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node_modules/pngjs/lib/packer.js

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+"use strict";
+
+let constants = require("./constants");
+let CrcStream = require("./crc");
+let bitPacker = require("./bitpacker");
+let filter = require("./filter-pack");
+let zlib = require("zlib");
+
+let Packer = (module.exports = function (options) {
+  this._options = options;
+
+  options.deflateChunkSize = options.deflateChunkSize || 32 * 1024;
+  options.deflateLevel =
+    options.deflateLevel != null ? options.deflateLevel : 9;
+  options.deflateStrategy =
+    options.deflateStrategy != null ? options.deflateStrategy : 3;
+  options.inputHasAlpha =
+    options.inputHasAlpha != null ? options.inputHasAlpha : true;
+  options.deflateFactory = options.deflateFactory || zlib.createDeflate;
+  options.bitDepth = options.bitDepth || 8;
+  // This is outputColorType
+  options.colorType =
+    typeof options.colorType === "number"
+      ? options.colorType
+      : constants.COLORTYPE_COLOR_ALPHA;
+  options.inputColorType =
+    typeof options.inputColorType === "number"
+      ? options.inputColorType
+      : constants.COLORTYPE_COLOR_ALPHA;
+
+  if (
+    [
+      constants.COLORTYPE_GRAYSCALE,
+      constants.COLORTYPE_COLOR,
+      constants.COLORTYPE_COLOR_ALPHA,
+      constants.COLORTYPE_ALPHA,
+    ].indexOf(options.colorType) === -1
+  ) {
+    throw new Error(
+      "option color type:" + options.colorType + " is not supported at present"
+    );
+  }
+  if (
+    [
+      constants.COLORTYPE_GRAYSCALE,
+      constants.COLORTYPE_COLOR,
+      constants.COLORTYPE_COLOR_ALPHA,
+      constants.COLORTYPE_ALPHA,
+    ].indexOf(options.inputColorType) === -1
+  ) {
+    throw new Error(
+      "option input color type:" +
+        options.inputColorType +
+        " is not supported at present"
+    );
+  }
+  if (options.bitDepth !== 8 && options.bitDepth !== 16) {
+    throw new Error(
+      "option bit depth:" + options.bitDepth + " is not supported at present"
+    );
+  }
+});
+
+Packer.prototype.getDeflateOptions = function () {
+  return {
+    chunkSize: this._options.deflateChunkSize,
+    level: this._options.deflateLevel,
+    strategy: this._options.deflateStrategy,
+  };
+};
+
+Packer.prototype.createDeflate = function () {
+  return this._options.deflateFactory(this.getDeflateOptions());
+};
+
+Packer.prototype.filterData = function (data, width, height) {
+  // convert to correct format for filtering (e.g. right bpp and bit depth)
+  let packedData = bitPacker(data, width, height, this._options);
+
+  // filter pixel data
+  let bpp = constants.COLORTYPE_TO_BPP_MAP[this._options.colorType];
+  let filteredData = filter(packedData, width, height, this._options, bpp);
+  return filteredData;
+};
+
+Packer.prototype._packChunk = function (type, data) {
+  let len = data ? data.length : 0;
+  let buf = Buffer.alloc(len + 12);
+
+  buf.writeUInt32BE(len, 0);
+  buf.writeUInt32BE(type, 4);
+
+  if (data) {
+    data.copy(buf, 8);
+  }
+
+  buf.writeInt32BE(
+    CrcStream.crc32(buf.slice(4, buf.length - 4)),
+    buf.length - 4
+  );
+  return buf;
+};
+
+Packer.prototype.packGAMA = function (gamma) {
+  let buf = Buffer.alloc(4);
+  buf.writeUInt32BE(Math.floor(gamma * constants.GAMMA_DIVISION), 0);
+  return this._packChunk(constants.TYPE_gAMA, buf);
+};
+
+Packer.prototype.packIHDR = function (width, height) {
+  let buf = Buffer.alloc(13);
+  buf.writeUInt32BE(width, 0);
+  buf.writeUInt32BE(height, 4);
+  buf[8] = this._options.bitDepth; // Bit depth
+  buf[9] = this._options.colorType; // colorType
+  buf[10] = 0; // compression
+  buf[11] = 0; // filter
+  buf[12] = 0; // interlace
+
+  return this._packChunk(constants.TYPE_IHDR, buf);
+};
+
+Packer.prototype.packIDAT = function (data) {
+  return this._packChunk(constants.TYPE_IDAT, data);
+};
+
+Packer.prototype.packIEND = function () {
+  return this._packChunk(constants.TYPE_IEND, null);
+};