excalidraw/src/distribute.ts

91 lines
2.4 KiB
TypeScript

import { ExcalidrawElement } from "./element/types";
import { newElementWith } from "./element/mutateElement";
import { getMaximumGroups } from "./groups";
import { getCommonBoundingBox } from "./element/bounds";
export interface Distribution {
space: "between";
axis: "x" | "y";
}
export const distributeElements = (
selectedElements: ExcalidrawElement[],
distribution: Distribution,
): ExcalidrawElement[] => {
const [start, mid, end, extent] =
distribution.axis === "x"
? (["minX", "midX", "maxX", "width"] as const)
: (["minY", "midY", "maxY", "height"] as const);
const bounds = getCommonBoundingBox(selectedElements);
const groups = getMaximumGroups(selectedElements)
.map((group) => [group, getCommonBoundingBox(group)] as const)
.sort((a, b) => a[1][mid] - b[1][mid]);
let span = 0;
for (const group of groups) {
span += group[1][extent];
}
const step = (bounds[extent] - span) / (groups.length - 1);
if (step < 0) {
// If we have a negative step, we'll need to distribute from centers
// rather than from gaps. Buckle up, this is a weird one.
// Get indices of boxes that define start and end of our bounding box
const index0 = groups.findIndex((g) => g[1][start] === bounds[start]);
const index1 = groups.findIndex((g) => g[1][end] === bounds[end]);
// Get our step, based on the distance between the center points of our
// start and end boxes
const step =
(groups[index1][1][mid] - groups[index0][1][mid]) / (groups.length - 1);
let pos = groups[index0][1][mid];
return groups.flatMap(([group, box], index) => {
const translation = {
x: 0,
y: 0,
};
// Don't move our start and end boxes
if (index !== index0 && index !== index1) {
pos += step;
translation[distribution.axis] = pos - box[mid];
}
return group.map((element) =>
newElementWith(element, {
x: element.x + translation.x,
y: element.y + translation.y,
}),
);
});
}
// Distribute from gaps
let pos = bounds[start];
return groups.flatMap(([group, box]) => {
const translation = {
x: 0,
y: 0,
};
translation[distribution.axis] = pos - box[start];
pos += step;
pos += box[extent];
return group.map((element) =>
newElementWith(element, {
x: element.x + translation.x,
y: element.y + translation.y,
}),
);
});
};