feat: enhance time interval calculation for zoom level in SequencerCanvas

src/components/sequencer/SequencerCanvas.tsx

@@ -125,6 +125,52 @@ function TrackRow({ track, duration, zoom, isPlaying, currentTime, draggedItem,
     onRemoveSound(soundId, track.id)
   }
 
+  // Calculate logical time intervals based on zoom level (same as main component)
+  const getTimeIntervals = (zoom: number, duration: number) => {
+    const durationSeconds = duration / 1000
+    const minorIntervals: number[] = []
+    const majorIntervals: number[] = []
+    
+    // Define logical interval progressions
+    const intervalSets = [
+      { minor: 1, major: 5 },      // 1s minor, 5s major (very zoomed in)
+      { minor: 5, major: 30 },     // 5s minor, 30s major 
+      { minor: 10, major: 60 },    // 10s minor, 1min major
+      { minor: 30, major: 300 },   // 30s minor, 5min major
+      { minor: 60, major: 600 },   // 1min minor, 10min major
+      { minor: 300, major: 1800 }, // 5min minor, 30min major
+      { minor: 600, major: 3600 }  // 10min minor, 1h major
+    ]
+    
+    // Find appropriate interval set based on zoom level
+    // We want major intervals to be roughly 100-200px apart
+    const targetMajorSpacing = 150
+    
+    let selectedIntervals = intervalSets[intervalSets.length - 1] // fallback to largest
+    for (const intervals of intervalSets) {
+      if (intervals.major * zoom >= targetMajorSpacing) {
+        selectedIntervals = intervals
+        break
+      }
+    }
+    
+    // Generate minor intervals (every interval)
+    for (let i = 0; i * selectedIntervals.minor <= durationSeconds; i++) {
+      const time = i * selectedIntervals.minor
+      minorIntervals.push(time)
+    }
+    
+    // Generate major intervals (at major boundaries)
+    for (let i = 0; i * selectedIntervals.major <= durationSeconds; i++) {
+      const time = i * selectedIntervals.major
+      majorIntervals.push(time)
+    }
+    
+    return { minorIntervals, majorIntervals, minorInterval: selectedIntervals.minor, majorInterval: selectedIntervals.major }
+  }
+
+  const { minorIntervals, majorIntervals } = getTimeIntervals(zoom, duration)
+
   return (
     <div className="relative" style={{ height: '80px' }}>
       <div
@@ -139,19 +185,20 @@ function TrackRow({ track, duration, zoom, isPlaying, currentTime, draggedItem,
       >
         {/* Grid lines for time markers */}
         <div className="absolute inset-0 pointer-events-none">
-          {Array.from({ length: Math.ceil(duration / 1000) + 1 }).map((_, i) => (
+          {/* Minor grid lines */}
+          {minorIntervals.map((time) => (
             <div
-              key={i}
+              key={`minor-${time}`}
               className="absolute top-0 bottom-0 w-px bg-border/30"
-              style={{ left: `${i * zoom}px` }}
+              style={{ left: `${time * zoom}px` }}
             />
           ))}
-          {/* Major grid lines every 10 seconds */}
-          {Array.from({ length: Math.floor(duration / 10000) + 1 }).map((_, i) => (
+          {/* Major grid lines */}
+          {majorIntervals.map((time) => (
             <div
-              key={`major-${i}`}
+              key={`major-${time}`}
               className="absolute top-0 bottom-0 w-px bg-border/60"
-              style={{ left: `${i * 10 * zoom}px` }}
+              style={{ left: `${time * zoom}px` }}
             />
           ))}
         </div>
@@ -228,7 +275,6 @@ export const SequencerCanvas = forwardRef<HTMLDivElement, SequencerCanvasProps>(
 }, ref) => {
   const totalWidth = (duration / 1000) * zoom  // Convert ms to seconds for zoom calculation
   const timelineRef = useRef<HTMLDivElement>(null)
-  const containerRef = useRef<HTMLDivElement>(null)
   
   // Add a fallback droppable for the entire canvas area
   const { setNodeRef: setCanvasDropRef } = useDroppable({
@@ -238,6 +284,53 @@ export const SequencerCanvas = forwardRef<HTMLDivElement, SequencerCanvasProps>(
     },
   })
 
+  // Calculate logical time intervals based on zoom level
+  const getTimeIntervals = (zoom: number, duration: number) => {
+    const durationSeconds = duration / 1000
+    const minorIntervals: number[] = []
+    const majorIntervals: number[] = []
+    
+    // Define logical interval progressions
+    const intervalSets = [
+      { minor: 0.1, major: 1 },    // 0.1s minor, 1s major (mega zoomed in)
+      { minor: 1, major: 5 },      // 1s minor, 5s major (very zoomed in)
+      { minor: 5, major: 30 },     // 5s minor, 30s major 
+      { minor: 10, major: 60 },    // 10s minor, 1min major
+      { minor: 30, major: 300 },   // 30s minor, 5min major
+      { minor: 60, major: 600 },   // 1min minor, 10min major
+      { minor: 300, major: 1800 }, // 5min minor, 30min major
+      { minor: 600, major: 3600 }  // 10min minor, 1h major
+    ]
+    
+    // Find appropriate interval set based on zoom level
+    // We want major intervals to be roughly 100-200px apart
+    const targetMajorSpacing = 150
+    
+    let selectedIntervals = intervalSets[intervalSets.length - 1] // fallback to largest
+    for (const intervals of intervalSets) {
+      if (intervals.major * zoom >= targetMajorSpacing) {
+        selectedIntervals = intervals
+        break
+      }
+    }
+    
+    // Generate minor intervals (every interval)
+    for (let i = 0; i * selectedIntervals.minor <= durationSeconds; i++) {
+      const time = i * selectedIntervals.minor
+      minorIntervals.push(time)
+    }
+    
+    // Generate major intervals (at major boundaries)
+    for (let i = 0; i * selectedIntervals.major <= durationSeconds; i++) {
+      const time = i * selectedIntervals.major
+      majorIntervals.push(time)
+    }
+    
+    return { minorIntervals, majorIntervals, minorInterval: selectedIntervals.minor, majorInterval: selectedIntervals.major }
+  }
+
+  const { minorIntervals, majorIntervals } = getTimeIntervals(zoom, duration)
+
   const handleTracksScroll = (e: React.UIEvent<HTMLDivElement>) => {
     // Sync timeline horizontal scroll with tracks
     if (timelineRef.current) {
@@ -264,23 +357,39 @@ export const SequencerCanvas = forwardRef<HTMLDivElement, SequencerCanvasProps>(
           }}
         >
           <div className="relative h-full" style={{ width: `${totalWidth}px` }}>
-            {Array.from({ length: Math.ceil(duration / 1000) + 1 }).map((_, i) => (
-              <div key={i} className="absolute top-0 bottom-0" style={{ left: `${i * zoom}px` }}>
-                {/* Time markers */}
-                {i % 5 === 0 && (
-                  <>
-                    <div className="absolute top-0 w-px h-3 bg-border/60" />
-                    <div className="absolute top-4 text-xs text-muted-foreground font-mono">
-                      {Math.floor(i / 60)}:{(i % 60).toString().padStart(2, '0')}
-                    </div>
-                  </>
-                )}
-                {i % 5 !== 0 && (
-                  <div className="absolute top-0 w-px h-2 bg-border/40" />
-                )}
+            {/* Minor time markers */}
+            {minorIntervals.map((time) => (
+              <div key={`ruler-minor-${time}`} className="absolute top-0 bottom-0" style={{ left: `${time * zoom}px` }}>
+                <div className="absolute top-0 w-px h-2 bg-border/40" />
               </div>
             ))}
             
+            {/* Major time markers with labels */}
+            {majorIntervals.map((time) => {
+              const formatTime = (seconds: number): string => {
+                if (seconds < 60) {
+                  // For times under 1 minute, show seconds with decimal places if needed
+                  return seconds < 10 && seconds % 1 !== 0 
+                    ? seconds.toFixed(1) + 's'
+                    : Math.floor(seconds) + 's'
+                } else {
+                  // For times over 1 minute, show MM:SS format
+                  const mins = Math.floor(seconds / 60)
+                  const secs = Math.floor(seconds % 60)
+                  return `${mins}:${secs.toString().padStart(2, '0')}`
+                }
+              }
+
+              return (
+                <div key={`ruler-major-${time}`} className="absolute top-0 bottom-0" style={{ left: `${time * zoom}px` }}>
+                  <div className="absolute top-0 w-px h-3 bg-border/60" />
+                  <div className="absolute top-4 text-xs text-muted-foreground font-mono whitespace-nowrap">
+                    {formatTime(time)}
+                  </div>
+                </div>
+              )
+            })}
+            
             {/* Playhead in ruler */}
             {isPlaying && (
               <div