Atelier

Geometry

Geometry values are immutable and renderer-neutral. They do not render, mutate, or depend on SVG.

Conventions

The y axis points down, matching SVG and Canvas. A consumer that needs y-up flips it in its own scale.

A zero-sized rectangle is a valid state and returns empty geometry rather than an error. Negative dimensions are rejected. No operation produces NAN.

The CSS vocabulary is borrowed, not implemented. Alignment::Stretch stretches unconditionally, fraction tracks ignore content, and percentage padding resolves against the matching axis rather than the inline size.

Value Types

  • Point: x/y coordinate.
  • Size: width/height.
  • Rect: x/y/width/height, anchors, inset.
  • Insets: top/right/bottom/left.
  • Bounds: union and expansion of rectangles. Groups computes one around solved frames.
  • RectIndex: immutable rectangle collision and occupancy queries.

Frame Model

BoxModel turns an outer rectangle into a content rectangle:

use Atelier\Layout\Geometry\BoxModel;
use Atelier\Layout\Geometry\Insets;
use Atelier\Layout\Geometry\Rect;
use Atelier\Layout\Geometry\StrokePlacement;

$content = (new BoxModel(
    outer: new Rect(0, 0, 200, 400),
    padding: new Insets(16, 8, 16, 8),
    strokeWidth: 10,
    strokePlacement: StrokePlacement::Inside,
))->contentRect();

This is the answer to fixed-canvas questions like:

In a 200x400 canvas with 4% padding and a fixed 10px contained stroke, what space remains?

Stroke placement is part of the arithmetic because it changes the answer. An inside stroke eats content space, an outside one does not, and a centered one eats half.

Circle Safe Areas

Circle exposes safe areas for labels:

use Atelier\Layout\Geometry\Circle;
use Atelier\Layout\Geometry\Point;

$safe = (new Circle(new Point(100, 200), 80))
    ->safeSquare(Insets::all(8), strokeWidth: 10, strokePlacement: StrokePlacement::Inside);

Consumers can lay text into that safe rectangle without knowing how the final renderer draws circles. Venn sets and pie labels use it.

Rect Index

RectIndex answers small collision questions over solved frames:

use Atelier\Layout\Geometry\RectIndex;

$index = RectIndex::from([
    'node.a' => $frameA,
    'node.b' => $frameB,
]);

$hits = $index->intersecting($candidateLabel);
$isFree = $index->isFree($candidateLabel, ignore: ['edge.ab.label']);

Edge-touching does not count as an intersection. That keeps dense scenes from rejecting labels that merely line up with an edge.

ignore exists because the most common query is "is this position free, apart from the thing I am about to move there".