image-size/dist/types/png.cjs

get dimensions of any image file

'use strict';

// lib/types/utils.ts
var decoder = new TextDecoder();
var toUTF8String = (input, start = 0, end = input.length) => decoder.decode(input.slice(start, end));
var getView = (input, offset) => new DataView(input.buffer, input.byteOffset + offset);
var readUInt32BE = (input, offset = 0) => getView(input, offset).getUint32(0, false);

// lib/types/png.ts
var pngSignature = "PNG\r\n\n";
var pngImageHeaderChunkName = "IHDR";
var pngFriedChunkName = "CgBI";
var PNG = {
  validate(input) {
    if (pngSignature === toUTF8String(input, 1, 8)) {
      let chunkName = toUTF8String(input, 12, 16);
      if (chunkName === pngFriedChunkName) {
        chunkName = toUTF8String(input, 28, 32);
      }
      if (chunkName !== pngImageHeaderChunkName) {
        throw new TypeError("Invalid PNG");
      }
      return true;
    }
    return false;
  },
  calculate(input) {
    if (toUTF8String(input, 12, 16) === pngFriedChunkName) {
      return {
        height: readUInt32BE(input, 36),
        width: readUInt32BE(input, 32)
      };
    }
    return {
      height: readUInt32BE(input, 20),
      width: readUInt32BE(input, 16)
    };
  }
};

exports.PNG = PNG;