Add FlMouseCursorPlugin (#18888)

Fixes https://github.com/flutter/flutter/issues/57595

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_mouse_cursor_plugin.cc
+FILE: ../../../flutter/shell/platform/linux/fl_mouse_cursor_plugin.h
 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

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_mouse_cursor_plugin.cc",
     "fl_platform_plugin.cc",
     "fl_plugin_registrar.cc",
     "fl_plugin_registry.cc",

shell/platform/linux/fl_mouse_cursor_plugin.cc

+// 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_mouse_cursor_plugin.h"
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_method_channel.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_standard_method_codec.h"
+
+#include <gtk/gtk.h>
+
+static constexpr char kChannelName[] = "flutter/mousecursor";
+static constexpr char kBadArgumentsError[] = "Bad Arguments";
+static constexpr char kActivateSystemCursorMethod[] = "activateSystemCursor";
+static constexpr char kKindKey[] = "kind";
+
+struct _FlMouseCursorPlugin {
+  GObject parent_instance;
+
+  FlMethodChannel* channel;
+
+  FlView* view;
+};
+
+G_DEFINE_TYPE(FlMouseCursorPlugin, fl_mouse_cursor_plugin, G_TYPE_OBJECT)
+
+// Sets the mouse cursor.
+FlMethodResponse* activate_system_cursor(FlMouseCursorPlugin* 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* kind_value = fl_value_lookup_string(args, kKindKey);
+  const gchar* kind = nullptr;
+  if (fl_value_get_type(kind_value) == FL_VALUE_TYPE_STRING)
+    kind = fl_value_get_string(kind_value);
+
+  const gchar* cursor_name = nullptr;
+  if (g_strcmp0(kind, "none") == 0)
+    cursor_name = "none";
+  else if (g_strcmp0(kind, "basic") == 0)
+    cursor_name = "default";
+  else if (g_strcmp0(kind, "click") == 0)
+    cursor_name = "pointer";
+  else if (g_strcmp0(kind, "text") == 0)
+    cursor_name = "text";
+  else if (g_strcmp0(kind, "forbidden") == 0)
+    cursor_name = "not-allowed";
+  else if (g_strcmp0(kind, "grab") == 0)
+    cursor_name = "grab";
+  else if (g_strcmp0(kind, "grabbing") == 0)
+    cursor_name = "grabbing";
+  else if (g_strcmp0(kind, "resizeLeftRight") == 0)
+    cursor_name = "ew-resize";
+  else if (g_strcmp0(kind, "resizeUpDown") == 0)
+    cursor_name = "ns-resize";
+  else
+    cursor_name = "default";
+
+  GdkWindow* window =
+      gtk_widget_get_window(gtk_widget_get_toplevel(GTK_WIDGET(self->view)));
+  g_autoptr(GdkCursor) cursor =
+      gdk_cursor_new_from_name(gdk_window_get_display(window), cursor_name);
+  gdk_window_set_cursor(window, cursor);
+
+  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) {
+  FlMouseCursorPlugin* self = FL_MOUSE_CURSOR_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, kActivateSystemCursorMethod) == 0)
+    response = activate_system_cursor(self, args);
+  else
+    response = FL_METHOD_RESPONSE(fl_method_not_implemented_response_new());
+
+  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);
+}
+
+static void view_weak_notify_cb(gpointer user_data, GObject* object) {
+  FlMouseCursorPlugin* self = FL_MOUSE_CURSOR_PLUGIN(object);
+  self->view = nullptr;
+}
+
+static void fl_mouse_cursor_plugin_dispose(GObject* object) {
+  FlMouseCursorPlugin* self = FL_MOUSE_CURSOR_PLUGIN(object);
+
+  g_clear_object(&self->channel);
+  if (self->view != nullptr) {
+    g_object_weak_unref(G_OBJECT(self->view), view_weak_notify_cb, self);
+    self->view = nullptr;
+  }
+
+  G_OBJECT_CLASS(fl_mouse_cursor_plugin_parent_class)->dispose(object);
+}
+
+static void fl_mouse_cursor_plugin_class_init(FlMouseCursorPluginClass* klass) {
+  G_OBJECT_CLASS(klass)->dispose = fl_mouse_cursor_plugin_dispose;
+}
+
+static void fl_mouse_cursor_plugin_init(FlMouseCursorPlugin* self) {}
+
+FlMouseCursorPlugin* fl_mouse_cursor_plugin_new(FlBinaryMessenger* messenger,
+                                                FlView* view) {
+  g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
+
+  FlMouseCursorPlugin* self = FL_MOUSE_CURSOR_PLUGIN(
+      g_object_new(fl_mouse_cursor_plugin_get_type(), nullptr));
+
+  g_autoptr(FlStandardMethodCodec) codec = fl_standard_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);
+  self->view = view;
+  g_object_weak_ref(G_OBJECT(view), view_weak_notify_cb, self);
+
+  return self;
+}

shell/platform/linux/fl_mouse_cursor_plugin.h

+// 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_MOUSE_CURSOR_LINUX_FL_MOUSE_CURSOR_PLUGIN_H_
+#define FLUTTER_SHELL_MOUSE_CURSOR_LINUX_FL_MOUSE_CURSOR_PLUGIN_H_
+
+#include <gdk/gdk.h>
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_view.h"
+
+G_BEGIN_DECLS
+
+G_DECLARE_FINAL_TYPE(FlMouseCursorPlugin,
+                     fl_mouse_cursor_plugin,
+                     FL,
+                     MOUSE_CURSOR_PLUGIN,
+                     GObject);
+
+/**
+ * FlMouseCursorPlugin:
+ *
+ * #FlMouseCursorPlugin is a mouse_cursor channel that implements the shell side
+ * of SystemChannels.mouseCursor from the Flutter services library.
+ */
+
+/**
+ * fl_mouse_cursor_plugin_new:
+ * @messenger: an #FlBinaryMessenger.
+ * @view: an #FlView to control.
+ *
+ * Creates a new plugin that implements SystemChannels.mouseCursor from the
+ * Flutter services library.
+ *
+ * Returns: a new #FlMouseCursorPlugin.
+ */
+FlMouseCursorPlugin* fl_mouse_cursor_plugin_new(FlBinaryMessenger* messenger,
+                                                FlView* view);
+
+G_END_DECLS
+
+#endif  // FLUTTER_SHELL_MOUSE_CURSOR_LINUX_FL_MOUSE_CURSOR_PLUGIN_H_

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_mouse_cursor_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"
@@ -34,6 +35,7 @@ struct _FlView {
 
   // Flutter system channel handlers.
   FlKeyEventPlugin* key_event_plugin;
+  FlMouseCursorPlugin* mouse_cursor_plugin;
   FlPlatformPlugin* platform_plugin;
   FlTextInputPlugin* text_input_plugin;
 };
@@ -131,6 +133,7 @@ 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->mouse_cursor_plugin = fl_mouse_cursor_plugin_new(messenger, self);
   self->platform_plugin = fl_platform_plugin_new(messenger);
   self->text_input_plugin = fl_text_input_plugin_new(messenger);
 }
@@ -186,6 +189,7 @@ 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->mouse_cursor_plugin);
   g_clear_object(&self->platform_plugin);
   g_clear_object(&self->text_input_plugin);