rendering correctly with backing window but some issues re pixel density, scroll & foregrounding on start

example/lib/main.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:typed_data';
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:permission_handler/permission_handler.dart';
 import 'package:polyvox_filament/animations/animation_data.dart';
 
@@ -14,7 +15,7 @@ import 'package:path_provider/path_provider.dart';
 import 'package:polyvox_filament/widgets/filament_gesture_detector.dart';
 import 'package:polyvox_filament/widgets/filament_widget.dart';
 
-void main() {
+void main() async {
   runApp(const MyApp());
 }
 
@@ -30,8 +31,10 @@ class _MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
   Widget build(BuildContext context) {
     return MaterialApp(
         // showPerformanceOverlay: true,
-        color: Colors.white,
+        home: Scaffold(
-        home: Scaffold(backgroundColor: Colors.white, body: ExampleWidget()));
+      body: 
+      ExampleWidget()
+    ));
   }
 }
 

ios/src/PolyvoxFilamentFFIApi.cpp

@@ -77,7 +77,9 @@ public:
 
   void doRender() {
     render(_viewer, 0, nullptr, nullptr, nullptr);
-    _renderCallback(_renderCallbackOwner);
+    if(_renderCallback) {
+      _renderCallback(_renderCallbackOwner);
+    }
   }
 
   void setFrameIntervalInMilliseconds(float frameIntervalInMilliseconds) {

lib/filament_controller.dart

@@ -19,6 +19,14 @@ class TextureDetails {
 }
 
 abstract class FilamentController {
+  
+  /// 
+  /// Whether a Flutter Texture widget should be inserted into the widget hierarchy.
+  /// This will be false on certain platforms where we use a transparent window underlay.
+  /// Used internally by [FilamentWidget]; you probably don't need to access this property directly.
+  /// 
+  bool get requiresTextureWidget;
+
   ///
   /// The Flutter texture ID and dimensions for current texture in use.
   /// This is only used by [FilamentWidget]; you shouldn't need to access directly yourself.

lib/filament_controller_ffi.dart

@@ -4,16 +4,21 @@ import 'dart:io';
 import 'dart:ui' as ui;
 import 'package:flutter/services.dart';
 import 'package:ffi/ffi.dart';
-import 'package:flutter/widgets.dart';
+
 import 'package:polyvox_filament/filament_controller.dart';
 
 import 'package:polyvox_filament/animations/animation_data.dart';
 import 'package:polyvox_filament/generated_bindings.dart';
 
+// ignore: constant_identifier_names
 const FilamentEntity _FILAMENT_ASSET_ERROR = 0;
 
 class FilamentControllerFFI extends FilamentController {
-  late MethodChannel _channel = MethodChannel("app.polyvox.filament/event");
+  
+  final _channel = const MethodChannel("app.polyvox.filament/event");
+
+  @override
+  bool get requiresTextureWidget => !Platform.isWindows;
 
   double _pixelRatio = 1.0;
 
@@ -25,9 +30,11 @@ class FilamentControllerFFI extends FilamentController {
 
   final String? uberArchivePath;
 
+  @override
   Stream<bool> get hasViewer => _hasViewerController.stream;
   final _hasViewerController = StreamController<bool>();
 
+  @override
   Stream<FilamentEntity> get pickResult => _pickResultController.stream;
   final _pickResultController = StreamController<FilamentEntity>.broadcast();
 
@@ -48,7 +55,7 @@ class FilamentControllerFFI extends FilamentController {
       _resizeTimer?.cancel();
       _resizingWidth = call.arguments[0];
       _resizingHeight = call.arguments[1];
-      _resizeTimer = Timer(Duration(milliseconds: 500), () async {
+      _resizeTimer = Timer(const Duration(milliseconds: 500), () async {
         await resize(_resizingWidth!, _resizingHeight!);
       });
       
@@ -160,7 +167,7 @@ class FilamentControllerFFI extends FilamentController {
 
     print("Using flutterTextureId $flutterTextureId, surface $surfaceAddress and nativeTexture $nativeTexture");
 
-    if (Platform.isWindows) {
+    if (Platform.isWindows && requiresTextureWidget) {
       _driver = Pointer<Void>.fromAddress(
           await _channel.invokeMethod("getDriverPlatform"));
     }
@@ -275,6 +282,10 @@ class FilamentControllerFFI extends FilamentController {
 
   @override
   Future resize(int width, int height, {double scaleFactor = 1.0}) async {
+
+    if(Platform.isWindows) {
+      return;
+    }
     // we defer to the FilamentWidget to ensure that every call to [resize] is synchronized
     // so this exception should never be thrown (right?)
     if (textureDetails.value == null) {

lib/widgets/filament_widget.dart

@@ -42,7 +42,7 @@ class _RenderResizeObserver extends RenderProxyBox {
   void performLayout() async {
     super.performLayout();
     if (size.width != _oldSize.width || size.height != _oldSize.height) {
-        onLayoutChangedCallback(size);
+      onLayoutChangedCallback(size);
       _oldSize = Size(size.width, size.height);
     }
   }
@@ -87,7 +87,7 @@ class _FilamentWidgetState extends State<FilamentWidget> {
 
     return ResizeObserver(
         onResized: (newSize) {
-          if(!Platform.isWindows) {
+          if (!Platform.isWindows) {
             return;
           }
           WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
@@ -124,10 +124,10 @@ class _SizedFilamentWidget extends StatefulWidget {
 }
 
 class _SizedFilamentWidgetState extends State<_SizedFilamentWidget> {
+
   String? _error;
 
   late final AppLifecycleListener _appLifecycleListener;
-  AppLifecycleState? _lastState;
 
   @override
   void initState() {
@@ -136,9 +136,6 @@ class _SizedFilamentWidgetState extends State<_SizedFilamentWidget> {
     );
 
     WidgetsBinding.instance.addPostFrameCallback((timeStamp) async {
-      if (!kReleaseMode) {
-        await Future.delayed(Duration(seconds: 2));
-      }
       try {
         await widget.controller.createViewer(widget.width, widget.height);
       } catch (err) {
@@ -171,7 +168,7 @@ class _SizedFilamentWidgetState extends State<_SizedFilamentWidget> {
       var width = size.width.ceil();
       var height = size.height.ceil();
       while (_resizing) {
-        await Future.delayed(Duration(milliseconds: 20));
+        await Future.delayed(const Duration(milliseconds: 20));
       }
       _resizing = true;
       await widget.controller.resize(width, height);
@@ -237,7 +234,6 @@ class _SizedFilamentWidgetState extends State<_SizedFilamentWidget> {
         await widget.controller.setRendering(_wasRenderingOnInactive);
         break;
     }
-    _lastState = state;
   }
 
   @override
@@ -252,31 +248,55 @@ class _SizedFilamentWidgetState extends State<_SizedFilamentWidget> {
           ]));
     }
 
-    return ListenableBuilder(listenable: widget.controller.textureDetails, builder: (BuildContext ctx, Widget? wdgt) {
+    if (!widget.controller.requiresTextureWidget) {
-
-      if (widget.controller.textureDetails.value == null) { 
-        return Stack(children: [
-          Positioned.fill(child: widget.initial ?? Container(color: Colors.red))
-        ]);
-      }
-      // see [FilamentControllerFFI.resize] for an explanation of how we deal with resizing
-      var texture = Texture(
-        key: ObjectKey("texture_${widget.controller.textureDetails.value!.textureId}"),
-        textureId: widget.controller.textureDetails.value!.textureId,
-        filterQuality: FilterQuality.none,
-        freeze: false,
-      );
-
       return Stack(children: [
-        Positioned.fill(
+        Positioned.fill(child: CustomPaint(painter: TransparencyPainter()))
-            child: Platform.isLinux || Platform.isWindows
-                ? Transform(
-                    alignment: Alignment.center,
-                    transform: Matrix4.rotationX(
-                        pi), // TODO - this rotation is due to OpenGL texture coordinate working in a different space from Flutter, can we move this to the C++ side somewhere?
-                    child: texture)
-                : texture)
       ]);
-    });
+    }
+
+    return ListenableBuilder(
+        listenable: widget.controller.textureDetails,
+        builder: (BuildContext ctx, Widget? wdgt) {
+          if (widget.controller.textureDetails.value == null) {
+            return Stack(children: [
+              Positioned.fill(
+                  child: widget.initial ?? Container(color: Colors.red))
+            ]);
+          }
+          // see [FilamentControllerFFI.resize] for an explanation of how we deal with resizing
+          var texture = Texture(
+            key: ObjectKey(
+                "texture_${widget.controller.textureDetails.value!.textureId}"),
+            textureId: widget.controller.textureDetails.value!.textureId,
+            filterQuality: FilterQuality.none,
+            freeze: false,
+          );
+
+          return Stack(children: [
+            Positioned.fill(
+                child: Platform.isLinux || Platform.isWindows
+                    ? Transform(
+                        alignment: Alignment.center,
+                        transform: Matrix4.rotationX(
+                            pi), // TODO - this rotation is due to OpenGL texture coordinate working in a different space from Flutter, can we move this to the C++ side somewhere?
+                        child: texture)
+                    : texture)
+          ]);
+        });
   }
 }
+
+class TransparencyPainter extends CustomPainter {
+  @override
+  void paint(Canvas canvas, Size size) {
+    canvas.drawRect(
+      Rect.fromLTWH(0, 0, size.width, size.height),
+      Paint()
+        ..blendMode = BlendMode.clear
+        ..color = const Color(0x00000000),
+    );
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter oldDelegate) => true;
+}

windows/CMakeLists.txt

@@ -23,21 +23,19 @@ list(APPEND PLUGIN_SOURCES
 )
 
 set(USE_ANGLE FALSE)
-
-if(!USE_ANGLE)
 set(WGL_USE_BACKING_WINDOW TRUE)
-endif()
 
 if(USE_ANGLE)
   add_compile_definitions(USE_ANGLE)
   list(APPEND PLUGIN_SOURCES    "flutter_angle_texture.cpp"   "egl_context.cpp"   )
 else() 
-  list(APPEND PLUGIN_SOURCES "wgl_context.cpp")
+  add_compile_definitions(WGL_USE_BACKING_WINDOW)
-  if(WGL_USE_BACKING_WINDOW)
+  list(APPEND PLUGIN_SOURCES "wgl_context.cpp" "opengl_texture_buffer.cpp" "backing_window.cpp")
-    list(APPEND PLUGIN_SOURCES "utils.cc" "backing_window.cpp")
+  # if(WGL_USE_BACKING_WINDOW)
-  else()
+  #   list(APPEND PLUGIN_SOURCES )
-    list(APPEND PLUGIN_SOURCES "opengl_texture_buffer.cpp")
+  # else()
-  endif()
+  #   list(APPEND PLUGIN_SOURCES )
+  # endif()
 endif()
 
 # Define the plugin library target. Its name must not be changed (see comment

windows/backing_window.cpp

@@ -1,5 +1,18 @@
 #include "backing_window.h"
 
+#include <cstdint>
+#include <iostream>
+#include <chrono> 
+#include <thread>
+
+#include <Commctrl.h>
+#include <Windows.h>
+#include <dwmapi.h>
+#include <ShObjIdl.h>
+
+#pragma comment(lib, "dwmapi.lib")
+#pragma comment(lib, "comctl32.lib")
+
 namespace polyvox_filament {
 
 static constexpr auto kClassName = L"FLUTTER_FILAMENT_WINDOW";
@@ -9,6 +22,116 @@ static WPARAM last_wm_size_wparam_ = SIZE_RESTORED;
 uint64_t last_thread_time_ = 0;
 static constexpr auto kNativeViewPositionAndShowDelay = 300;
 
+typedef enum _WINDOWCOMPOSITIONATTRIB {
+  WCA_UNDEFINED = 0,
+  WCA_NCRENDERING_ENABLED = 1,
+  WCA_NCRENDERING_POLICY = 2,
+  WCA_TRANSITIONS_FORCEDISABLED = 3,
+  WCA_ALLOW_NCPAINT = 4,
+  WCA_CAPTION_BUTTON_BOUNDS = 5,
+  WCA_NONCLIENT_RTL_LAYOUT = 6,
+  WCA_FORCE_ICONIC_REPRESENTATION = 7,
+  WCA_EXTENDED_FRAME_BOUNDS = 8,
+  WCA_HAS_ICONIC_BITMAP = 9,
+  WCA_THEME_ATTRIBUTES = 10,
+  WCA_NCRENDERING_EXILED = 11,
+  WCA_NCADORNMENTINFO = 12,
+  WCA_EXCLUDED_FROM_LIVEPREVIEW = 13,
+  WCA_VIDEO_OVERLAY_ACTIVE = 14,
+  WCA_FORCE_ACTIVEWINDOW_APPEARANCE = 15,
+  WCA_DISALLOW_PEEK = 16,
+  WCA_CLOAK = 17,
+  WCA_CLOAKED = 18,
+  WCA_ACCENT_POLICY = 19,
+  WCA_FREEZE_REPRESENTATION = 20,
+  WCA_EVER_UNCLOAKED = 21,
+  WCA_VISUAL_OWNER = 22,
+  WCA_HOLOGRAPHIC = 23,
+  WCA_EXCLUDED_FROM_DDA = 24,
+  WCA_PASSIVEUPDATEMODE = 25,
+  WCA_USEDARKMODECOLORS = 26,
+  WCA_LAST = 27
+} WINDOWCOMPOSITIONATTRIB;
+
+typedef struct _WINDOWCOMPOSITIONATTRIBDATA {
+  WINDOWCOMPOSITIONATTRIB Attrib;
+  PVOID pvData;
+  SIZE_T cbData;
+} WINDOWCOMPOSITIONATTRIBDATA;
+
+typedef enum _ACCENT_STATE {
+  ACCENT_DISABLED = 0,
+  ACCENT_ENABLE_GRADIENT = 1,
+  ACCENT_ENABLE_TRANSPARENTGRADIENT = 2,
+  ACCENT_ENABLE_BLURBEHIND = 3,
+  ACCENT_ENABLE_ACRYLICBLURBEHIND = 4,
+  ACCENT_ENABLE_HOSTBACKDROP = 5,
+  ACCENT_INVALID_STATE = 6
+} ACCENT_STATE;
+
+typedef struct _ACCENT_POLICY {
+  ACCENT_STATE AccentState;
+  DWORD AccentFlags;
+  DWORD GradientColor;
+  DWORD AnimationId;
+} ACCENT_POLICY;
+
+typedef BOOL(WINAPI* _GetWindowCompositionAttribute)(
+    HWND, WINDOWCOMPOSITIONATTRIBDATA*);
+typedef BOOL(WINAPI* _SetWindowCompositionAttribute)(
+    HWND, WINDOWCOMPOSITIONATTRIBDATA*);
+
+static _SetWindowCompositionAttribute g_set_window_composition_attribute = NULL;
+static bool g_set_window_composition_attribute_initialized = false;
+
+typedef LONG NTSTATUS, *PNTSTATUS;
+#define STATUS_SUCCESS (0x00000000)
+
+typedef NTSTATUS(WINAPI* RtlGetVersionPtr)(PRTL_OSVERSIONINFOW);
+
+RTL_OSVERSIONINFOW GetWindowsVersion() {
+  HMODULE hmodule = ::GetModuleHandleW(L"ntdll.dll");
+  if (hmodule) {
+    RtlGetVersionPtr rtl_get_version_ptr =
+        (RtlGetVersionPtr)::GetProcAddress(hmodule, "RtlGetVersion");
+    if (rtl_get_version_ptr != nullptr) {
+      RTL_OSVERSIONINFOW rovi = {0};
+      rovi.dwOSVersionInfoSize = sizeof(rovi);
+      if (STATUS_SUCCESS == rtl_get_version_ptr(&rovi)) {
+        return rovi;
+      }
+    }
+  }
+  RTL_OSVERSIONINFOW rovi = {0};
+  return rovi;
+}
+
+void SetWindowComposition(HWND window, int32_t accent_state,
+                          int32_t gradient_color) {
+  // TODO: Look for a better available API.
+  if (GetWindowsVersion().dwBuildNumber >= 18362) {
+    if (!g_set_window_composition_attribute_initialized) {
+      auto user32 = ::GetModuleHandleA("user32.dll");
+      if (user32) {
+        g_set_window_composition_attribute =
+            reinterpret_cast<_SetWindowCompositionAttribute>(
+                ::GetProcAddress(user32, "SetWindowCompositionAttribute"));
+        if (g_set_window_composition_attribute) {
+          g_set_window_composition_attribute_initialized = true;
+        }
+      }
+    }
+    ACCENT_POLICY accent = {static_cast<ACCENT_STATE>(accent_state), 2,
+                            static_cast<DWORD>(gradient_color), 0};
+    WINDOWCOMPOSITIONATTRIBDATA data;
+    data.Attrib = WCA_ACCENT_POLICY;
+    data.pvData = &accent;
+    data.cbData = sizeof(accent);
+    g_set_window_composition_attribute(window, &data);
+  }
+}
+
+
 LRESULT NativeViewSubclassProc(HWND window, UINT message, WPARAM wparam,
                                LPARAM lparam, UINT_PTR subclass_id,
                                DWORD_PTR ref_data) noexcept {
@@ -17,11 +140,12 @@ LRESULT NativeViewSubclassProc(HWND window, UINT message, WPARAM wparam,
     // Prevent erasing of |window| when it is unfocused and minimized or
     // moved out of screen etc.
     return 1;
+    break;
   }
   case WM_SIZE: {
     // Prevent unnecessary maxmize, minimize or restore messages for |window|.
-    // Since it is |SetParent|'ed into native view container.
     return 1;
+    break;
   }
   default:
     break;
@@ -32,6 +156,8 @@ LRESULT NativeViewSubclassProc(HWND window, UINT message, WPARAM wparam,
 LRESULT CALLBACK FilamentWindowProc(HWND const window, UINT const message,
                                     WPARAM const wparam,
                                     LPARAM const lparam) noexcept {
+                                          // std::cout << "FILAMENT WINDOW EVENT " << message << std::endl;                                            
+
   switch (message) {
   case WM_MOUSEMOVE: {
     std::cout << "FILAMENT MOUSE MOVE" << std::endl;
@@ -56,14 +182,14 @@ LRESULT CALLBACK FilamentWindowProc(HWND const window, UINT const message,
     std::cout << "FILAMENT ERASE BKGND" << std::endl;
     // Prevent erasing of |window| when it is unfocused and minimized or
     // moved out of screen etc.
-    return 1;
+    break;
   }
   case WM_SIZE:
   case WM_MOVE:
   case WM_MOVING:
   case WM_ACTIVATE:
   case WM_WINDOWPOSCHANGED: {
-    std::cout << "FILAMENT POS CHANGED" << std::endl;
+    // std::cout << "FILAMENT POS CHANGED" << std::endl;
     // NativeViewCore::GetInstance()->SetHitTestBehavior(0);
     auto user_data = ::GetWindowLongPtr(window, GWLP_USERDATA);
     if (user_data) {
@@ -83,168 +209,178 @@ LRESULT CALLBACK FilamentWindowProc(HWND const window, UINT const message,
   return ::DefWindowProc(window, message, wparam, lparam);
 }
 
+BackingWindow::BackingWindow(flutter::PluginRegistrarWindows *pluginRegistrar,
+                             int initialWidth, int initialHeight) {
+  // a Flutter application actually has two windows - the innner window contains the FlutterView.
+  // although we will use the outer window for various events,  we always position things relative to the inner window.
+  _flutterViewWindow = pluginRegistrar->GetView()->GetNativeWindow();
+  _flutterRootWindow = ::GetAncestor(_flutterViewWindow, GA_ROOT);
 
-class BackingWindow {
+  RECT flutterChildRect;
+  ::GetWindowRect(_flutterViewWindow, &flutterChildRect);
+  // ::GetClientRect(flutterWindow, &flutterChildRect);
 
-    BackingWindow::BackingWindow(
+  std::cout << "child rect " << flutterChildRect.left << " " << flutterChildRect.top << " " << flutterChildRect.right << " " << flutterChildRect.bottom << std::endl;
-        flutter::PluginRegistrarWindows *pluginRegistrar,
-        int initialWidth, 
-        int initialHeight) { 
-        // get the root Flutter window
-        HWND flutterWindow = pluginRegistrar->GetView()->GetNativeWindow();
-        _flutterRootWindow = ::GetAncestor(flutterWindow, GA_ROOT);
 
-        // set composition to allow transparency
+  // set composition to allow transparency
-        flutternativeview::SetWindowComposition(_flutterRootWindow, 6, 0);
+  SetWindowComposition(_flutterRootWindow, 6, 0);
 
-        // register a top-level WindowProcDelegate to handle window events
+  // register a top-level WindowProcDelegate to handle window events
-        pluginRegistrar->RegisterTopLevelWindowProcDelegate([=](HWND hwnd,
+  pluginRegistrar->RegisterTopLevelWindowProcDelegate([=](HWND hwnd,
-                                                                UINT message,
+                                                          UINT message,
-                                                                WPARAM wparam,
+                                                          WPARAM wparam,
-                                                                LPARAM lparam) {
+                                                          LPARAM lparam) {
-        switch (message) {
+    // std::cout << "TOP LEVEL EVENT " << message << std::endl;    
-            case WM_ACTIVATE: {
+    switch (message) {
-            std::cout << "WM_ACTIVATE" << std::endl;
+    case WM_MOUSEMOVE: {
-            RECT window_rect;
+        // std::cout << "FLUTTER MOUSE MOVE" << std::endl;
-            ::GetWindowRect(_flutterRootWindow, &window_rect);
+        break;
-            // Position |native_view| such that it's z order is behind |window_| &
+      }
-            // redraw aswell.
+    case WM_ACTIVATE: {
-            ::SetWindowPos(_windowHandle, _flutterRootWindow, window_rect.left,
+      std::cout << "WM_ACTIVATE" << std::endl;
-                            window_rect.top, window_rect.right - window_rect.left,
+      RECT rootWindowRect;
-                            window_rect.bottom - window_rect.top, SWP_NOACTIVATE);
+      ::GetWindowRect(_flutterViewWindow, &rootWindowRect);
-            break;
+      // Position |native_view| such that it's z order is behind |window_| &
-            }
+      // redraw aswell.
-            case WM_SIZE: {
+      ::SetWindowPos(_windowHandle, _flutterRootWindow, rootWindowRect.left,
-            std::cout << "WM_SIZE" << std::endl;
+                     rootWindowRect.top, rootWindowRect.right - rootWindowRect.left,
-
+                     rootWindowRect.bottom - rootWindowRect.top, SWP_NOACTIVATE);
-            // Handle Windows's minimize & maximize animations properly.
+      break;
-            // Since |SetWindowPos| & other Win32 APIs on |native_view_container_|
-            // do not re-produce the same DWM animations like  actual user
-            // interractions on the |window_| do (though both windows are overlapped
-            // tightly but maximize and minimze animations can't be mimiced for the
-            // both of them at the same time), the best solution is to make the
-            // |window_| opaque & hide |native_view_container_| & alter it's position.
-            // After that, finally make |native_view_container_| visible again &
-            // |window_| transparent again. This approach is not perfect, but it's the
-            // best we can do. The minimize & maximize animations on the |window_|
-            // look good with just a slight glitch on the visible native views. In
-            // future, maybe replacing the |NativeView| widget (Flutter-side) with
-            // equivalent window screenshot will result in a totally seamless
-            // experience.
-            if (wparam != SIZE_RESTORED || last_wm_size_wparam_ == SIZE_MINIMIZED ||
-                last_wm_size_wparam_ == SIZE_MAXIMIZED ||
-                was_window_hidden_due_to_minimize_) {
-                was_window_hidden_due_to_minimize_ = false;
-                // Minimize condition is handled separately inside |WM_WINDOWPOSCHANGED|
-                // case, since we don't want to cause unnecessary redraws (& show/hide)
-                // when user is resizing the window by dragging the window border.
-                SetWindowComposition(_flutterRootWindow, 0, 0);
-                ::ShowWindow(_windowHandle, SW_HIDE);
-                last_thread_time_ =
-                    std::chrono::duration_cast<std::chrono::milliseconds>(
-                        std::chrono::system_clock::now().time_since_epoch())
-                        .count();
-                std::thread(
-                    [=](uint64_t time) {
-                    if (time < last_thread_time_) {
-                        return;
-                    }
-                    std::this_thread::sleep_for(
-                        std::chrono::milliseconds(kNativeViewPositionAndShowDelay));
-                    SetWindowComposition(_flutterRootWindow, 6, 0);
-                    // Handling SIZE_MINIMIZED separately.
-                    if (wparam != SIZE_MINIMIZED) {
-                        ::ShowWindow(_windowHandle, SW_SHOWNOACTIVATE);
-                    }
-                    },
-                    last_thread_time_)
-                    .detach();
-            }
-            last_wm_size_wparam_ = wparam;
-            break;
-            }
-            // Keep |native_view_container_| behind the |window_|.
-            case WM_MOVE:
-            case WM_MOVING:
-            case WM_WINDOWPOSCHANGED: {
-            std::cout << "FLUTTER WINDOWPOSCHANGED"<< std::endl;
-            RECT window_rect;
-            ::GetWindowRect(_flutterRootWindow, &window_rect);
-            if (window_rect.right - window_rect.left > 0 &&
-                window_rect.bottom - window_rect.top > 0) {
-                ::SetWindowPos(_windowHandle, _flutterRootWindow, window_rect.left,
-                            window_rect.top, window_rect.right - window_rect.left,
-                            window_rect.bottom - window_rect.top, SWP_NOACTIVATE);
-                // |window_| is minimized.
-                if (window_rect.left < 0 && window_rect.top < 0 &&
-                    window_rect.right < 0 && window_rect.bottom < 0) {
-                // Hide |native_view_container_| to prevent showing
-                // |native_view_container_| before |window_| placement
-                // i.e when restoring window after clicking the taskbar icon.
-                SetWindowComposition(_flutterRootWindow, 0, 0);
-                ::ShowWindow(_windowHandle, SW_HIDE);
-                was_window_hidden_due_to_minimize_ = true;
-                }
-            }
-            break;
-            }
-            case WM_CLOSE: {
-            // close
-            break;
-            }
-            default:
-            break;
-        }
-        return NULL;
-        });
-
-        // create the HWND for Filament 
-        auto window_class = WNDCLASSEX{};
-        ::SecureZeroMemory(&window_class, sizeof(window_class));
-        window_class.cbSize = sizeof(window_class);
-        window_class.style = CS_HREDRAW | CS_VREDRAW;
-        window_class.lpfnWndProc = FilamentWindowProc;
-        window_class.hInstance = 0;
-        window_class.lpszClassName = kClassName;
-        window_class.hCursor = ::LoadCursorW(nullptr, IDC_ARROW);
-        window_class.hbrBackground = ::CreateSolidBrush(RGB(0, 255, 0));
-        ::RegisterClassExW(&window_class);
-        _windowHandle =
-            ::CreateWindow(kClassName, kWindowName, WS_OVERLAPPEDWINDOW, 0, 0, initialWidth, initialHeight,
-                            nullptr, nullptr, GetModuleHandle(nullptr), nullptr);
-
-        // Disable DWM animations
-        auto disable_window_transitions = TRUE;
-        DwmSetWindowAttribute(_windowHandle, DWMWA_TRANSITIONS_FORCEDISABLED,
-                            &disable_window_transitions,
-                            sizeof(disable_window_transitions));
-
-        ::SetWindowSubclass(_windowHandle, NativeViewSubclassProc, 69420,
-                            NULL); // what does this do?
-
-        auto style = ::GetWindowLongPtr(_windowHandle, GWL_STYLE);
-        style &= ~(WS_CAPTION | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX |
-                    WS_EX_APPWINDOW);
-        ::SetWindowLongPtr(_windowHandle, GWL_STYLE, style);
-
-        RECT flutterWindowRect;
-        ::GetClientRect(_flutterRootWindow, &flutterWindowRect);
-
-        ::SetWindowLongPtr(_windowHandle, GWLP_USERDATA,
-                            reinterpret_cast<LONG>(_flutterRootWindow));
-
-        ::SetWindowPos(_windowHandle, _flutterRootWindow, flutterWindowRect.left,
-                        flutterWindowRect.top, initialWidth, initialHeight, SWP_SHOWWINDOW);
-        //  flutterWindowRect.right - flutterWindowRect.left,
-        //  flutterWindowRect.bottom - flutterWindowRect.top, SWP_SHOWWINDOW);
-        ::ShowWindow(_windowHandle, SW_SHOW);
-        ::ShowWindow(_flutterRootWindow, SW_SHOW);
-        ::SetFocus(_flutterRootWindow);
-        }
     }
+    case WM_SIZE: {
+      std::cout << "WM_SIZE" << std::endl;
 
-    BackingWindow::GetHandle() { 
+      // Handle Windows's minimize & maximize animations properly.
-      return _windowHandle;
+      // Since |SetWindowPos| & other Win32 APIs on |native_view_container_|
+      // do not re-produce the same DWM animations like  actual user
+      // interractions on the |window_| do (though both windows are overlapped
+      // tightly but maximize and minimze animations can't be mimiced for the
+      // both of them at the same time), the best solution is to make the
+      // |window_| opaque & hide |native_view_container_| & alter it's position.
+      // After that, finally make |native_view_container_| visible again &
+      // |window_| transparent again. This approach is not perfect, but it's the
+      // best we can do. The minimize & maximize animations on the |window_|
+      // look good with just a slight glitch on the visible native views. In
+      // future, maybe replacing the |NativeView| widget (Flutter-side) with
+      // equivalent window screenshot will result in a totally seamless
+      // experience.
+      if (wparam != SIZE_RESTORED || last_wm_size_wparam_ == SIZE_MINIMIZED ||
+          last_wm_size_wparam_ == SIZE_MAXIMIZED ||
+          was_window_hidden_due_to_minimize_) {
+        was_window_hidden_due_to_minimize_ = false;
+        // Minimize condition is handled separately inside |WM_WINDOWPOSCHANGED|
+        // case, since we don't want to cause unnecessary redraws (& show/hide)
+        // when user is resizing the window by dragging the window border.
+        SetWindowComposition(_flutterRootWindow, 0, 0);
+        ::ShowWindow(_windowHandle, SW_HIDE);
+        last_thread_time_ =
+            std::chrono::duration_cast<std::chrono::milliseconds>(
+                std::chrono::system_clock::now().time_since_epoch())
+                .count();
+        std::thread(
+            [=](uint64_t time) {
+              if (time < last_thread_time_) {
+                return;
+              }
+              std::this_thread::sleep_for(
+                  std::chrono::milliseconds(kNativeViewPositionAndShowDelay));
+              SetWindowComposition(_flutterRootWindow, 6, 0);
+              // Handling SIZE_MINIMIZED separately.
+              if (wparam != SIZE_MINIMIZED) {
+                ::ShowWindow(_windowHandle, SW_SHOWNOACTIVATE);
+              }
+            },
+            last_thread_time_)
+            .detach();
+      }
+      last_wm_size_wparam_ = wparam;
+      break;
     }
+    // Keep |native_view_container_| behind the |window_|.
+    case WM_MOVE:
+    case WM_MOVING:
+    case WM_WINDOWPOSCHANGED: {
+      RECT rootWindowRect;
+      ::GetWindowRect(_flutterViewWindow, &rootWindowRect);
+      // std::cout << "FLUTTER WINDOWPOSCHANGED TO " << rootWindowRect.left << " " << rootWindowRect.top << " " << rootWindowRect.right << " " << rootWindowRect.bottom << std::endl;
+      if (rootWindowRect.right - rootWindowRect.left > 0 &&
+          rootWindowRect.bottom - rootWindowRect.top > 0) {
+        ::SetWindowPos(_windowHandle, _flutterRootWindow, rootWindowRect.left,
+                       rootWindowRect.top, rootWindowRect.right - rootWindowRect.left,
+                       rootWindowRect.bottom - rootWindowRect.top, SWP_NOACTIVATE);
+        // |window_| is minimized.
+        if (rootWindowRect.left < 0 && rootWindowRect.top < 0 &&
+            rootWindowRect.right < 0 && rootWindowRect.bottom < 0) {
+          // Hide |native_view_container_| to prevent showing
+          // |native_view_container_| before |window_| placement
+          // i.e when restoring window after clicking the taskbar icon.
+          SetWindowComposition(_flutterRootWindow, 0, 0);
+          ::ShowWindow(_windowHandle, SW_HIDE);
+          was_window_hidden_due_to_minimize_ = true;
+        }
+      }
+      break;
+    }
+    case WM_CLOSE: {
+      // close
+      break;
+    }
+    default:
+      break;
+    }
+    return std::nullopt;
+  });
 
+  // create the HWND for Filament
+  auto window_class = WNDCLASSEX{};
+  ::SecureZeroMemory(&window_class, sizeof(window_class));
+  window_class.cbSize = sizeof(window_class);
+  window_class.style = CS_HREDRAW | CS_VREDRAW;
+  window_class.lpfnWndProc = FilamentWindowProc;
+  window_class.hInstance = 0;
+  window_class.lpszClassName = kClassName;
+  window_class.hCursor = ::LoadCursorW(nullptr, IDC_ARROW);
+  window_class.hbrBackground = ::CreateSolidBrush(0);
+  ::RegisterClassExW(&window_class);
+  _windowHandle = ::CreateWindow(kClassName, kWindowName, WS_OVERLAPPEDWINDOW,
+                                 0, 0, initialWidth, initialHeight, nullptr,
+                                 nullptr, GetModuleHandle(nullptr), nullptr);
+
+  // Disable DWM animations
+  auto disable_window_transitions = TRUE;
+  DwmSetWindowAttribute(_windowHandle, DWMWA_TRANSITIONS_FORCEDISABLED,
+                        &disable_window_transitions,
+                        sizeof(disable_window_transitions));
+
+  ::SetWindowSubclass(_windowHandle, NativeViewSubclassProc, 69420,
+                      NULL); // what does this do?
+
+  auto style = ::GetWindowLongPtr(_windowHandle, GWL_STYLE);
+  style &= ~(WS_CAPTION | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX |
+             WS_EX_APPWINDOW);
+  ::SetWindowLongPtr(_windowHandle, GWL_STYLE, style);
+
+  RECT flutterViewRect;
+  ::GetClientRect(_flutterViewWindow, &flutterViewRect);
+
+  ::SetWindowLongPtr(_windowHandle, GWLP_USERDATA,
+                     reinterpret_cast<LONG>(_flutterRootWindow));
+
+  ::SetWindowPos(_windowHandle, _flutterRootWindow, flutterViewRect.left,
+                 flutterViewRect.top, flutterViewRect.right - flutterViewRect.left, flutterViewRect.bottom - flutterViewRect.top,
+                 SWP_NOACTIVATE);
+
+  // remove taskbar entry for the window we created
+  ITaskbarList3* taskbar = nullptr;
+  ::CoCreateInstance(CLSID_TaskbarList, 0, CLSCTX_INPROC_SERVER,
+                     IID_PPV_ARGS(&taskbar));
+  taskbar->DeleteTab(_windowHandle);
+  taskbar->Release();
+
+  ::ShowWindow(_windowHandle, SW_SHOW);
+  ::ShowWindow(_flutterRootWindow, SW_SHOW);
+  ::SetFocus(_flutterRootWindow);
 }
+
+HWND BackingWindow::GetHandle() { return _windowHandle; }
+} // namespace polyvox_filament

windows/backing_window.h

@@ -17,7 +17,8 @@ class BackingWindow {
     private:
         HWND _windowHandle;
         HWND _flutterRootWindow;
-}
+        HWND _flutterViewWindow;
+};
 
 }
 #endif 

windows/polyvox_filament_plugin.cpp

@@ -36,8 +36,6 @@
 #include <dwmapi.h>
 #include <wrl.h>
 
-#include "utils.h"
-
 #include "flutter_render_context.h"
 
 #if USE_ANGLE
@@ -181,7 +179,7 @@ void PolyvoxFilamentPlugin::CreateTexture(
     _context = std::make_unique<WGLContext>(_pluginRegistrar, _textureRegistrar);
 #endif
   }
-  //_context->CreateTexture(width, height, std::move(result));
+  _context->CreateTexture(width, height, std::move(result));
 }
 
 void PolyvoxFilamentPlugin::DestroyTexture(
@@ -228,14 +226,15 @@ void PolyvoxFilamentPlugin::HandleMethodCall(
   } else if (methodCall.method_name() == "destroyTexture") {
     DestroyTexture(methodCall, std::move(result));
   } else if (methodCall.method_name() == "getRenderCallback") {
+    flutter::EncodableList resultList;
     #if !ANGLE && WGL_USE_BACKING_WINDOW
-      result->Success(nullptr);
+        resultList.push_back(flutter::EncodableValue((int64_t)nullptr));
+        resultList.push_back(flutter::EncodableValue((int64_t)nullptr));
     #else
-        flutter::EncodableList resultList;
         resultList.push_back(flutter::EncodableValue((int64_t)&render_callback));
         resultList.push_back(flutter::EncodableValue((int64_t)this));
-        result->Success(resultList);
     #endif
+    result->Success(resultList);
   } else if (methodCall.method_name() == "getDriverPlatform") {
 #ifdef USE_ANGLE
     result->Success(flutter::EncodableValue((int64_t)_platform));

windows/utils.cc

@@ -1,130 +0,0 @@
-// This file is a part of flutter_native_view
-// (https://github.com/alexmercerind/flutter_native_view).
-//
-// Copyright (c) 2022, Hitesh Kumar Saini <saini123hitesh@gmail.com>.
-// All rights reserved.
-// Use of this source code is governed by MIT license that can be found in the
-// LICENSE file.
-
-#include "utils.h"
-#include <iostream>
-
-#pragma comment(lib, "dwmapi.lib")
-#pragma comment(lib, "comctl32.lib")
-
-namespace flutternativeview {
-
-typedef enum _WINDOWCOMPOSITIONATTRIB {
-  WCA_UNDEFINED = 0,
-  WCA_NCRENDERING_ENABLED = 1,
-  WCA_NCRENDERING_POLICY = 2,
-  WCA_TRANSITIONS_FORCEDISABLED = 3,
-  WCA_ALLOW_NCPAINT = 4,
-  WCA_CAPTION_BUTTON_BOUNDS = 5,
-  WCA_NONCLIENT_RTL_LAYOUT = 6,
-  WCA_FORCE_ICONIC_REPRESENTATION = 7,
-  WCA_EXTENDED_FRAME_BOUNDS = 8,
-  WCA_HAS_ICONIC_BITMAP = 9,
-  WCA_THEME_ATTRIBUTES = 10,
-  WCA_NCRENDERING_EXILED = 11,
-  WCA_NCADORNMENTINFO = 12,
-  WCA_EXCLUDED_FROM_LIVEPREVIEW = 13,
-  WCA_VIDEO_OVERLAY_ACTIVE = 14,
-  WCA_FORCE_ACTIVEWINDOW_APPEARANCE = 15,
-  WCA_DISALLOW_PEEK = 16,
-  WCA_CLOAK = 17,
-  WCA_CLOAKED = 18,
-  WCA_ACCENT_POLICY = 19,
-  WCA_FREEZE_REPRESENTATION = 20,
-  WCA_EVER_UNCLOAKED = 21,
-  WCA_VISUAL_OWNER = 22,
-  WCA_HOLOGRAPHIC = 23,
-  WCA_EXCLUDED_FROM_DDA = 24,
-  WCA_PASSIVEUPDATEMODE = 25,
-  WCA_USEDARKMODECOLORS = 26,
-  WCA_LAST = 27
-} WINDOWCOMPOSITIONATTRIB;
-
-typedef struct _WINDOWCOMPOSITIONATTRIBDATA {
-  WINDOWCOMPOSITIONATTRIB Attrib;
-  PVOID pvData;
-  SIZE_T cbData;
-} WINDOWCOMPOSITIONATTRIBDATA;
-
-typedef enum _ACCENT_STATE {
-  ACCENT_DISABLED = 0,
-  ACCENT_ENABLE_GRADIENT = 1,
-  ACCENT_ENABLE_TRANSPARENTGRADIENT = 2,
-  ACCENT_ENABLE_BLURBEHIND = 3,
-  ACCENT_ENABLE_ACRYLICBLURBEHIND = 4,
-  ACCENT_ENABLE_HOSTBACKDROP = 5,
-  ACCENT_INVALID_STATE = 6
-} ACCENT_STATE;
-
-typedef struct _ACCENT_POLICY {
-  ACCENT_STATE AccentState;
-  DWORD AccentFlags;
-  DWORD GradientColor;
-  DWORD AnimationId;
-} ACCENT_POLICY;
-
-typedef BOOL(WINAPI* _GetWindowCompositionAttribute)(
-    HWND, WINDOWCOMPOSITIONATTRIBDATA*);
-typedef BOOL(WINAPI* _SetWindowCompositionAttribute)(
-    HWND, WINDOWCOMPOSITIONATTRIBDATA*);
-
-static _SetWindowCompositionAttribute g_set_window_composition_attribute = NULL;
-static bool g_set_window_composition_attribute_initialized = false;
-
-typedef LONG NTSTATUS, *PNTSTATUS;
-#define STATUS_SUCCESS (0x00000000)
-
-typedef NTSTATUS(WINAPI* RtlGetVersionPtr)(PRTL_OSVERSIONINFOW);
-
-RTL_OSVERSIONINFOW GetWindowsVersion() {
-  HMODULE hmodule = ::GetModuleHandleW(L"ntdll.dll");
-  if (hmodule) {
-    RtlGetVersionPtr rtl_get_version_ptr =
-        (RtlGetVersionPtr)::GetProcAddress(hmodule, "RtlGetVersion");
-    if (rtl_get_version_ptr != nullptr) {
-      RTL_OSVERSIONINFOW rovi = {0};
-      rovi.dwOSVersionInfoSize = sizeof(rovi);
-      if (STATUS_SUCCESS == rtl_get_version_ptr(&rovi)) {
-        return rovi;
-      }
-    }
-  }
-  RTL_OSVERSIONINFOW rovi = {0};
-  return rovi;
-}
-
-void SetWindowComposition(HWND window, int32_t accent_state,
-                          int32_t gradient_color) {
-  // TODO: Look for a better available API.
-  if (GetWindowsVersion().dwBuildNumber >= 18362) {
-    std::cout << "got win ver" << std::endl;
-    if (!g_set_window_composition_attribute_initialized) {
-      std::cout << "not init" << std::endl;
-      auto user32 = ::GetModuleHandleA("user32.dll");
-      if (user32) {
-        std::cout << "user32" << std::endl;
-        g_set_window_composition_attribute =
-            reinterpret_cast<_SetWindowCompositionAttribute>(
-                ::GetProcAddress(user32, "SetWindowCompositionAttribute"));
-        if (g_set_window_composition_attribute) {
-          std::cout << "set" << std::endl;
-          g_set_window_composition_attribute_initialized = true;
-        }
-      }
-    }
-    ACCENT_POLICY accent = {static_cast<ACCENT_STATE>(accent_state), 2,
-                            static_cast<DWORD>(gradient_color), 0};
-    WINDOWCOMPOSITIONATTRIBDATA data;
-    data.Attrib = WCA_ACCENT_POLICY;
-    data.pvData = &accent;
-    data.cbData = sizeof(accent);
-    g_set_window_composition_attribute(window, &data);
-  }
-}
-
-}  // namespace flutternativeview

windows/utils.h

@@ -1,20 +0,0 @@
-// This file is a part of flutter_native_view
-// (https://github.com/alexmercerind/flutter_native_view).
-//
-// Copyright (c) 2022, Hitesh Kumar Saini <saini123hitesh@gmail.com>.
-// All rights reserved.
-// Use of this source code is governed by MIT license that can be found in the
-// LICENSE file.
-
-#include <dwmapi.h>
-
-#include <cstdint>
-
-namespace flutternativeview {
-
-RTL_OSVERSIONINFOW GetWindowsVersion();
-
-void SetWindowComposition(HWND window, int32_t accent_state,
-                          int32_t gradient_color);
-
-}  // namespace flutternativeview

windows/wgl_context.cpp

@@ -9,7 +9,8 @@
 namespace polyvox_filament {
 
 WGLContext::WGLContext(flutter::PluginRegistrarWindows *pluginRegistrar,
-                       flutter::TextureRegistrar *textureRegistrar) {
+                       flutter::TextureRegistrar *textureRegistrar)
+    : _pluginRegistrar(pluginRegistrar), _textureRegistrar(textureRegistrar) {
 
   auto hwnd = pluginRegistrar->GetView()->GetNativeWindow();
 
@@ -99,27 +100,24 @@ void WGLContext::CreateTexture(
     uint32_t width, uint32_t height,
     std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
 
-#ifdef WGL_USE_BACKING_WINDOW
+#if WGL_USE_BACKING_WINDOW
-  _backingWindow = std::make_unique<BackingWindow>()
+  _backingWindow = std::make_unique<BackingWindow>(
-      : std::vector<flutter::EncodableValue> resultList;
+      _pluginRegistrar, static_cast<int>(width), static_cast<int>(height));
+  std::vector<flutter::EncodableValue> resultList;
   resultList.push_back(flutter::EncodableValue((int64_t) nullptr));
   resultList.push_back(
       flutter::EncodableValue((int64_t)_backingWindow->GetHandle()));
   resultList.push_back(flutter::EncodableValue((int64_t) nullptr));
   result->Success(resultList);
-}
-else {
-  result->Error("FOO", "ERROR", nullptr);
-}
 #else
   if (_active.get()) {
     result->Error("ERROR",
                   "Texture already exists. You must call destroyTexture before "
                   "attempting to create a new one.");
   } else {
-    _active = std::make_unique<OpenGLTextureBuffer>(_pluginRegistrar, _textureRegistrar,
+    _active = std::make_unique<OpenGLTextureBuffer>(
-                                          std::move(result), width, height,
+        _pluginRegistrar, _textureRegistrar, std::move(result), width, height,
-                                          _context);
+        _context);
 
     if (_active->flutterTextureId != -1) {
       std::vector<flutter::EncodableValue> resultList;

windows/wgl_context.h

@@ -15,6 +15,8 @@ namespace polyvox_filament {
         void CreateTexture(uint32_t width, uint32_t height, std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
         void* GetSharedContext();    
     private:
+        flutter::PluginRegistrarWindows* _pluginRegistrar = nullptr;
+        flutter::TextureRegistrar* _textureRegistrar = nullptr;
         HGLRC _context = NULL;
         #if WGL_USE_BACKING_WINDOW
         std::unique_ptr<BackingWindow> _backingWindow = nullptr;