Add FlPlatformPlugin (flutter/engine#18316)

Fixes https://github.com/flutter/flutter/issues/54857

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -1225,6 +1225,8 @@ FILE: ../../../flutter/shell/platform/linux/fl_method_codec_private.h
 FILE: ../../../flutter/shell/platform/linux/fl_method_codec_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_method_response.cc
 FILE: ../../../flutter/shell/platform/linux/fl_method_response_test.cc
+FILE: ../../../flutter/shell/platform/linux/fl_platform_plugin.cc
+FILE: ../../../flutter/shell/platform/linux/fl_platform_plugin.h
 FILE: ../../../flutter/shell/platform/linux/fl_plugin_registrar.cc
 FILE: ../../../flutter/shell/platform/linux/fl_plugin_registrar_private.h
 FILE: ../../../flutter/shell/platform/linux/fl_plugin_registry.cc

engine/src/flutter/shell/platform/linux/BUILD.gn

@@ -89,6 +89,7 @@ source_set("flutter_linux_sources") {
     "fl_method_channel.cc",
     "fl_method_codec.cc",
     "fl_method_response.cc",
+    "fl_platform_plugin.cc",
     "fl_plugin_registrar.cc",
     "fl_plugin_registry.cc",
     "fl_renderer.cc",

engine/src/flutter/shell/platform/linux/fl_platform_plugin.cc

@@ -0,0 +1,171 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/linux/fl_platform_plugin.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_json_method_codec.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_method_channel.h"
+
+#include <gtk/gtk.h>
+
+static constexpr char kChannelName[] = "flutter/platform";
+static constexpr char kBadArgumentsError[] = "Bad Arguments";
+static constexpr char kUnknownClipboardFormatError[] =
+    "Unknown Clipboard Format";
+static constexpr char kClipboardRequestError[] = "Clipboard Request Failed";
+static constexpr char kFailedError[] = "Failed";
+static constexpr char kGetClipboardDataMethod[] = "Clipboard.getData";
+static constexpr char kSetClipboardDataMethod[] = "Clipboard.setData";
+static constexpr char kSystemNavigatorPopMethod[] = "SystemNavigator.pop";
+static constexpr char kTextKey[] = "text";
+
+static constexpr char kTextPlainFormat[] = "text/plain";
+
+struct _FlPlatformPlugin {
+  GObject parent_instance;
+
+  FlMethodChannel* channel;
+};
+
+G_DEFINE_TYPE(FlPlatformPlugin, fl_platform_plugin, G_TYPE_OBJECT)
+
+// Sends the method call response to Flutter.
+static void send_response(FlMethodCall* method_call,
+                          FlMethodResponse* response) {
+  g_autoptr(GError) error = nullptr;
+  if (!fl_method_call_respond(method_call, response, &error))
+    g_warning("Failed to send method call response: %s", error->message);
+}
+
+// Called when clipboard text received.
+static void clipboard_text_cb(GtkClipboard* clipboard,
+                              const gchar* text,
+                              gpointer user_data) {
+  g_autoptr(FlMethodCall) method_call = FL_METHOD_CALL(user_data);
+
+  g_autoptr(FlMethodResponse) response = nullptr;
+  if (text != nullptr) {
+    g_autoptr(FlValue) result = fl_value_new_map();
+    fl_value_set_string_take(result, kTextKey, fl_value_new_string(text));
+    response = FL_METHOD_RESPONSE(fl_method_success_response_new(nullptr));
+  } else {
+    response = FL_METHOD_RESPONSE(fl_method_error_response_new(
+        kClipboardRequestError, "Failed to retrieve clipboard text from GTK",
+        nullptr));
+  }
+
+  send_response(method_call, response);
+}
+
+// Called when Flutter wants to copy to the clipboard.
+static FlMethodResponse* clipboard_set_data(FlPlatformPlugin* self,
+                                            FlValue* args) {
+  if (fl_value_get_type(args) != FL_VALUE_TYPE_MAP) {
+    return FL_METHOD_RESPONSE(fl_method_error_response_new(
+        kBadArgumentsError, "Argument map missing or malformed", nullptr));
+  }
+
+  FlValue* text_value = fl_value_lookup_string(args, kTextKey);
+  if (text_value == nullptr ||
+      fl_value_get_type(text_value) != FL_VALUE_TYPE_STRING) {
+    return FL_METHOD_RESPONSE(fl_method_error_response_new(
+        kBadArgumentsError, "Missing clipboard text", nullptr));
+  }
+
+  GtkClipboard* clipboard =
+      gtk_clipboard_get_default(gdk_display_get_default());
+  gtk_clipboard_set_text(clipboard, fl_value_get_string(text_value), -1);
+
+  return FL_METHOD_RESPONSE(fl_method_success_response_new(nullptr));
+}
+
+// Called when Flutter wants to paste from the clipboard.
+static FlMethodResponse* clipboard_get_data_async(FlPlatformPlugin* self,
+                                                  FlMethodCall* method_call) {
+  FlValue* args = fl_method_call_get_args(method_call);
+
+  if (fl_value_get_type(args) != FL_VALUE_TYPE_STRING) {
+    return FL_METHOD_RESPONSE(fl_method_error_response_new(
+        kBadArgumentsError, "Expected string", nullptr));
+  }
+
+  const gchar* format = fl_value_get_string(args);
+  if (strcmp(format, kTextPlainFormat) != 0) {
+    return FL_METHOD_RESPONSE(fl_method_error_response_new(
+        kUnknownClipboardFormatError, "GTK clipboard API only supports text",
+        nullptr));
+  }
+
+  GtkClipboard* clipboard =
+      gtk_clipboard_get_default(gdk_display_get_default());
+  gtk_clipboard_request_text(clipboard, clipboard_text_cb,
+                             g_object_ref(method_call));
+
+  // Will response later.
+  return nullptr;
+}
+
+// Called when Flutter wants to quit the application.
+static FlMethodResponse* system_navigator_pop(FlPlatformPlugin* self) {
+  GApplication* app = g_application_get_default();
+  if (app == nullptr) {
+    return FL_METHOD_RESPONSE(fl_method_error_response_new(
+        kFailedError, "Unable to get GApplication", nullptr));
+  }
+
+  g_application_quit(app);
+
+  return FL_METHOD_RESPONSE(fl_method_success_response_new(nullptr));
+}
+
+// Called when a method call is received from Flutter.
+static void method_call_cb(FlMethodChannel* channel,
+                           FlMethodCall* method_call,
+                           gpointer user_data) {
+  FlPlatformPlugin* self = FL_PLATFORM_PLUGIN(user_data);
+
+  const gchar* method = fl_method_call_get_name(method_call);
+  FlValue* args = fl_method_call_get_args(method_call);
+
+  g_autoptr(FlMethodResponse) response = nullptr;
+  if (strcmp(method, kSetClipboardDataMethod) == 0)
+    response = clipboard_set_data(self, args);
+  else if (strcmp(method, kGetClipboardDataMethod) == 0)
+    response = clipboard_get_data_async(self, method_call);
+  else if (strcmp(method, kSystemNavigatorPopMethod) == 0)
+    response = system_navigator_pop(self);
+  else
+    response = FL_METHOD_RESPONSE(fl_method_not_implemented_response_new());
+
+  if (response != nullptr)
+    send_response(method_call, response);
+}
+
+static void fl_platform_plugin_dispose(GObject* object) {
+  FlPlatformPlugin* self = FL_PLATFORM_PLUGIN(object);
+
+  g_clear_object(&self->channel);
+
+  G_OBJECT_CLASS(fl_platform_plugin_parent_class)->dispose(object);
+}
+
+static void fl_platform_plugin_class_init(FlPlatformPluginClass* klass) {
+  G_OBJECT_CLASS(klass)->dispose = fl_platform_plugin_dispose;
+}
+
+static void fl_platform_plugin_init(FlPlatformPlugin* self) {}
+
+FlPlatformPlugin* fl_platform_plugin_new(FlBinaryMessenger* messenger) {
+  g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
+
+  FlPlatformPlugin* self =
+      FL_PLATFORM_PLUGIN(g_object_new(fl_platform_plugin_get_type(), nullptr));
+
+  g_autoptr(FlJsonMethodCodec) codec = fl_json_method_codec_new();
+  self->channel =
+      fl_method_channel_new(messenger, kChannelName, FL_METHOD_CODEC(codec));
+  fl_method_channel_set_method_call_handler(self->channel, method_call_cb, self,
+                                            nullptr);
+
+  return self;
+}

engine/src/flutter/shell/platform/linux/fl_platform_plugin.h

@@ -0,0 +1,38 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_LINUX_FL_PLATFORM_PLUGIN_H_
+#define FLUTTER_SHELL_PLATFORM_LINUX_FL_PLATFORM_PLUGIN_H_
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
+
+G_BEGIN_DECLS
+
+G_DECLARE_FINAL_TYPE(FlPlatformPlugin,
+                     fl_platform_plugin,
+                     FL,
+                     PLATFORM_PLUGIN,
+                     GObject);
+
+/**
+ * FlPlatformPlugin:
+ *
+ * #FlPlatformPlugin is a plugin that implements the shell side
+ * of PlatformPlugins.platform from the Flutter services library.
+ */
+
+/**
+ * fl_platform_plugin_new:
+ * @messenger: an #FlBinaryMessenger
+ *
+ * Creates a new plugin that implements SystemChannels.platform from the
+ * Flutter services library.
+ *
+ * Returns: a new #FlPlatformPlugin
+ */
+FlPlatformPlugin* fl_platform_plugin_new(FlBinaryMessenger* messenger);
+
+G_END_DECLS
+
+#endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_PLATFORM_PLUGIN_H_

engine/src/flutter/shell/platform/linux/fl_view.cc

@@ -6,6 +6,7 @@
 
 #include "flutter/shell/platform/linux/fl_engine_private.h"
 #include "flutter/shell/platform/linux/fl_key_event_plugin.h"
+#include "flutter/shell/platform/linux/fl_platform_plugin.h"
 #include "flutter/shell/platform/linux/fl_plugin_registrar_private.h"
 #include "flutter/shell/platform/linux/fl_renderer_x11.h"
 #include "flutter/shell/platform/linux/fl_text_input_plugin.h"
@@ -33,6 +34,7 @@ struct _FlView {
 
   // Flutter system channel handlers.
   FlKeyEventPlugin* key_event_plugin;
+  FlPlatformPlugin* platform_plugin;
   FlTextInputPlugin* text_input_plugin;
 };
 
@@ -129,6 +131,7 @@ static void fl_view_constructed(GObject* object) {
   // Create system channel handlers.
   FlBinaryMessenger* messenger = fl_engine_get_binary_messenger(self->engine);
   self->key_event_plugin = fl_key_event_plugin_new(messenger);
+  self->platform_plugin = fl_platform_plugin_new(messenger);
   self->text_input_plugin = fl_text_input_plugin_new(messenger);
 }
 
@@ -183,6 +186,7 @@ static void fl_view_dispose(GObject* object) {
   g_clear_object(&self->renderer);
   g_clear_object(&self->engine);
   g_clear_object(&self->key_event_plugin);
+  g_clear_object(&self->platform_plugin);
   g_clear_object(&self->text_input_plugin);
 
   G_OBJECT_CLASS(fl_view_parent_class)->dispose(object);