Highlight active panel controls

Nifro/Screens/DisplayPanel.swift

@@ -281,8 +281,8 @@ private struct DisplayColumn: View {
 			PanelButton(
 				symbol: column.rotationMode.symbol,
 				label: column.rotationMode.label,
-				// Lit while it is doing something. Pinned is the resting state and says so by staying dark.
-				isOn: column.rotationMode != .pinned
+				// This always names the selected mode, so Pin, Loop and Random all use the selected state.
+				isOn: true
 			) {
 				model.cycleRotationMode(on: column.display)
 			}
@@ -442,6 +442,7 @@ private struct DisplayColumn: View {
 				PanelButton(
 					symbol: column.isMuted ? "speaker.slash.fill" : "speaker.wave.2.fill",
 					label: column.isMuted ? String(localized: "Muted") : String(localized: "Playing sound"),
+					isOn: !column.isMuted,
 					isEnabled: hasPage
 				) {
 					model.toggleMuted(on: column.display)
@@ -453,7 +454,7 @@ private struct DisplayColumn: View {
 					// Lit while the wallpaper is up, like every other lit control in the panel. It used
 					// to be the inverse — lit while the display was switched *off* — which made this the
 					// one control reading its lit state as "this button is engaged" instead of as "the
-					// thing it turns on is on". Five controls now answer that question the same way.
+					// thing it turns on is on". The panel's stateful controls answer that question the same way.
 					isOn: column.isShowing
 				) {
 					model.toggleShowing(on: column.display)

Tests/PanelControlStateTests.swift

@@ -0,0 +1,55 @@
+import Foundation
+import Testing
+
+/**
+The panel uses button-shaped toggles for state that is already in effect.  Their colour is the
+quick reading of that state, so treating one selected mode or an audible page as unselected makes
+the panel contradict itself even though its actions still work.
+*/
+@Suite("Panel controls show enabled state")
+struct PanelControlStateTests {
+	private static let repository = URL(filePath: #filePath)
+		.deletingLastPathComponent()
+		.deletingLastPathComponent()
+
+	@Test("The current rotation mode is always highlighted, including Pin")
+	func currentRotationModeIsHighlighted() throws {
+		let controls = try Self.rotationControls()
+
+		#expect(
+			controls.contains("isOn: true"),
+			"Pin is a selected rotation mode, so it must be highlighted just like Loop and Random."
+		)
+	}
+
+	@Test("Sound is highlighted only while it is playing")
+	func playingSoundIsHighlighted() throws {
+		let controls = try Self.pictureControls()
+
+		#expect(
+			controls.contains("isOn: !column.isMuted"),
+			"The speaker control must be highlighted when sound is playing and unhighlighted when it is muted."
+		)
+	}
+
+	private static func rotationControls() throws -> Substring {
+		try controls(between: "private var rotationControls: some View", and: "private var modeButtons: some View")
+	}
+
+	private static func pictureControls() throws -> Substring {
+		try controls(between: "private var preview: some View", and: "private func reading(")
+	}
+
+	private static func controls(between start: String, and end: String) throws -> Substring {
+		let source = try String(
+			contentsOf: repository.appending(path: "Nifro/Screens/DisplayPanel.swift"),
+			encoding: .utf8
+		)
+
+		guard let range = source.range(of: start)?.lowerBound, let end = source.range(of: end)?.lowerBound else {
+			throw CocoaError(.fileReadCorruptFile)
+		}
+
+		return source[range..<end]
+	}
+}