This plugin adds support for resizable PNG images using the Android-style 9-patch format. It enables scalable UI elements by preserving corners and edges while stretching the center.

• Stretch and padding regions are read from black pixels in the image’s 1-pixel border.

• Follows Android’s 9-patch format for parsing and scaling logic.

• Only .png images with 1-pixel black border markers are supported.

Example

Given an image like this:

Scaling the image non-uniformly would result into a highly stretched one:

Using 9-tile-scaling would solve this, as it only scales the edges and center of the image:

Usage

Import the plugin:

#import "@preview/nine-patch:0.1.0": auto-9patch, scale-9patch

Simple Scaling

#let img = read("bubble.9.png", encoding: none)

#scale-9patch(img, 400pt, 400pt)

Auto-scaling with context content

The auto-9patch function automatically resizes to its content size.

#let img = read("bubble.9.png", encoding: none)

#context auto-9patch(img, scale: .1pt)[
  #box(width: 300pt,lorem(20))
]

Develop

Build the Plugin:

To compile the plugin for WebAssembly, run:

cargo build --target wasm32-unknown-unknown --release

Run Tests:

To run the tests for the plugin, use:

cargo test

Make sure you have the appropriate Rust toolchain for WebAssembly (wasm32-unknown-unknown) installed before building.