Add support for multi-window popups on Windows (#16)

Author: hbatagelo

engine/src/flutter/ci/licenses_golden/excluded_files

@@ -402,8 +402,10 @@
 ../../../flutter/shell/platform/windows/direct_manipulation_unittests.cc
 ../../../flutter/shell/platform/windows/dpi_utils_unittests.cc
 ../../../flutter/shell/platform/windows/fixtures
+../../../flutter/shell/platform/windows/flutter_host_window_controller_unittests.cc
 ../../../flutter/shell/platform/windows/flutter_project_bundle_unittests.cc
 ../../../flutter/shell/platform/windows/flutter_window_unittests.cc
+../../../flutter/shell/platform/windows/flutter_windowing_handler_unittests.cc
 ../../../flutter/shell/platform/windows/flutter_windows_engine_unittests.cc
 ../../../flutter/shell/platform/windows/flutter_windows_texture_registrar_unittests.cc
 ../../../flutter/shell/platform/windows/flutter_windows_unittests.cc

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -43825,6 +43825,8 @@ ORIGIN: ../../../flutter/shell/platform/common/text_editing_delta.h + ../../../f
 ORIGIN: ../../../flutter/shell/platform/common/text_input_model.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/common/text_input_model.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/common/text_range.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/common/windowing.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/common/windowing.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/availability_version_check.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/availability_version_check.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/buffer_conversions.h + ../../../flutter/LICENSE
@@ -44556,6 +44558,10 @@ ORIGIN: ../../../flutter/shell/platform/windows/flutter_platform_node_delegate_w
 ORIGIN: ../../../flutter/shell/platform/windows/flutter_platform_node_delegate_windows.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/flutter_project_bundle.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/flutter_project_bundle.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/windows/flutter_host_window.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/windows/flutter_host_window.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/windows/flutter_host_window_controller.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/windows/flutter_host_window_controller.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/flutter_window.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/flutter_window.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/flutter_windows.cc + ../../../flutter/LICENSE
@@ -44605,6 +44611,8 @@ ORIGIN: ../../../flutter/shell/platform/windows/window_binding_handler_delegate.
 ORIGIN: ../../../flutter/shell/platform/windows/window_proc_delegate_manager.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/window_proc_delegate_manager.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/window_state.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/windows/windowing_handle.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/windows/windowing_handle.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/windows_lifecycle_manager.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/windows_lifecycle_manager.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/windows_proc_table.cc + ../../../flutter/LICENSE
@@ -46778,6 +46786,8 @@ FILE: ../../../flutter/shell/platform/common/text_editing_delta.h
 FILE: ../../../flutter/shell/platform/common/text_input_model.cc
 FILE: ../../../flutter/shell/platform/common/text_input_model.h
 FILE: ../../../flutter/shell/platform/common/text_range.h
+FILE: ../../../flutter/shell/platform/common/windowing.cc
+FILE: ../../../flutter/shell/platform/common/windowing.h
 FILE: ../../../flutter/shell/platform/darwin/common/availability_version_check.cc
 FILE: ../../../flutter/shell/platform/darwin/common/availability_version_check.h
 FILE: ../../../flutter/shell/platform/darwin/common/buffer_conversions.h
@@ -47524,6 +47534,10 @@ FILE: ../../../flutter/shell/platform/windows/flutter_platform_node_delegate_win
 FILE: ../../../flutter/shell/platform/windows/flutter_platform_node_delegate_windows.h
 FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle.h
+FILE: ../../../flutter/shell/platform/windows/flutter_host_window.cc
+FILE: ../../../flutter/shell/platform/windows/flutter_host_window.h
+FILE: ../../../flutter/shell/platform/windows/flutter_host_window_controller.cc
+FILE: ../../../flutter/shell/platform/windows/flutter_host_window_controller.h
 FILE: ../../../flutter/shell/platform/windows/flutter_window.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_window.h
 FILE: ../../../flutter/shell/platform/windows/flutter_windows.cc
@@ -47573,6 +47587,8 @@ FILE: ../../../flutter/shell/platform/windows/window_binding_handler_delegate.h
 FILE: ../../../flutter/shell/platform/windows/window_proc_delegate_manager.cc
 FILE: ../../../flutter/shell/platform/windows/window_proc_delegate_manager.h
 FILE: ../../../flutter/shell/platform/windows/window_state.h
+FILE: ../../../flutter/shell/platform/windows/windowing_handler.cc
+FILE: ../../../flutter/shell/platform/windows/windowing_handler.h
 FILE: ../../../flutter/shell/platform/windows/windows_lifecycle_manager.cc
 FILE: ../../../flutter/shell/platform/windows/windows_lifecycle_manager.h
 FILE: ../../../flutter/shell/platform/windows/windows_proc_table.cc

engine/src/flutter/common/settings.h

@@ -367,6 +367,10 @@ struct Settings {
   // If true, the UI thread is the platform thread on supported
   // platforms.
   bool merged_platform_ui_thread = true;
+
+  // Enable support for multiple windows. Ignored if not supported on the
+  // platform.
+  bool enable_multi_window = false;
 };
 
 }  // namespace flutter

engine/src/flutter/shell/common/switches.cc

@@ -532,6 +532,17 @@ Settings SettingsFromCommandLine(const fml::CommandLine& command_line) {
   settings.merged_platform_ui_thread = !command_line.HasOption(
       FlagForSwitch(Switch::DisableMergedPlatformUIThread));
 
+#if FML_OS_WIN
+  // Process the EnableMultiWindow switch on Windows.
+  {
+    std::string enable_multi_window_value;
+    if (command_line.GetOptionValue(FlagForSwitch(Switch::EnableMultiWindow),
+                                    &enable_multi_window_value)) {
+      settings.enable_multi_window = "true" == enable_multi_window_value;
+    }
+  }
+#endif  // FML_OS_WIN
+
   return settings;
 }
 

engine/src/flutter/shell/common/switches.h

@@ -300,6 +300,10 @@ DEF_SWITCH(DisableMergedPlatformUIThread,
 DEF_SWITCH(DisableAndroidSurfaceControl,
            "disable-surface-control",
            "Disable the SurfaceControl backed swapchain even when supported.")
+DEF_SWITCH(EnableMultiWindow,
+           "enable-multi-window",
+           "Enable support for multiple windows. Ignored if not supported on "
+           "the platform.")
 DEF_SWITCHES_END
 
 void PrintUsage(const std::string& executable_name);

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

@@ -142,9 +142,13 @@ source_set("common_cpp_core") {
   public = [
     "geometry.h",
     "path_utils.h",
+    "windowing.h",
   ]
 
-  sources = [ "path_utils.cc" ]
+  sources = [
+    "path_utils.cc",
+    "windowing.cc",
+  ]
 
   public_configs = [ "//flutter:config" ]
 }
@@ -157,7 +161,10 @@ if (enable_unittests) {
   executable("common_cpp_core_unittests") {
     testonly = true
 
-    sources = [ "path_utils_unittests.cc" ]
+    sources = [
+      "path_utils_unittests.cc",
+      "windowing_unittests.cc",
+    ]
 
     deps = [
       ":common_cpp_core",