input_common: add TouchFromButtonDevice

src/input_common/touch_from_button.h

@@ -0,0 +1,24 @@
+// Copyright 2020 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include "core/frontend/input.h"
+
+namespace InputCommon {
+
+/**
+ * A touch device factory that takes a list of button devices and combines them into a touch device.
+ */
+class TouchFromButtonFactory final : public Input::Factory<Input::TouchDevice> {
+public:
+    /**
+     * Creates a touch device from a list of button devices
+     * @param unused
+     */
+    std::unique_ptr<Input::TouchDevice> Create(const Common::ParamPackage& params) override;
+};
+
+} // namespace InputCommon