README.md

GraphCompose Core

io.github.demchaav:graph-compose-core

The lean document engine: the canonical authoring surface (com.demcha.compose.document.* — DSL, semantic nodes, themes, layout snapshots) and the deterministic two-pass layout behind it, with no PDFBox, POI, or template code on its dependency tree.

When to depend on it

• You want the smallest engine and will bring your own render backend — add graph-compose-render-pdf, or implement the FixedLayoutBackendProvider SPI. A custom backend needs both halves of the SPI: opening a session measures text through a FontMetricsProvider, so publish one alongside your backend. graph-compose-render-pdf is the only shipped artifact that registers one.
• You are building a library on top of GraphCompose and don't want to impose a backend on your consumers.

Most applications should depend on graph-compose (core + the PDF backend, the 1.x drop-in) or graph-compose-bundle (batteries included) instead.

Smallest complete example

Author against the canonical surface. Core cannot open a session on its own: create() resolves a FontMetricsProvider through ServiceLoader, so a core-only classpath throws MissingBackendException there — before any render call — and the message names the artifact to add. With graph-compose-render-pdf present the whole path works:

Path out = Path.of("hello.pdf");
try (DocumentSession doc = GraphCompose.document(out).create()) {
    doc.pageFlow().addParagraph("Hello").build();
    doc.buildPdf();                 // writes hello.pdf
}

toPdfBytes() and toImages(int dpi) are the in-memory counterparts.

Install

Same version as the rest of the GraphCompose train (lockstep):

<dependency>
    <groupId>io.github.demchaav</groupId>
    <artifactId>graph-compose-core</artifactId>
    <version>2.1.0</version>
</dependency>

dependencies { implementation("io.github.demchaav:graph-compose-core:2.1.0") }

The full "which artifact?" table: root README → Installation. Upgrading from 1.x: modules migration guide.