easy-png-tools2/web/src/lib/core/analyze.ts

import type { PixelImage } from "./types";

export type ImageInfo = {
	width: number;
	height: number;
	hasAlpha: boolean;
	colorCount: number;
};

export function imageInfo(img: PixelImage): ImageInfo {
	let hasAlpha = false;
	const seen = new Set<number>();
	for (let i = 0; i < img.data.length; i += 4) {
		if (!hasAlpha && img.data[i + 3] !== 255) {
			hasAlpha = true;
		}
		const key =
			((img.data[i] << 24) |
				(img.data[i + 1] << 16) |
				(img.data[i + 2] << 8) |
				img.data[i + 3]) >>>
			0;
		seen.add(key);
	}
	return {
		width: img.width,
		height: img.height,
		hasAlpha,
		colorCount: seen.size,
	};
}

export function isGrayscale(img: PixelImage): boolean {
	for (let i = 0; i < img.data.length; i += 4) {
		if (
			img.data[i] !== img.data[i + 1] ||
			img.data[i + 1] !== img.data[i + 2]
		) {
			return false;
		}
	}
	return true;
}

export function hasTransparency(img: PixelImage): boolean {
	for (let i = 3; i < img.data.length; i += 4) {
		if (img.data[i] < 255) return true;
	}
	return false;
}

export type Orientation = "portrait" | "landscape" | "square";

export function orientationOf(img: PixelImage): Orientation {
	if (img.height > img.width) return "portrait";
	if (img.width > img.height) return "landscape";
	return "square";
}