A toolkit providing utilities and knowledge for creating animated GIFs optimized for Slack.

Slack GIF Creator A toolkit providing utilities and knowledge for creating animated GIFs optimized for Slack. Catalog modification notice: clarified Slack recommendations and validator limits, corrected GIF duration/format checks and basic builder input handling. The bundled Apache 2.0 license text is retained; this review does not establish missing upstream authorship metadata. Run from the resolved skill root (or add it to the Python module path), using an isolated environment and the bundled requirements. Decode untrusted images with bounded dimensions/frame counts and retain Pillow decompression bomb protections. Export to a new task local path; sharing/uploading requires the requested workspace and permission. Avoid flashing animations and provide a still preview. Slack Targets and Recommendations Dimensions: Emoji GIFs: 128x128 (recommended) Message GIFs: 480x480 Slack recommends square custom images below 128 KB and supports GIFs with up to 50 frames; see [Slack custom emoji guidance](https://slack.com/help/articles/206870177 Add custom emoji and aliases to your workspace). The dimensions/FPS/color/duration values here are design targets, not complete platform acceptance rules. Message GIF dimensions are suggestions. 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 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: Drawing from Scratch When drawing graphics from scratch, use PIL ImageDraw primitives: 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: Validators ( core.validators ) Check if GIF meets Slack requirements: Easing Functions ( core.easing ) Smooth motion instead of linear: Frame Helpers ( core.frame composer ) Convenience functions for common needs: 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 shortens timing in this implementation; leave false when pauses or duration must be preserved 5. Emoji mode optimize for emoji=True auto optimizes 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 When to Use This skill is applicable to execute the workflow or actions described in the overview. is slack ready checks local encoding/target constraints, not actual upload acceptance. RGB conversion drops transparency. Emoji optimization mutates stored frames and may shorten the animation; inspect the encoded file rather than trusting nominal FPS or the returned palette count. The package does not upload anything to Slack. Limitations Use this skill only when the task clearly matches the scope described above. Do not treat the output as a substitute for environment specific validation, testing, or expert review. Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

slack-gif-creator