Add joystick plugin (#39)

https://github.com/sony/flutter-elinux-plugins/issues/35

packages/joystick/elinux/.gitignore

@@ -0,0 +1 @@
+flutter/

packages/joystick/elinux/CMakeLists.txt

@@ -0,0 +1,25 @@
+cmake_minimum_required(VERSION 3.10)
+set(PROJECT_NAME "joystick")
+project(${PROJECT_NAME} LANGUAGES CXX)
+
+# This value is used when generating builds using this plugin, so it must
+# not be changed
+set(PLUGIN_NAME "joystick_plugin")
+
+add_library(${PLUGIN_NAME} SHARED
+  "joystick_plugin.cc"
+  "linux_joystick.cc"
+)
+apply_standard_settings(${PLUGIN_NAME})
+set_target_properties(${PLUGIN_NAME} PROPERTIES
+  CXX_VISIBILITY_PRESET hidden)
+target_compile_definitions(${PLUGIN_NAME} PRIVATE FLUTTER_PLUGIN_IMPL)
+target_include_directories(${PLUGIN_NAME} INTERFACE
+  "${CMAKE_CURRENT_SOURCE_DIR}/include")
+target_link_libraries(${PLUGIN_NAME} PRIVATE flutter flutter_wrapper_plugin)
+
+# List of absolute paths to libraries that should be bundled with the plugin
+set(joystick_bundled_libraries
+  ""
+  PARENT_SCOPE
+)

packages/joystick/elinux/include/joystick/joystick_plugin.h

@@ -0,0 +1,23 @@
+#ifndef FLUTTER_PLUGIN_JOYSTICK_PLUGIN_H_
+#define FLUTTER_PLUGIN_JOYSTICK_PLUGIN_H_
+
+#include <flutter_plugin_registrar.h>
+
+#ifdef FLUTTER_PLUGIN_IMPL
+#define FLUTTER_PLUGIN_EXPORT __attribute__((visibility("default")))
+#else
+#define FLUTTER_PLUGIN_EXPORT
+#endif
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+FLUTTER_PLUGIN_EXPORT void JoystickPluginRegisterWithRegistrar(
+    FlutterDesktopPluginRegistrarRef registrar);
+
+#if defined(__cplusplus)
+}  // extern "C"
+#endif
+
+#endif  // FLUTTER_PLUGIN_JOYSTICK_PLUGIN_H_

packages/joystick/elinux/joystick_plugin.cc

@@ -0,0 +1,41 @@
+// Copyright 2021 Sony Group Corporation. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "include/joystick/joystick_plugin.h"
+
+#include <flutter/plugin_registrar.h>
+
+#include <memory>
+#include <sstream>
+
+namespace {
+
+class JoystickPlugin : public flutter::Plugin {
+ public:
+  static void RegisterWithRegistrar(flutter::PluginRegistrar *registrar);
+
+  JoystickPlugin();
+
+  virtual ~JoystickPlugin();
+};
+
+// static
+void JoystickPlugin::RegisterWithRegistrar(
+    flutter::PluginRegistrar *registrar) {
+  auto plugin = std::make_unique<JoystickPlugin>();
+  registrar->AddPlugin(std::move(plugin));
+}
+
+JoystickPlugin::JoystickPlugin() {}
+
+JoystickPlugin::~JoystickPlugin() {}
+
+}  // namespace
+
+void JoystickPluginRegisterWithRegistrar(
+    FlutterDesktopPluginRegistrarRef registrar) {
+  JoystickPlugin::RegisterWithRegistrar(
+      flutter::PluginRegistrarManager::GetInstance()
+          ->GetRegistrar<flutter::PluginRegistrar>(registrar));
+}

packages/joystick/elinux/linux_joystick.cc

@@ -0,0 +1,27 @@
+// Copyright 2021 Sony Group Corporation. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/joystick.h>
+#include <stdio.h>
+#include <unistd.h>
+
+extern "C" __attribute__((visibility("default"))) int joystick_open(
+    const char* device) {
+  int fd = open(device, O_NONBLOCK);
+  if (fd < 0) {
+    fprintf(stderr, "Failed to open %s (%d)\n", device, errno);
+  }
+  return fd;
+}
+
+extern "C" __attribute__((visibility("default"))) int joystick_read(
+    int fd, js_event* ev) {
+  int bytes = read(fd, ev, sizeof(*ev));
+  if (bytes < 0) {
+    return -1;
+  }
+  return bytes == sizeof(*ev);
+}