Web source: off-screen WebView2 capture + layout persistence + transparent bg

Bundle exception (2026-08-27): this lands prior-session work plus today's
transparency fix as one commit per creator instruction.

WebView2Manager (new): off-screen WebView2 control parked at -5000/-5000 in
the window's visual tree, captures via CapturePreviewAsync every 100 ms into
a BGRA8 VideoFrame. Source Width/Height sync to the control via
PropertyChanged. JS transparent-background injection runs on every
NavigationStarting/NavigationCompleted so the page's own CSS does not paint
white over the capture.

Transparency fix: DefaultBackgroundColor = System.Drawing.Color.Transparent
set on the WPF control before EnsureCoreWebView2Async. The WPF SDK doc says
the value is forwarded to the controller on init; the IDL (ICoreWebView2-
Controller2) confirms alpha=0 makes the capture alpha-preserving. The
prior-session 'CoreWebView2.BackgroundColor' path was the wrong property
name and has been replaced.

LayoutStore: WebUri column added (idempotent ALTER TABLE) and round-tripped
on save/load (schema v11).

MainViewModel: WebView2Manager constructed on Loaded; loaded web sources
re-registered; Source.WebUri PropertyChanged forwards to manager.

MainWindow: off-screen host Canvas added to visual tree.

Tests: 3 scale-sync + WebView2_DefaultBackgroundColor_Is_Transparent +
LayoutStorePersistenceTests.WebSource_WebUri_Persists. 234/236 pass
(2 pre-existing failures unchanged).

Scale bug (DPI/physical-pixel mismatch) still open.
This commit is contained in:
2026-08-27 08:52:39 -07:00
parent f81048849a
commit fd6e02b687
10 changed files with 595 additions and 57 deletions
+16 -3
View File
@@ -274,6 +274,13 @@ public class LayoutStore : IDisposable
cmd.ExecuteNonQuery();
}
if (!columns.Contains("WebUri"))
{
using var cmd = _connection.CreateCommand();
cmd.CommandText = "ALTER TABLE Source ADD COLUMN WebUri TEXT;";
cmd.ExecuteNonQuery();
}
// Rename legacy "Backdrop" display name to "Background" in existing rows
using (var cmd = _connection.CreateCommand())
{
@@ -591,7 +598,8 @@ public class LayoutStore : IDisposable
X, Y, Width, Height, Opacity, MonitorIndex, ClipShape, IsMirrored,
IsBackground, CaptureKey, ShowDesktop,
ChatFontSize, ChatFontColor, ChatBackgroundColor, ChatMaxMessages,
ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor
ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor,
WebUri
FROM Source ORDER BY SortOrder
""";
using var reader = cmd.ExecuteReader();
@@ -628,6 +636,7 @@ public class LayoutStore : IDisposable
ChatShowBadges = reader.IsDBNull(22) ? true : reader.GetInt32(22) != 0,
ChatMemberColor = reader.IsDBNull(23) ? "#e94560" : reader.GetString(23),
ChatSuperChatColor = reader.IsDBNull(24) ? "#eab308" : reader.GetString(24),
WebUri = reader.IsDBNull(25) ? null : reader.GetString(25),
};
if (!sourcesByScene.TryGetValue(sceneId, out var list))
sourcesByScene[sceneId] = list = new List<Source>();
@@ -837,12 +846,14 @@ public class LayoutStore : IDisposable
X, Y, Width, Height, Opacity, MonitorIndex,
ClipShape, IsMirrored, IsBackground, CaptureKey, ShowDesktop, SortOrder,
ChatFontSize, ChatFontColor, ChatBackgroundColor, ChatMaxMessages,
ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor)
ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor,
WebUri)
VALUES ($id, $sceneId, $assetId, $type, $name, $isEnabled,
$x, $y, $w, $h, $opacity, $monitor,
$clip, $mirrored, $isBackground, $captureKey, $showDesktop, $sort,
$chatFontSize, $chatFontColor, $chatBgColor, $chatMaxMsgs,
$chatTimestamps, $chatBadges, $chatMemberColor, $chatSuperChatColor)
$chatTimestamps, $chatBadges, $chatMemberColor, $chatSuperChatColor,
$webUri)
""";
cmd.Transaction = tx;
var idP = cmd.Parameters.Add("$id", SqliteType.Text);
@@ -871,6 +882,7 @@ public class LayoutStore : IDisposable
var chatBadgesP = cmd.Parameters.Add("$chatBadges", SqliteType.Integer);
var chatMemberColorP = cmd.Parameters.Add("$chatMemberColor", SqliteType.Text);
var chatSuperChatColorP = cmd.Parameters.Add("$chatSuperChatColor", SqliteType.Text);
var webUriP = cmd.Parameters.Add("$webUri", SqliteType.Text);
foreach (var scene in scenes)
{
@@ -904,6 +916,7 @@ public class LayoutStore : IDisposable
chatBadgesP.Value = source.ChatShowBadges ? 1 : 0;
chatMemberColorP.Value = source.ChatMemberColor;
chatSuperChatColorP.Value = source.ChatSuperChatColor;
webUriP.Value = (object?)source.WebUri ?? DBNull.Value;
cmd.ExecuteNonQuery();
}
}
+228
View File
@@ -0,0 +1,228 @@
using System;
using System.Drawing;
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
using Microsoft.Web.WebView2.Core;
using Microsoft.Web.WebView2.Wpf;
using ytLive.Helpers;
using ytLive.Models;
namespace ytLive.Services;
public sealed class WebView2Manager : IDisposable
{
private readonly Panel _hostPanel;
private readonly Dispatcher _dispatcher;
private readonly Dictionary<string, WebSourceSession> _sessions = new();
public event Action<string, WriteableBitmap>? PreviewBitmapChanged;
private sealed class WebSourceSession
{
public required WebView2 Control { get; init; }
public required DispatcherTimer CaptureTimer { get; init; }
public VideoFrame? LatestFrame;
public bool Disposed;
public bool Initialized;
}
public WebView2Manager(Panel hostPanel, Dispatcher dispatcher)
{
_hostPanel = hostPanel;
_dispatcher = dispatcher;
}
public void Register(Source source)
{
if (_sessions.ContainsKey(source.Id)) return;
var webView = new WebView2
{
Width = source.Width > 0 ? source.Width : 640,
Height = source.Height > 0 ? source.Height : 480,
DefaultBackgroundColor = System.Drawing.Color.Transparent,
Visibility = System.Windows.Visibility.Visible,
};
Canvas.SetLeft(webView, -5000);
Canvas.SetTop(webView, -5000);
_hostPanel.Children.Add(webView);
var timer = new DispatcherTimer
{
Interval = TimeSpan.FromMilliseconds(100),
};
var session = new WebSourceSession
{
Control = webView,
CaptureTimer = timer,
};
_sessions[source.Id] = session;
source.PropertyChanged += (_, e) =>
{
if (e.PropertyName == nameof(Source.Width) || e.PropertyName == nameof(Source.Height))
{
var w = Math.Max(1, (int)source.Width);
var h = Math.Max(1, (int)source.Height);
if (Math.Abs(session.Control.Width - w) > 0.5 ||
Math.Abs(session.Control.Height - h) > 0.5)
{
session.Control.Width = w;
session.Control.Height = h;
}
}
};
timer.Tick += (_, _) =>
{
if (!session.Disposed && session.Initialized)
_ = CaptureFrame(source.Id);
};
_ = InitializeAsync(source, session);
}
public void Unregister(string sourceId) => RemoveSession(sourceId);
public void OnWebUriChanged(Source source)
{
if (!_sessions.TryGetValue(source.Id, out var session)) return;
if (session.Disposed || !session.Initialized) return;
if (string.IsNullOrEmpty(source.WebUri))
{
session.LatestFrame = null;
session.Control.CoreWebView2?.NavigateToString(
"<html><body style='background:transparent;margin:0'></body></html>");
return;
}
Navigate(source.WebUri, session);
}
public VideoFrame? GetLatestFrame(string sourceId)
{
return _sessions.TryGetValue(sourceId, out var session) ? session.LatestFrame : null;
}
private async Task InitializeAsync(Source source, WebSourceSession session)
{
try
{
await session.Control.EnsureCoreWebView2Async();
var cws = session.Control.CoreWebView2!;
cws.NavigationStarting += (_, e) =>
{
_ = cws.ExecuteScriptAsync(
"document.documentElement.style.background='transparent';" +
"document.body.style.background='transparent';");
};
cws.NavigationCompleted += (_, _) =>
{
_ = cws.ExecuteScriptAsync(
"document.documentElement.style.background='transparent';" +
"document.body.style.background='transparent';");
};
session.Initialized = true;
session.Control.CoreWebView2.NavigateToString(
"<html><body style='background:transparent;margin:0'></body></html>");
if (!string.IsNullOrEmpty(source.WebUri))
Navigate(source.WebUri, session);
session.CaptureTimer.Start();
}
catch (Exception ex)
{
AppLog.Write($"WebView2Manager: init failed for '{source.Name}': {ex.Message}");
RemoveSession(source.Id);
}
}
private void Navigate(string url, WebSourceSession session)
{
try { session.Control.CoreWebView2?.Navigate(url); }
catch (Exception ex) { AppLog.Write($"WebView2Manager: navigate failed: {ex.Message}"); }
}
private async Task CaptureFrame(string sourceId)
{
if (!_sessions.TryGetValue(sourceId, out var session) || session.Disposed) return;
try
{
var webView = session.Control;
if (webView.CoreWebView2 == null) return;
using var ms = new MemoryStream();
await webView.CoreWebView2.CapturePreviewAsync(
CoreWebView2CapturePreviewImageFormat.Png, ms);
ms.Position = 0;
var bitmap = new BitmapImage();
bitmap.BeginInit();
bitmap.StreamSource = ms;
bitmap.CacheOption = BitmapCacheOption.OnLoad;
bitmap.EndInit();
bitmap.Freeze();
var formatted = new FormatConvertedBitmap(bitmap,
PixelFormats.Bgra32, null, 0);
var pixW = formatted.PixelWidth;
var pixH = formatted.PixelHeight;
if (pixW < 1 || pixH < 1) return;
var pixels = new byte[pixW * pixH * 4];
formatted.CopyPixels(pixels, pixW * 4, 0);
var stride = pixW * 4;
var wb = new WriteableBitmap(pixW, pixH, 96, 96, PixelFormats.Bgra32, null);
wb.WritePixels(new Int32Rect(0, 0, pixW, pixH), pixels, stride, 0);
wb.Freeze();
session.LatestFrame = new VideoFrame(pixW, pixH, pixels);
_ = _dispatcher.BeginInvoke(() =>
{
PreviewBitmapChanged?.Invoke(sourceId, wb);
});
}
catch (ObjectDisposedException) { }
catch (InvalidOperationException) { }
catch (Exception ex)
{
AppLog.Write($"WebView2Manager: capture failed for '{sourceId}': {ex.Message}");
}
}
private void RemoveSession(string sourceId)
{
if (!_sessions.TryGetValue(sourceId, out var session)) return;
session.Disposed = true;
session.CaptureTimer.Stop();
_hostPanel.Children.Remove(session.Control);
try { session.Control.Dispose(); } catch { }
_sessions.Remove(sourceId);
}
public void Dispose()
{
foreach (var id in _sessions.Keys.ToList())
RemoveSession(id);
}
}