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slack-gif-creator · anthropics-skills · Flowy
🧩 Skill
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.
One skill from anthropics-skills . Installed with the plugin, it fires itself as you prompt.
$ npx -y skills add anthropics/skills --skill slack-gif-creator --agent claude-codeInstalls just this skill. Get the whole plugin for auto-invocation.
SKILL.md
slack-gif-creator.SKILL.md
---
name : slack-gif-creator
description : 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."
license : Complete terms in LICENSE.txt
---
# 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.)
Flowy
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
```
