gecko-dev/image/test/unit/test_encoder_png.js

/*
 * Test for PNG encoding in ImageLib
 *
 */

var png1A = {
  // A 3x3 image, rows are red, green, blue.
  // RGB format, transparency defaults.

  transparency: null,

  frames: [
    {
      width: 3,
      height: 3,

      format: Ci.imgIEncoder.INPUT_FORMAT_RGB,
      stride: 9,

      pixels: [
        255, 0, 0, 255, 0, 0, 255, 0, 0, 0, 255, 0, 0, 255, 0, 0, 255, 0, 0, 0,
        255, 0, 0, 255, 0, 0, 255,
      ],
    },
  ],
  expected:
    "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAIAAADZSiLoAAAAFElEQVQIW2P8zwAFjAwwJiMDjAkANiQDAUpvlioAAAAASUVORK5CYII=",
};

var png1B = {
  // A 3x3 image, rows are red, green, blue.
  // RGB format, transparency=none.

  transparency: "none",

  frames: [
    {
      width: 3,
      height: 3,

      format: Ci.imgIEncoder.INPUT_FORMAT_RGB,
      stride: 9,

      pixels: [
        255, 0, 0, 255, 0, 0, 255, 0, 0, 0, 255, 0, 0, 255, 0, 0, 255, 0, 0, 0,
        255, 0, 0, 255, 0, 0, 255,
      ],
    },
  ],
  expected:
    "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAIAAADZSiLoAAAAFElEQVQIW2P8zwAFjAwwJiMDjAkANiQDAUpvlioAAAAASUVORK5CYII=",
};

var png2A = {
  // A 3x3 image, rows are: red, green, blue. Columns are: 0%, 33%, 66% transparent.

  transparency: null,

  frames: [
    {
      width: 3,
      height: 3,

      format: Ci.imgIEncoder.INPUT_FORMAT_RGBA,
      stride: 12,

      pixels: [
        255, 0, 0, 255, 255, 0, 0, 170, 255, 0, 0, 85, 0, 255, 0, 255, 0, 255,
        0, 170, 0, 255, 0, 85, 0, 0, 255, 255, 0, 0, 255, 170, 0, 0, 255, 85,
      ],
    },
  ],
  expected:
    "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAYAAABWKLW/AAAAGUlEQVQIW2P8z8AARAyrQZgRyETiMPyHcwDKCwoAGxxLEQAAAABJRU5ErkJggg==",
};

var png2B = {
  // A 3x3 image, rows are: red, green, blue. Columns are: 0%, 33%, 66% transparent,
  // but transparency will be ignored.

  transparency: "none",

  frames: [
    {
      width: 3,
      height: 3,

      format: Ci.imgIEncoder.INPUT_FORMAT_RGBA,
      stride: 12,

      pixels: [
        255, 0, 0, 255, 255, 0, 0, 170, 255, 0, 0, 85, 0, 255, 0, 255, 0, 255,
        0, 170, 0, 255, 0, 85, 0, 0, 255, 255, 0, 0, 255, 170, 0, 0, 255, 85,
      ],
    },
  ],
  expected:
    "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAIAAADZSiLoAAAAFElEQVQIW2P8zwAFjAwwJiMDjAkANiQDAUpvlioAAAAASUVORK5CYII=",
};

// Main test entry point.
function run_test() {
  dump("Checking png1A...\n");
  run_test_for(png1A);
  dump("Checking png1B...\n");
  run_test_for(png1B);
  dump("Checking png2A...\n");
  run_test_for(png2A);
  dump("Checking png2B...\n");
  run_test_for(png2B);
}

function run_test_for(input) {
  var encoder, dataURL;

  encoder = encodeImage(input);
  dataURL = makeDataURL(encoder, "image/png");
  Assert.equal(dataURL, input.expected);

  encoder = encodeImageAsync(input);
  dataURL = makeDataURLFromAsync(encoder, "image/png", input.expected);
}

function encodeImage(input) {
  var encoder =
    Cc["@mozilla.org/image/encoder;2?type=image/png"].createInstance();
  encoder.QueryInterface(Ci.imgIEncoder);

  var options = "";
  if (input.transparency) {
    options += "transparency=" + input.transparency;
  }

  var frame = input.frames[0];
  encoder.initFromData(
    frame.pixels,
    frame.pixels.length,
    frame.width,
    frame.height,
    frame.stride,
    frame.format,
    options
  );
  return encoder;
}

function _encodeImageAsyncFactory(frame, options, encoder) {
  function finishEncode() {
    encoder.addImageFrame(
      frame.pixels,
      frame.pixels.length,
      frame.width,
      frame.height,
      frame.stride,
      frame.format,
      options
    );
    encoder.endImageEncode();
  }
  return finishEncode;
}

function encodeImageAsync(input) {
  var encoder =
    Cc["@mozilla.org/image/encoder;2?type=image/png"].createInstance();
  encoder.QueryInterface(Ci.imgIEncoder);

  var options = "";
  if (input.transparency) {
    options += "transparency=" + input.transparency;
  }

  var frame = input.frames[0];
  encoder.startImageEncode(frame.width, frame.height, frame.format, options);

  do_timeout(50, _encodeImageAsyncFactory(frame, options, encoder));
  return encoder;
}

function makeDataURL(encoder, mimetype) {
  var rawStream = encoder.QueryInterface(Ci.nsIInputStream);

  var stream = Cc["@mozilla.org/binaryinputstream;1"].createInstance();
  stream.QueryInterface(Ci.nsIBinaryInputStream);

  stream.setInputStream(rawStream);

  var bytes = stream.readByteArray(stream.available()); // returns int[]

  var base64String = toBase64(bytes);

  return "data:" + mimetype + ";base64," + base64String;
}

function makeDataURLFromAsync(encoder, mimetype, expected) {
  do_test_pending();
  var rawStream = encoder.QueryInterface(Ci.nsIAsyncInputStream);

  var currentThread =
    Cc["@mozilla.org/thread-manager;1"].getService().currentThread;

  var bytes = [];

  var binarystream = Cc["@mozilla.org/binaryinputstream;1"].createInstance();
  binarystream.QueryInterface(Ci.nsIBinaryInputStream);

  var asyncReader = {
    onInputStreamReady(stream) {
      binarystream.setInputStream(stream);
      var available = 0;
      try {
        available = stream.available();
      } catch (e) {}

      if (available > 0) {
        bytes = bytes.concat(binarystream.readByteArray(available));
        stream.asyncWait(this, 0, 0, currentThread);
      } else {
        var base64String = toBase64(bytes);
        var dataURL = "data:" + mimetype + ";base64," + base64String;
        Assert.equal(dataURL, expected);
        do_test_finished();
      }
    },
  };
  rawStream.asyncWait(asyncReader, 0, 0, currentThread);
}

/* toBase64 copied from extensions/xml-rpc/src/nsXmlRpcClient.js */

/* Convert data (an array of integers) to a Base64 string. */
const toBase64Table =
  // eslint-disable-next-line no-useless-concat
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" + "0123456789+/";
const base64Pad = "=";
function toBase64(data) {
  var result = "";
  var length = data.length;
  var i;
  // Convert every three bytes to 4 ascii characters.
  for (i = 0; i < length - 2; i += 3) {
    result += toBase64Table[data[i] >> 2];
    result += toBase64Table[((data[i] & 0x03) << 4) + (data[i + 1] >> 4)];
    result += toBase64Table[((data[i + 1] & 0x0f) << 2) + (data[i + 2] >> 6)];
    result += toBase64Table[data[i + 2] & 0x3f];
  }

  // Convert the remaining 1 or 2 bytes, pad out to 4 characters.
  if (length % 3) {
    i = length - (length % 3);
    result += toBase64Table[data[i] >> 2];
    if (length % 3 == 2) {
      result += toBase64Table[((data[i] & 0x03) << 4) + (data[i + 1] >> 4)];
      result += toBase64Table[(data[i + 1] & 0x0f) << 2];
      result += base64Pad;
    } else {
      result += toBase64Table[(data[i] & 0x03) << 4];
      result += base64Pad + base64Pad;
    }
  }

  return result;
}