Added rudimentary Canvas based keyboard not touch-activated

Sources/Keyboard/Layouts/Piano.swift

@@ -13,9 +13,7 @@ struct Piano<Content>: View where Content: View {
             ZStack(alignment: .topLeading) {
                 HStack(spacing: 0) {
                     ForEach(spacer.whiteKeys, id: \.self) { pitch in
-                        KeyContainer(model: keyboard,
-                                     pitch: pitch,
-                                     content: content)
+                        KeyContainer(model: keyboard, pitch: pitch, content: content)
                             .frame(width: spacer.whiteKeyWidth(geo.size.width))
                     }
                 }

Sources/Keyboard/MIDIMonitorKeyboard.swift

@@ -0,0 +1,95 @@
+
+import SwiftUI
+import Tonic
+
+extension GraphicsContext {
+    func fill(rect: CGRect, with color: Color) {
+        fill(Path(roundedRect: rect, cornerRadius: 0), with: GraphicsContext.Shading.color(color))
+    }
+}
+
+struct MIDIMonitorKeyboard: View {
+
+    var layout: KeyboardLayout
+    var activatedPitches: PitchSet
+    var colorFunction: (Pitch)->Color
+    var spacer: PianoSpacer = PianoSpacer(pitchRange: Pitch(60) ... Pitch(72), initialSpacerRatio: PianoSpacer.defaultInitialSpacerRatio, spacerRatio: PianoSpacer.defaultSpacerRatio)
+
+    public init(layout: KeyboardLayout = .piano(pitchRange: Pitch(60) ... Pitch(72)),
+                activatedPitches: PitchSet = PitchSet(),
+                colorFunction: @escaping (Pitch)->Color = { _ in Color.red }
+    )
+    {
+        self.layout = layout
+        self.activatedPitches = activatedPitches
+        self.colorFunction = colorFunction
+
+        switch layout {
+            case let .piano(pitchRange, initialSpacerRatio, spacerRatio, relativeBlackKeyWidth, relativeBlackKeyHeight):
+                spacer = PianoSpacer(pitchRange: pitchRange,
+                                     initialSpacerRatio: initialSpacerRatio,
+                                     spacerRatio: spacerRatio,
+                                     relativeBlackKeyWidth: relativeBlackKeyWidth,
+                                     relativeBlackKeyHeight: relativeBlackKeyHeight)
+            default:
+                print("Unimplimented")
+        }
+    }
+
+    var body: some View {
+        switch layout {
+            case let .piano(pitchRange, initialSpacerRatio, spacerRatio, relativeBlackKeyWidth, relativeBlackKeyHeight):
+
+                Canvas { cx, size in
+                    cx.fill(rect: CGRect(origin: .zero, size: size), with: .black)
+                    var color = Color.white
+                    for (i, pitch) in spacer.whiteKeys.enumerated() {
+                        color = Color.white
+                        if activatedPitches.contains(pitch) {
+                            color = colorFunction(pitch)
+                        }
+                        let r = CGRect(x: CGFloat(i) * spacer.whiteKeyWidth(size.width),
+                                       y: 0,
+                                       width: spacer.whiteKeyWidth(size.width) - 1,
+                                       height: size.height)
+                        cx.fill(rect: r, with: color)
+                    }
+
+                    var x: CGFloat = spacer.initialSpacerWidth(size.width)
+                    if spacer.pitchRange.lowerBound != spacer.pitchRangeBoundedByNaturals.lowerBound {
+                        x += spacer.lowerBoundSpacerWidth(size.width)
+                    }
+                    for pitch in spacer.pitchRange {
+                        color = Color.black
+
+                        let r = CGRect(x: x,
+                                       y: 0,
+                                       width: spacer.blackKeyWidth(size.width),
+                                       height: size.height * spacer.relativeBlackKeyHeight)
+
+                        if activatedPitches.contains(pitch) {
+                            color = colorFunction(pitch)
+                        }
+
+
+                        if spacer.isBlackKey(pitch) {
+                            cx.fill(rect: r, with: color)
+                            x += spacer.blackKeyWidth(size.width)
+                        } else {
+                            x += spacer.blackKeySpacerWidth(size.width, pitch: pitch)
+                        }
+                    }
+                }
+            default:
+                EmptyView()
+        }
+    }
+}
+
+var p = PitchSet(pitches: [Pitch(65), Pitch(68), Pitch(71), Pitch(74)])
+#Preview {
+    MIDIMonitorKeyboard(layout: .piano(pitchRange: Pitch(61)...Pitch(88)),
+                        activatedPitches: p,
+                        colorFunction: { x in Color(cgColor: PitchColor.helmholtz[Int(x.pitchClass)])}
+    ).frame(width: 600, height: 100)
+}