AutoSkill FastAPI Dynamic Image Resizing and Serving

Implements a FastAPI endpoint to serve images from a database path with dynamic resizing, aspect ratio preservation, and file-based caching. Supports multiple resize modes including stretch, centered crop, and fit.

install

source · Clone the upstream repo

git clone https://github.com/ECNU-ICALK/AutoSkill

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/ECNU-ICALK/AutoSkill "$T" && mkdir -p ~/.claude/skills && cp -r "$T/SkillBank/ConvSkill/english_gpt4_8/fastapi-dynamic-image-resizing-and-serving" ~/.claude/skills/ecnu-icalk-autoskill-fastapi-dynamic-image-resizing-and-serving && rm -rf "$T"

manifest: SkillBank/ConvSkill/english_gpt4_8/fastapi-dynamic-image-resizing-and-serving/SKILL.md

source content

FastAPI Dynamic Image Resizing and Serving

Prompt

Role & Objective

You are a FastAPI backend developer specializing in image processing. Your task is to implement an endpoint that serves image files from a local path (retrieved via database ID) with dynamic resizing capabilities.

Operational Rules & Constraints

Endpoint Parameters: The endpoint must accept
```
image_id
```
(path parameter),
```
width
```
(optional query),
```
height
```
(optional query), and
```
resize_mode
```
(optional query).
Aspect Ratio Calculation: If only
```
width
```
or only
```
height
```
is provided, calculate the missing dimension based on the original image's aspect ratio to maintain proportions.
Resize Modes: Support the following behaviors for
```
resize_mode
```
:
- ```
stretch
```
  (default): Resize to exact dimensions, ignoring aspect ratio.
- ```
crop
```
  : Resize to cover the dimensions, cropping equally from both sides (left/right or top/bottom) to keep the image centered.
- ```
fit
```
  : Resize to fit within the dimensions while maintaining aspect ratio (contain).
Caching: Implement file-based caching for resized images. Before processing, check if a thumbnail file exists (e.g., named
```
image_id__widthxheight.ext
```
). If it exists, serve it directly using
```
FileResponse
```
. If not, generate it, save it, and then serve it.
Dependencies: Use Pillow (PIL) for image manipulation and
```
FileResponse
```
for serving files.
Security: Ensure file paths are validated and served only if they correspond to valid database entries.

Anti-Patterns

Do not serve files directly from user input paths without database validation.
Do not crop from only one side (e.g., just right or bottom); cropping must be centered.
Do not ignore the
```
resize_mode
```
parameter if provided.

Triggers

create an endpoint to serve thumbnails with width and height
resize image based on aspect ratio in FastAPI
implement image serving with crop and fit modes
fastapi dynamic image resizing endpoint