[Linux] use top-level GTK IM client window (flutter/engine#35272)

This PR takes a step back and changes the GTK IM client window back from FlView to GtkApplicationWindow as it was before #33111. The window was originally changed to FlView to make the code testable by cutting a dependency to gtk_widget_translate_coordinates(). The change was hard to revert because there were several conflicting changes on top. Therefore, this PR introduces an FlTextInputViewDelegate to be able to provide coordinate mapping in a testable way.

Fixes: flutter/flutter#108832

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -2321,6 +2321,8 @@ FILE: ../../../flutter/shell/platform/linux/fl_task_runner.h
 FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin.cc
 FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin.h
 FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin_test.cc
+FILE: ../../../flutter/shell/platform/linux/fl_text_input_view_delegate.cc
+FILE: ../../../flutter/shell/platform/linux/fl_text_input_view_delegate.h
 FILE: ../../../flutter/shell/platform/linux/fl_texture.cc
 FILE: ../../../flutter/shell/platform/linux/fl_texture_gl.cc
 FILE: ../../../flutter/shell/platform/linux/fl_texture_gl_private.h

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

@@ -141,6 +141,7 @@ source_set("flutter_linux_sources") {
     "fl_task_runner.cc",
     "fl_task_runner.h",
     "fl_text_input_plugin.cc",
+    "fl_text_input_view_delegate.cc",
     "fl_texture.cc",
     "fl_texture_gl.cc",
     "fl_texture_registrar.cc",
@@ -234,6 +235,7 @@ executable("flutter_linux_unittests") {
     "testing/mock_settings.cc",
     "testing/mock_signal_handler.cc",
     "testing/mock_text_input_plugin.cc",
+    "testing/mock_text_input_view_delegate.cc",
     "testing/mock_texture_registrar.cc",
   ]
 

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

@@ -80,6 +80,8 @@ struct FlTextInputPluginPrivate {
   // Input method.
   GtkIMContext* im_context;
 
+  FlTextInputViewDelegate* view_delegate;
+
   flutter::TextInputModel* text_model;
 
   // A 4x4 matrix that maps from `EditableText` local coordinates to the
@@ -487,9 +489,13 @@ static void update_im_cursor_position(FlTextInputPlugin* self) {
            priv->composing_rect.y * priv->editabletext_transform[1][1] +
            priv->editabletext_transform[3][1] + priv->composing_rect.height;
 
+  // Transform from Flutter view coordinates to GTK window coordinates.
+  GdkRectangle preedit_rect = {};
+  fl_text_input_view_delegate_translate_coordinates(
+      priv->view_delegate, x, y, &preedit_rect.x, &preedit_rect.y);
+
   // Set the cursor location in window coordinates so that GTK can position any
   // system input method windows.
-  GdkRectangle preedit_rect = {x, y, 0, 0};
   gtk_im_context_set_cursor_location(priv->im_context, &preedit_rect);
 }
 
@@ -587,6 +593,12 @@ static void fl_text_input_plugin_dispose(GObject* object) {
     delete priv->text_model;
     priv->text_model = nullptr;
   }
+  if (priv->view_delegate != nullptr) {
+    g_object_remove_weak_pointer(
+        G_OBJECT(priv->view_delegate),
+        reinterpret_cast<gpointer*>(&(priv->view_delegate)));
+    priv->view_delegate = nullptr;
+  }
 
   G_OBJECT_CLASS(fl_text_input_plugin_parent_class)->dispose(object);
 }
@@ -719,10 +731,13 @@ static void init_im_context(FlTextInputPlugin* self, GtkIMContext* im_context) {
                           G_CONNECT_SWAPPED);
 }
 
-FlTextInputPlugin* fl_text_input_plugin_new(FlBinaryMessenger* messenger,
-                                            GtkIMContext* im_context) {
+FlTextInputPlugin* fl_text_input_plugin_new(
+    FlBinaryMessenger* messenger,
+    GtkIMContext* im_context,
+    FlTextInputViewDelegate* view_delegate) {
   g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
   g_return_val_if_fail(GTK_IS_IM_CONTEXT(im_context), nullptr);
+  g_return_val_if_fail(FL_IS_TEXT_INPUT_VIEW_DELEGATE(view_delegate), nullptr);
 
   FlTextInputPlugin* self = FL_TEXT_INPUT_PLUGIN(
       g_object_new(fl_text_input_plugin_get_type(), nullptr));
@@ -737,6 +752,11 @@ FlTextInputPlugin* fl_text_input_plugin_new(FlBinaryMessenger* messenger,
 
   init_im_context(self, im_context);
 
+  priv->view_delegate = view_delegate;
+  g_object_add_weak_pointer(
+      G_OBJECT(view_delegate),
+      reinterpret_cast<gpointer*>(&(priv->view_delegate)));
+
   return self;
 }
 

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

@@ -8,6 +8,7 @@
 #include <gtk/gtk.h>
 
 #include "flutter/shell/platform/linux/fl_key_event.h"
+#include "flutter/shell/platform/linux/fl_text_input_view_delegate.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
 
 G_BEGIN_DECLS
@@ -38,14 +39,17 @@ struct _FlTextInputPluginClass {
  * fl_text_input_plugin_new:
  * @messenger: an #FlBinaryMessenger.
  * @im_context: (allow-none): a #GtkIMContext.
+ * @view_delegate: an #FlTextInputViewDelegate.
  *
  * Creates a new plugin that implements SystemChannels.textInput from the
  * Flutter services library.
  *
  * Returns: a new #FlTextInputPlugin.
  */
-FlTextInputPlugin* fl_text_input_plugin_new(FlBinaryMessenger* messenger,
-                                            GtkIMContext* im_context);
+FlTextInputPlugin* fl_text_input_plugin_new(
+    FlBinaryMessenger* messenger,
+    GtkIMContext* im_context,
+    FlTextInputViewDelegate* view_delegate);
 
 /**
  * fl_text_input_plugin_filter_keypress

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

@@ -11,6 +11,7 @@
 #include "flutter/shell/platform/linux/testing/mock_binary_messenger.h"
 #include "flutter/shell/platform/linux/testing/mock_binary_messenger_response_handle.h"
 #include "flutter/shell/platform/linux/testing/mock_im_context.h"
+#include "flutter/shell/platform/linux/testing/mock_text_input_view_delegate.h"
 #include "flutter/testing/testing.h"
 
 #include "gmock/gmock.h"
@@ -189,9 +190,10 @@ static void send_key_event(FlTextInputPlugin* plugin,
 TEST(FlTextInputPluginTest, MessageHandler) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   EXPECT_TRUE(messenger.HasMessageHandler("flutter/textinput"));
@@ -200,9 +202,10 @@ TEST(FlTextInputPluginTest, MessageHandler) {
 TEST(FlTextInputPluginTest, SetClient) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   g_autoptr(FlValue) args = build_input_config({.client_id = 1});
@@ -222,9 +225,10 @@ TEST(FlTextInputPluginTest, SetClient) {
 TEST(FlTextInputPluginTest, Show) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   EXPECT_CALL(context,
@@ -246,9 +250,10 @@ TEST(FlTextInputPluginTest, Show) {
 TEST(FlTextInputPluginTest, Hide) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   EXPECT_CALL(context,
@@ -270,9 +275,10 @@ TEST(FlTextInputPluginTest, Hide) {
 TEST(FlTextInputPluginTest, ClearClient) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   g_autoptr(FlValue) null = fl_value_new_null();
@@ -291,9 +297,10 @@ TEST(FlTextInputPluginTest, ClearClient) {
 TEST(FlTextInputPluginTest, PerformAction) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   // set input config
@@ -366,9 +373,10 @@ TEST(FlTextInputPluginTest, PerformAction) {
 TEST(FlTextInputPluginTest, MoveCursor) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   // set input config
@@ -443,9 +451,10 @@ TEST(FlTextInputPluginTest, MoveCursor) {
 TEST(FlTextInputPluginTest, Select) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   // set input config
@@ -520,9 +529,10 @@ TEST(FlTextInputPluginTest, Select) {
 TEST(FlTextInputPluginTest, Composing) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   g_signal_emit_by_name(context, "preedit-start", nullptr);
@@ -589,9 +599,10 @@ TEST(FlTextInputPluginTest, Composing) {
 TEST(FlTextInputPluginTest, SurroundingText) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   // set input config
@@ -658,9 +669,10 @@ TEST(FlTextInputPluginTest, SurroundingText) {
 TEST(FlTextInputPluginTest, SetMarkedTextRect) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   g_signal_emit_by_name(context, "preedit-start", nullptr);
@@ -719,11 +731,18 @@ TEST(FlTextInputPluginTest, SetMarkedTextRect) {
                              ::testing::_, SuccessResponse(null), ::testing::_))
       .WillOnce(::testing::Return(true));
 
+  EXPECT_CALL(delegate, fl_text_input_view_delegate_translate_coordinates(
+                            ::testing::Eq<FlTextInputViewDelegate*>(delegate),
+                            ::testing::Eq(27), ::testing::Eq(32), ::testing::_,
+                            ::testing::_))
+      .WillOnce(::testing::DoAll(::testing::SetArgPointee<3>(123),
+                                 ::testing::SetArgPointee<4>(456)));
+
   EXPECT_CALL(context, gtk_im_context_set_cursor_location(
                            ::testing::Eq<GtkIMContext*>(context),
                            ::testing::Pointee(::testing::AllOf(
-                               ::testing::Field(&GdkRectangle::x, 27),
-                               ::testing::Field(&GdkRectangle::y, 32),
+                               ::testing::Field(&GdkRectangle::x, 123),
+                               ::testing::Field(&GdkRectangle::y, 456),
                                ::testing::Field(&GdkRectangle::width, 0),
                                ::testing::Field(&GdkRectangle::height, 0)))));
 
@@ -733,9 +752,10 @@ TEST(FlTextInputPluginTest, SetMarkedTextRect) {
 TEST(FlTextInputPluginTest, TextInputTypeNone) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   g_autoptr(FlValue) args = build_input_config({
@@ -775,9 +795,10 @@ TEST(FlTextInputPluginTest, TextInputTypeNone) {
 TEST(FlTextInputPluginTest, TextEditingDelta) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   // set config
@@ -846,9 +867,10 @@ TEST(FlTextInputPluginTest, TextEditingDelta) {
 TEST(FlTextInputPluginTest, ComposingDelta) {
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
   ::testing::NiceMock<flutter::testing::MockIMContext> context;
+  ::testing::NiceMock<flutter::testing::MockTextInputViewDelegate> delegate;
 
   g_autoptr(FlTextInputPlugin) plugin =
-      fl_text_input_plugin_new(messenger, context);
+      fl_text_input_plugin_new(messenger, context, delegate);
   EXPECT_NE(plugin, nullptr);
 
   // set config

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

@@ -0,0 +1,24 @@
+// 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_text_input_view_delegate.h"
+
+G_DEFINE_INTERFACE(FlTextInputViewDelegate,
+                   fl_text_input_view_delegate,
+                   G_TYPE_OBJECT)
+
+static void fl_text_input_view_delegate_default_init(
+    FlTextInputViewDelegateInterface* iface) {}
+
+void fl_text_input_view_delegate_translate_coordinates(
+    FlTextInputViewDelegate* self,
+    gint view_x,
+    gint view_y,
+    gint* window_x,
+    gint* window_y) {
+  g_return_if_fail(FL_IS_TEXT_INPUT_VIEW_DELEGATE(self));
+
+  FL_TEXT_INPUT_VIEW_DELEGATE_GET_IFACE(self)->translate_coordinates(
+      self, view_x, view_y, window_x, window_y);
+}

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

@@ -0,0 +1,48 @@
+// 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_TEXT_INPUT_VIEW_DELEGATE_H_
+#define FLUTTER_SHELL_PLATFORM_LINUX_FL_TEXT_INPUT_VIEW_DELEGATE_H_
+
+#include <gdk/gdk.h>
+
+#include "flutter/shell/platform/embedder/embedder.h"
+
+G_BEGIN_DECLS
+
+G_DECLARE_INTERFACE(FlTextInputViewDelegate,
+                    fl_text_input_view_delegate,
+                    FL,
+                    TEXT_INPUT_VIEW_DELEGATE,
+                    GObject);
+
+/**
+ * FlTextInputViewDelegate:
+ *
+ * An interface for a class that provides `FlTextInputPlugin` with
+ * view-related features.
+ *
+ * This interface is typically implemented by `FlView`.
+ */
+
+struct _FlTextInputViewDelegateInterface {
+  GTypeInterface g_iface;
+
+  void (*translate_coordinates)(FlTextInputViewDelegate* delegate,
+                                gint view_x,
+                                gint view_y,
+                                gint* window_x,
+                                gint* window_y);
+};
+
+void fl_text_input_view_delegate_translate_coordinates(
+    FlTextInputViewDelegate* delegate,
+    gint view_x,
+    gint view_y,
+    gint* window_x,
+    gint* window_y);
+
+G_END_DECLS
+
+#endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_TEXT_INPUT_VIEW_DELEGATE_H_

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

@@ -20,6 +20,7 @@
 #include "flutter/shell/platform/linux/fl_scrolling_manager.h"
 #include "flutter/shell/platform/linux/fl_scrolling_view_delegate.h"
 #include "flutter/shell/platform/linux/fl_text_input_plugin.h"
+#include "flutter/shell/platform/linux/fl_text_input_view_delegate.h"
 #include "flutter/shell/platform/linux/fl_view_accessible.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_engine.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_plugin_registry.h"
@@ -82,6 +83,9 @@ static void fl_view_keyboard_delegate_iface_init(
 static void fl_view_scrolling_delegate_iface_init(
     FlScrollingViewDelegateInterface* iface);
 
+static void fl_view_text_input_delegate_iface_init(
+    FlTextInputViewDelegateInterface* iface);
+
 G_DEFINE_TYPE_WITH_CODE(
     FlView,
     fl_view,
@@ -91,18 +95,22 @@ G_DEFINE_TYPE_WITH_CODE(
         G_IMPLEMENT_INTERFACE(fl_keyboard_view_delegate_get_type(),
                               fl_view_keyboard_delegate_iface_init)
             G_IMPLEMENT_INTERFACE(fl_scrolling_view_delegate_get_type(),
-                                  fl_view_scrolling_delegate_iface_init))
+                                  fl_view_scrolling_delegate_iface_init)
+                G_IMPLEMENT_INTERFACE(fl_text_input_view_delegate_get_type(),
+                                      fl_view_text_input_delegate_iface_init))
 
 // Initialize keyboard manager.
 static void init_keyboard(FlView* self) {
   FlBinaryMessenger* messenger = fl_engine_get_binary_messenger(self->engine);
 
-  GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(self));
+  GdkWindow* window =
+      gtk_widget_get_window(gtk_widget_get_toplevel(GTK_WIDGET(self)));
   g_return_if_fail(GDK_IS_WINDOW(window));
   g_autoptr(GtkIMContext) im_context = gtk_im_multicontext_new();
   gtk_im_context_set_client_window(im_context, window);
 
-  self->text_input_plugin = fl_text_input_plugin_new(messenger, im_context);
+  self->text_input_plugin = fl_text_input_plugin_new(
+      messenger, im_context, FL_TEXT_INPUT_VIEW_DELEGATE(self));
   self->keyboard_manager =
       fl_keyboard_manager_new(FL_KEYBOARD_VIEW_DELEGATE(self));
 }
@@ -333,6 +341,18 @@ static void fl_view_scrolling_delegate_iface_init(
       };
 }
 
+static void fl_view_text_input_delegate_iface_init(
+    FlTextInputViewDelegateInterface* iface) {
+  iface->translate_coordinates = [](FlTextInputViewDelegate* delegate,
+                                    gint view_x, gint view_y, gint* window_x,
+                                    gint* window_y) {
+    FlView* self = FL_VIEW(delegate);
+    gtk_widget_translate_coordinates(GTK_WIDGET(self),
+                                     gtk_widget_get_toplevel(GTK_WIDGET(self)),
+                                     view_x, view_y, window_x, window_y);
+  };
+}
+
 // Signal handler for GtkWidget::button-press-event
 static gboolean button_press_event_cb(GtkWidget* widget,
                                       GdkEventButton* event,

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

@@ -0,0 +1,74 @@
+// 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/testing/mock_text_input_view_delegate.h"
+
+using namespace flutter::testing;
+
+G_DECLARE_FINAL_TYPE(FlMockTextInputViewDelegate,
+                     fl_mock_text_input_view_delegate,
+                     FL,
+                     MOCK_TEXT_INPUT_VIEW_DELEGATE,
+                     GObject)
+
+struct _FlMockTextInputViewDelegate {
+  GObject parent_instance;
+  MockTextInputViewDelegate* mock;
+};
+
+static FlTextInputViewDelegate* fl_mock_text_input_view_delegate_new(
+    MockTextInputViewDelegate* mock) {
+  FlMockTextInputViewDelegate* self = FL_MOCK_TEXT_INPUT_VIEW_DELEGATE(
+      g_object_new(fl_mock_text_input_view_delegate_get_type(), nullptr));
+  self->mock = mock;
+  return FL_TEXT_INPUT_VIEW_DELEGATE(self);
+}
+
+MockTextInputViewDelegate::MockTextInputViewDelegate()
+    : instance_(fl_mock_text_input_view_delegate_new(this)) {}
+
+MockTextInputViewDelegate::~MockTextInputViewDelegate() {
+  if (FL_IS_TEXT_INPUT_VIEW_DELEGATE(instance_)) {
+    g_clear_object(&instance_);
+  }
+}
+
+MockTextInputViewDelegate::operator FlTextInputViewDelegate*() {
+  return instance_;
+}
+
+static void fl_mock_text_input_view_delegate_iface_init(
+    FlTextInputViewDelegateInterface* iface);
+
+G_DEFINE_TYPE_WITH_CODE(
+    FlMockTextInputViewDelegate,
+    fl_mock_text_input_view_delegate,
+    G_TYPE_OBJECT,
+    G_IMPLEMENT_INTERFACE(fl_text_input_view_delegate_get_type(),
+                          fl_mock_text_input_view_delegate_iface_init))
+
+static void fl_mock_text_input_view_delegate_class_init(
+    FlMockTextInputViewDelegateClass* klass) {}
+
+static void fl_mock_text_input_view_delegate_translate_coordinates(
+    FlTextInputViewDelegate* view_delegate,
+    gint view_x,
+    gint view_y,
+    gint* window_x,
+    gint* window_y) {
+  g_return_if_fail(FL_IS_MOCK_TEXT_INPUT_VIEW_DELEGATE(view_delegate));
+  FlMockTextInputViewDelegate* self =
+      FL_MOCK_TEXT_INPUT_VIEW_DELEGATE(view_delegate);
+  self->mock->fl_text_input_view_delegate_translate_coordinates(
+      view_delegate, view_x, view_y, window_x, window_y);
+}
+
+static void fl_mock_text_input_view_delegate_iface_init(
+    FlTextInputViewDelegateInterface* iface) {
+  iface->translate_coordinates =
+      fl_mock_text_input_view_delegate_translate_coordinates;
+}
+
+static void fl_mock_text_input_view_delegate_init(
+    FlMockTextInputViewDelegate* self) {}

engine/src/flutter/shell/platform/linux/testing/mock_text_input_view_delegate.h

@@ -0,0 +1,39 @@
+// 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_TESTING_MOCK_TEXT_INPUT_VIEW_DELEGATE_H_
+#define FLUTTER_SHELL_PLATFORM_LINUX_TESTING_MOCK_TEXT_INPUT_VIEW_DELEGATE_H_
+
+#include <unordered_map>
+
+#include "flutter/shell/platform/linux/fl_text_input_view_delegate.h"
+
+#include "gmock/gmock.h"
+
+namespace flutter {
+namespace testing {
+
+// Mock for FlTextInputVuewDelegate.
+class MockTextInputViewDelegate {
+ public:
+  MockTextInputViewDelegate();
+  ~MockTextInputViewDelegate();
+
+  operator FlTextInputViewDelegate*();
+
+  MOCK_METHOD5(fl_text_input_view_delegate_translate_coordinates,
+               void(FlTextInputViewDelegate* delegate,
+                    gint view_x,
+                    gint view_y,
+                    gint* window_x,
+                    gint* window_y));
+
+ private:
+  FlTextInputViewDelegate* instance_ = nullptr;
+};
+
+}  // namespace testing
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_LINUX_TESTING_MOCK_TEXT_INPUT_VIEW_DELEGATE_H_