Feat: WIP pattern view redesign

src/engine/sequencer.rs

@@ -149,6 +149,7 @@ pub struct ActivePatternState {
     pub pattern: usize,
     pub step_index: usize,
     pub iter: usize,
+    pub last_step_beat: f64,
 }
 
 pub type StepTracesMap = HashMap<(usize, usize, usize), ExecutionTrace>;
@@ -208,6 +209,19 @@ impl SequencerSnapshot {
             .map(|p| p.step_index)
     }
 
+    /// Returns smooth progress (0.0..1.0) through the pattern by interpolating
+    /// between discrete steps using beat timing.
+    pub fn get_smooth_progress(&self, bank: usize, pattern: usize, length: usize, speed_mult: f64) -> Option<f64> {
+        let p = self.active_patterns.iter().find(|p| p.bank == bank && p.pattern == pattern)?;
+        if length == 0 || self.tempo <= 0.0 {
+            return Some(0.0);
+        }
+        let step_duration_beats = 1.0 / (4.0 * speed_mult);
+        let elapsed = (self.beat - p.last_step_beat).max(0.0);
+        let phase = (elapsed / step_duration_beats).clamp(0.0, 1.0);
+        Some((p.step_index as f64 + phase) / length as f64)
+    }
+
     pub fn get_iter(&self, bank: usize, pattern: usize) -> Option<usize> {
         self.active_patterns
             .iter()
@@ -260,6 +274,7 @@ struct ActivePattern {
     pattern: usize,
     step_index: usize,
     iter: usize,
+    last_step_beat: f64,
 }
 
 #[derive(Clone, Copy)]
@@ -821,6 +836,7 @@ impl SequencerState {
                         pattern: pending.id.pattern,
                         step_index: start_step,
                         iter: 0,
+                        last_step_beat: beat,
                     },
                 );
                 self.buf_activated.push(pending.id);
@@ -902,6 +918,7 @@ impl SequencerState {
 
             for step_beat in step_beats {
                 result.any_step_fired = true;
+                active.last_step_beat = step_beat;
                 let step_idx = active.step_index % pattern.length;
 
                 let beat_delta = step_beat - beat;
@@ -1099,6 +1116,7 @@ impl SequencerState {
                     pattern: a.pattern,
                     step_index: a.step_index,
                     iter: a.iter,
+                    last_step_beat: a.last_step_beat,
                 })
                 .collect(),
             step_traces: Arc::clone(&self.step_traces),