Update ViewGraph.NextUpdate (#697)

Author: Kyle-Ye

Sources/OpenSwiftUICore/View/Graph/ViewGraph.swift

@@ -90,8 +90,8 @@ package final class ViewGraph: GraphHost {
 
     private var mainUpdates: Int = 0
 
-    // MARK: - ViewGraph + NextUpdate
-    
+    // MARK: - ViewGraph + NextUpdate [6.5.4]
+
     package struct NextUpdate {
         package private(set) var time: Time = .infinity
 
@@ -101,6 +101,8 @@ package final class ViewGraph: GraphHost {
             _interval.isFinite ? _interval : .zero
         }
 
+        private var _defaultIntervalWasRequested: Bool = false
+
         package private(set) var reasons: Set<UInt32> = []
 
         package mutating func at(_ next: Time) {
@@ -113,18 +115,23 @@ package final class ViewGraph: GraphHost {
             }
             let interval = velocity < 320 ? 1 / 80.0 : 1 / 120.0
             let highFrameRateReason: UInt32 = _HighFrameRateReasonMake(0)
-            _interval = min(interval, _interval)
+            var newInterval = min(interval, _interval)
+            if _defaultIntervalWasRequested && newInterval > 1 / 60.0 {
+                newInterval = .infinity
+            }
+            _interval = newInterval
             reasons.insert(highFrameRateReason)
         }
 
         package mutating func interval(_ interval: Double, reason: UInt32? = nil) {
             if interval == .zero {
-                if _interval > 1 / 60 {
-                    _interval = .infinity
-                }
+                _defaultIntervalWasRequested = true
             } else {
                 _interval = min(interval, _interval)
             }
+            if _defaultIntervalWasRequested && _interval > 1 / 60 {
+                _interval = .infinity
+            }
             if let reason {
                 reasons.insert(reason)
             }

Tests/OpenSwiftUICoreTests/View/Graph/ViewGraphTests.swift

@@ -10,10 +10,32 @@ struct ViewGraphTests {
     struct NextUpdateTests {
         typealias Update = ViewGraph.NextUpdate
 
-        @Test
-        func interval() {
-            let update = Update()
-            #expect(update.interval == .zero)
+        @Test(arguments: [
+            (0.0, Double.zero, Set<UInt32>()),
+            (159.0, Double.zero, Set<UInt32>()),
+            (160.0, 1 / 80.0, [0x27_0000]),
+            (319.0, 1 / 80.0, [0x27_0000]),
+            (320.0, 1 / 120.0, [0x27_0000]),
+            (1000.0, 1 / 120.0, [0x27_0000]),
+        ] as [(Double, Double, Set<UInt32>)])
+        func maxVelocity(velocity: Double, expectedInterval: Double, expectedReasons: Set<UInt32>) {
+            var update = Update()
+            update.maxVelocity(velocity)
+            #expect(update.interval == expectedInterval)
+            #expect(update.reasons == expectedReasons)
+        }
+
+        @Test(arguments: [
+            (0.05, nil, 0.05, Set<UInt32>()),
+            (0.025, nil, 0.025, Set<UInt32>()),
+            (0.025, 1 as UInt32?, 0.025, [1] as Set<UInt32>),
+            (0.0, nil, Double.zero, Set<UInt32>()),
+        ] as [(Double, UInt32?, Double, Set<UInt32>)])
+        func intervalWithReason(interval: Double, reason: UInt32?, expectedInterval: Double, expectedReasons: Set<UInt32>) {
+            var update = Update()
+            update.interval(interval, reason: reason)
+            #expect(update.interval == expectedInterval)
+            #expect(update.reasons == expectedReasons)
         }
     }
 }