YueWen/node_modules/pngjs/lib/png.js

'use strict';

var util = require('util');
var Stream = require('stream');
var Parser = require('./parser-async');
var Packer = require('./packer-async');
var PNGSync = require('./png-sync');


var PNG = exports.PNG = function(options) {
  Stream.call(this);

  options = options || {}; // eslint-disable-line no-param-reassign

  // coerce pixel dimensions to integers (also coerces undefined -> 0):
  this.width = options.width | 0;
  this.height = options.height | 0;

  this.data = this.width > 0 && this.height > 0 ?
    new Buffer(4 * this.width * this.height) : null;

  if (options.fill && this.data) {
    this.data.fill(0);
  }

  this.gamma = 0;
  this.readable = this.writable = true;

  this._parser = new Parser(options);

  this._parser.on('error', this.emit.bind(this, 'error'));
  this._parser.on('close', this._handleClose.bind(this));
  this._parser.on('metadata', this._metadata.bind(this));
  this._parser.on('gamma', this._gamma.bind(this));
  this._parser.on('parsed', function(data) {
    this.data = data;
    this.emit('parsed', data);
  }.bind(this));

  this._packer = new Packer(options);
  this._packer.on('data', this.emit.bind(this, 'data'));
  this._packer.on('end', this.emit.bind(this, 'end'));
  this._parser.on('close', this._handleClose.bind(this));
  this._packer.on('error', this.emit.bind(this, 'error'));

};
util.inherits(PNG, Stream);

PNG.sync = PNGSync;

PNG.prototype.pack = function() {

  if (!this.data || !this.data.length) {
    this.emit('error', 'No data provided');
    return this;
  }

  process.nextTick(function() {
    this._packer.pack(this.data, this.width, this.height, this.gamma);
  }.bind(this));

  return this;
};


PNG.prototype.parse = function(data, callback) {

  if (callback) {
    var onParsed, onError;

    onParsed = function(parsedData) {
      this.removeListener('error', onError);

      this.data = parsedData;
      callback(null, this);
    }.bind(this);

    onError = function(err) {
      this.removeListener('parsed', onParsed);

      callback(err, null);
    }.bind(this);

    this.once('parsed', onParsed);
    this.once('error', onError);
  }

  this.end(data);
  return this;
};

PNG.prototype.write = function(data) {
  this._parser.write(data);
  return true;
};

PNG.prototype.end = function(data) {
  this._parser.end(data);
};

PNG.prototype._metadata = function(metadata) {
  this.width = metadata.width;
  this.height = metadata.height;

  this.emit('metadata', metadata);
};

PNG.prototype._gamma = function(gamma) {
  this.gamma = gamma;
};

PNG.prototype._handleClose = function() {
  if (!this._parser.writable && !this._packer.readable) {
    this.emit('close');
  }
};


PNG.bitblt = function(src, dst, srcX, srcY, width, height, deltaX, deltaY) { // eslint-disable-line max-params
  // coerce pixel dimensions to integers (also coerces undefined -> 0):
  /* eslint-disable no-param-reassign */
  srcX |= 0;
  srcY |= 0;
  width |= 0;
  height |= 0;
  deltaX |= 0;
  deltaY |= 0;
  /* eslint-enable no-param-reassign */

  if (srcX > src.width || srcY > src.height || srcX + width > src.width || srcY + height > src.height) {
    throw new Error('bitblt reading outside image');
  }

  if (deltaX > dst.width || deltaY > dst.height || deltaX + width > dst.width || deltaY + height > dst.height) {
    throw new Error('bitblt writing outside image');
  }

  for (var y = 0; y < height; y++) {
    src.data.copy(dst.data,
      ((deltaY + y) * dst.width + deltaX) << 2,
      ((srcY + y) * src.width + srcX) << 2,
      ((srcY + y) * src.width + srcX + width) << 2
    );
  }
};


PNG.prototype.bitblt = function(dst, srcX, srcY, width, height, deltaX, deltaY) { // eslint-disable-line max-params

  PNG.bitblt(this, dst, srcX, srcY, width, height, deltaX, deltaY);
  return this;
};

PNG.adjustGamma = function(src) {
  if (src.gamma) {
    for (var y = 0; y < src.height; y++) {
      for (var x = 0; x < src.width; x++) {
        var idx = (src.width * y + x) << 2;

        for (var i = 0; i < 3; i++) {
          var sample = src.data[idx + i] / 255;
          sample = Math.pow(sample, 1 / 2.2 / src.gamma);
          src.data[idx + i] = Math.round(sample * 255);
        }
      }
    }
    src.gamma = 0;
  }
};

PNG.prototype.adjustGamma = function() {
  PNG.adjustGamma(this);
};