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encode_png: RGB565 framebuffer to PNG - #36
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Adds encode_png() for encoding RGB565 framebuffers to PNG byte strings, used by roku_companion's frame server to stream display output to Roku TVs. C implementation (src/gfx_png.c): - Minimal PNG encoder: IHDR, IDAT (deflate via uzlib), IEND - RGB565 to RGB888 conversion during encoding - Exposed as pygraphics.encode_png() via MicroPython bindings Pure-Python fallback (lib/pygraphics/_png.py): - zlib-based PNG encoder for CPython and environments without the C module - Same API: encode_png(buffer, width, height, format) Build system: - micropython.mk, micropython.cmake, circuitpython.mk updated - qstr definitions for encode_png added Tests: - test_files.py updated with encode_png coverage
…e parity tool's staged files; import order
bdbarnett
marked this pull request as ready for review
October 6, 2026 07:07
…_png and FrameBuffer.to_png, MicroPython gets FrameBuffer.to_png, and every saver writes PNG for a .png name or RGB888 through one shared rule (gfx_png_wanted)
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A PNG encoder for RGB565 framebuffers (also RGB888 and GS8),
pygraphics.encode_png(fb, width=None, height=None, format=None): C insrc/gfx_png.c(deflate via uzlib) with a pure-Python fallback inlib/pygraphics/_png.py. It's half of the Roku companion feature written on 2026-09-30, and Brad wants it for the casting work (2026-10-06). The examples half is PyDevices/pydevices-examples#158.CI fixes (2026-10-06):
_png.pyis now inpygraphics.toml, regenerated with the publisher's generator; its--checkpasses._png.pyis now intools/compare_graphics.py's staged files. Without it the MicroPython job failed:no module named 'pygraphics_py._png'.Tested locally, 2026-10-06:
ruff check lib testspasses, and CPythonunittestis OK.implementation() == native_cmod):test_area,test_subclass,test_parity(45 public names),compare_graphics_run(385 checks) andcompare_framebuf_mpall pass.Known limit: MicroPython's built-in
framebuf.FrameBufferisn't recognised as a framebuffer, onlypygraphics.FrameBufferis, so passwidthandheightwith it (that works, and is tested above).