Pasted picture size

Drawing units per pixel of a pasted picture.

units per pixel = W ÷ pixel width

One 64-bit division; the result is stored as both axis vectors (ux and vy), so pixels are square. With no width given the picture is one drawing unit per pixel. The fade value is rounded to a whole percent between 0 and 100.

const W = width > 0 ? width : rec.w;
const px = W / rec.w;
const f = Math.max(0, Math.min(100, Math.round(fade) || 0));
const pic = { file: name, x: 0, y: 0, ux: px, uy: 0, vx: 0, vy: px, w: rec.w, h: rec.h, ...(f ? { fade: f } : {}), ...(transparent ? { transparent: true } : {}) };

The factor that turns a size in millimeters into the drawing's units.

units per mm = units per point × 72 ÷ 25.4

unitScale (pdfmodel.js) gives drawing units per PDF point from the drawing's units, for example 25.4 ÷ 72 for millimeters and 1 ÷ 72 for inches. It is multiplied by 72 and then divided by 25.4, three rounded operations in all.

export const unitsPerMm = (doc) => unitScale(doc) * 72 / 25.4;

The width and height a copied area takes in the drawing, on paper or at its real size.

size = size in mm × units per mm

The area's width and height in millimeters (areaclip.js sizeMm) are each multiplied once by the factor above. Without a scale on the copied sheet the real size is not known and nothing is returned.

export function areaSize(doc, clip, use = 'real') {
  const mm = sizeMm(clip, { use });
  if (!mm) return null;
  const k = unitsPerMm(doc);
  return [mm[0] * k, mm[1] * k];
}