perf: defer full-frame compression when a partial upload may succeed#95
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upload_image always encoded and zlib-compressed the whole frame before attempting the partial (0x76) path. When the partial upload succeeds, that compression (2.7ms @800x480, 15.7ms @1600x1200) is pure waste. Skip it when state is not None by preparing with compress=False, and compress lazily in _dispatch_upload on the full-upload fallback. The zipxl path already recompressed on window mismatch; extend the same lazy behavior to the non-zipxl branch so the fallback produces byte-identical output to before. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01JRrm95f1qNZzDM9r2SB6KW
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Semantic conflict between OpenDisplay#95 and OpenDisplay#96: the lazy compression branch for non-ZIPXL devices referenced DEFAULT_ZLIB_WINDOW_BITS, which device.py never imported (NameError at runtime), and even spelled correctly a 15-bit window is rejected by current firmware — prepare_image has compressed everything at 9 bits since OpenDisplay#96. The deferred path now uses the same 9-bit window. ZIPXL window repair and the non-ZIPXL 50KB size gate keep their existing behavior.
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Summary
upload_imagealways encoded and zlib-compressed the entire frame before attempting the partial (0x76) path. When the partial upload succeeds (the common case for small changes), that full-frame compression is pure waste — 2.7 ms @800×480, 15.7 ms @1600×1200.This PR defers full-frame compression when
state is not None:upload_imageprepares withcompress=Falsewhen a partial upload may be attempted._dispatch_uploadcompresses lazily on the full-upload fallback. The ZIPXL path already recompressed on window mismatch; this extends the same lazy behavior to the non-ZIPXL branch.Correctness
state is None(plain full upload): unchanged —prepare_imagestill compresses eagerly, and_dispatch_upload's newelif compressed_data is Nonebranch is never taken.state is not None, partial succeeds: full-frame compression skipped entirely (the win).state is not None, fallback to full:_dispatch_uploadcompresses with the same window bitsprepare_imagewould have used (ZIPXL=9 / DEFAULT=15), so the bytes on the wire are identical to before — just computed later.Test plan
uv run pytest -q→ 439 passedruff check,ruff format,mypyclean🤖 Generated with Claude Code