Slack Gif Creator
Agent skill walkthrough for generating themed Slack GIF packs, managing prompts, frame pipelines, and review checklists.
Source: Content adapted from anthropics/skills (MIT).
A toolkit providing utilities and knowledge for creating animated GIFs optimized for Slack.
Slack Requirements
Dimensions:
- Emoji GIFs: 128x128 (recommended)
- Message GIFs: 480x480
Parameters:
- FPS: 10-30 (lower is smaller file size)
- Colors: 48-128 (fewer = smaller file size)
- Duration: Keep under 3 seconds for emoji GIFs
Core Workflow
from core.gif_builder import GIFBuilder
from PIL import Image, ImageDraw
# 1. Create builder
builder = GIFBuilder(width=128, height=128, fps=10)
# 2. Generate frames
for i in range(12):
frame = Image.new('RGB', (128, 128), (240, 248, 255))
draw = ImageDraw.Draw(frame)
# Draw your animation using PIL primitives
# (circles, polygons, lines, etc.)
builder.add_frame(frame)
# 3. Save with optimization
builder.save('output.gif', num_colors=48, optimize_for_emoji=True)Drawing Graphics
Working with User-Uploaded Images
If a user uploads an image, consider whether they want to:
- Use it directly (e.g., "animate this", "split this into frames")
- Use it as inspiration (e.g., "make something like this")
Load and work with images using PIL:
from PIL import Image
uploaded = Image.open('file.png')
# Use directly, or just as reference for colors/styleDrawing from Scratch
When drawing graphics from scratch, use PIL ImageDraw primitives:
from PIL import ImageDraw
draw = ImageDraw.Draw(frame)
# Circles/ovals
draw.ellipse([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)
# Stars, triangles, any polygon
points = [(x1, y1), (x2, y2), (x3, y3), ...]
draw.polygon(points, fill=(r, g, b), outline=(r, g, b), width=3)
# Lines
draw.line([(x1, y1), (x2, y2)], fill=(r, g, b), width=5)
# Rectangles
draw.rectangle([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)Don't use: Emoji fonts (unreliable across platforms) or assume pre-packaged graphics exist in this skill.
Making Graphics Look Good
Graphics should look polished and creative, not basic. Here's how:
Use thicker lines - Always set width=2 or higher for outlines and lines. Thin lines (width=1) look choppy and amateurish.
Add visual depth:
- Use gradients for backgrounds (
create_gradient_background) - Layer multiple shapes for complexity (e.g., a star with a smaller star inside)
Make shapes more interesting:
- Don't just draw a plain circle - add highlights, rings, or patterns
- Stars can have glows (draw larger, semi-transparent versions behind)
- Combine multiple shapes (stars + sparkles, circles + rings)
Pay attention to colors:
- Use vibrant, complementary colors
- Add contrast (dark outlines on light shapes, light outlines on dark shapes)
- Consider the overall composition
For complex shapes (hearts, snowflakes, etc.):
- Use combinations of polygons and ellipses
- Calculate points carefully for symmetry
- Add details (a heart can have a highlight curve, snowflakes have intricate branches)
Be creative and detailed! A good Slack GIF should look polished, not like placeholder graphics.
Available Utilities
GIFBuilder (core.gif_builder)
Assembles frames and optimizes for Slack:
builder = GIFBuilder(width=128, height=128, fps=10)
builder.add_frame(frame) # Add PIL Image
builder.add_frames(frames) # Add list of frames
builder.save('out.gif', num_colors=48, optimize_for_emoji=True, remove_duplicates=True)Validators (core.validators)
Check if GIF meets Slack requirements:
from core.validators import validate_gif, is_slack_ready
# Detailed validation
passes, info = validate_gif('my.gif', is_emoji=True, verbose=True)
# Quick check
if is_slack_ready('my.gif'):
print("Ready!")Easing Functions (core.easing)
Smooth motion instead of linear:
from core.easing import interpolate
# Progress from 0.0 to 1.0
t = i / (num_frames - 1)
# Apply easing
y = interpolate(start=0, end=400, t=t, easing='ease_out')
# Available: linear, ease_in, ease_out, ease_in_out,
# bounce_out, elastic_out, back_outFrame Helpers (core.frame_composer)
Convenience functions for common needs:
from core.frame_composer import (
create_blank_frame, # Solid color background
create_gradient_background, # Vertical gradient
draw_circle, # Helper for circles
draw_text, # Simple text rendering
draw_star # 5-pointed star
)Animation Concepts
Shake/Vibrate
Offset object position with oscillation:
- Use
math.sin()ormath.cos()with frame index - Add small random variations for natural feel
- Apply to x and/or y position
Pulse/Heartbeat
Scale object size rhythmically:
- Use
math.sin(t * frequency * 2 * math.pi)for smooth pulse - For heartbeat: two quick pulses then pause (adjust sine wave)
- Scale between 0.8 and 1.2 of base size
Bounce
Object falls and bounces:
- Use
interpolate()witheasing='bounce_out'for landing - Use
easing='ease_in'for falling (accelerating) - Apply gravity by increasing y velocity each frame
Spin/Rotate
Rotate object around center:
- PIL:
image.rotate(angle, resample=Image.BICUBIC) - For wobble: use sine wave for angle instead of linear
Fade In/Out
Gradually appear or disappear:
- Create RGBA image, adjust alpha channel
- Or use
Image.blend(image1, image2, alpha) - Fade in: alpha from 0 to 1
- Fade out: alpha from 1 to 0
Slide
Move object from off-screen to position:
- Start position: outside frame bounds
- End position: target location
- Use
interpolate()witheasing='ease_out'for smooth stop - For overshoot: use
easing='back_out'
Zoom
Scale and position for zoom effect:
- Zoom in: scale from 0.1 to 2.0, crop center
- Zoom out: scale from 2.0 to 1.0
- Can add motion blur for drama (PIL filter)
Explode/Particle Burst
Create particles radiating outward:
- Generate particles with random angles and velocities
- Update each particle:
x += vx,y += vy - Add gravity:
vy += gravity_constant - Fade out particles over time (reduce alpha)
Optimization Strategies
Only when asked to make the file size smaller, implement a few of the following methods:
- Fewer frames - Lower FPS (10 instead of 20) or shorter duration
- Fewer colors -
num_colors=48instead of 128 - Smaller dimensions - 128x128 instead of 480x480
- Remove duplicates -
remove_duplicates=Truein save() - Emoji mode -
optimize_for_emoji=Trueauto-optimizes
# Maximum optimization for emoji
builder.save(
'emoji.gif',
num_colors=48,
optimize_for_emoji=True,
remove_duplicates=True
)Philosophy
This skill provides:
- Knowledge: Slack's requirements and animation concepts
- Utilities: GIFBuilder, validators, easing functions
- Flexibility: Create the animation logic using PIL primitives
It does NOT provide:
- Rigid animation templates or pre-made functions
- Emoji font rendering (unreliable across platforms)
- A library of pre-packaged graphics built into the skill
Note on user uploads: This skill doesn't include pre-built graphics, but if a user uploads an image, use PIL to load and work with it - interpret based on their request whether they want it used directly or just as inspiration.
Be creative! Combine concepts (bouncing + rotating, pulsing + sliding, etc.) and use PIL's full capabilities.
Dependencies
pip install pillow imageio numpyResource Files
LICENSE.txt
Binary resource
core/easing.py
Binary resource
core/frame_composer.py
Download core/frame_composer.py
#!/usr/bin/env python3
"""
Frame Composer - Utilities for composing visual elements into frames.
Provides functions for drawing shapes, text, emojis, and compositing elements
together to create animation frames.
"""
from typing import Optional
import numpy as np
from PIL import Image, ImageDraw, ImageFont
def create_blank_frame(
width: int, height: int, color: tuple[int, int, int] = (255, 255, 255)
) -> Image.Image:
"""
Create a blank frame with solid color background.
Args:
width: Frame width
height: Frame height
color: RGB color tuple (default: white)
Returns:
PIL Image
"""
return Image.new("RGB", (width, height), color)
def draw_circle(
frame: Image.Image,
center: tuple[int, int],
radius: int,
fill_color: Optional[tuple[int, int, int]] = None,
outline_color: Optional[tuple[int, int, int]] = None,
outline_width: int = 1,
) -> Image.Image:
"""
Draw a circle on a frame.
Args:
frame: PIL Image to draw on
center: (x, y) center position
radius: Circle radius
fill_color: RGB fill color (None for no fill)
outline_color: RGB outline color (None for no outline)
outline_width: Outline width in pixels
Returns:
Modified frame
"""
draw = ImageDraw.Draw(frame)
x, y = center
bbox = [x - radius, y - radius, x + radius, y + radius]
draw.ellipse(bbox, fill=fill_color, outline=outline_color, width=outline_width)
return frame
def draw_text(
frame: Image.Image,
text: str,
position: tuple[int, int],
color: tuple[int, int, int] = (0, 0, 0),
centered: bool = False,
) -> Image.Image:
"""
Draw text on a frame.
Args:
frame: PIL Image to draw on
text: Text to draw
position: (x, y) position (top-left unless centered=True)
color: RGB text color
centered: If True, center text at position
Returns:
Modified frame
"""
draw = ImageDraw.Draw(frame)
# Uses Pillow's default font.
# If the font should be changed for the emoji, add additional logic here.
font = ImageFont.load_default()
if centered:
bbox = draw.textbbox((0, 0), text, font=font)
text_width = bbox[2] - bbox[0]
text_height = bbox[3] - bbox[1]
x = position[0] - text_width // 2
y = position[1] - text_height // 2
position = (x, y)
draw.text(position, text, fill=color, font=font)
return frame
def create_gradient_background(
width: int,
height: int,
top_color: tuple[int, int, int],
bottom_color: tuple[int, int, int],
) -> Image.Image:
"""
Create a vertical gradient background.
Args:
width: Frame width
height: Frame height
top_color: RGB color at top
bottom_color: RGB color at bottom
Returns:
PIL Image with gradient
"""
frame = Image.new("RGB", (width, height))
draw = ImageDraw.Draw(frame)
# Calculate color step for each row
r1, g1, b1 = top_color
r2, g2, b2 = bottom_color
for y in range(height):
# Interpolate color
ratio = y / height
r = int(r1 * (1 - ratio) + r2 * ratio)
g = int(g1 * (1 - ratio) + g2 * ratio)
b = int(b1 * (1 - ratio) + b2 * ratio)
# Draw horizontal line
draw.line([(0, y), (width, y)], fill=(r, g, b))
return frame
def draw_star(
frame: Image.Image,
center: tuple[int, int],
size: int,
fill_color: tuple[int, int, int],
outline_color: Optional[tuple[int, int, int]] = None,
outline_width: int = 1,
) -> Image.Image:
"""
Draw a 5-pointed star.
Args:
frame: PIL Image to draw on
center: (x, y) center position
size: Star size (outer radius)
fill_color: RGB fill color
outline_color: RGB outline color (None for no outline)
outline_width: Outline width
Returns:
Modified frame
"""
import math
draw = ImageDraw.Draw(frame)
x, y = center
# Calculate star points
points = []
for i in range(10):
angle = (i * 36 - 90) * math.pi / 180 # 36 degrees per point, start at top
radius = size if i % 2 == 0 else size * 0.4 # Alternate between outer and inner
px = x + radius * math.cos(angle)
py = y + radius * math.sin(angle)
points.append((px, py))
# Draw star
draw.polygon(points, fill=fill_color, outline=outline_color, width=outline_width)
return framecore/gif_builder.py
Binary resource
core/validators.py
#!/usr/bin/env python3
"""
Validators - Check if GIFs meet Slack's requirements.
These validators help ensure your GIFs meet Slack's size and dimension constraints.
"""
from pathlib import Path
def validate_gif(
gif_path: str | Path, is_emoji: bool = True, verbose: bool = True
) -> tuple[bool, dict]:
"""
Validate GIF for Slack (dimensions, size, frame count).
Args:
gif_path: Path to GIF file
is_emoji: True for emoji (128x128 recommended), False for message GIF
verbose: Print validation details
Returns:
Tuple of (passes: bool, results: dict with all details)
"""
from PIL import Image
gif_path = Path(gif_path)
if not gif_path.exists():
return False, {"error": f"File not found: {gif_path}"}
# Get file size
size_bytes = gif_path.stat().st_size
size_kb = size_bytes / 1024
size_mb = size_kb / 1024
# Get dimensions and frame info
try:
with Image.open(gif_path) as img:
width, height = img.size
# Count frames
frame_count = 0
try:
while True:
img.seek(frame_count)
frame_count += 1
except EOFError:
pass
# Get duration
try:
duration_ms = img.info.get("duration", 100)
total_duration = (duration_ms * frame_count) / 1000
fps = frame_count / total_duration if total_duration > 0 else 0
except:
total_duration = None
fps = None
except Exception as e:
return False, {"error": f"Failed to read GIF: {e}"}
# Validate dimensions
if is_emoji:
optimal = width == height == 128
acceptable = width == height and 64 <= width <= 128
dim_pass = acceptable
else:
aspect_ratio = (
max(width, height) / min(width, height)
if min(width, height) > 0
else float("inf")
)
dim_pass = aspect_ratio <= 2.0 and 320 <= min(width, height) <= 640
results = {
"file": str(gif_path),
"passes": dim_pass,
"width": width,
"height": height,
"size_kb": size_kb,
"size_mb": size_mb,
"frame_count": frame_count,
"duration_seconds": total_duration,
"fps": fps,
"is_emoji": is_emoji,
"optimal": optimal if is_emoji else None,
}
# Print if verbose
if verbose:
print(f"\nValidating {gif_path.name}:")
print(
f" Dimensions: {width}x{height}"
+ (
f" ({'optimal' if optimal else 'acceptable'})"
if is_emoji and acceptable
else ""
)
)
print(
f" Size: {size_kb:.1f} KB"
+ (f" ({size_mb:.2f} MB)" if size_mb >= 1.0 else "")
)
print(
f" Frames: {frame_count}"
+ (f" @ {fps:.1f} fps ({total_duration:.1f}s)" if fps else "")
)
if not dim_pass:
print(
f" Note: {'Emoji should be 128x128' if is_emoji else 'Unusual dimensions for Slack'}"
)
if size_mb > 5.0:
print(f" Note: Large file size - consider fewer frames/colors")
return dim_pass, results
def is_slack_ready(
gif_path: str | Path, is_emoji: bool = True, verbose: bool = True
) -> bool:
"""
Quick check if GIF is ready for Slack.
Args:
gif_path: Path to GIF file
is_emoji: True for emoji GIF, False for message GIF
verbose: Print feedback
Returns:
True if dimensions are acceptable
"""
passes, _ = validate_gif(gif_path, is_emoji, verbose)
return passesrequirements.txt
pillow>=10.0.0
imageio>=2.31.0
imageio-ffmpeg>=0.4.9
numpy>=1.24.0
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