Web source: geometry-agnostic viewport==box model — viewport locked to element box, Stretch=Fill, no dead space

Services/WebView2Manager.cs

@@ -15,20 +15,6 @@ namespace ytLive.Services;
 
 public sealed class WebView2Manager : IDisposable
 {
-    // Eliminates the wrapper padding/whitespace between the box and the page:
-    // clears UA margins/paddings, forces html/body to fill the viewport and
-    // anchors content at (0,0) so the rendered frame matches the widget's size.
-    private const string CssResetInjection =
-        "(function(){" +
-        "var s=document.createElement('style');" +
-        "s.textContent='html,body{margin:0!important;padding:0!important;" +
-        "width:100%!important;height:100%!important;overflow:hidden!important;" +
-        "background:transparent!important}';" +
-        "(document.head||document.documentElement).appendChild(s);" +
-        "if(document.documentElement)document.documentElement.style.background='transparent';" +
-        "if(document.body)document.body.style.background='transparent';" +
-        "})();";
-
     private readonly Panel _hostPanel;
     private readonly Dispatcher _dispatcher;
     private readonly Dictionary<string, WebSourceSession> _sessions = new();
@@ -54,13 +40,14 @@ public sealed class WebView2Manager : IDisposable
     {
         if (_sessions.ContainsKey(source.Id)) return;
 
-        // OBS pattern: the browser viewport is the canvas size (1920×1080),
-        // never the element box. The page renders full at its designed size;
-        // the preview scales the captured frame independently (Stretch=Uniform).
+        // Geometry-agnostic OBS model: the browser viewport IS the element box.
+        // The page renders at exactly Source.Width × Source.Height, so the
+        // captured frame and the selection rect are always the same rectangle —
+        // no fixed render size, no aspect assumptions, no dead space or padding.
         var webView = new WebView2
         {
-            Width = 1920,
-            Height = 1080,
+            Width = Math.Max(1, source.Width),
+            Height = Math.Max(1, source.Height),
             DefaultBackgroundColor = System.Drawing.Color.Transparent,
             Visibility = System.Windows.Visibility.Visible,
         };
@@ -82,6 +69,22 @@ public sealed class WebView2Manager : IDisposable
 
         _sessions[source.Id] = session;
 
+        // Interop sync: keep the viewport locked to the element box so the
+        // selection rect always bounds the actual rendered content.
+        source.PropertyChanged += (_, e) =>
+        {
+            if (e.PropertyName is not (nameof(Source.Width) or nameof(Source.Height))) return;
+            if (session.Disposed) return;
+            if (Math.Abs(session.Control.Width - source.Width) > 0.5 ||
+                Math.Abs(session.Control.Height - source.Height) > 0.5)
+            {
+                session.Control.Width = Math.Max(1, source.Width);
+                session.Control.Height = Math.Max(1, source.Height);
+                if (session.Initialized)
+                    _ = CaptureFrame(source.Id);
+            }
+        };
+
         timer.Tick += (_, _) =>
         {
             if (!session.Disposed && session.Initialized)
@@ -122,11 +125,18 @@ public sealed class WebView2Manager : IDisposable
 
             var cws = session.Control.CoreWebView2!;
 
-            await cws.AddScriptToExecuteOnDocumentCreatedAsync(CssResetInjection);
+            cws.NavigationStarting += (_, _) =>
+            {
+                _ = cws.ExecuteScriptAsync(
+                    "document.documentElement.style.background='transparent';" +
+                    "document.body.style.background='transparent';");
+            };
 
             cws.NavigationCompleted += (_, _) =>
             {
-                _ = cws.ExecuteScriptAsync(CssResetInjection);
+                _ = cws.ExecuteScriptAsync(
+                    "document.documentElement.style.background='transparent';" +
+                    "document.body.style.background='transparent';");
                 _ = CaptureFrame(source.Id);
             };