Merge pull request #24 from canonical/regular-windows-modify

feature: implemented modifyRegular + fixed a bug where a widget tree was mandatory on accident

Author: mattkae

engine/src/flutter/shell/platform/common/geometry.h

@@ -45,6 +45,7 @@ class Size {
   bool operator==(const Size& other) const {
     return width_ == other.width_ && height_ == other.height_;
   }
+  bool operator!=(const Size& other) const { return !(*this == other); }
 
  private:
   double width_ = 0.0;

engine/src/flutter/shell/platform/common/windowing.h

@@ -75,6 +75,16 @@ struct WindowCreationSettings {
   std::optional<WindowState> state;
 };
 
+// Settings for modifying a Flutter window.
+struct WindowModificationSettings {
+  // The new requested size, in logical coordinates.
+  std::optional<Size> size;
+  // The new window title.
+  std::optional<std::string> title;
+  // The new window state.
+  std::optional<WindowState> state;
+};
+
 // Window metadata returned as the result of creating a Flutter window.
 struct WindowMetadata {
   // The ID of the view used for this window, which is unique to each window.

engine/src/flutter/shell/platform/windows/flutter_host_window.cc

@@ -213,16 +213,15 @@ bool IsClassRegistered(LPCWSTR class_name) {
 }
 
 // Convert std::string to std::wstring.
-std::wstring StringToWstring(std::string const& str) {
+std::wstring StringToWstring(std::string_view str) {
   if (str.empty()) {
     return {};
   }
   if (int buffer_size =
-          MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, nullptr, 0)) {
+          MultiByteToWideChar(CP_UTF8, 0, str.data(), str.size(), nullptr, 0)) {
     std::wstring wide_str(buffer_size, L'\0');
-    if (MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, &wide_str[0],
+    if (MultiByteToWideChar(CP_UTF8, 0, str.data(), str.size(), &wide_str[0],
                             buffer_size)) {
-      wide_str.pop_back();
       return wide_str;
     }
   }
@@ -447,28 +446,12 @@ FlutterHostWindow* FlutterHostWindow::GetThisFromHandle(HWND hwnd) {
       GetWindowLongPtr(hwnd, GWLP_USERDATA));
 }
 
-WindowArchetype FlutterHostWindow::GetArchetype() const {
-  return archetype_;
-}
-
-FlutterViewId FlutterHostWindow::GetFlutterViewId() const {
-  return view_controller_->view()->view_id();
-};
-
-WindowState FlutterHostWindow::GetState() const {
-  return state_;
-}
-
 HWND FlutterHostWindow::GetWindowHandle() const {
   return window_handle_;
 }
 
-void FlutterHostWindow::SetQuitOnClose(bool quit_on_close) {
-  quit_on_close_ = quit_on_close;
-}
-
-bool FlutterHostWindow::GetQuitOnClose() const {
-  return quit_on_close_;
+WindowState FlutterHostWindow::GetState() const {
+  return state_;
 }
 
 void FlutterHostWindow::FocusViewOf(FlutterHostWindow* window) {
@@ -587,6 +570,19 @@ LRESULT FlutterHostWindow::HandleMessage(HWND hwnd,
   return DefWindowProc(hwnd, message, wparam, lparam);
 }
 
+void FlutterHostWindow::SetClientSize(Size const& client_size) const {
+  WINDOWINFO window_info = {.cbSize = sizeof(WINDOWINFO)};
+  GetWindowInfo(window_handle_, &window_info);
+
+  std::optional<Size> const window_size = GetWindowSizeForClientSize(
+      client_size, min_size_, max_size_, window_info.dwStyle,
+      window_info.dwExStyle, nullptr);
+
+  Size const size = window_size.value_or(client_size);
+  SetWindowPos(window_handle_, NULL, 0, 0, size.width(), size.height(),
+               SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE);
+}
+
 void FlutterHostWindow::SetChildContent(HWND content) {
   child_content_ = content;
   SetParent(content, window_handle_);
@@ -597,4 +593,28 @@ void FlutterHostWindow::SetChildContent(HWND content) {
              client_rect.bottom - client_rect.top, true);
 }
 
+void FlutterHostWindow::SetState(WindowState state) {
+  WINDOWPLACEMENT window_placement = {.length = sizeof(WINDOWPLACEMENT)};
+  GetWindowPlacement(window_handle_, &window_placement);
+  window_placement.showCmd = [&]() {
+    switch (state) {
+      case WindowState::kRestored:
+        return SW_RESTORE;
+      case WindowState::kMaximized:
+        return SW_MAXIMIZE;
+      case WindowState::kMinimized:
+        return SW_MINIMIZE;
+      default:
+        FML_UNREACHABLE();
+    };
+  }();
+  SetWindowPlacement(window_handle_, &window_placement);
+  state_ = state;
+}
+
+void FlutterHostWindow::SetTitle(std::string_view title) const {
+  std::wstring title_wide = StringToWstring(title);
+  SetWindowText(window_handle_, title_wide.c_str());
+}
+
 }  // namespace flutter

engine/src/flutter/shell/platform/windows/flutter_host_window.h

@@ -33,25 +33,13 @@ class FlutterHostWindow {
   // Returns the instance pointer for |hwnd| or nulllptr if invalid.
   static FlutterHostWindow* GetThisFromHandle(HWND hwnd);
 
-  // Returns the window archetype.
-  WindowArchetype GetArchetype() const;
-
-  // Returns the hosted Flutter view's ID.
-  FlutterViewId GetFlutterViewId() const;
-
   // Returns the current window state.
   WindowState GetState() const;
 
   // Returns the backing window handle, or nullptr if the native window is not
   // created or has already been destroyed.
   HWND GetWindowHandle() const;
 
-  // Sets whether closing this window will quit the application.
-  void SetQuitOnClose(bool quit_on_close);
-
-  // Returns whether closing this window will quit the application.
-  bool GetQuitOnClose() const;
-
  private:
   friend FlutterHostWindowController;
 
@@ -69,9 +57,18 @@ class FlutterHostWindow {
   // inheriting classes can handle.
   LRESULT HandleMessage(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam);
 
+  // Resizes the window to accommodate a client area of the given |client_size|.
+  void SetClientSize(Size const& client_size) const;
+
   // Inserts |content| into the window tree.
   void SetChildContent(HWND content);
 
+  // Sets the window state.
+  void SetState(WindowState state);
+
+  // Sets the window title.
+  void SetTitle(std::string_view title) const;
+
   // Controller for this window.
   FlutterHostWindowController* const window_controller_;
 

engine/src/flutter/shell/platform/windows/flutter_host_window_controller.cc

@@ -8,6 +8,7 @@
 
 #include "flutter/shell/platform/common/windowing.h"
 #include "flutter/shell/platform/windows/flutter_windows_engine.h"
+#include "flutter/shell/platform/windows/flutter_windows_view_controller.h"
 
 namespace flutter {
 
@@ -38,39 +39,76 @@ FlutterHostWindowController::~FlutterHostWindowController() {
 std::optional<WindowMetadata> FlutterHostWindowController::CreateHostWindow(
     WindowCreationSettings const& settings) {
   auto window = std::make_unique<FlutterHostWindow>(this, settings);
+
   if (!window->GetWindowHandle()) {
+    FML_LOG(ERROR) << "Failed to create host window";
     return std::nullopt;
   }
 
   // Assume first window is the main window.
   if (windows_.empty()) {
-    window->SetQuitOnClose(true);
+    window->quit_on_close_ = true;
   }
 
-  FlutterViewId const view_id = window->GetFlutterViewId();
-  WindowState const state = window->GetState();
+  FlutterViewId const view_id = window->view_controller_->view()->view_id();
+  WindowState const state = window->state_;
   windows_[view_id] = std::move(window);
 
   WindowMetadata const result = {.view_id = view_id,
                                  .archetype = settings.archetype,
-                                 .size = GetWindowSize(view_id),
+                                 .size = GetViewSize(view_id),
                                  .parent_id = std::nullopt,
                                  .state = state};
 
   return result;
 }
 
-bool FlutterHostWindowController::DestroyHostWindow(FlutterViewId view_id) {
-  if (auto const it = windows_.find(view_id); it != windows_.end()) {
-    FlutterHostWindow* const window = it->second.get();
-    HWND const window_handle = window->GetWindowHandle();
+bool FlutterHostWindowController::ModifyHostWindow(
+    FlutterViewId view_id,
+    WindowModificationSettings const& settings) const {
+  FlutterHostWindow* const window = GetHostWindow(view_id);
+  if (!window) {
+    FML_LOG(ERROR) << "Failed to find window with view ID " << view_id;
+    return false;
+  }
+
+  std::optional<Size> changed_size;
+  Size const size_before = GetViewSize(view_id);
+
+  if (settings.size.has_value()) {
+    window->SetClientSize(*settings.size);
+  }
+  if (settings.title.has_value()) {
+    window->SetTitle(*settings.title);
+  }
+  if (settings.state.has_value()) {
+    window->SetState(*settings.state);
+  }
 
-    // |window| will be removed from |windows_| when WM_NCDESTROY is handled.
-    PostMessage(window->GetWindowHandle(), WM_CLOSE, 0, 0);
+  Size const size_after = GetViewSize(view_id);
+  if (size_before != size_after) {
+    changed_size = size_after;
+  }
 
-    return true;
+  if (changed_size) {
+    SendOnWindowChanged(view_id, changed_size, std::nullopt);
   }
-  return false;
+
+  return true;
+}
+
+bool FlutterHostWindowController::DestroyHostWindow(
+    FlutterViewId view_id) const {
+  FlutterHostWindow* const window = GetHostWindow(view_id);
+  if (!window) {
+    FML_LOG(ERROR) << "Failed to find window with view ID " << view_id;
+    return false;
+  }
+
+  // |window| will be removed from |windows_| when WM_NCDESTROY is handled.
+  PostMessage(window->GetWindowHandle(), WM_CLOSE, 0, 0);
+
+  return true;
 }
 
 FlutterHostWindow* FlutterHostWindowController::GetHostWindow(
@@ -93,7 +131,7 @@ LRESULT FlutterHostWindowController::HandleMessage(HWND hwnd,
           });
       if (it != windows_.end()) {
         FlutterViewId const view_id = it->first;
-        bool const quit_on_close = it->second->GetQuitOnClose();
+        bool const quit_on_close = it->second->quit_on_close_;
 
         windows_.erase(it);
 
@@ -118,7 +156,7 @@ LRESULT FlutterHostWindowController::HandleMessage(HWND hwnd,
                                ? WindowState::kMinimized
                                : WindowState::kRestored;
         }
-        SendOnWindowChanged(view_id, GetWindowSize(view_id), std::nullopt);
+        SendOnWindowChanged(view_id, GetViewSize(view_id), std::nullopt);
       }
     } break;
     default:
@@ -155,17 +193,14 @@ void FlutterHostWindowController::DestroyAllWindows() {
   }
 }
 
-Size FlutterHostWindowController::GetWindowSize(FlutterViewId view_id) const {
-  HWND const hwnd = windows_.at(view_id)->GetWindowHandle();
-  RECT frame_rect;
-  DwmGetWindowAttribute(hwnd, DWMWA_EXTENDED_FRAME_BOUNDS, &frame_rect,
-                        sizeof(frame_rect));
-
-  // Convert to logical coordinates.
-  double const dpr = FlutterDesktopGetDpiForHWND(hwnd) /
+Size FlutterHostWindowController::GetViewSize(FlutterViewId view_id) const {
+  HWND const window_handle = GetHostWindow(view_id)->GetWindowHandle();
+  RECT rect;
+  GetClientRect(window_handle, &rect);
+  double const dpr = FlutterDesktopGetDpiForHWND(window_handle) /
                      static_cast<double>(USER_DEFAULT_SCREEN_DPI);
-  double const width = (frame_rect.right - frame_rect.left) / dpr;
-  double const height = (frame_rect.bottom - frame_rect.top) / dpr;
+  double const width = rect.right / dpr;
+  double const height = rect.bottom / dpr;
   return {width, height};
 }
 

engine/src/flutter/shell/platform/windows/flutter_host_window_controller.h

@@ -34,11 +34,21 @@ class FlutterHostWindowController {
   virtual std::optional<WindowMetadata> CreateHostWindow(
       WindowCreationSettings const& settings);
 
+  // Modifies the attributes of the window hosting the view with ID |view_id|
+  // according to the given |settings|. A "onWindowChanged" message is sent if
+  // at least one attribute is modified.
+  //
+  // Returns false if the controller does not have a window hosting a view with
+  // ID |view_id|.
+  virtual bool ModifyHostWindow(
+      FlutterViewId view_id,
+      WindowModificationSettings const& settings) const;
+
   // Destroys the window that hosts the view with ID |view_id|.
   //
   // Returns false if the controller does not have a window hosting a view with
   // ID |view_id|.
-  virtual bool DestroyHostWindow(FlutterViewId view_id);
+  virtual bool DestroyHostWindow(FlutterViewId view_id) const;
 
   // Gets the window hosting the view with ID |view_id|.
   //
@@ -62,9 +72,8 @@ class FlutterHostWindowController {
   // Destroys all windows managed by this controller.
   void DestroyAllWindows();
 
-  // Gets the size of the host window for the view with ID |view_id|. The size
-  // is in logical coordinates and excludes the drop-shadow area.
-  Size GetWindowSize(FlutterViewId view_id) const;
+  // Retrieves the size of the view with ID |view_id|, in logical coordinates.
+  Size GetViewSize(FlutterViewId view_id) const;
 
   // Sends the "onWindowChanged" message to the Flutter engine.
   void SendOnWindowChanged(FlutterViewId view_id,