sickn33/antigravity-awesome-skills/slack-gif-creator

Slack GIF Creator

A toolkit providing utilities and knowledge for creating animated GIFs optimized for Slack.

Catalog modification notice: clarified Slack recommendations and validator limits, corrected GIF duration/format checks and basic builder input handling. The bundled Apache-2.0 license text is retained; this review does not establish missing upstream authorship metadata.

Run from the resolved skill root (or add it to the Python module path), using an isolated environment and the bundled requirements. Decode untrusted images with bounded dimensions/frame counts and retain Pillow decompression-bomb protections. Export to a new task-local path; sharing/uploading requires the requested workspace and permission. Avoid flashing animations and provide a still preview.

Slack Targets and Recommendations

Dimensions:

• Emoji GIFs: 128x128 (recommended)
• Message GIFs: 480x480

Slack recommends square custom images below 128 KB and supports GIFs with up to 50 frames; see Slack custom emoji guidance. The dimensions/FPS/color/duration values here are design targets, not complete platform acceptance rules. Message GIF dimensions are suggestions.

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 (these may overshoot the range)

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:

1. Fewer frames - Lower FPS (10 instead of 20) or shorter duration
2. Fewer colors - num_colors=48 instead of 128
3. Smaller dimensions - 128x128 instead of 480x480
4. Remove duplicates - remove_duplicates=True shortens timing in this implementation; leave false when pauses or duration must be preserved
5. 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

When to Use

This skill is applicable to execute the workflow or actions described in the overview.

is_slack_ready checks local encoding/target constraints, not actual upload acceptance. RGB conversion drops transparency. Emoji optimization mutates stored frames and may shorten the animation; inspect the encoded file rather than trusting nominal FPS or the returned palette count. The package does not upload anything to Slack.

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.