Serve only the desktop's primary screen over VNC

krdp streams every screen, so the VNC screen is now the primary's size and the
FreeRDP window is shifted so the primary fills it (ft-layout remote-view gives
the offset). It resizes and reconnects when the layout changes. With remote
access on, KWin's D-Bus screenshot interface is open too, for scripts that look
at the screens without the headset.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
(cherry picked from commit 6f5a23c80f2ecd26e6a96c86b102be36d518ee25)

layout/ft_layout.py

@@ -50,6 +50,7 @@ Usage (on the Frame host; Frametop Display Settings calls it too):
   ft-layout scale                    per-screen scale, positions (as the screens are around
                                      you), and primary to KWin
   ft-layout screen-args              ft-screens' --screen arguments for the session script
+  ft-layout remote-view              the primary screen's place in the workspace, for the VNC bridge
   ft-layout toggle                   hide or show all screens (ft-screens)
   ft-layout pin all|N left|right|head  pin screens to a wrist or your head as they are;
                                      unpin all|N
@@ -754,6 +755,13 @@ def send_scales(outs):
         log(f"scale: {e}")
 
 
+def logical_size(o):
+    """An output's size in logical units. kscreen's "size" is in pixels (already turned for a
+    rotation); positions are logical, the pixels divided by the scale (KWin rounds up)."""
+    s = float(o.get("scale", 1))
+    return (math.ceil(o["size"]["width"] / s - 1e-6), math.ceil(o["size"]["height"] / s - 1e-6))
+
+
 def apply_scales():
     """Per-screen scale and rotation, positions side by side, and the primary screen (the
     taskbar goes there) to KWin, which keeps them in the session's config."""
@@ -780,11 +788,7 @@ def apply_scales():
     # the pointer and dragged windows cross to the screen you see next to this one.
     outs = outputs(env)
     send_scales(outs)
-    # kscreen's "size" is in pixels (already turned for a rotation); positions are in
-    # logical units, the pixels divided by the scale (KWin rounds up).
-    sizes = [(math.ceil(o["size"]["width"] / float(o.get("scale", 1)) - 1e-6),
-              math.ceil(o["size"]["height"] / float(o.get("scale", 1)) - 1e-6))
-             for o in outs if o.get("size")]
+    sizes = [logical_size(o) for o in outs if o.get("size")]
     if len(sizes) == len(outs) and outs:
         columns = arrangement(len(outs))
         if not columns or sorted(i for c in columns for i in c) != list(range(len(outs))):
@@ -818,6 +822,24 @@ def kwin_follow():
         log(f"kwin: {e}")
 
 
+def remote_view():
+    """Where the primary screen sits in the workspace (all screens' bounding box), in
+    logical units: "x y width height workspace_width workspace_height". The VNC bridge
+    (session/vnc-bridge.sh) shows that part of krdp's workspace stream."""
+    env = nested_env()
+    if not env:
+        raise RuntimeError("the Frametop desktop isn't running")
+    outs = [o for o in outputs(env) if o.get("enabled", True) and o.get("size") and o.get("pos")]
+    if not outs:
+        raise RuntimeError("the Frametop desktop has no screens yet")
+    rects = [(o["pos"]["x"], o["pos"]["y"], *logical_size(o)) for o in outs]
+    left, top = min(r[0] for r in rects), min(r[1] for r in rects)
+    right, bottom = max(r[0] + r[2] for r in rects), max(r[1] + r[3] for r in rects)
+    p = next((i for i, o in enumerate(outs) if o.get("priority") == 1), 0)
+    x, y, w, h = rects[p]
+    return f"{x - left} {y - top} {w} {h} {right - left} {bottom - top}"
+
+
 def main(argv):
     if len(argv) < 2 or argv[1] in ("-h", "--help"):
         print(__doc__.split("Usage")[1].split("\n", 1)[1])
@@ -829,6 +851,8 @@ def main(argv):
             print(json.dumps(plan(layout, screen_count(layout))))
         elif cmd == "screen-args":
             print(screen_args())
+        elif cmd == "remote-view":
+            print(remote_view())
         elif cmd == "toggle":
             log(screens_socket().ask("toggle"))
         elif cmd == "layouts":