Move FlMouseCursorHandler from FlView to FlEngine (flutter/engine#56026)

Author: robert-ancell

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

@@ -54,6 +54,9 @@ struct _FlEngine {
   // Implements the flutter/platform channel.
   FlPlatformHandler* platform_handler;
 
+  // Implements the flutter/mousecursor channel.
+  FlMouseCursorHandler* mouse_cursor_handler;
+
   // Manages textures rendered by native code.
   FlTextureRegistrar* texture_registrar;
 
@@ -449,6 +452,7 @@ static void fl_engine_dispose(GObject* object) {
   g_clear_object(&self->binary_messenger);
   g_clear_object(&self->settings_handler);
   g_clear_object(&self->platform_handler);
+  g_clear_object(&self->mouse_cursor_handler);
   g_clear_object(&self->task_runner);
 
   if (self->platform_message_handler_destroy_notify) {
@@ -629,6 +633,8 @@ gboolean fl_engine_start(FlEngine* self, GError** error) {
   fl_settings_handler_start(self->settings_handler, settings);
 
   self->platform_handler = fl_platform_handler_new(self->binary_messenger);
+  self->mouse_cursor_handler =
+      fl_mouse_cursor_handler_new(self->binary_messenger);
 
   result = self->embedder_api.UpdateSemanticsEnabled(self->engine, TRUE);
   if (result != kSuccess) {
@@ -1051,3 +1057,8 @@ void fl_engine_request_app_exit(FlEngine* self) {
   g_return_if_fail(FL_IS_ENGINE(self));
   fl_platform_handler_request_app_exit(self->platform_handler);
 }
+
+FlMouseCursorHandler* fl_engine_get_mouse_cursor_handler(FlEngine* self) {
+  g_return_val_if_fail(FL_IS_ENGINE(self), nullptr);
+  return self->mouse_cursor_handler;
+}

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

@@ -8,6 +8,7 @@
 #include <glib-object.h>
 
 #include "flutter/shell/platform/embedder/embedder.h"
+#include "flutter/shell/platform/linux/fl_mouse_cursor_handler.h"
 #include "flutter/shell/platform/linux/fl_renderer.h"
 #include "flutter/shell/platform/linux/fl_task_runner.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_dart_project.h"
@@ -424,6 +425,16 @@ void fl_engine_update_accessibility_features(FlEngine* engine, int32_t flags);
  */
 void fl_engine_request_app_exit(FlEngine* engine);
 
+/**
+ * fl_engine_get_mouse_cursor_handler:
+ * @engine: an #FlEngine.
+ *
+ * Gets the mouse cursor handler used by this engine.
+ *
+ * Returns: a #FlMouseCursorHandler.
+ */
+FlMouseCursorHandler* fl_engine_get_mouse_cursor_handler(FlEngine* engine);
+
 G_END_DECLS
 
 #endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_ENGINE_PRIVATE_H_

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

@@ -4,7 +4,6 @@
 
 #include "flutter/shell/platform/linux/fl_mouse_cursor_handler.h"
 
-#include <gtk/gtk.h>
 #include <cstring>
 
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_method_channel.h"
@@ -22,11 +21,16 @@ struct _FlMouseCursorHandler {
 
   FlMethodChannel* channel;
 
-  GWeakRef view;
-
   GHashTable* system_cursor_table;
+
+  // The current cursor.
+  gchar* cursor_name;
 };
 
+enum { kSignalCursorChanged, kSignalLastSignal };
+
+static guint fl_mouse_cursor_handler_signals[kSignalLastSignal];
+
 G_DEFINE_TYPE(FlMouseCursorHandler, fl_mouse_cursor_handler, G_TYPE_OBJECT)
 
 // Insert a new entry into a hashtable from strings to strings.
@@ -109,14 +113,10 @@ FlMethodResponse* activate_system_cursor(FlMouseCursorHandler* self,
     cursor_name = kFallbackCursor;
   }
 
-  g_autoptr(FlView) view = FL_VIEW(g_weak_ref_get(&self->view));
-  if (view != nullptr) {
-    GdkWindow* window =
-        gtk_widget_get_window(gtk_widget_get_toplevel(GTK_WIDGET(view)));
-    g_autoptr(GdkCursor) cursor =
-        gdk_cursor_new_from_name(gdk_window_get_display(window), cursor_name);
-    gdk_window_set_cursor(window, cursor);
-  }
+  g_free(self->cursor_name);
+  self->cursor_name = g_strdup(cursor_name);
+
+  g_signal_emit(self, fl_mouse_cursor_handler_signals[kSignalCursorChanged], 0);
 
   return FL_METHOD_RESPONSE(fl_method_success_response_new(nullptr));
 }
@@ -147,21 +147,27 @@ static void fl_mouse_cursor_handler_dispose(GObject* object) {
   FlMouseCursorHandler* self = FL_MOUSE_CURSOR_HANDLER(object);
 
   g_clear_object(&self->channel);
-  g_weak_ref_clear(&self->view);
   g_clear_pointer(&self->system_cursor_table, g_hash_table_unref);
+  g_clear_pointer(&self->cursor_name, g_free);
 
   G_OBJECT_CLASS(fl_mouse_cursor_handler_parent_class)->dispose(object);
 }
 
 static void fl_mouse_cursor_handler_class_init(
     FlMouseCursorHandlerClass* klass) {
   G_OBJECT_CLASS(klass)->dispose = fl_mouse_cursor_handler_dispose;
+
+  fl_mouse_cursor_handler_signals[kSignalCursorChanged] =
+      g_signal_new("cursor-changed", fl_mouse_cursor_handler_get_type(),
+                   G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL, G_TYPE_NONE, 0);
 }
 
-static void fl_mouse_cursor_handler_init(FlMouseCursorHandler* self) {}
+static void fl_mouse_cursor_handler_init(FlMouseCursorHandler* self) {
+  self->cursor_name = g_strdup("");
+}
 
-FlMouseCursorHandler* fl_mouse_cursor_handler_new(FlBinaryMessenger* messenger,
-                                                  FlView* view) {
+FlMouseCursorHandler* fl_mouse_cursor_handler_new(
+    FlBinaryMessenger* messenger) {
   g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
 
   FlMouseCursorHandler* self = FL_MOUSE_CURSOR_HANDLER(
@@ -172,7 +178,12 @@ FlMouseCursorHandler* fl_mouse_cursor_handler_new(FlBinaryMessenger* messenger,
       fl_method_channel_new(messenger, kChannelName, FL_METHOD_CODEC(codec));
   fl_method_channel_set_method_call_handler(self->channel, method_call_cb, self,
                                             nullptr);
-  g_weak_ref_init(&self->view, view);
 
   return self;
 }
+
+const gchar* fl_mouse_cursor_handler_get_cursor_name(
+    FlMouseCursorHandler* self) {
+  g_return_val_if_fail(FL_IS_MOUSE_CURSOR_HANDLER(self), nullptr);
+  return self->cursor_name;
+}

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

@@ -8,7 +8,6 @@
 #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
 
@@ -28,15 +27,24 @@ G_DECLARE_FINAL_TYPE(FlMouseCursorHandler,
 /**
  * fl_mouse_cursor_handler_new:
  * @messenger: an #FlBinaryMessenger.
- * @view: an #FlView to control.
  *
  * Creates a new handler that implements SystemChannels.mouseCursor from the
  * Flutter services library.
  *
  * Returns: a new #FlMouseCursorHandler.
  */
-FlMouseCursorHandler* fl_mouse_cursor_handler_new(FlBinaryMessenger* messenger,
-                                                  FlView* view);
+FlMouseCursorHandler* fl_mouse_cursor_handler_new(FlBinaryMessenger* messenger);
+
+/**
+ * fl_mouse_cursor_handler_get_cursor_name:
+ * @handler: an #FlMouseCursorHandler.
+ *
+ * Get the name of the current mouse cursor.
+ *
+ * Returns: a mouse cursor name.
+ */
+const gchar* fl_mouse_cursor_handler_get_cursor_name(
+    FlMouseCursorHandler* handler);
 
 G_END_DECLS
 

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

@@ -16,7 +16,6 @@
 #include "flutter/shell/platform/linux/fl_keyboard_handler.h"
 #include "flutter/shell/platform/linux/fl_keyboard_manager.h"
 #include "flutter/shell/platform/linux/fl_keyboard_view_delegate.h"
-#include "flutter/shell/platform/linux/fl_mouse_cursor_handler.h"
 #include "flutter/shell/platform/linux/fl_plugin_registrar_private.h"
 #include "flutter/shell/platform/linux/fl_pointer_manager.h"
 #include "flutter/shell/platform/linux/fl_renderer_gdk.h"
@@ -68,11 +67,13 @@ struct _FlView {
   // Flutter system channel handlers.
   FlKeyboardHandler* keyboard_handler;
   FlTextInputHandler* text_input_handler;
-  FlMouseCursorHandler* mouse_cursor_handler;
 
   // Accessible tree from Flutter, exposed as an AtkPlug.
   FlViewAccessible* view_accessible;
 
+  // Signal subscripton for cursor changes.
+  guint cursor_changed_cb_id;
+
   GCancellable* cancellable;
 };
 
@@ -184,6 +185,28 @@ static gboolean get_mouse_button(GdkEvent* event, int64_t* button) {
   }
 }
 
+// Called when the mouse cursor changes.
+static void cursor_changed_cb(FlView* self) {
+  FlMouseCursorHandler* handler =
+      fl_engine_get_mouse_cursor_handler(self->engine);
+  const gchar* cursor_name = fl_mouse_cursor_handler_get_cursor_name(handler);
+  GdkWindow* window =
+      gtk_widget_get_window(gtk_widget_get_toplevel(GTK_WIDGET(self)));
+  g_autoptr(GdkCursor) cursor =
+      gdk_cursor_new_from_name(gdk_window_get_display(window), cursor_name);
+  gdk_window_set_cursor(window, cursor);
+}
+
+// Set the mouse cursor.
+static void setup_cursor(FlView* self) {
+  FlMouseCursorHandler* handler =
+      fl_engine_get_mouse_cursor_handler(self->engine);
+
+  self->cursor_changed_cb_id = g_signal_connect_swapped(
+      handler, "cursor-changed", G_CALLBACK(cursor_changed_cb), self);
+  cursor_changed_cb(self);
+}
+
 // Updates the engine with the current window metrics.
 static void handle_geometry_changed(FlView* self) {
   GtkAllocation allocation;
@@ -457,10 +480,7 @@ static GdkGLContext* create_context_cb(FlView* self) {
   fl_renderer_gdk_set_window(self->renderer,
                              gtk_widget_get_parent_window(GTK_WIDGET(self)));
 
-  // Create system channel handlers.
-  FlBinaryMessenger* messenger = fl_engine_get_binary_messenger(self->engine);
   init_scrolling(self);
-  self->mouse_cursor_handler = fl_mouse_cursor_handler_new(messenger, self);
 
   g_autoptr(GError) error = nullptr;
   if (!fl_renderer_gdk_create_contexts(self->renderer, &error)) {
@@ -505,6 +525,8 @@ static void realize_cb(FlView* self) {
     return;
   }
 
+  setup_cursor(self);
+
   handle_geometry_changed(self);
 
   self->view_accessible = fl_view_accessible_new(self->engine);
@@ -567,6 +589,13 @@ static void fl_view_dispose(GObject* object) {
     fl_engine_set_update_semantics_handler(self->engine, nullptr, nullptr,
                                            nullptr);
 
+    FlMouseCursorHandler* handler =
+        fl_engine_get_mouse_cursor_handler(self->engine);
+    if (self->cursor_changed_cb_id != 0) {
+      g_signal_handler_disconnect(handler, self->cursor_changed_cb_id);
+      self->cursor_changed_cb_id = 0;
+    }
+
     // Stop rendering.
     fl_renderer_remove_view(FL_RENDERER(self->renderer), self->view_id);
 
@@ -589,7 +618,6 @@ static void fl_view_dispose(GObject* object) {
   g_clear_object(&self->pointer_manager);
   g_clear_object(&self->keyboard_manager);
   g_clear_object(&self->keyboard_handler);
-  g_clear_object(&self->mouse_cursor_handler);
   g_clear_object(&self->view_accessible);
   g_clear_object(&self->cancellable);
 
@@ -750,6 +778,8 @@ G_MODULE_EXPORT FlView* fl_view_new_for_engine(FlEngine* engine) {
 
   self->pointer_manager = fl_pointer_manager_new(self->view_id, engine);
 
+  setup_cursor(self);
+
   return self;
 }
 

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

@@ -82,6 +82,9 @@ TEST(FlViewTest, SecondaryView) {
         return kSuccess;
       }));
 
+  g_autoptr(GError) error = nullptr;
+  EXPECT_TRUE(fl_engine_start(engine, &error));
+
   FlView* secondary_view = fl_view_new_for_engine(engine);
   EXPECT_EQ(view_id, fl_view_get_id(secondary_view));
 }
@@ -103,6 +106,9 @@ TEST(FlViewTest, SecondaryViewError) {
         return kInvalidArguments;
       }));
 
+  g_autoptr(GError) error = nullptr;
+  EXPECT_TRUE(fl_engine_start(engine, &error));
+
   FlView* secondary_view = fl_view_new_for_engine(engine);
   EXPECT_EQ(view_id, fl_view_get_id(secondary_view));
 }
@@ -125,6 +131,9 @@ TEST(FlViewTest, ViewDestroy) {
         return kSuccess;
       }));
 
+  g_autoptr(GError) error = nullptr;
+  EXPECT_TRUE(fl_engine_start(engine, &error));
+
   FlView* secondary_view = fl_view_new_for_engine(engine);
 
   int64_t implicit_view_id = fl_view_get_id(implicit_view);
@@ -155,6 +164,9 @@ TEST(FlViewTest, ViewDestroyError) {
         return kInvalidArguments;
       }));
 
+  g_autoptr(GError) error = nullptr;
+  EXPECT_TRUE(fl_engine_start(engine, &error));
+
   FlView* secondary_view = fl_view_new_for_engine(engine);
 
   gtk_widget_destroy(GTK_WIDGET(secondary_view));

engine/src/flutter/shell/platform/linux/testing/mock_window.cc

@@ -15,3 +15,18 @@ MockWindow::MockWindow() {
 GdkWindowState gdk_window_get_state(GdkWindow* window) {
   return mock->gdk_window_get_state(window);
 }
+
+GdkDisplay* gdk_window_get_display(GdkWindow* window) {
+  return nullptr;
+}
+
+GdkMonitor* gdk_display_get_monitor_at_window(GdkDisplay* display,
+                                              GdkWindow* window) {
+  return nullptr;
+}
+
+GdkCursor* gdk_cursor_new_from_name(GdkDisplay* display, const gchar* name) {
+  return nullptr;
+}
+
+void gdk_window_set_cursor(GdkWindow* window, GdkCursor* cursor) {}