Skill

anthropics/skills111.5k

slack-gif-creator

Knowledge and utilities for creating animated GIFs optimized for Slack. Provides constraints, validation tools, and animation concepts. Use when users request animated GIFs for Slack like "make me a GIF of X doing Y for Slack."

$npx clawhub@latest install slack-gif-creator

GitHub

Overview

# 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

```python

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:

```python

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:

```python

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:

```python

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:

```python

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:

```python

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:

```python

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` in save()

5. **Emoji mode** - `optimize_for_emoji=True` auto-optimizes

```python

# 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

```bash

pip install pillow imageio numpy

```

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