gifgen — render lvgl_clock styles to GIFs

Generates animated GIFs of the clock by running the real lvgl_clock rendering code against desktop LVGL — no ESPHome, no device, no SDL. The component’s lvgl_clock.cpp is compiled unchanged, so frames are pixel-identical to the hardware (same LVGL rasterizer, caps, anti-aliasing).

How it works

main.cpp is a tiny headless harness: it lv_init()s, creates a canvas exactly like the ESPHome codegen does, drives the clock frame-by-frame off a virtual clock (deterministic, so animations loop cleanly), and dumps one PPM per frame — reading straight from the canvas buffer (the display is never flushed, so no SDL/window is needed).
The shim/ tree provides the ~6 ESPHome symbols the component references (Color, Component, millis(), no-op logging, RealTimeClock/ESPTime, LvCompound) so it links without pulling in ESPHome.
make_gif.py runs the binary and stitches the frames into a looping GIF with Pillow.

LVGL itself is compiled from the source in the examples’ .esphome build tree, using a host lv_conf.h (a copy of the ESPHome one with the custom allocator swapped for the C library).

Requirements

clang++ (already on macOS). No cmake, sdl2, or ffmpeg.
Python Pillow (pip install pillow).
The component built at least once so LVGL source exists: esphome config examples/example_analog.yaml.

Usage

cd tools/gifgen
./build.sh                     # one-time ~5s (LVGL lib is cached afterwards)
python3 make_gif.py --style clockclock24 --width 480 --height 320 \
    --frames 150 --dt 33 --out out/clockclock24.gif

Options: --style (clockclock24 | analog | digital), --width/--height, --frames, --dt (ms/frame = virtual clock step), --fps (playback, default 1000/dt), --scale (downscale the GIF), --colors (palette size), --out.

Build artifacts (the LVGL lib, objects, binary) go to build/ by default, or $BUILD_DIR if set. ./build.sh caches liblvgl_host.a — delete it to force a full LVGL rebuild.

Per-style look

The harness sets sensible demo parameters per style in main.cpp (e.g. clockclock24 runs in demo mode with the long sweep). Tweak that if (style == ...) block to change colours, movement, ticks, etc. Only clockclock24/analog/digital are wired so far; add a branch for others.