Enable SWT text detection via opencv_contrib build option

[Copilot]

SWT (Stroke Width Transform) from OpenCV's text module is in opencv_contrib, not the main opencv repository. The default opencv.js build excludes contrib modules.

Changes

Build workflow (.github/workflows/build-opencv-js.yml)

• Added enable_contrib boolean input to trigger opencv_contrib integration
• Clones opencv_contrib repository matching OpenCV version
• Passes --extra_modules path and text module config to build script
• Uses bash arrays for argument construction (prevents shell injection)

Module configuration (opencv_js_text.config.py)

• Whitelists text module functions for JavaScript export
• Exports detectTextSWT and extensibility stubs for other text functions

Type definitions (src/types/opencv/text.ts)

• TypeScript declarations for detectTextSWT function
• Leverages existing RectVector type from _hacks.ts

Documentation

• README: Build instructions and basic usage
• doc/SWT_USAGE.md: Complete examples for Node.js, Browser, TypeScript
• doc/SWT_IMPLEMENTATION.md: Technical implementation details

Usage

Build with contrib enabled via Actions workflow (set enable_contrib=true), then:

const cv = await cvModule;
const img = cv.imread('imageId');
const results = new cv.RectVector();
const draw = new cv.Mat();

// Detect dark text on light background
cv.detectTextSWT(img, results, true, draw);

console.log(`Found ${results.size()} text regions`);

results.delete();
draw.delete();
img.delete();

Default builds remain unchanged for backward compatibility.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• docs.opencv.org
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Can SWT work with it?</issue_title>
<issue_description>https://docs.opencv.org/4.7.0/d8/de7/namespacecv_1_1text.html#a9370f4e7849c94fb418eebd915a6839d</issue_description>

<agent_instructions>any chance to change the compiling option to make SWT work in the opencv.js library?</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Can SWT work with it? #28

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.