face-api/src/dom/imageToSquare.ts

28 lines
1.1 KiB
TypeScript

import { env } from '../env/index';
import { createCanvas, createCanvasFromMedia } from './createCanvas';
import { getContext2dOrThrow } from './getContext2dOrThrow';
import { getMediaDimensions } from './getMediaDimensions';
export function imageToSquare(input: HTMLImageElement | HTMLCanvasElement, inputSize: number, centerImage: boolean = false) {
const { Image, Canvas } = env.getEnv();
if (!(input instanceof Image || input instanceof Canvas)) {
throw new Error('imageToSquare - expected arg0 to be HTMLImageElement | HTMLCanvasElement');
}
const dims = getMediaDimensions(input);
const scale = inputSize / Math.max(dims.height, dims.width);
const width = scale * dims.width;
const height = scale * dims.height;
const targetCanvas = createCanvas({ width: inputSize, height: inputSize });
const inputCanvas = input instanceof Canvas ? input : createCanvasFromMedia(input);
const offset = Math.abs(width - height) / 2;
const dx = centerImage && width < height ? offset : 0;
const dy = centerImage && height < width ? offset : 0;
getContext2dOrThrow(targetCanvas).drawImage(inputCanvas, dx, dy, width, height);
return targetCanvas;
}