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rustdesk/libs
rustdeskandClaude Opus 5.5 d64ff4961b cursor: name a shape by what it looks like, not by its handle
A cursor id was the platform's handle for the shape: HCURSOR on
Windows, the XFixes serial on X11. Apps mint a new handle for a shape
they have shown before (Chrome, Electron, Qt custom cursors), and an
X11 animated cursor gets one per frame, so one arrow arrived under
thousands of ids over a session. The controlled side cached and sent
it again under each, and the controller decoded, rendered and kept it
again under each, and grew by gigabytes over weeks of connection.

The controlled side now names a shape by an xxh3 hash of its size,
hotspot and pixels, taken once when a handle is first seen, before
the pixels are compressed. The per-connection send already sends a
shape once and afterwards only its id, so a shape now crosses once
however many handles it has. The id is opaque in the protocol, so
controllers of any version accept it. The DRM backend already named
shapes by content with FNV-1a; it uses the same hash now.

A peer before 1.5.0 still names shapes by handle, and the fix has to
work against every deployed peer. For those peers the controller
hashes each CursorData's compressed colors with its geometry: one
peer compresses the same pixels to the same bytes, so a shape seen
before is recognised without being decompressed. The UI gets that
shape once, under one id, and every later handle for it is passed on
as a cursor_id of that id. The map from the peer's ids is kept for the
connection, unbounded, since the peer sends a shape once and may
select any id it named again; an entry is two integers. From 1.5.0
the controller passes the peer's ids through unchanged, on the old
path.

The web core in flutter/web does the same in its own tree.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab
2026-09-23 19:52:42 +08:00
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2026-09-23 17:30:22 +08:00
2026-09-23 17:30:22 +08:00