gramps
ea347f211c
The one-shot dump + alpha log was bound to the FIRST capture ever = the initial
about:blank placeholder (alpha=0, rgb=0, 5/5 sessions) — a blind instrument. The
pre-parse transparency injection (1a39b09) is intact but was NEVER verified
(MyMistakes '? VERIFY'), and the 2026-09-10 take still shows a black, opaque
block. Stop guessing: NavigationCompleted for a non-about:blank document now
arms WidgetDumpRemaining=5; the next 5 post-paint captures dump
%TEMP%\ytLive-web-<id>-w1..5.png + shared AlphaStats(min/max/mean/zero%) +
FindContentBounds to startup.log.
The stats line alone names the branch: zero%≈opaque ⇒ the injection did not hold
for this widget's CSS (fix: !important stylesheet / chroma-key); large zero% +
tight bounds ⇒ capture IS transparent and the black lives in the compositor
blend. No new test: WebView2 runtime is not instantiable in the suite and the
re-point is log-only; 8/8 WebView2 tests still pass.
438 lines
18 KiB
C#
438 lines
18 KiB
C#
using System;
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using System.Diagnostics;
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using System.Drawing;
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using System.IO;
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using System.Text.Json;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Media;
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using System.Windows.Media.Imaging;
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using System.Windows.Threading;
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using Microsoft.Web.WebView2.Core;
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using Microsoft.Web.WebView2.Wpf;
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using ytLive.Helpers;
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using ytLive.Models;
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namespace ytLive.Services;
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public sealed class WebView2Manager : IDisposable
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{
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private readonly Panel _hostPanel;
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private readonly Dispatcher _dispatcher;
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private readonly Dictionary<string, WebSourceSession> _sessions = new();
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private Task<CoreWebView2Environment>? _environmentTask;
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private int _captureIntervalMs = 200; // idle pace; recording drops it to ~30Hz via SetCaptureInterval
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public event Action<string, WriteableBitmap>? PreviewBitmapChanged;
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private sealed class WebSourceSession
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{
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public required WebView2 Control { get; init; }
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public required CaptureScheduler Scheduler { get; init; }
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public VideoFrame? LatestFrame;
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public bool Disposed;
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public bool Initialized;
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// Buffer reuse (2026-09-04): every capture tick used to mint a fresh
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// 8.3MB canvas array + a fresh crop array (~83MB/s of LOH at 10Hz →
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// gen2 pauses surfaced as the pump's 35-40ms "worst render" spikes).
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// CanvasScratch is reused while the size holds. The frame handed to the
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// compositor is always the FULL canvas (transparent margins reveal layers
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// beneath); the crop is only for the preview WriteableBitmap. Epoch is
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// monotonic per canvas generation (identity-keyed consumers see each frame).
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public byte[]? CanvasScratch;
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public readonly byte[]?[] OutRing = new byte[8][];
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public int OutRingNext;
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public long Epoch;
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public WriteableBitmap? PreviewBitmap;
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public bool DebugPngWritten;
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public int WidgetDumpRemaining;
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public int TelemetryCaptureCount;
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public byte[] RentOutBuffer(int size)
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{
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for (var tries = 0; tries < OutRing.Length; tries++)
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{
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var idx = (OutRingNext + tries) % OutRing.Length;
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var buf = OutRing[idx];
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if (buf != null && buf.Length == size)
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{
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OutRingNext = (idx + 1) % OutRing.Length;
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return buf;
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}
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}
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var slot = OutRingNext;
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OutRingNext = (slot + 1) % OutRing.Length;
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var fresh = new byte[size];
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OutRing[slot] = fresh;
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return fresh;
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}
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}
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public WebView2Manager(Panel hostPanel, Dispatcher dispatcher)
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{
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_hostPanel = hostPanel;
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_dispatcher = dispatcher;
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}
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public void Register(Source source)
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{
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if (_sessions.ContainsKey(source.Id)) return;
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// OBS model: the page renders at the MASTER CANVAS size (1920×1080),
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// stable, never tracked. Full-bleed widgets (designed for the canvas)
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// render fully instead of being clipped to a small box-sized viewport;
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// dragging the box never reflows the page. The capture is tightly
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// cropped to the widget's ALPHA bounding box (FindContentBounds) and
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// the display (Stretch=Fill) maps it flush under the box, anchored at
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// (0,0) — no DOM query, so no timing fragility; worst case is the
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// full frame, which is the confirmed-good rendering.
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var webView = new WebView2
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{
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Width = 1920,
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Height = 1080,
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DefaultBackgroundColor = System.Drawing.Color.Transparent,
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Visibility = System.Windows.Visibility.Visible,
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};
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Canvas.SetLeft(webView, -5000);
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Canvas.SetTop(webView, -5000);
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_hostPanel.Children.Add(webView);
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var scheduler = new CaptureScheduler(
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_dispatcher,
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_captureIntervalMs,
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() => CaptureFrame(source.Id));
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var session = new WebSourceSession
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{
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Control = webView,
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Scheduler = scheduler,
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};
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_sessions[source.Id] = session;
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_ = InitializeAsync(source, session);
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}
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/// <summary>Changes the capture cadence for every session. Recording runs at
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/// ~30Hz (33ms) — the practical PNG-capture ceiling — idle drops back to 200ms so
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/// the preview alone doesn't burn a core decoding full-HD captures.</summary>
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public void SetCaptureInterval(int milliseconds)
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{
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_captureIntervalMs = milliseconds;
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foreach (var session in _sessions.Values)
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if (!session.Disposed)
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session.Scheduler.SetInterval(milliseconds);
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}
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public void Unregister(string sourceId) => RemoveSession(sourceId);
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public void OnWebUriChanged(Source source)
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{
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if (!_sessions.TryGetValue(source.Id, out var session)) return;
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if (session.Disposed || !session.Initialized) return;
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if (string.IsNullOrEmpty(source.WebUri))
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{
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session.LatestFrame = null;
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session.Control.CoreWebView2?.NavigateToString(
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"<html><body style='background:transparent;margin:0'></body></html>");
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return;
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}
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Navigate(source.WebUri, session);
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}
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public VideoFrame? GetLatestFrame(string sourceId)
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{
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return _sessions.TryGetValue(sourceId, out var session) ? session.LatestFrame : null;
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}
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// Injected BEFORE the document is parsed (AddScriptToExecuteOnDocumentCreatedAsync) so
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// the widget page's own CSS/scripts cannot repaint html/body opaque — the reason the
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// late NavigationStarting/NavigationCompleted ExecuteScriptAsync injection lost the
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// fight (page styles ran first). CapturePreviewAsync "will always honor a webpage's
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// background content" (MicrosoftEdge/WebView2Feedback specs/BackgroundColor.md), so a
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// transparent capture REQUIRES the transparency to be in place before the page paints.
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private const string TransparentBackgroundScript =
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"document.documentElement.style.background='transparent';" +
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"document.documentElement.style.overflow='hidden';" +
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"document.documentElement.style.margin='0';" +
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"if(document.body){document.body.style.background='transparent';" +
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"document.body.style.overflow='hidden';document.body.style.margin='0';}";
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private async Task InitializeAsync(Source source, WebSourceSession session)
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{
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try
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{
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await session.Control.EnsureCoreWebView2Async(await GetEnvironmentAsync());
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var cws = session.Control.CoreWebView2!;
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// Pre-page hook: runs after the global object exists but BEFORE the document
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// parses / any page script runs — must complete before navigating away from
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// about:blank for it to apply to the widget document.
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await cws.AddScriptToExecuteOnDocumentCreatedAsync(TransparentBackgroundScript);
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cws.NavigationStarting += (_, _) =>
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{
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_ = cws.ExecuteScriptAsync(TransparentBackgroundScript);
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};
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cws.NavigationCompleted += (_, e) =>
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{
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_ = cws.ExecuteScriptAsync(TransparentBackgroundScript);
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if (e.IsSuccess && session.Control.CoreWebView2?.Source is { } src && src != "about:blank")
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{
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// Arm a one-shot diagnostic dump of the REAL widget document
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// (a few post-paint captures so styles/backgrounds settle) —
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// the old first-capture dump only ever saw the about:blank
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// document, so whether this widget's capture actually HAS the
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// transparent margins the injection promises has never been
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// verified (MyMistakes: "? VERIFY").
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session.WidgetDumpRemaining = 5;
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}
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_ = CaptureFrame(source.Id);
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};
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session.Initialized = true;
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session.Control.CoreWebView2.NavigateToString(
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"<html><body style='background:transparent;margin:0'></body></html>");
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if (!string.IsNullOrEmpty(source.WebUri))
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Navigate(source.WebUri, session);
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session.Scheduler.Start();
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}
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catch (Exception ex)
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{
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AppLog.Write($"WebView2Manager: init failed for '{source.Name}': {ex.Message}");
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RemoveSession(source.Id);
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}
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}
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// The widget page is rendered off-screen; Chromium throttles hidden pages
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// (rAF parked, timers clamped to ~1s) the moment the app window is unfocused or
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// covered — WebView2Feedback#1172/#3070, Chrome 88 timer throttling. These flags
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// (the Electron-class embedder answer) keep the renderer at full rate:
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// --disable-backgrounding-occluded-windows, --disable-renderer-backgrounding,
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// and disable the native-window occlusion detector that marks the page hidden.
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// The environment MUST exist before EnsureCoreWebView2Async — it's created once
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// and shared by every session (one browser process).
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private Task<CoreWebView2Environment> GetEnvironmentAsync()
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{
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if (_environmentTask != null) return _environmentTask;
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var options = new CoreWebView2EnvironmentOptions
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{
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AdditionalBrowserArguments =
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"--disable-backgrounding-occluded-windows --disable-renderer-backgrounding --disable-features=CalculateNativeWinOcclusion",
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};
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return _environmentTask = CoreWebView2Environment.CreateAsync(null, null, options);
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}
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private void Navigate(string url, WebSourceSession session)
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{
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try { session.Control.CoreWebView2?.Navigate(url); }
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catch (Exception ex) { AppLog.Write($"WebView2Manager: navigate failed: {ex.Message}"); }
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}
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// The widget's extent is measured from the captured frame itself: the
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// bounding box of non-transparent pixels (the background is injected
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// transparent, so the alpha channel IS the widget). This is immune to
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// DOM timing (fonts/images/animations), needs no JS round-trip, and
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// CANNOT break the render: if the widget fills the canvas the box equals
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// the full frame; if it floats in transparent margin the box is the
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// measured content extent — used ONLY for the preview bitmap / selection.
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// The frame handed to the compositor is always the FULL canvas, so the
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// page's transparent margins keep revealing the layers beneath (the
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// "black square over webcam" was the crop fed to the compositor:
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// UniformToFill zoomed the opaque content box to cover the whole element).
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internal static (int X, int Y, int W, int H) FindContentBounds(byte[] pixels, int pixW, int pixH, int stride)
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{
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int minX = pixW, minY = pixH, maxX = -1, maxY = -1;
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for (var y = 0; y < pixH; y++)
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{
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var row = y * stride;
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for (var x = 0; x < pixW; x++)
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{
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if (pixels[row + x * 4 + 3] == 0) continue;
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if (x < minX) minX = x;
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if (x > maxX) maxX = x;
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if (y < minY) minY = y;
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if (y > maxY) maxY = y;
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}
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}
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if (maxX < minX || maxY < minY) return (0, 0, pixW, pixH);
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return (minX, minY, maxX - minX + 1, maxY - minY + 1);
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}
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// alpha[min/max/mean/zero%] — the one number that decides whether a widget's
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// capture really has transparent margins (0% = opaque, ~100% if the page
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// painted transparent-only). Sampled every 16th pixel like the original log.
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private static string AlphaStats(byte[] pixels, int pixW, int pixH, int stride)
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{
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int minA = 255, maxA = 0;
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long sumA = 0, nA = 0, zeroA = 0;
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for (var y = 0; y < pixH; y += 16)
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{
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var row = y * stride;
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for (var x = 0; x < pixW; x += 16)
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{
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var a = pixels[row + x * 4 + 3];
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if (a < minA) minA = a;
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if (a > maxA) maxA = a;
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sumA += a;
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if (a == 0) zeroA++;
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nA++;
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}
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}
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return $"alpha[min={minA},max={maxA},mean={sumA / (double)nA:F1},zero={100.0 * zeroA / nA:F1}%]";
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}
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private async Task CaptureFrame(string sourceId)
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{
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if (!_sessions.TryGetValue(sourceId, out var session) || session.Disposed) return;
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var sw = Stopwatch.StartNew();
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try
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{
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var webView = session.Control;
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if (webView.CoreWebView2 == null) return;
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using var ms = new MemoryStream();
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await webView.CoreWebView2.CapturePreviewAsync(
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CoreWebView2CapturePreviewImageFormat.Png, ms);
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if (!session.DebugPngWritten)
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{
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session.DebugPngWritten = true;
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try
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{
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ms.Position = 0;
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var dbg = Path.Combine(Path.GetTempPath(), $"ytLive-web-{sourceId}.png");
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File.WriteAllBytes(dbg, ms.ToArray());
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AppLog.Write($"WebView2Manager: debug capture dump -> {dbg}");
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}
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catch (Exception dex) { AppLog.Write($"WebView2Manager: debug dump failed: {dex.Message}"); }
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}
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ms.Position = 0;
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var bitmap = new BitmapImage();
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bitmap.BeginInit();
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bitmap.StreamSource = ms;
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bitmap.CacheOption = BitmapCacheOption.OnLoad;
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bitmap.EndInit();
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bitmap.Freeze();
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var formatted = new FormatConvertedBitmap(bitmap,
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PixelFormats.Bgra32, null, 0);
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var pixW = formatted.PixelWidth;
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var pixH = formatted.PixelHeight;
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if (pixW < 1 || pixH < 1) return;
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var need = pixW * pixH * 4;
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var pixels = session.CanvasScratch is { } scratch && scratch.Length >= need
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? scratch
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: (session.CanvasScratch = new byte[need]);
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formatted.CopyPixels(pixels, pixW * 4, 0);
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var stride = pixW * 4;
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var (cropX, cropY, cropW, cropH) = FindContentBounds(pixels, pixW, pixH, stride);
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if (session.Epoch == 0)
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{
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AppLog.Write(
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$"WebView2Manager: first capture for '{sourceId}' {pixW}x{pixH} " +
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$"{AlphaStats(pixels, pixW, pixH, stride)} " +
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$"contentBounds=({cropX},{cropY},{cropW},{cropH})");
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}
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if (session.WidgetDumpRemaining > 0)
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{
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var dumpNo = 5 - session.WidgetDumpRemaining + 1;
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session.WidgetDumpRemaining--;
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try
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{
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var dbg = Path.Combine(Path.GetTempPath(), $"ytLive-web-{sourceId}-w{dumpNo}.png");
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File.WriteAllBytes(dbg, ms.ToArray());
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AppLog.Write(
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$"WebView2Manager: widget capture [{dumpNo}/5] for '{sourceId}' {pixW}x{pixH} " +
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$"{AlphaStats(pixels, pixW, pixH, stride)} " +
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$"contentBounds=({cropX},{cropY},{cropW},{cropH}) -> {dbg}");
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}
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catch (Exception dex)
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{
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AppLog.Write($"WebView2Manager: widget dump failed: {dex.Message}");
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}
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}
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var outPixels = session.RentOutBuffer(cropW * cropH * 4);
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if (cropW == pixW && cropH == pixH && cropX == 0 && cropY == 0)
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Buffer.BlockCopy(pixels, 0, outPixels, 0, outPixels.Length);
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else
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for (var r = 0; r < cropH; r++)
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Buffer.BlockCopy(pixels, (cropY + r) * stride + cropX * 4, outPixels, r * cropW * 4, cropW * 4);
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if (session.PreviewBitmap == null
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|| session.PreviewBitmap.PixelWidth != cropW || session.PreviewBitmap.PixelHeight != cropH)
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session.PreviewBitmap = new WriteableBitmap(cropW, cropH, 96, 96, PixelFormats.Bgra32, null);
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session.PreviewBitmap.WritePixels(new Int32Rect(0, 0, cropW, cropH), outPixels, cropW * 4, 0);
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session.LatestFrame = new VideoFrame(pixW, pixH, pixels)
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{
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Epoch = ++session.Epoch,
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CropBounds = (cropX, cropY, cropW, cropH),
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};
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// The preview bitmap is now MUTABLE and reused (CameraManager precedent):
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// WPF re-renders it after WritePixels; handlers must not Freeze it.
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var preview = session.PreviewBitmap;
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_ = _dispatcher.BeginInvoke(() =>
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{
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PreviewBitmapChanged?.Invoke(sourceId, preview);
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});
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// Capture-cost telemetry for the first ~30 captures of a session: PNG encode
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// (CapturePreviewAsync) + decode cost decide whether ~30Hz recording cadence
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// is affordable or must drop to ~20Hz. The FramePump drops frames (never
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// time-lapses) if the UI thread's GC churn starves it, so startup.log shows
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// the real budget before anything is tuned further.
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if (session.TelemetryCaptureCount < 30)
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{
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session.TelemetryCaptureCount++;
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AppLog.Write(
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$"WebView2Manager: capture #{session.TelemetryCaptureCount} for '{sourceId}' " +
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$"{pixW}x{pixH} took {sw.ElapsedMilliseconds}ms");
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}
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}
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catch (ObjectDisposedException) { }
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catch (InvalidOperationException) { }
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catch (Exception ex)
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{
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AppLog.Write($"WebView2Manager: capture failed for '{sourceId}': {ex.Message}");
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}
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}
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private void RemoveSession(string sourceId)
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{
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if (!_sessions.TryGetValue(sourceId, out var session)) return;
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session.Disposed = true;
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session.Scheduler.Stop();
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_hostPanel.Children.Remove(session.Control);
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try { session.Control.Dispose(); } catch { }
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_sessions.Remove(sourceId);
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}
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public void Dispose()
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{
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foreach (var id in _sessions.Keys.ToList())
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RemoveSession(id);
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}
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}
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