Apply viewport emulation to prerender targets (#2444)

* Apply viewport emulation to prerender targets

* Remove extra assigment

Author: kblok

lib/PuppeteerSharp.Tests/PrerenderTests/WithEmulationTests.cs

@@ -0,0 +1,44 @@
+using System.Diagnostics;
+using System.Threading.Tasks;
+using NUnit.Framework;
+using PuppeteerSharp.Nunit;
+using PuppeteerSharp.Tests.Attributes;
+
+namespace PuppeteerSharp.Tests.PrerenderTests;
+
+public class WithEmulationTests : PuppeteerPageBaseTest
+{
+    [PuppeteerTest("prerender.spec.ts", "Prerender with emulation", "can configure viewport for prerendered pages")]
+    [Skip(SkipAttribute.Targets.Firefox)]
+    public async Task CanConfigureViewportForPrerenderedPages()
+    {
+        await Page.SetViewportAsync(new ViewPortOptions()
+        {
+            Width = 300,
+            Height = 400,
+        });
+
+        await Page.GoToAsync(TestConstants.ServerUrl + "/prerender/index.html");
+
+        var button = await Page.WaitForSelectorAsync("button");
+        await button.ClickAsync();
+
+        var mainFrame = Page.MainFrame;
+        var link = await mainFrame.WaitForSelectorAsync("a");
+        await Task.WhenAll(
+            mainFrame.WaitForNavigationAsync(),
+            link.ClickAsync()
+        );
+
+        var result = await Page.EvaluateFunctionAsync<decimal[]>(@"() => {
+            return [
+                document.documentElement.clientWidth,
+                document.documentElement.clientHeight,
+                window.devicePixelRatio,
+            ];
+        }");
+
+        Assert.AreEqual(300 * result[2], result[0]);
+        Assert.AreEqual(400 * result[2], result[1]);
+    }
+}

lib/PuppeteerSharp/EmulationManager.cs

@@ -1,16 +1,20 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
+using PuppeteerSharp.Helpers;
 using PuppeteerSharp.Media;
 using PuppeteerSharp.Messaging;
 
 namespace PuppeteerSharp
 {
     internal class EmulationManager
     {
+        private readonly ConcurrentSet<CDPSession> _secondaryClients = [];
         private CDPSession _client;
         private bool _emulatingMobile;
         private bool _hasTouch;
+        private ViewPortOptions _viewport;
 
         public EmulationManager(CDPSession client)
         {
@@ -19,7 +23,18 @@ public EmulationManager(CDPSession client)
 
         public bool JavascriptEnabled { get; private set; } = true;
 
-        internal void UpdateClient(CDPSession client) => _client = client;
+        internal void UpdateClient(CDPSession client)
+        {
+            _client = client;
+            _secondaryClients.Remove(client);
+        }
+
+        internal async Task RegisterSecondaryPageAsync(CDPSession client)
+        {
+            _secondaryClients.Add(client);
+            await ApplyViewportAsync(client).ConfigureAwait(false);
+            client.Disconnected += (sender, e) => _secondaryClients.Remove(client);
+        }
 
         internal async Task EmulateTimezoneAsync(string timezoneId)
         {
@@ -72,33 +87,22 @@ await _client.SendAsync(
 
         internal async Task<bool> EmulateViewportAsync(ViewPortOptions viewport)
         {
-            var mobile = viewport.IsMobile;
-            var width = viewport.Width;
-            var height = viewport.Height;
-            var deviceScaleFactor = viewport.DeviceScaleFactor;
-            var screenOrientation = viewport.IsLandscape
-                ? new ScreenOrientation { Angle = 90, Type = ScreenOrientationType.LandscapePrimary, }
-                : new ScreenOrientation { Angle = 0, Type = ScreenOrientationType.PortraitPrimary, };
-            var hasTouch = viewport.HasTouch;
+            _viewport = viewport;
 
-            await Task.WhenAll(
-            [
-                _client.SendAsync("Emulation.setDeviceMetricsOverride", new EmulationSetDeviceMetricsOverrideRequest
-                {
-                    Mobile = mobile,
-                    Width = width,
-                    Height = height,
-                    DeviceScaleFactor = deviceScaleFactor,
-                    ScreenOrientation = screenOrientation,
-                }),
-                _client.SendAsync(
-                    "Emulation.setTouchEmulationEnabled",
-                    new EmulationSetTouchEmulationEnabledRequest { Enabled = hasTouch, }),
-            ]).ConfigureAwait(false);
+            await ApplyViewportAsync(_client).ConfigureAwait(false);
 
+            var mobile = viewport.IsMobile;
+            var hasTouch = viewport.HasTouch;
             var reloadNeeded = _emulatingMobile != mobile || _hasTouch != hasTouch;
             _emulatingMobile = mobile;
             _hasTouch = hasTouch;
+
+            if (!reloadNeeded)
+            {
+                // If the page will be reloaded, no need to adjust secondary clients.
+                await Task.WhenAll(_secondaryClients.Select(ApplyViewportAsync)).ConfigureAwait(false);
+            }
+
             return reloadNeeded;
         }
 
@@ -165,5 +169,38 @@ internal Task SetJavaScriptEnabledAsync(bool enabled)
                 Value = !enabled,
             });
         }
+
+        private async Task ApplyViewportAsync(CDPSession client)
+        {
+            var viewport = _viewport;
+            if (viewport == null)
+            {
+                return;
+            }
+
+            var mobile = viewport.IsMobile;
+            var width = viewport.Width;
+            var height = viewport.Height;
+            var deviceScaleFactor = viewport.DeviceScaleFactor;
+            var screenOrientation = viewport.IsLandscape
+                ? new ScreenOrientation { Angle = 90, Type = ScreenOrientationType.LandscapePrimary, }
+                : new ScreenOrientation { Angle = 0, Type = ScreenOrientationType.PortraitPrimary, };
+            var hasTouch = viewport.HasTouch;
+
+            await Task.WhenAll(
+            [
+                client.SendAsync("Emulation.setDeviceMetricsOverride", new EmulationSetDeviceMetricsOverrideRequest
+                {
+                    Mobile = mobile,
+                    Width = width,
+                    Height = height,
+                    DeviceScaleFactor = deviceScaleFactor,
+                    ScreenOrientation = screenOrientation,
+                }),
+                client.SendAsync(
+                    "Emulation.setTouchEmulationEnabled",
+                    new EmulationSetTouchEmulationEnabledRequest { Enabled = hasTouch, }),
+            ]).ConfigureAwait(false);
+        }
     }
 }

lib/PuppeteerSharp/Page.cs

@@ -124,6 +124,7 @@ private Page(
                     }
 
                     await FrameManager.RegisterSpeculativeSessionAsync(session).ConfigureAwait(false);
+                    await _emulationManager.RegisterSecondaryPageAsync(session).ConfigureAwait(false);
                 }
                 catch (Exception ex)
                 {