tick).abs() < 0.001 {
+                            delta = Some(n as f64 * tick);
+                        } else {
+                            let tick = info.mpb / 1000.0;
+                            delta = Some(n as f64 * tick);
+                        }
+                        break;
+                    }
+                }
+            }
+            if let Some(delta) = delta {
+                song.set_position(pos + delta)?;
+            }
+        }
+        Ok(())
+    }
 }
 
 impl EventHandler for Game {
@@ -287,7 +314,20 @@ impl EventHandler for Game {
             Space => self.toggle_playing(),
             Colon => {}
             _ => {}
-        }
+        };
+    }
+
+    fn key_down_event(&mut self, _: &mut Context, keycode: KeyCode, _: KeyMods, _: bool) {
+        use KeyCode::*;
+        match keycode {
+            Left => {
+                self.seek_by_steps(-1);
+            }
+            Right => {
+                self.seek_by_steps(1);
+            }
+            _ => {}
+        };
     }
 
     fn draw(&mut self, ctx: &mut Context) -> GameResult {

src/game/seeker.rs

@@ -1,13 +1,14 @@
 use anyhow::Result;
 use ggez::{
-    graphics::{self, DrawParam, Mesh, Rect},
+    graphics::{self, Color, DrawParam, Mesh, Rect},
     nalgebra::Point2,
     Context,
 };
+use libosu::timing::TimingPointKind;
 
 use super::Game;
 
-pub const BOUNDS: Rect = Rect::new(46.0, 722.0, 932.0, 36.0);
+pub const BOUNDS: Rect = Rect::new(46.0, 732.0, 932.0, 36.0);
 
 impl Game {
     pub(super) fn draw_seeker(&self, ctx: &mut Context) -> Result<()> {
@@ -24,7 +25,30 @@ impl Game {
         graphics::draw(ctx, &line, DrawParam::default())?;
 
         if let Some(song) = &self.song {
-            let percent = song.position()? / song.length()?;
+            let len = song.length()?;
+
+            for timing_point in self.beatmap.inner.timing_points.iter() {
+                let color = match timing_point.kind {
+                    TimingPointKind::Inherited(_) => Color::new(0.0, 1.0, 0.0, 0.5),
+                    TimingPointKind::Uninherited(_) => Color::new(1.0, 0.0, 0.0, 0.5),
+                };
+
+                let percent = timing_point.time.as_seconds() / len;
+                let x = BOUNDS.x + percent as f32 * BOUNDS.w;
+
+                let line = Mesh::new_line(
+                    ctx,
+                    &[
+                        Point2::new(x, BOUNDS.y),
+                        Point2::new(x, BOUNDS.y + BOUNDS.h),
+                    ],
+                    1.0,
+                    color,
+                )?;
+                graphics::draw(ctx, &line, DrawParam::default())?;
+            }
+
+            let percent = song.position()? / len;
             let x = BOUNDS.x + percent as f32 * BOUNDS.w;
             let line = Mesh::new_line(
                 ctx,