/anthropic-slack-gif-creator

name: anthropic-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

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

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