Implement positioning logic in Dart + nits

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

@@ -158,10 +158,10 @@ source_set("flutter_linux_sources") {
     "fl_view.cc",
     "fl_view_accessible.cc",
     "fl_window_state_monitor.cc",
-    "fl_windowing_channel.cc",
-    "fl_windowing_handler.cc",
     "fl_windowing.cc",
     "fl_windowing.h",
+    "fl_windowing_channel.cc",
+    "fl_windowing_handler.cc",
     "key_mapping.g.cc",
   ]
 

examples/multi_window_ref_app/lib/app/main_window.dart

@@ -149,7 +149,7 @@ class _ActiveWindowsTable extends StatelessWidget {
                   }
                 },
                 cells: [
-                  DataCell(Text('$controller.controller.rootView.viewId')),
+                  DataCell(Text('${controller.controller.rootView.viewId}')),
                   DataCell(
                     ListenableBuilder(
                         listenable: controller.controller,

examples/multi_window_ref_app/lib/app/regular_window_edit_dialog.dart

@@ -74,7 +74,10 @@ void showRegularWindowEditDialog(BuildContext context,
               String? title =
                   titleController.text.isEmpty ? null : titleController.text;
 
-              onSave?.call(width, height, title, selectedState);
+              onSave?.call(width, height, title, WindowState.restored);
+              if (selectedState != WindowState.restored) {
+                onSave?.call(null, null, title, selectedState);
+              }
               Navigator.of(context).pop();
             },
             child: Text("Save"),

packages/flutter/lib/src/widgets/window.dart

@@ -56,8 +56,7 @@ enum WindowState {
 abstract class WindowController with ChangeNotifier {
   @protected
   /// Sets the view associated with this window.
-  // ignore: use_setters_to_change_properties
-  void setView(FlutterView view) {
+  set view(FlutterView view) {
     _view = view;
   }
 

packages/flutter/lib/src/widgets/window_linux.dart

@@ -74,7 +74,7 @@ class PopupWindowControllerLinux extends PopupWindowController {
     final FlutterView flutterView = WidgetsBinding.instance.platformDispatcher.views.firstWhere(
       (FlutterView view) => view.viewId == viewId,
     );
-    setView(flutterView);
+    view = flutterView;
   }
 
   Pointer<Void> getWindowHandle() {
@@ -142,7 +142,7 @@ class RegularWindowControllerLinux extends RegularWindowController {
     final FlutterView flutterView = WidgetsBinding.instance.platformDispatcher.views.firstWhere(
       (FlutterView view) => view.viewId == viewId,
     );
-    setView(flutterView);
+    view = flutterView;
     if (title != null) {
       setTitle(title);
     }

packages/flutter/lib/src/widgets/window_macos.dart

@@ -73,7 +73,7 @@ class PopupWindowControllerMacOS extends PopupWindowController {
     final FlutterView flutterView = WidgetsBinding.instance.platformDispatcher.views.firstWhere(
       (FlutterView view) => view.viewId == viewId,
     );
-    setView(flutterView);
+    view = flutterView;
     // This calculates absolute position using the [WindowPositioner]. On Linux it would instead convert
     // the positioner xdg_positioner and pass it to the window manager.
     _positionWindow(parentWindow, position, anchorRect);
@@ -164,7 +164,7 @@ class RegularWindowControllerMacOS extends RegularWindowController {
     final FlutterView flutterView = WidgetsBinding.instance.platformDispatcher.views.firstWhere(
       (FlutterView view) => view.viewId == viewId,
     );
-    setView(flutterView);
+    view = flutterView;
     if (title != null) {
       setTitle(title);
     }

packages/flutter/lib/src/widgets/window_positioning.dart

@@ -212,7 +212,7 @@ class WindowPositioner {
   final Set<WindowPositionerConstraintAdjustment> constraintAdjustment;
 
   /// Computes the screen-space rectangle for a child window placed according to
-  /// the this position. [childSize] is the frame size of the child window.
+  /// this [WindowPositioner]. [childSize] is the frame size of the child window.
   /// [anchorRect] is the rectangle relative to which the child window is placed.
   /// [parentRect] is the parent window's rectangle. [outputRect] is the output
   /// display area where the child window will be placed. All sizes and rectangles
@@ -233,91 +233,202 @@ class WindowPositioner {
         return defaultResult;
       }
     }
-    // TODO: Finish
+
+    if (constraintAdjustment.contains(WindowPositionerConstraintAdjustment.flipX)) {
+      final Offset result =
+          _constraintTo(
+            parentRect,
+            parentAnchor.flipX().anchorPositionFor(anchorRect) + _flipX(offset),
+          ) +
+          childAnchor.flipX().offsetFor(childSize);
+      if (_rectContains(outputRect, result & childSize)) {
+        return result & childSize;
+      }
+    }
+
+    if (constraintAdjustment.contains(WindowPositionerConstraintAdjustment.flipY)) {
+      final Offset result =
+          _constraintTo(
+            parentRect,
+            parentAnchor.flipY().anchorPositionFor(anchorRect) + _flipY(offset),
+          ) +
+          childAnchor.flipY().offsetFor(childSize);
+      if (_rectContains(outputRect, result & childSize)) {
+        return result & childSize;
+      }
+    }
+
+    if (constraintAdjustment.containsAll(<WindowPositionerConstraintAdjustment>{
+      WindowPositionerConstraintAdjustment.flipX,
+      WindowPositionerConstraintAdjustment.flipY,
+    })) {
+      final Offset result =
+          _constraintTo(
+            parentRect,
+            parentAnchor.flipY().flipX().anchorPositionFor(anchorRect) + _flipX(_flipY(offset)),
+          ) +
+          childAnchor.flipY().flipX().offsetFor(childSize);
+      if (_rectContains(outputRect, result & childSize)) {
+        return result & childSize;
+      }
+    }
+
+    {
+      Offset result =
+          _constraintTo(parentRect, parentAnchor.anchorPositionFor(anchorRect) + offset) +
+          childAnchor.offsetFor(childSize);
+
+      if (constraintAdjustment.contains(WindowPositionerConstraintAdjustment.slideX)) {
+        final double leftOverhang = result.dx - outputRect.left;
+        final double rightOverhang = result.dx + childSize.width - outputRect.right;
+        if (leftOverhang < 0.0) {
+          result = result.translate(-leftOverhang, 0.0);
+        } else if (rightOverhang > 0.0) {
+          result = result.translate(-rightOverhang, 0.0);
+        }
+      }
+
+      if (constraintAdjustment.contains(WindowPositionerConstraintAdjustment.slideY)) {
+        final double topOverhang = result.dy - outputRect.top;
+        final double bottomOverhang = result.dy + childSize.height - outputRect.bottom;
+        if (topOverhang < 0.0) {
+          result = result.translate(0.0, -topOverhang);
+        } else if (bottomOverhang > 0.0) {
+          result = result.translate(0.0, -bottomOverhang);
+        }
+      }
+
+      if (_rectContains(outputRect, result & childSize)) {
+        return result & childSize;
+      }
+    }
+
+    {
+      Offset result =
+          _constraintTo(parentRect, parentAnchor.anchorPositionFor(anchorRect) + offset) +
+          childAnchor.offsetFor(childSize);
+
+      if (constraintAdjustment.contains(WindowPositionerConstraintAdjustment.resizeX)) {
+        final double leftOverhang = result.dx - outputRect.left;
+        final double rightOverhang = result.dx + childSize.width - outputRect.right;
+        if (leftOverhang < 0.0) {
+          result = result.translate(-leftOverhang, 0.0);
+          childSize = Size(childSize.width + leftOverhang, childSize.height);
+        }
+        if (rightOverhang > 0.0) {
+          childSize = Size(childSize.width - rightOverhang, childSize.height);
+        }
+      }
+
+      if (constraintAdjustment.contains(WindowPositionerConstraintAdjustment.resizeY)) {
+        final double topOverhang = result.dy - outputRect.top;
+        final double bottomOverhang = result.dy + childSize.height - outputRect.bottom;
+        if (topOverhang < 0.0) {
+          result = result.translate(0.0, -topOverhang);
+          childSize = Size(childSize.width, childSize.height + topOverhang);
+        }
+        if (bottomOverhang > 0.0) {
+          childSize = Size(childSize.width, childSize.height - bottomOverhang);
+        }
+      }
+
+      if (_rectContains(outputRect, result & childSize)) {
+        return result & childSize;
+      }
+    }
+
     return defaultResult;
   }
 }
 
 extension on WindowPositionerAnchor {
   WindowPositionerAnchor flipX() {
     switch (this) {
-      case WindowPositionerAnchor.topLeft:
-        return WindowPositionerAnchor.topRight;
-      case WindowPositionerAnchor.topRight:
-        return WindowPositionerAnchor.topLeft;
+      case WindowPositionerAnchor.center:
+        return WindowPositionerAnchor.center;
+      case WindowPositionerAnchor.top:
+        return WindowPositionerAnchor.top;
+      case WindowPositionerAnchor.bottom:
+        return WindowPositionerAnchor.bottom;
       case WindowPositionerAnchor.left:
         return WindowPositionerAnchor.right;
       case WindowPositionerAnchor.right:
         return WindowPositionerAnchor.left;
+      case WindowPositionerAnchor.topLeft:
+        return WindowPositionerAnchor.topRight;
       case WindowPositionerAnchor.bottomLeft:
         return WindowPositionerAnchor.bottomRight;
+      case WindowPositionerAnchor.topRight:
+        return WindowPositionerAnchor.topLeft;
       case WindowPositionerAnchor.bottomRight:
         return WindowPositionerAnchor.bottomLeft;
-      default:
-        return this;
     }
   }
 
   WindowPositionerAnchor flipY() {
     switch (this) {
-      case WindowPositionerAnchor.topLeft:
-        return WindowPositionerAnchor.bottomLeft;
+      case WindowPositionerAnchor.center:
+        return WindowPositionerAnchor.center;
       case WindowPositionerAnchor.top:
         return WindowPositionerAnchor.bottom;
-      case WindowPositionerAnchor.topRight:
-        return WindowPositionerAnchor.bottomRight;
-      case WindowPositionerAnchor.bottomLeft:
-        return WindowPositionerAnchor.topLeft;
       case WindowPositionerAnchor.bottom:
         return WindowPositionerAnchor.top;
+      case WindowPositionerAnchor.left:
+        return WindowPositionerAnchor.left;
+      case WindowPositionerAnchor.right:
+        return WindowPositionerAnchor.right;
+      case WindowPositionerAnchor.topLeft:
+        return WindowPositionerAnchor.bottomLeft;
+      case WindowPositionerAnchor.bottomLeft:
+        return WindowPositionerAnchor.topLeft;
+      case WindowPositionerAnchor.topRight:
+        return WindowPositionerAnchor.bottomRight;
       case WindowPositionerAnchor.bottomRight:
         return WindowPositionerAnchor.topRight;
-      default:
-        return this;
     }
   }
 
   Offset offsetFor(Size size) {
     switch (this) {
-      case WindowPositionerAnchor.topLeft:
-        return Offset.zero;
+      case WindowPositionerAnchor.center:
+        return Offset(-size.width / 2.0, -size.height / 2.0);
       case WindowPositionerAnchor.top:
         return Offset(-size.width / 2.0, 0.0);
-      case WindowPositionerAnchor.topRight:
-        return Offset(-size.width, 0.0);
+      case WindowPositionerAnchor.bottom:
+        return Offset(-size.width / 2.0, -1.0 * size.height);
       case WindowPositionerAnchor.left:
         return Offset(0.0, -size.height / 2.0);
-      case WindowPositionerAnchor.center:
-        return Offset(-size.width / 2.0, -size.height / 2.0);
       case WindowPositionerAnchor.right:
         return Offset(-1.0 * size.width, -size.height / 2.0);
+      case WindowPositionerAnchor.topLeft:
+        return Offset.zero;
       case WindowPositionerAnchor.bottomLeft:
         return Offset(0.0, -1.0 * size.height);
-      case WindowPositionerAnchor.bottom:
-        return Offset(-size.width / 2.0, -1.0 * size.height);
+      case WindowPositionerAnchor.topRight:
+        return Offset(-size.width, 0.0);
       case WindowPositionerAnchor.bottomRight:
         return Offset(-1.0 * size.width, -1.0 * size.height);
     }
   }
 
   Offset anchorPositionFor(Rect rect) {
     switch (this) {
-      case WindowPositionerAnchor.topLeft:
-        return rect.topLeft;
+      case WindowPositionerAnchor.center:
+        return rect.center;
       case WindowPositionerAnchor.top:
         return rect.topCenter;
-      case WindowPositionerAnchor.topRight:
-        return rect.topRight;
+      case WindowPositionerAnchor.bottom:
+        return rect.bottomCenter;
       case WindowPositionerAnchor.left:
         return rect.centerLeft;
-      case WindowPositionerAnchor.center:
-        return rect.center;
       case WindowPositionerAnchor.right:
         return rect.centerRight;
+      case WindowPositionerAnchor.topLeft:
+        return rect.topLeft;
       case WindowPositionerAnchor.bottomLeft:
         return rect.bottomLeft;
-      case WindowPositionerAnchor.bottom:
-        return rect.bottomCenter;
+      case WindowPositionerAnchor.topRight:
+        return rect.topRight;
       case WindowPositionerAnchor.bottomRight:
         return rect.bottomRight;
     }

packages/flutter/lib/src/widgets/window_win32.dart

@@ -114,7 +114,6 @@ class RegularWindowControllerWin32 extends RegularWindowController
   }) : _owner = owner,
        _delegate = delegate,
        super.empty() {
-    owner.addMessageHandler(this);
     final Pointer<_WindowCreationRequest> request =
         ffi.calloc<_WindowCreationRequest>()
           ..ref.width = size.width
@@ -128,7 +127,8 @@ class RegularWindowControllerWin32 extends RegularWindowController
     final FlutterView flutterView = WidgetsBinding.instance.platformDispatcher.views.firstWhere(
       (FlutterView view) => view.viewId == viewId,
     );
-    setView(flutterView);
+    view = flutterView;
+    owner.addMessageHandler(this);
   }
 
   @override
@@ -199,7 +199,6 @@ class RegularWindowControllerWin32 extends RegularWindowController
       return;
     }
     _destroyWindow(getWindowHandle());
-    ;
     _destroyed = true;
     _delegate.onWindowDestroyed();
     _owner.removeMessageHandler(this);