{"id":"slack-gif-creator","name":"slack-gif-creator","summary":"Slackに最適化されたアニメーションGIF作成の知識とユーティリティ。制約、検証ツール、アニメーションの概念を提供します。","body":"# Slack GIF Creator\n\nA toolkit providing utilities and knowledge for creating animated GIFs optimized for Slack.\n\n## Slack Requirements\n\n**Dimensions:**\n- Emoji GIFs: 128x128 (recommended)\n- Message GIFs: 480x480\n\n**Parameters:**\n- FPS: 10-30 (lower is smaller file size)\n- Colors: 48-128 (fewer = smaller file size)\n- Duration: Keep under 3 seconds for emoji GIFs\n\n## Core Workflow\n\n```python\nfrom core.gif_builder import GIFBuilder\nfrom PIL import Image, ImageDraw\n\n# 1. Create builder\nbuilder = GIFBuilder(width=128, height=128, fps=10)\n\n# 2. Generate frames\nfor i in range(12):\n    frame = Image.new('RGB', (128, 128), (240, 248, 255))\n    draw = ImageDraw.Draw(frame)\n\n    # Draw your animation using PIL primitives\n    # (circles, polygons, lines, etc.)\n\n    builder.add_frame(frame)\n\n# 3. Save with optimization\nbuilder.save('output.gif', num_colors=48, optimize_for_emoji=True)\n```\n\n## Drawing Graphics\n\n### Working with User-Uploaded Images\nIf a user uploads an image, consider whether they want to:\n- **Use it directly** (e.g., \"animate this\", \"split this into frames\")\n- **Use it as inspiration** (e.g., \"make something like this\")\n\nLoad and work with images using PIL:\n```python\nfrom PIL import Image\n\nuploaded = Image.open('file.png')\n# Use directly, or just as reference for colors/style\n```\n\n### Drawing from Scratch\nWhen drawing graphics from scratch, use PIL ImageDraw primitives:\n\n```python\nfrom PIL import ImageDraw\n\ndraw = ImageDraw.Draw(frame)\n\n# Circles/ovals\ndraw.ellipse([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)\n\n# Stars, triangles, any polygon\npoints = [(x1, y1), (x2, y2), (x3, y3), ...]\ndraw.polygon(points, fill=(r, g, b), outline=(r, g, b), width=3)\n\n# Lines\ndraw.line([(x1, y1), (x2, y2)], fill=(r, g, b), width=5)\n\n# Rectangles\ndraw.rectangle([x1, y1, x2, y2], fill=(r, g, b), outline=(r, g, b), width=3)\n```\n\n**Don't use:** Emoji fonts (unreliable across platforms) or assume pre-packaged graphics exist in this skill.\n\n### Making Graphics Look Good\n\nGraphics should look polished and creative, not basic. Here's how:\n\n**Use thicker lines** - Always set `width=2` or higher for outlines and lines. Thin lines (width=1) look choppy and amateurish.\n\n**Add visual depth**:\n- Use gradients for backgrounds (`create_gradient_background`)\n- Layer multiple shapes for complexity (e.g., a star with a smaller star inside)\n\n**Make shapes more interesting**:\n- Don't just draw a plain circle - add highlights, rings, or patterns\n- Stars can have glows (draw larger, semi-transparent versions behind)\n- Combine multiple shapes (stars + sparkles, circles + rings)\n\n**Pay attention to colors**:\n- Use vibrant, complementary colors\n- Add contrast (dark outlines on light shapes, light outlines on dark shapes)\n- Consider the overall composition\n\n**For complex shapes** (hearts, snowflakes, etc.):\n- Use combinations of polygons and ellipses\n- Calculate points carefully for symmetry\n- Add details (a heart can have a highlight curve, snowflakes have intricate branches)\n\nBe creative and detailed! A good Slack GIF should look polished, not like placeholder graphics.\n\n## Available Utilities\n\n### GIFBuilder (`core.gif_builder`)\nAssembles frames and optimizes for Slack:\n```python\nbuilder = GIFBuilder(width=128, height=128, fps=10)\nbuilder.add_frame(frame)  # Add PIL Image\nbuilder.add_frames(frames)  # Add list of frames\nbuilder.save('out.gif', num_colors=48, optimize_for_emoji=True, remove_duplicates=True)\n```\n\n### Validators (`core.validators`)\nCheck if GIF meets Slack requirements:\n```python\nfrom core.validators import validate_gif, is_slack_ready\n\n# Detailed validation\npasses, info = validate_gif('my.gif', is_emoji=True, verbose=True)\n\n# Quick check\nif is_slack_ready('my.gif'):\n    print(\"Ready!\")\n```\n\n### Easing Functions (`core.easing`)\nSmooth motion instead of linear:\n```python\nfrom core.easing import interpolate\n\n# Progress from 0.0 to 1.0\nt = i / (num_frames - 1)\n\n# Apply easing\ny = interpolate(start=0, end=400, t=t, easing='ease_out')\n\n# Available: linear, ease_in, ease_out, ease_in_out,\n#           bounce_out, elastic_out, back_out\n```\n\n### Frame Helpers (`core.frame_composer`)\nConvenience functions for common needs:\n```python\nfrom core.frame_composer import (\n    create_blank_frame,         # Solid color background\n    create_gradient_background,  # Vertical gradient\n    draw_circle,                # Helper for circles\n    draw_text,                  # Simple text rendering\n    draw_star                   # 5-pointed star\n)\n```\n\n## Animation Concepts\n\n### Shake/Vibrate\nOffset object position with oscillation:\n- Use `math.sin()` or `math.cos()` with frame index\n- Add small random variations for natural feel\n- Apply to x and/or y position\n\n### Pulse/Heartbeat\nScale object size rhythmically:\n- Use `math.sin(t * frequency * 2 * math.pi)` for smooth pulse\n- For heartbeat: two quick pulses then pause (adjust sine wave)\n- Scale between 0.8 and 1.2 of base size\n\n### Bounce\nObject falls and bounces:\n- Use `interpolate()` with `easing='bounce_out'` for landing\n- Use `easing='ease_in'` for falling (accelerating)\n- Apply gravity by increasing y velocity each frame\n\n### Spin/Rotate\nRotate object around center:\n- PIL: `image.rotate(angle, resample=Image.BICUBIC)`\n- For wobble: use sine wave for angle instead of linear\n\n### Fade In/Out\nGradually appear or disappear:\n- Create RGBA image, adjust alpha channel\n- Or use `Image.blend(image1, image2, alpha)`\n- Fade in: alpha from 0 to 1\n- Fade out: alpha from 1 to 0\n\n### Slide\nMove object from off-screen to position:\n- Start position: outside frame bounds\n- End position: target location\n- Use `interpolate()` with `easing='ease_out'` for smooth stop\n- For overshoot: use `easing='back_out'`\n\n### Zoom\nScale and position for zoom effect:\n- Zoom in: scale from 0.1 to 2.0, crop center\n- Zoom out: scale from 2.0 to 1.0\n- Can add motion blur for drama (PIL filter)\n\n### Explode/Particle Burst\nCreate particles radiating outward:\n- Generate particles with random angles and velocities\n- Update each particle: `x += vx`, `y += vy`\n- Add gravity: `vy += gravity_constant`\n- Fade out particles over time (reduce alpha)\n\n## Optimization Strategies\n\nOnly when asked to make the file size smaller, implement a few of the following methods:\n\n1. **Fewer frames** - Lower FPS (10 instead of 20) or shorter duration\n2. **Fewer colors** - `num_colors=48` instead of 128\n3. **Smaller dimensions** - 128x128 instead of 480x480\n4. **Remove duplicates** - `remove_duplicates=True` in save()\n5. **Emoji mode** - `optimize_for_emoji=True` auto-optimizes\n\n```python\n# Maximum optimization for emoji\nbuilder.save(\n    'emoji.gif',\n    num_colors=48,\n    optimize_for_emoji=True,\n    remove_duplicates=True\n)\n```\n\n## Philosophy\n\nThis skill provides:\n- **Knowledge**: Slack's requirements and animation concepts\n- **Utilities**: GIFBuilder, validators, easing functions\n- **Flexibility**: Create the animation logic using PIL primitives\n\nIt does NOT provide:\n- Rigid animation templates or pre-made functions\n- Emoji font rendering (unreliable across platforms)\n- A library of pre-packaged graphics built into the skill\n\n**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.\n\nBe creative! Combine concepts (bouncing + rotating, pulsing + sliding, etc.) and use PIL's full capabilities.\n\n## Dependencies\n\n```bash\npip install pillow imageio numpy\n```","author":"@anthropics","ownerProfile":null,"authorContacts":null,"sourceUrl":"https://github.com/anthropics/skills/tree/main/skills/slack-gif-creator","license":"Apache-2.0","category":"coding","lang":"en","tokens":1922,"stars":0,"calls30d":1,"claimed":false,"visibility":"public","origin":"crawler","version":"0.1.0","createdAt":"2026-08-22","updatedAt":"2026-08-22","files":[{"path":"core/easing.py","size":6265,"sha256":"60bc943449802541f0f0881a874faa7ef408aaaf0b758fde756664ada7740452"},{"path":"core/frame_composer.py","size":4548,"sha256":"a127ea8f2a58893ea10a5c7b5cab4e2010af6515adc538676eb0cc14f5a03985"},{"path":"core/gif_builder.py","size":9847,"sha256":"b6f50d738c491ee0438a2e86e897f71cdab9792494ba4605f140befb0bddbf89"},{"path":"core/validators.py","size":3785,"sha256":"56bd19e3aae05f8387d78ec8185d6098b3dc909d1fa041211753da37212528a3"},{"path":"LICENSE.txt","size":11345,"sha256":"bc6b3af2f331cbc7fb0da1344efb2cbe5877a31498b4d70dbc7000f3405a1362"},{"path":"requirements.txt","size":66,"sha256":"edc7108a0c6b56183566c71ee96830f6dc791e3b41952112d9cb56b33a6bd757"}],"requires":{"mcp":[],"tools":[]},"safety":{"flags":[],"scannedAt":"2026-08-22","hasScripts":true,"networkEndpoints":[]}}