Add support for individual lines waveform (#3)

Some audio files are more suitable to individual lines representation.
This PR adds a support for that.

Author: jcavar

README.md

@@ -54,11 +54,12 @@ class MyAudioTests: XCTestCase {
 - [x] `AVAudioPCMBuffer` waveform snapshots
 - [x] `AVAudioPCMBuffer` overlayed waveform snapshots
 - [ ] Spectrogram
-- [ ] Spectra
+- [x] Spectra
+- [x] Different waveform rendering strategies
 - [ ] Test against other reference implementations and with known audio files
 - [ ] Documentation
 - [ ] Mention JUCE
-- [ ] Link blog post
+- [ ] Link blog post and talk
 
 ## Contributing
 

Sources/AudioSnapshotTesting/AudioSnapshotTesting.swift

@@ -20,7 +20,8 @@ public extension Snapshotting where Format == PlatformImage, Value == (AVAudioPC
     /// - Parameters:
     ///    - width: The width of the resulting image.
     ///    - height: The height of the resulting image.
-    static func waveform(width: Int, height: Int) -> Snapshotting {
+    ///    - strategy: The strategy to use when generating the waveform. Defaults to `.joinedLines`.
+    static func waveform(width: Int, height: Int, strategy: WaveformStrategy = .joinedLines) -> Snapshotting {
         Snapshotting<PlatformView, PlatformImage>.image(size: .init(width: width, height: height))
             .pullback { buffer1, buffer2 in
                 let (buckets1, max1) = buffer1.reduce(bucketCount: width)
@@ -33,13 +34,15 @@ public extension Snapshotting where Format == PlatformImage, Value == (AVAudioPC
                     buckets: data1,
                     absMax: max1,
                     height: waveformHeight,
-                    color: .red
+                    color: .red,
+                    strategy: strategy
                 )
                 let waveform2 = WaveformView(
                     buckets: data2,
                     absMax: max2,
                     height: waveformHeight,
-                    color: .green
+                    color: .green,
+                    strategy: strategy
                 )
                 let waveform = ZStack {
                     waveform1
@@ -58,7 +61,8 @@ public extension Snapshotting where Format == PlatformImage, Value == AVAudioPCM
     /// - Parameters:
     ///    - width: The width of the resulting image.
     ///    - height: The height of the resulting image.
-    static func waveform(width: Int, height: Int) -> Snapshotting {
+    ///    - strategy: The strategy to use when generating the waveform. Defaults to `.joinedLines`.
+    static func waveform(width: Int, height: Int, strategy: WaveformStrategy = .joinedLines) -> Snapshotting {
         Snapshotting<PlatformView, PlatformImage>.image(size: .init(width: width, height: height))
             .pullback { buffer in
                 let verticalPadding: CGFloat = 4
@@ -69,7 +73,8 @@ public extension Snapshotting where Format == PlatformImage, Value == AVAudioPCM
                     buckets: data,
                     absMax: max,
                     height: waveformHeight,
-                    color: .red
+                    color: .red,
+                    strategy: strategy
                 )
                 .padding(.vertical, verticalPadding)
                 .background(Color.black)

Sources/AudioSnapshotTesting/WaveformView.swift

@@ -8,16 +8,30 @@ struct WaveformView: View {
         buckets: [Bucket],
         absMax: Float,
         height: CGFloat,
-        color: Color
+        color: Color,
+        strategy: WaveformStrategy = .joinedLines
     ) {
         self.color = color
         let halfHeight = height / 2
-        path = Path { path in
-            path.move(to: CGPoint(x: 0, y: halfHeight))
-            for (index, bucket) in buckets.enumerated() {
-                let sampleHeight = absMax > 0 ? (CGFloat(bucket.max) / CGFloat(absMax)) * halfHeight : 0
-                let point = CGPoint(x: CGFloat(index), y: halfHeight - sampleHeight)
-                path.addLine(to: point)
+        switch strategy {
+        case .joinedLines:
+            path = Path { path in
+                path.move(to: CGPoint(x: 0, y: halfHeight))
+                for (index, bucket) in buckets.enumerated() {
+                    let sampleHeight = absMax > 0 ? (CGFloat(bucket.max) / CGFloat(absMax)) * halfHeight : 0
+                    let point = CGPoint(x: CGFloat(index), y: halfHeight - sampleHeight)
+                    path.addLine(to: point)
+                }
+            }
+        case .individualLines:
+            path = Path { path in
+                for (index, bucket) in buckets.enumerated() {
+                    let sampleHeight = absMax > 0 ? (CGFloat(bucket.max) / CGFloat(absMax)) * halfHeight : 0
+                    let pointMax = CGPoint(x: CGFloat(index), y: halfHeight - sampleHeight)
+                    let pointMin = CGPoint(x: CGFloat(index), y: halfHeight + sampleHeight)
+                    path.move(to: pointMax)
+                    path.addLine(to: pointMin)
+                }
             }
         }
     }
@@ -28,3 +42,8 @@ struct WaveformView: View {
         }
     }
 }
+
+public enum WaveformStrategy {
+    case joinedLines
+    case individualLines
+}

Tests/AudioSnapshotTestingTests/AudioSnapshotTestingTests.swift

@@ -17,6 +17,16 @@ func fileWaveform(wave: String) async throws {
     )
 }
 
+@Test(.snapshots(record: false, diffTool: .ksdiff))
+@MainActor
+func fileWaveformMetronome() async throws {
+    assertSnapshot(
+        of: try AVAudioPCMBuffer.read(wave: "metronome"),
+        as: .waveform(width: 800, height: 400, strategy: .individualLines),
+        named: "metronome"
+    )
+}
+
 @Test(.snapshots(record: false, diffTool: .ksdiff))
 @MainActor
 func fileWaveformOverlay() async throws {