interface BitmapInfoHeader

BITMAPINFOHEADER — the 40-byte DIB header used by virtually all modern BMP files.

The size field is what tells decoders which DIB header variant follows; for BITMAPINFOHEADER it is always 40. Larger variants (V4/V5) are not handled by this coder — read size first and dispatch externally if you need to support them.

width is signed but in practice non-negative. height is signed: a negative value means the image is stored top-down (rows in natural reading order) instead of the BMP-default bottom-up. We deliberately preserve the sign rather than auto-flipping rows; row orientation is the caller's concern.

Examples

Shape of a BITMAPINFOHEADER for a 2×2 24bpp top-down image

import { assertEquals } from "@std/assert";
import type { BitmapInfoHeader } from "@binstruct/bmp";

const dib: BitmapInfoHeader = {
  size: 40,
  width: 2,
  height: -2,
  planes: 1,
  bpp: 24,
  compression: 0,
  imageSize: 16,
  xPixelsPerMeter: 2835,
  yPixelsPerMeter: 2835,
  colorsUsed: 0,
  importantColors: 0,
};

assertEquals(dib.size, 40);
assertEquals(dib.height < 0, true);

Properties

size: number
width: number
height: number
planes: number
bpp: number
imageSize: number
colorsUsed: number

Usage

import { type BitmapInfoHeader } from ".";