DolphinQt: Rework TAS input threading, part 2 (analog inputs)

Source/Core/DolphinQt/TAS/TASSpinBox.h

@@ -0,0 +1,29 @@
+// Copyright 2023 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <QSpinBox>
+
+#include "DolphinQt/TAS/TASControlState.h"
+
+class TASInputWindow;
+
+class TASSpinBox : public QSpinBox
+{
+  Q_OBJECT
+public:
+  explicit TASSpinBox(QWidget* parent = nullptr);
+
+  // Can be called from the CPU thread
+  int GetValue() const;
+  // Must be called from the CPU thread
+  void OnControllerValueChanged(int new_value);
+
+private slots:
+  void OnUIValueChanged(int new_value);
+  void ApplyControllerValueChange();
+
+private:
+  TASControlState m_state;
+};