From 45c1fe434894e222c2cd895a3da1228605fe4366 Mon Sep 17 00:00:00 2001
From: Dan Field <dnfield@google.com>
Date: Thu, 25 May 2023 09:46:58 -0700
Subject: [PATCH] Implement PlatformDispatcher.displays on web
 (flutter/engine#42297)

I missed this before.
---
 .../lib/src/engine/platform_dispatcher.dart   | 27 ++++++++++++++++++-
 .../lib/web_ui/lib/src/engine/window.dart     | 25 +----------------
 .../platform_dispatcher_test.dart             |  4 +++
 3 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart b/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart
index 4dee3ef5724..7ff4c674121 100644
--- a/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart
+++ b/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart
@@ -73,6 +73,24 @@ class HighContrastSupport {
   }
 }
 
+class EngineFlutterDisplay extends ui.Display {
+  EngineFlutterDisplay({
+    required this.id,
+    required this.devicePixelRatio,
+    required this.size,
+    required this.refreshRate,
+  });
+
+  @override
+  final int id;
+  @override
+  final double devicePixelRatio;
+  @override
+  final ui.Size size;
+  @override
+  final double refreshRate;
+}
+
 /// Platform event dispatcher.
 ///
 /// This is the central entry point for platform messages and configuration
@@ -135,7 +153,14 @@ class EnginePlatformDispatcher extends ui.PlatformDispatcher {
   }
 
   @override
-  Iterable<ui.Display> get displays => <ui.Display>[];
+  Iterable<ui.Display> get displays => <ui.Display>[
+    EngineFlutterDisplay(
+      id: 0,
+      size: ui.Size(domWindow.screen?.width ?? 0, domWindow.screen?.height ?? 0),
+      devicePixelRatio: domWindow.devicePixelRatio,
+      refreshRate: 60,
+    )
+  ];
 
   /// The current list of windows.
   @override
diff --git a/engine/src/flutter/lib/web_ui/lib/src/engine/window.dart b/engine/src/flutter/lib/web_ui/lib/src/engine/window.dart
index 3076ada9d2d..1370d458029 100644
--- a/engine/src/flutter/lib/web_ui/lib/src/engine/window.dart
+++ b/engine/src/flutter/lib/web_ui/lib/src/engine/window.dart
@@ -29,24 +29,6 @@ const bool debugPrintPlatformMessages = false;
 /// The view ID for the implicit flutter view provided by the platform.
 const int kImplicitViewId = 0;
 
-class EngineFlutterDisplay extends ui.Display {
-  EngineFlutterDisplay({
-    required this.id,
-    required this.devicePixelRatio,
-    required this.size,
-    required this.refreshRate,
-  });
-
-  @override
-  final int id;
-  @override
-  final double devicePixelRatio;
-  @override
-  final ui.Size size;
-  @override
-  final double refreshRate;
-}
-
 /// The Web implementation of [ui.SingletonFlutterWindow].
 class EngineFlutterWindow extends ui.SingletonFlutterWindow {
   EngineFlutterWindow(this.viewId, this.platformDispatcher) {
@@ -66,12 +48,7 @@ class EngineFlutterWindow extends ui.SingletonFlutterWindow {
 
   @override
   ui.Display get display {
-    return EngineFlutterDisplay(
-      id: 0,
-      size: ui.Size(domWindow.screen?.width ?? 0, domWindow.screen?.height ?? 0),
-      devicePixelRatio: domWindow.devicePixelRatio,
-      refreshRate: 60,
-    );
+    return ui.PlatformDispatcher.instance.displays.first;
   }
 
   @override
diff --git a/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart b/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart
index 7cecb112425..366011e9625 100644
--- a/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart
+++ b/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart
@@ -18,6 +18,10 @@ void testMain() {
   ensureFlutterViewEmbedderInitialized();
 
   group('PlatformDispatcher', () {
+    test('reports at least one display', () {
+      expect(ui.PlatformDispatcher.instance.displays.length, greaterThan(0));
+    });
+
     test('high contrast in accessibilityFeatures has the correct value', () {
       final MockHighContrastSupport mockHighContrast =
           MockHighContrastSupport();