Slack GIF Creator

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/style

Drawing 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_out

Frame 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() or math.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() with easing='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() with easing='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=48 instead of 128

• Smaller dimensions - 128x128 instead of 480x480

• Remove duplicates - remove_duplicates=True in save()

• Emoji mode - optimize_for_emoji=True auto-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 numpy