headpat-gif

Turn any image into a "pet-pet" GIF: a hand pats the subject on the head while the subject squashes flat and springs back, exactly like clicking a pet in the reference demo.

from headpat_gif import petpet

gif = petpet("pet.png", duration=2.0)
gif.save("pet.gif")

Everything is swappable: bring your own animated overlay (the thing that appears on the head) and your own subject. The result is an io.BytesIO subclass, so it goes straight into discord.File with no temporary file:

import discord
from headpat_gif import petpet

@bot.command()
async def pet(ctx, url: str):
    await ctx.send(file=discord.File(petpet(url, duration=2.0)))

Install

uv add headpat-gif          # or: pip install headpat-gif
uv add "headpat-gif[discord]"   # optional: pulls discord.py for the test suite

Requires Python 3.10+ and Pillow 10+. ASCII-art style GIFs are left to you; the only runtime dependency is Pillow.

Usage

from headpat_gif import petpet, save

# One pat, as long as the overlay takes to play.
gif = petpet("pet.png")

# Two seconds of continuous patting (loop is on by default).
gif = petpet("pet.png", duration=2.0)

# Two seconds of GIF, patting at double rate.
gif = petpet("pet.png", duration=2.0, speed=2.0)

# Pat once and then rest for the remainder of the two seconds.
gif = petpet("pet.png", duration=2.0, loop=False)

# A small hand resting on the head instead of filling the picture.
gif = petpet("pet.png", overlay_scale=0.4, overlay_position=(0.35, 0.2))

# Where the overlay hangs from: the fraction of the GIF its visible top-left
# corner is pinned to. (0, 0) - the default - is the GIF's own corner, so the
# hand touches the left and top edges.
gif = petpet("pet.png", overlay_position=(0.0, 0.0))    # flush with the corner
gif = petpet("pet.png", overlay_position=(0.5, 0.0))    # top edge, centred
gif = petpet("pet.png", overlay_position=(0.0, 0.5))    # half way down the left side

# Nudge the hand. Fractions of the canvas; negative y is up. The canvas grows
# by whatever the nudge displaces, so the hand is never sliced off.
gif = petpet("pet.png", overlay_offset=(0.0, -0.3))   # 30% taller, hand complete
gif = petpet("pet.png", overlay_offset=(0.1, 0.15))   # down and to the right

# Your own overlay: a path, bytes, an open file or a PIL image - GIF or still.
gif = petpet("pet.png", "heart.gif")
gif = petpet("pet.png", requests.get(url, timeout=10).content)

# Tune the look.
gif = petpet(
    "pet.png",
    "heart.gif",
    duration=1.5,
    squash=1.4,                 # harder squash
    overlay_scale=0.6,          # shrink the overlay to a hop-on-the-head size
    overlay_position=(0.3, 0.1),  # ...and hang it over the head
)

save(gif, "out/pet.gif")   # or: gif.save("out/pet.gif")

Images from anywhere

image and overlay accept all of these:

Animated overlays (GIF, animated WebP, APNG) keep their own frame timing; the squash is synchronised to that timeline. A still overlay is shown for static_overlay_ms (500ms by default) per cycle.

API

petpet(image, overlay=None, *, ...) -> PetPetGif

duration and speed are independent knobs. duration is the total runtime of the file; speed scales how long the pat itself takes inside it. So duration=2.0, speed=2.0 means "two seconds of GIF, patting at double rate".

With loop=True (the default) the total is divided into a whole number of pats, so an infinitely looping GIF never jumps mid-pat; the cycle length is nudged by less than one frame to make that fit. Pass loop=False for the one-pat-then-rest look.

PetPetGif

An io.BytesIO subclass holding the encoded GIF.

gif.save("out.gif")     # -> pathlib.Path
gif.to_bytes()          # -> bytes, without moving the read position
gif.name                # -> "petpet.gif", the name discord.py picks up
gif.size                # -> (width, height)
gif.n_frames            # -> frame count
gif.duration_ms         # -> total runtime in milliseconds
gif.cycle_ms            # -> length of one pat cycle in milliseconds

discord.File(gif) validates seekable()/readable() and takes the attachment name from .name, so the object is accepted as-is.

Careful: a discord.File is single-use. Build a fresh PetPetGif for every send, or reuse the bytes with io.BytesIO(gif.to_bytes()).

save(gif, path) -> pathlib.Path

Module level convenience wrapper around PetPetGif.save.

How it works

1. The subject is scaled to fit a square of max_size, then drawn at image_scale of the canvas, anchored 92% down so its feet stay put.
2. A triangular envelope drives the squash: untouched at the start of a cycle, widest and shortest in the middle, untouched again at the end. The amplitude matches pet-pet-gif (0.8 → 0.9 wide, 0.8 → 0.55 tall), so the motion feels like the GIFs people already know.
3. The overlay is pasted on top, sampled against its own frame durations, and plays exactly once per pat. It is scaled uniformly: one factor, from whichever canvas axis asks for the bigger one, then multiplied by overlay_scale (0.8 by default). Its visible top-left corner - measured from the alpha channel, so a padded GIF does not leave a gap - is pinned to overlay_position of the canvas, (0.0, 0.0) being the corner of the finished GIF. Anything the overlay puts past the canvas edge is cropped.
4. Every frame is converted to palette mode with a dedicated transparent index and saved with disposal=3 ("restore to previous"). Without the palette step Pillow writes black boxes around transparent areas; with disposal 2 instead of 3, decoders restore the background colour and the result is either an opaque black box (FFmpeg) or a stale copy of the previous frame (Pillow) - the classic transparent GIF bug, and very visible the moment an overlay moves or leaves. Both halves are covered by tests.

Housekeeping notes

• GIF frame delays below 20ms are silently clamped to 100ms by browsers and Discord, so fps tops out at 50 and every delay is at least 20ms.
• Output is byte-for-byte deterministic: no randomness is involved, which keeps caching and snapshot tests sane.
• Want a smaller file? Lower max_size, lower duration, or pass duration=None and speed to shorten the tail.
• duration shorter than one cycle truncates the pat mid-way; use speed when the goal is a faster pat rather than a shorter one.

Development

uv sync                                        # environment
uvx ruff check --fix .                         # style
uvx ty check                                   # types
uv run pytest                                  # tests

scripts/check.ps1 (PowerShell) and scripts/check.sh (bash) run all four in order. They also redirect UV_CACHE_DIR / UV_TOOL_DIR into .uv/, which is needed when working inside a sandbox that cannot write to %APPDATA%\uv.

If Windows refuses to run the script with "running scripts is disabled on this system", either run it as powershell -ExecutionPolicy Bypass -File scripts/check.ps1, or just run the three commands above directly.

License

MIT - see LICENSE. Bundled artwork and ported code are credited in NOTICE.