slack-gif-creator

Slack GIF Creator

A toolkit that provides tools and knowledge for creating animated GIFs optimized for Slack.

Slack Requirements

Size:

Emoji GIF: 128x128 (recommended)
Message GIF: 480x480

Parameters:

FPS: 10-30 (lower values reduce file size)
Colors: 48-128 (fewer colors = smaller file)
Duration: Emoji GIFs should be kept under 3 seconds

Core Workflow

from core.gif_builder import GIFBuilder
from PIL import Image, ImageDraw

# 1. 创建构建器
builder = GIFBuilder(width=128, height=128, fps=10)

# 2. 生成帧
for i in range(12):
    frame = Image.new('RGB', (128, 128), (240, 248, 255))
    draw = ImageDraw.Draw(frame)

    # 使用 PIL 基础图形绘制你的动画
    # （圆形、多边形、线条等）

    builder.add_frame(frame)

# 3. 保存并优化
builder.save('output.gif', num_colors=48, optimize_for_emoji=True)

Draw Graphics

Process User-Uploaded Images

If the user uploaded an image, consider that they want:

Direct use(e.g., "animate this", "split this into frames")
Use as inspiration/reference(e.g., "make something like this")

Use PIL to load and process images:

from PIL import Image

uploaded = Image.open('file.png')
# 直接使用，或仅作为颜色/风格的参考

Draw from Scratch

When drawing graphics from scratch, use PIL ImageDraw basic shapes:

from PIL import ImageDraw

draw = ImageDraw.Draw(frame)

# 圆形/椭圆
draw.ellipse([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)

# 星形、三角形、任何多边形
points = [(x1, y1), (x2, y2), (x3, y3), ...]
draw.polygon(points, fill=(r, g, b), outline=(r, g, b), width=3)

# 线条
draw.line([(x1, y1), (x2, y2)], fill=(r, g, b), width=5)

# 矩形
draw.rectangle([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)

Do not use: Emoji fonts (they render inconsistently across platforms) or assume there are pre-packaged graphics in this skill.

Make Graphics More Beautiful

Graphics should look polished and creative, not crude. Here's how:

Use thicker lines - Always set outlines and lines to width=2 or higher. Thin lines (width=1) look rough and amateurish.

Add visual depth：

Use gradient backgrounds (create_gradient_background）
Overlay multiple shapes to add complexity (e.g., a small star inside a star)

Make shapes more interesting：

Don't just draw a plain circle - add highlights, halos, or patterns
Stars can have a glow (draw a larger semi-transparent version behind them)
Combine multiple shapes (star + sparkle, circle + halo)

Pay attention to color schemes：

Use vibrant complementary colors
Add contrast (dark outlines for light shapes, light outlines for dark shapes)
Consider the overall composition

For complex shapes(hearts, snowflakes, etc.):

Use combinations of polygons and ellipses
Calculate points carefully to maintain symmetry
Add details (hearts can have highlight curves, snowflakes have fine branches)

Be creative and detail-oriented! A good Slack GIF should look polished, not like a placeholder graphic.

Available Tools

GIFBuilder (`core.gif_builder`)

Assemble frames and optimize for Slack:

builder = GIFBuilder(width=128, height=128, fps=10)
builder.add_frame(frame)  # 添加 PIL Image
builder.add_frames(frames)  # 添加帧列表
builder.save('out.gif', num_colors=48, optimize_for_emoji=True, remove_duplicates=True)

Validator (`core.validators`)

Check whether a GIF meets Slack requirements:

from core.validators import validate_gif, is_slack_ready

# 详细验证
passes, info = validate_gif('my.gif', is_emoji=True, verbose=True)

# 快速检查
if is_slack_ready('my.gif'):
    print("准备就绪！")

Easing Functions (`core.easing`)

Smooth motion instead of linear:

from core.easing import interpolate

# 进度从 0.0 到 1.0
t = i / (num_frames - 1)

# 应用缓动
y = interpolate(start=0, end=400, t=t, easing='ease_out')

# 可用：linear, ease_in, ease_out, ease_in_out,
#      bounce_out, elastic_out, back_out

Frame Helper Functions (`core.frame_composer`)

Convenience functions for common needs:

from core.frame_composer import (
    create_blank_frame,         # 纯色背景
    create_gradient_background,  # 垂直渐变
    draw_circle,                # 圆形辅助函数
    draw_text,                  # 简单文字渲染
    draw_star                   # 五角星
)

Animation Concepts

Shake/Vibrate

Offset an object's position with oscillation:

Use math.sin() or math.cos() with the frame index
Add small random variation for a natural feel
Apply to the x and/or y position

Pulse/Heartbeat

Scale the object size rhythmically:

Use math.sin(t * frequency * 2 * math.pi) to achieve smooth pulsing
For a heartbeat effect: two quick pulses then a pause (adjust the sine wave)
Scale between 0.8 and 1.2 times the base size

Bounce

The object falls and bounces:

Use interpolate() with easing='bounce_out' to achieve the landing effect
Use easing='ease_in' to achieve the falling (accelerating) effect
Simulate gravity by increasing the y velocity each frame

Rotation

Rotate the object around its center:

PIL：image.rotate(angle, resample=Image.BICUBIC)
For a swaying effect: use a sine wave to control the angle instead of linear change

Fade In/Fade Out

Gradually appear or disappear:

Create an RGBA image, adjust the 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 the object from off-screen to a specified position:

Start position: outside the frame bounds
End position: target position
Use interpolate() with easing='ease_out' to achieve a smooth stop
For an overshoot effect: use easing='back_out'

Zoom

Scale and position to achieve a zoom effect:

Zoom in: scale from 0.1 to 2.0, crop the center
Zoom out: scale from 2.0 to 1.0
Motion blur can be added for a dramatic effect (PIL filter)

Explosion/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 (decrease alpha)

Optimization Strategies

Only when asked to reduce file size, implement the following methods:

Reduce frame count - Lower the FPS (use 10 instead of 20) or shorten the duration
Reduce colors - num_colors=48 instead of 128
Reduce size - 128x128 instead of 480x480
Remove duplicate frames - Use in save() remove_duplicates=True
Emoji mode - optimize_for_emoji=True automatically optimizes

# 表情符号最大优化
builder.save(
    'emoji.gif',
    num_colors=48,
    optimize_for_emoji=True,
    remove_duplicates=True
)

Design Philosophy

This skill provides:

Knowledge: Slack's requirements and animation concepts
Tools: GIFBuilder, validators, easing functions
Flexibility: Create animation logic using PIL basic shapes

This skill does not provide:

Rigid animation templates or pre-made functions
Emoji font rendering (behaves inconsistently across platforms)
Pre-packaged graphics libraries built into the skill

Note about user uploads: This skill does not include pre-built graphics, but if the user uploads an image, use PIL to load and process it - based on their request, decide whether to use it directly or only as inspiration.

Get creative! Combine various concepts (bounce + rotation, pulse + slide, etc.) and make full use of PIL's capabilities.

Dependencies

pip install pillow imageio numpy