Clean up several messy chunks of code, and add support for dragging notes and events.

source/funkin/ui/debug/charting/commands/ExtendNoteLengthCommand.hx

@@ -0,0 +1,52 @@
+package funkin.ui.debug.charting.commands;
+
+import funkin.data.song.SongData.SongNoteData;
+
+/**
+ * Command that modifies the length of a hold note in the chart editor.
+ * If it is not a hold note, it will become one, and if it is already a hold note, its length will change.
+ */
+@:nullSafety
+@:access(funkin.ui.debug.charting.ChartEditorState)
+class ExtendNoteLengthCommand implements ChartEditorCommand
+{
+  var note:SongNoteData;
+  var oldLength:Float;
+  var newLength:Float;
+
+  public function new(note:SongNoteData, newLength:Float)
+  {
+    this.note = note;
+    this.oldLength = note.length;
+    this.newLength = newLength;
+  }
+
+  public function execute(state:ChartEditorState):Void
+  {
+    note.length = newLength;
+
+    state.saveDataDirty = true;
+    state.noteDisplayDirty = true;
+    state.notePreviewDirty = true;
+
+    state.sortChartData();
+  }
+
+  public function undo(state:ChartEditorState):Void
+  {
+    state.playSound(Paths.sound('chartingSounds/undo'));
+
+    note.length = oldLength;
+
+    state.saveDataDirty = true;
+    state.noteDisplayDirty = true;
+    state.notePreviewDirty = true;
+
+    state.sortChartData();
+  }
+
+  public function toString():String
+  {
+    return 'Extend Note Length';
+  }
+}