Allow dragging tempo markers

OpenUtau.Core/Commands/MoveTempoChangeCommand.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using OpenUtau.Core.Ustx;
+
+namespace OpenUtau.Core {
+    public class MoveTempoChangeCommand : AddTempoChangeCommand {
+        private readonly UTempo tempo;
+        private readonly int oldTick;
+        private readonly int newTick;
+
+        public MoveTempoChangeCommand(UProject project, UTempo tempo, int newTick)
+            : this(project, tempo, tempo.position, newTick) { }
+
+        private MoveTempoChangeCommand(
+            UProject project,
+            UTempo tempo,
+            int oldTick,
+            int newTick) : base(project) {
+            this.tempo = tempo;
+            this.oldTick = oldTick;
+            this.newTick = newTick;
+        }
+
+        public override void Execute() => MoveTempo(oldTick, newTick);
+
+        public override void Unexecute() => MoveTempo(newTick, oldTick);
+
+        private void MoveTempo(int fromTick, int toTick) {
+            var currentTempo = project.tempos.Contains(tempo) && tempo.position == fromTick
+                ? tempo
+                : project.tempos.FirstOrDefault(candidate => candidate.position == fromTick);
+            if (currentTempo == null) {
+                throw new InvalidOperationException(
+                    $"Cannot find tempo change at {fromTick} to move to {toTick}.");
+            }
+            currentTempo.position = toTick;
+        }
+
+        public override bool CanMerge(IList<UCommand> commands) {
+            var moves = commands.OfType<MoveTempoChangeCommand>().ToList();
+            return moves.Count == commands.Count &&
+                moves.All(command => command.tempo == tempo);
+        }
+
+        public override UCommand Merge(IList<UCommand> commands) {
+            var moves = commands.Cast<MoveTempoChangeCommand>().ToList();
+            return new MoveTempoChangeCommand(
+                project,
+                tempo,
+                moves.First().oldTick,
+                moves.Last().newTick);
+        }
+
+        public override string ToString() =>
+            $"Move tempo change {tempo.bpm} from {oldTick} to {newTick}";
+    }
+}

OpenUtau.Test/Core/Commands/MoveTempoChangeCommandTest.cs

@@ -0,0 +1,64 @@
+using System.Collections.Generic;
+using OpenUtau.Core.Ustx;
+using Xunit;
+
+namespace OpenUtau.Core {
+    public class MoveTempoChangeCommandTest {
+        [Fact]
+        public void ExecuteAndUnexecute() {
+            var project = new UProject();
+            var tempo = new UTempo(480, 140);
+            project.tempos.Add(tempo);
+            var command = new MoveTempoChangeCommand(project, tempo, 720);
+
+            command.Execute();
+            Assert.Equal(720, tempo.position);
+
+            command.Unexecute();
+            Assert.Equal(480, tempo.position);
+
+            command.Execute();
+            Assert.Equal(720, tempo.position);
+        }
+
+        [Fact]
+        public void UnexecuteAfterTempoIsRecreated() {
+            var project = new UProject();
+            var tempo = new UTempo(480, 140);
+            project.tempos.Add(tempo);
+            var command = new MoveTempoChangeCommand(project, tempo, 720);
+            command.Execute();
+
+            project.tempos.Remove(tempo);
+            var recreatedTempo = new UTempo(720, 140);
+            project.tempos.Add(recreatedTempo);
+
+            command.Unexecute();
+            Assert.Equal(480, recreatedTempo.position);
+
+            command.Execute();
+            Assert.Equal(720, recreatedTempo.position);
+        }
+
+        [Fact]
+        public void MergeKeepsFirstAndLastPositions() {
+            var project = new UProject();
+            var tempo = new UTempo(480, 140);
+            project.tempos.Add(tempo);
+            var firstMove = new MoveTempoChangeCommand(project, tempo, 600);
+            firstMove.Execute();
+            var secondMove = new MoveTempoChangeCommand(project, tempo, 720);
+            secondMove.Execute();
+            var commands = new List<UCommand> { firstMove, secondMove };
+
+            Assert.True(secondMove.CanMerge(commands));
+            var merged = secondMove.Merge(commands);
+
+            merged.Unexecute();
+            Assert.Equal(480, tempo.position);
+
+            merged.Execute();
+            Assert.Equal(720, tempo.position);
+        }
+    }
+}

OpenUtau/Controls/TickBackground.cs

@@ -5,9 +5,20 @@
 using Avalonia.Media;
 using Avalonia.Media.Immutable;
 using OpenUtau.App.ViewModels;
+using OpenUtau.Core.Ustx;
 using ReactiveUI;
 
 namespace OpenUtau.App.Controls {
+    class TempoMarkerHighlightEvent {
+        public object DataContext { get; }
+        public UTempo? Tempo { get; }
+
+        public TempoMarkerHighlightEvent(object dataContext, UTempo? tempo) {
+            DataContext = dataContext;
+            Tempo = tempo;
+        }
+    }
+
     class TickBackground : TemplatedControl {
         private static readonly IDashStyle DashStyle = new ImmutableDashStyle(new double[] { 2, 4 }, 0);
 
@@ -46,6 +57,11 @@ class TickBackground : TemplatedControl {
                 nameof(ShowBar),
                 o => o.ShowBar,
                 (o, v) => o.ShowBar = v);
+        public static readonly DirectProperty<TickBackground, UTempo?> HighlightedTempoProperty =
+            AvaloniaProperty.RegisterDirect<TickBackground, UTempo?>(
+                nameof(HighlightedTempo),
+                o => o.HighlightedTempo,
+                (o, v) => o.HighlightedTempo = v);
 
         public int Resolution {
             get => _resolution;
@@ -76,6 +92,13 @@ public bool ShowBar {
             get => _showBar;
             set => SetAndRaise(ShowBarProperty, ref _showBar, value);
         }
+        public UTempo? HighlightedTempo {
+            get => _highlightedTempo;
+            private set => SetAndRaise(
+                HighlightedTempoProperty,
+                ref _highlightedTempo,
+                value);
+        }
 
         private int _resolution = 480;
         private double _tickWidth;
@@ -84,6 +107,7 @@ public bool ShowBar {
         private int _snapDiv;
         private ObservableCollection<int>? _snapTicks;
         private bool _showBar = true;
+        private UTempo? _highlightedTempo;
 
         private Pen penBar;
         private Pen penBeatUnit;
@@ -99,6 +123,12 @@ public TickBackground() {
                 .Subscribe(e => InvalidateVisual());
             MessageBus.Current.Listen<TimeAxisChangedEvent>()
                 .Subscribe(e => InvalidateVisual());
+            MessageBus.Current.Listen<TempoMarkerHighlightEvent>()
+                .Subscribe(e => {
+                    if (ReferenceEquals(e.DataContext, DataContext)) {
+                        HighlightedTempo = e.Tempo;
+                    }
+                });
         }
 
         protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change) {
@@ -117,7 +147,8 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
                 change.Property == TickWidthProperty ||
                 change.Property == TickOffsetProperty ||
                 change.Property == SnapDivProperty ||
-                change.Property == ShowBarProperty) {
+                change.Property == ShowBarProperty ||
+                change.Property == HighlightedTempoProperty) {
                 InvalidateVisual();
             }
         }
@@ -184,9 +215,16 @@ public override void Render(DrawingContext context) {
 
             if (ShowBar) {
                 foreach (var tempo in project.tempos) {
+                    bool highlighted = ReferenceEquals(tempo, HighlightedTempo);
                     double x = Math.Round(tempo.position * TickWidth - pixelOffset) + 0.5;
-                    context.DrawLine(penDanshed, new Point(x, 0), new Point(x, 24));
-                    var textLayout = TextLayoutCache.Get(tempo.bpm.ToString("#0.00"), ThemeManager.BarNumberBrush, 10);
+                    var markerPen = highlighted
+                        ? ThemeManager.AccentPen2Thickness2
+                        : penDanshed;
+                    var textBrush = highlighted
+                        ? ThemeManager.AccentBrush2
+                        : ThemeManager.BarNumberBrush;
+                    context.DrawLine(markerPen, new Point(x, 0), new Point(x, 24));
+                    var textLayout = TextLayoutCache.Get(tempo.bpm.ToString("#0.00"), textBrush, 10);
                     using (var state = context.PushTransform(Matrix.CreateTranslation(x + 3, 0))) {
                         textLayout.Draw(context, new Point());
                     }