YueWen/node_modules/pngjs/lib/packer-sync.js

'use strict';

var hasSyncZlib = true;
var zlib = require('zlib');
if (!zlib.deflateSync) {
  hasSyncZlib = false;
}
var constants = require('./constants');
var Packer = require('./packer');

module.exports = function(metaData, opt) {

  if (!hasSyncZlib) {
    throw new Error('To use the sync capability of this library in old node versions, please pin pngjs to v2.3.0');
  }

  var options = opt || {};

  var packer = new Packer(options);

  var chunks = [];

  // Signature
  chunks.push(new Buffer(constants.PNG_SIGNATURE));

  // Header
  chunks.push(packer.packIHDR(metaData.width, metaData.height));

  if (metaData.gamma) {
    chunks.push(packer.packGAMA(metaData.gamma));
  }

  var filteredData = packer.filterData(metaData.data, metaData.width, metaData.height);

  // compress it
  var compressedData = zlib.deflateSync(filteredData, packer.getDeflateOptions());
  filteredData = null;

  if (!compressedData || !compressedData.length) {
    throw new Error('bad png - invalid compressed data response');
  }
  chunks.push(packer.packIDAT(compressedData));

  // End
  chunks.push(packer.packIEND());

  return Buffer.concat(chunks);
};