InputCommon: Simplified StickGate interface and moved class into its own file. Changed default input radius to perform no resizing. Tweaked the indicator colors a bit to improve visibility. Cleaned up some math and code.

Source/Core/InputCommon/ControllerEmu/StickGate.h

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+// Copyright 2018 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "InputCommon/ControlReference/ControlReference.h"
+
+namespace ControllerEmu
+{
+// An abstract class representing the plastic shell that limits an analog stick's movement.
+class StickGate
+{
+public:
+  // Angle is in radians and should be non-negative
+  virtual ControlState GetRadiusAtAngle(double ang) const = 0;
+
+  virtual ~StickGate() = default;
+};
+
+// An octagon-shaped stick gate is found on most Nintendo GC/Wii analog sticks.
+class OctagonStickGate : public StickGate
+{
+public:
+  // Radius of circumscribed circle
+  explicit OctagonStickGate(ControlState radius);
+  ControlState GetRadiusAtAngle(double ang) const override final;
+
+private:
+  const ControlState m_radius;
+};
+
+// A round-shaped stick gate. Possibly found on 3rd-party accessories.
+class RoundStickGate : public StickGate
+{
+public:
+  explicit RoundStickGate(ControlState radius);
+  ControlState GetRadiusAtAngle(double ang) const override final;
+
+private:
+  const ControlState m_radius;
+};
+
+// A square-shaped stick gate. e.g. keyboard input.
+class SquareStickGate : public StickGate
+{
+public:
+  explicit SquareStickGate(ControlState half_width);
+  ControlState GetRadiusAtAngle(double ang) const override final;
+
+private:
+  const ControlState m_half_width;
+};
+
+}  // namespace ControllerEmu