path: root/image/encoders/bmp/nsBMPEncoder.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsCRT.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/UniquePtrExtensions.h"
#include "nsBMPEncoder.h"
#include "prprf.h"
#include "nsString.h"
#include "nsStreamUtils.h"
#include "nsTArray.h"
#include "mozilla/CheckedInt.h"

using namespace mozilla;
using namespace mozilla::image;
using namespace mozilla::image::bmp;

NS_IMPL_ISUPPORTS(nsBMPEncoder, imgIEncoder, nsIInputStream,
                  nsIAsyncInputStream)

nsBMPEncoder::nsBMPEncoder() : mImageBufferStart(nullptr),
                               mImageBufferCurr(0),
                               mImageBufferSize(0),
                               mImageBufferReadPoint(0),
                               mFinished(false),
                               mCallback(nullptr),
                               mCallbackTarget(nullptr),
                               mNotifyThreshold(0)
{
}

nsBMPEncoder::~nsBMPEncoder()
{
  if (mImageBufferStart) {
    free(mImageBufferStart);
    mImageBufferStart = nullptr;
    mImageBufferCurr = nullptr;
  }
}

// nsBMPEncoder::InitFromData
//
// One output option is supported: bpp=<bpp_value>
// bpp specifies the bits per pixel to use where bpp_value can be 24 or 32
NS_IMETHODIMP
nsBMPEncoder::InitFromData(const uint8_t* aData,
                           uint32_t aLength, // (unused, req'd by JS)
                           uint32_t aWidth,
                           uint32_t aHeight,
                           uint32_t aStride,
                           uint32_t aInputFormat,
                           const nsAString& aOutputOptions)
{
  // validate input format
  if (aInputFormat != INPUT_FORMAT_RGB &&
      aInputFormat != INPUT_FORMAT_RGBA &&
      aInputFormat != INPUT_FORMAT_HOSTARGB) {
    return NS_ERROR_INVALID_ARG;
  }

  CheckedInt32 check = CheckedInt32(aWidth) * 4;
  if (MOZ_UNLIKELY(!check.isValid())) {
    return NS_ERROR_INVALID_ARG;
  }

  // Stride is the padded width of each row, so it better be longer
  if ((aInputFormat == INPUT_FORMAT_RGB &&
       aStride < aWidth * 3) ||
      ((aInputFormat == INPUT_FORMAT_RGBA ||
        aInputFormat == INPUT_FORMAT_HOSTARGB) &&
       aStride < aWidth * 4)) {
      NS_WARNING("Invalid stride for InitFromData");
      return NS_ERROR_INVALID_ARG;
  }

  nsresult rv;
  rv = StartImageEncode(aWidth, aHeight, aInputFormat, aOutputOptions);
  if (NS_FAILED(rv)) {
    return rv;
  }

  rv = AddImageFrame(aData, aLength, aWidth, aHeight, aStride,
                     aInputFormat, aOutputOptions);
  if (NS_FAILED(rv)) {
    return rv;
  }

  rv = EndImageEncode();
  return rv;
}

// Just a helper method to make it explicit in calculations that we are dealing
// with bytes and not bits
static inline uint16_t
BytesPerPixel(uint16_t aBPP)
{
  return aBPP / 8;
}

// Calculates the number of padding bytes that are needed per row of image data
static inline uint32_t
PaddingBytes(uint16_t aBPP, uint32_t aWidth)
{
  uint32_t rowSize = aWidth * BytesPerPixel(aBPP);
  uint8_t paddingSize = 0;
  if (rowSize % 4) {
    paddingSize = (4 - (rowSize % 4));
  }
  return paddingSize;
}

// See ::InitFromData for other info.
NS_IMETHODIMP
nsBMPEncoder::StartImageEncode(uint32_t aWidth,
                               uint32_t aHeight,
                               uint32_t aInputFormat,
                               const nsAString& aOutputOptions)
{
  // can't initialize more than once
  if (mImageBufferStart || mImageBufferCurr) {
    return NS_ERROR_ALREADY_INITIALIZED;
  }

  // validate input format
  if (aInputFormat != INPUT_FORMAT_RGB &&
      aInputFormat != INPUT_FORMAT_RGBA &&
      aInputFormat != INPUT_FORMAT_HOSTARGB) {
    return NS_ERROR_INVALID_ARG;
  }

  // parse and check any provided output options
  Version version;
  uint16_t bpp;
  nsresult rv = ParseOptions(aOutputOptions, version, bpp);
  if (NS_FAILED(rv)) {
    return rv;
  }
  MOZ_ASSERT(bpp <= 32);

  rv = InitFileHeader(version, bpp, aWidth, aHeight);
  if (NS_FAILED(rv)) {
    return rv;
  }
  rv = InitInfoHeader(version, bpp, aWidth, aHeight);
  if (NS_FAILED(rv)) {
    return rv;
  }

  mImageBufferSize = mBMPFileHeader.filesize;
  mImageBufferStart = static_cast<uint8_t*>(malloc(mImageBufferSize));
  if (!mImageBufferStart) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  mImageBufferCurr = mImageBufferStart;

  EncodeFileHeader();
  EncodeInfoHeader();

  return NS_OK;
}

// Returns the number of bytes in the image buffer used.
// For a BMP file, this is all bytes in the buffer.
NS_IMETHODIMP
nsBMPEncoder::GetImageBufferUsed(uint32_t* aOutputSize)
{
  NS_ENSURE_ARG_POINTER(aOutputSize);
  *aOutputSize = mImageBufferSize;
  return NS_OK;
}

// Returns a pointer to the start of the image buffer
NS_IMETHODIMP
nsBMPEncoder::GetImageBuffer(char** aOutputBuffer)
{
  NS_ENSURE_ARG_POINTER(aOutputBuffer);
  *aOutputBuffer = reinterpret_cast<char*>(mImageBufferStart);
  return NS_OK;
}

NS_IMETHODIMP
nsBMPEncoder::AddImageFrame(const uint8_t* aData,
                            uint32_t aLength, // (unused, req'd by JS)
                            uint32_t aWidth,
                            uint32_t aHeight,
                            uint32_t aStride,
                            uint32_t aInputFormat,
                            const nsAString& aFrameOptions)
{
  // must be initialized
  if (!mImageBufferStart || !mImageBufferCurr) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  // validate input format
  if (aInputFormat != INPUT_FORMAT_RGB &&
      aInputFormat != INPUT_FORMAT_RGBA &&
      aInputFormat != INPUT_FORMAT_HOSTARGB) {
    return NS_ERROR_INVALID_ARG;
  }

  if (mBMPInfoHeader.width < 0) {
    return NS_ERROR_ILLEGAL_VALUE;
  }

  CheckedUint32 size =
    CheckedUint32(mBMPInfoHeader.width) * CheckedUint32(BytesPerPixel(mBMPInfoHeader.bpp));
  if (MOZ_UNLIKELY(!size.isValid())) {
    return NS_ERROR_FAILURE;
  }

  auto row = MakeUniqueFallible<uint8_t[]>(size.value());
  if (!row) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  CheckedUint32 check = CheckedUint32(mBMPInfoHeader.height) * aStride;
  if (MOZ_UNLIKELY(!check.isValid())) {
    return NS_ERROR_FAILURE;
  }

  // write each row: if we add more input formats, we may want to
  // generalize the conversions
  if (aInputFormat == INPUT_FORMAT_HOSTARGB) {
    // BMP requires RGBA with post-multiplied alpha, so we need to convert
    for (int32_t y = mBMPInfoHeader.height - 1; y >= 0 ; y --) {
      ConvertHostARGBRow(&aData[y * aStride], row, mBMPInfoHeader.width);
      if(mBMPInfoHeader.bpp == 24) {
        EncodeImageDataRow24(row.get());
      } else {
        EncodeImageDataRow32(row.get());
      }
    }
  } else if (aInputFormat == INPUT_FORMAT_RGBA) {
    // simple RGBA, no conversion needed
    for (int32_t y = 0; y < mBMPInfoHeader.height; y++) {
      if (mBMPInfoHeader.bpp == 24) {
        EncodeImageDataRow24(row.get());
      } else {
        EncodeImageDataRow32(row.get());
      }
    }
  } else if (aInputFormat == INPUT_FORMAT_RGB) {
    // simple RGB, no conversion needed
    for (int32_t y = 0; y < mBMPInfoHeader.height; y++) {
      if (mBMPInfoHeader.bpp == 24) {
        EncodeImageDataRow24(&aData[y * aStride]);
      } else {
        EncodeImageDataRow32(&aData[y * aStride]);
      }
    }
  } else {
    NS_NOTREACHED("Bad format type");
    return NS_ERROR_INVALID_ARG;
  }

  return NS_OK;
}


NS_IMETHODIMP
nsBMPEncoder::EndImageEncode()
{
  // must be initialized
  if (!mImageBufferStart || !mImageBufferCurr) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  mFinished = true;
  NotifyListener();

  // if output callback can't get enough memory, it will free our buffer
  if (!mImageBufferStart || !mImageBufferCurr) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  return NS_OK;
}


// Parses the encoder options and sets the bits per pixel to use
// See InitFromData for a description of the parse options
nsresult
nsBMPEncoder::ParseOptions(const nsAString& aOptions, Version& aVersionOut,
                           uint16_t& aBppOut)
{
  aVersionOut = VERSION_3;
  aBppOut = 24;

  // Parse the input string into a set of name/value pairs.
  // From a format like: name=value;bpp=<bpp_value>;name=value
  // to format: [0] = name=value, [1] = bpp=<bpp_value>, [2] = name=value
  nsTArray<nsCString> nameValuePairs;
  if (!ParseString(NS_ConvertUTF16toUTF8(aOptions), ';', nameValuePairs)) {
    return NS_ERROR_INVALID_ARG;
  }

  // For each name/value pair in the set
  for (uint32_t i = 0; i < nameValuePairs.Length(); ++i) {

    // Split the name value pair [0] = name, [1] = value
    nsTArray<nsCString> nameValuePair;
    if (!ParseString(nameValuePairs[i], '=', nameValuePair)) {
      return NS_ERROR_INVALID_ARG;
    }
    if (nameValuePair.Length() != 2) {
      return NS_ERROR_INVALID_ARG;
    }

    // Parse the bpp portion of the string name=value;version=<version_value>;
    // name=value
    if (nameValuePair[0].Equals("version",
                                nsCaseInsensitiveCStringComparator())) {
      if (nameValuePair[1].EqualsLiteral("3")) {
        aVersionOut = VERSION_3;
      } else if (nameValuePair[1].EqualsLiteral("5")) {
        aVersionOut = VERSION_5;
      } else {
        return NS_ERROR_INVALID_ARG;
      }
    }

    // Parse the bpp portion of the string name=value;bpp=<bpp_value>;name=value
    if (nameValuePair[0].Equals("bpp", nsCaseInsensitiveCStringComparator())) {
      if (nameValuePair[1].EqualsLiteral("24")) {
        aBppOut = 24;
      } else if (nameValuePair[1].EqualsLiteral("32")) {
        aBppOut = 32;
      } else {
        return NS_ERROR_INVALID_ARG;
      }
    }
  }

  return NS_OK;
}

NS_IMETHODIMP
nsBMPEncoder::Close()
{
  if (mImageBufferStart) {
    free(mImageBufferStart);
    mImageBufferStart = nullptr;
    mImageBufferSize = 0;
    mImageBufferReadPoint = 0;
    mImageBufferCurr = nullptr;
  }

  return NS_OK;
}

// Obtains the available bytes to read
NS_IMETHODIMP
nsBMPEncoder::Available(uint64_t* _retval)
{
  if (!mImageBufferStart || !mImageBufferCurr) {
    return NS_BASE_STREAM_CLOSED;
  }

  *_retval = GetCurrentImageBufferOffset() - mImageBufferReadPoint;
  return NS_OK;
}

// [noscript] Reads bytes which are available
NS_IMETHODIMP
nsBMPEncoder::Read(char* aBuf, uint32_t aCount, uint32_t* _retval)
{
  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
}

// [noscript] Reads segments
NS_IMETHODIMP
nsBMPEncoder::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
                           uint32_t aCount, uint32_t* _retval)
{
  uint32_t maxCount = GetCurrentImageBufferOffset() - mImageBufferReadPoint;
  if (maxCount == 0) {
    *_retval = 0;
    return mFinished ? NS_OK : NS_BASE_STREAM_WOULD_BLOCK;
  }

  if (aCount > maxCount) {
    aCount = maxCount;
  }
  nsresult rv = aWriter(this, aClosure,
                        reinterpret_cast<const char*>(mImageBufferStart +
                                                      mImageBufferReadPoint),
                        0, aCount, _retval);
  if (NS_SUCCEEDED(rv)) {
    NS_ASSERTION(*_retval <= aCount, "bad write count");
    mImageBufferReadPoint += *_retval;
  }
  // errors returned from the writer end here!
  return NS_OK;
}

NS_IMETHODIMP
nsBMPEncoder::IsNonBlocking(bool* _retval)
{
  *_retval = true;
  return NS_OK;
}

NS_IMETHODIMP
nsBMPEncoder::AsyncWait(nsIInputStreamCallback* aCallback,
                        uint32_t aFlags,
                        uint32_t aRequestedCount,
                        nsIEventTarget* aTarget)
{
  if (aFlags != 0) {
    return NS_ERROR_NOT_IMPLEMENTED;
  }

  if (mCallback || mCallbackTarget) {
    return NS_ERROR_UNEXPECTED;
  }

  mCallbackTarget = aTarget;
  // 0 means "any number of bytes except 0"
  mNotifyThreshold = aRequestedCount;
  if (!aRequestedCount) {
    mNotifyThreshold = 1024; // We don't want to notify incessantly
  }

  // We set the callback absolutely last, because NotifyListener uses it to
  // determine if someone needs to be notified.  If we don't set it last,
  // NotifyListener might try to fire off a notification to a null target
  // which will generally cause non-threadsafe objects to be used off the
  // main thread
  mCallback = aCallback;

  // What we are being asked for may be present already
  NotifyListener();
  return NS_OK;
}

NS_IMETHODIMP
nsBMPEncoder::CloseWithStatus(nsresult aStatus)
{
  return Close();
}

// nsBMPEncoder::ConvertHostARGBRow
//
//    Our colors are stored with premultiplied alphas, but we need
//    an output with no alpha in machine-independent byte order.
//
void
nsBMPEncoder::ConvertHostARGBRow(const uint8_t* aSrc,
                                 const UniquePtr<uint8_t[]>& aDest,
                                 uint32_t aPixelWidth)
{
  uint16_t bytes = BytesPerPixel(mBMPInfoHeader.bpp);

  if (mBMPInfoHeader.bpp == 32) {
    for (uint32_t x = 0; x < aPixelWidth; x++) {
      const uint32_t& pixelIn = ((const uint32_t*)(aSrc))[x];
      uint8_t* pixelOut = &aDest[x * bytes];

      pixelOut[0] = (pixelIn & 0x00ff0000) >> 16;
      pixelOut[1] = (pixelIn & 0x0000ff00) >>  8;
      pixelOut[2] = (pixelIn & 0x000000ff) >>  0;
      pixelOut[3] = (pixelIn & 0xff000000) >> 24;
    }
  } else {
    for (uint32_t x = 0; x < aPixelWidth; x++) {
      const uint32_t& pixelIn = ((const uint32_t*)(aSrc))[x];
      uint8_t* pixelOut = &aDest[x * bytes];

      pixelOut[0] = (pixelIn & 0xff0000) >> 16;
      pixelOut[1] = (pixelIn & 0x00ff00) >>  8;
      pixelOut[2] = (pixelIn & 0x0000ff) >>  0;
    }
  }
}

void
nsBMPEncoder::NotifyListener()
{
  if (mCallback &&
      (GetCurrentImageBufferOffset() - mImageBufferReadPoint >=
       mNotifyThreshold || mFinished)) {
    nsCOMPtr<nsIInputStreamCallback> callback;
    if (mCallbackTarget) {
      callback = NS_NewInputStreamReadyEvent(mCallback, mCallbackTarget);
    } else {
      callback = mCallback;
    }

    NS_ASSERTION(callback, "Shouldn't fail to make the callback");
    // Null the callback first because OnInputStreamReady could
    // reenter AsyncWait
    mCallback = nullptr;
    mCallbackTarget = nullptr;
    mNotifyThreshold = 0;

    callback->OnInputStreamReady(this);
  }
}

// Initializes the BMP file header mBMPFileHeader to the passed in values
nsresult
nsBMPEncoder::InitFileHeader(Version aVersion, uint16_t aBPP, uint32_t aWidth,
                             uint32_t aHeight)
{
  memset(&mBMPFileHeader, 0, sizeof(mBMPFileHeader));
  mBMPFileHeader.signature[0] = 'B';
  mBMPFileHeader.signature[1] = 'M';

  if (aVersion == VERSION_3) {
    mBMPFileHeader.dataoffset = FILE_HEADER_LENGTH + InfoHeaderLength::WIN_V3;
  } else { // aVersion == 5
    mBMPFileHeader.dataoffset = FILE_HEADER_LENGTH + InfoHeaderLength::WIN_V5;
  }

  // The color table is present only if BPP is <= 8
  if (aBPP <= 8) {
    uint32_t numColors = 1 << aBPP;
    mBMPFileHeader.dataoffset += 4 * numColors;
    CheckedUint32 filesize =
      CheckedUint32(mBMPFileHeader.dataoffset) + CheckedUint32(aWidth) * aHeight;
    if (MOZ_UNLIKELY(!filesize.isValid())) {
      return NS_ERROR_INVALID_ARG;
    }
    mBMPFileHeader.filesize = filesize.value();
  } else {
    CheckedUint32 filesize =
      CheckedUint32(mBMPFileHeader.dataoffset) +
        (CheckedUint32(aWidth) * BytesPerPixel(aBPP) + PaddingBytes(aBPP, aWidth)) * aHeight;
    if (MOZ_UNLIKELY(!filesize.isValid())) {
      return NS_ERROR_INVALID_ARG;
    }
    mBMPFileHeader.filesize = filesize.value();
  }

  mBMPFileHeader.reserved = 0;

  return NS_OK;
}

#define ENCODE(pImageBufferCurr, value) \
    memcpy(*pImageBufferCurr, &value, sizeof value); \
    *pImageBufferCurr += sizeof value;

// Initializes the bitmap info header mBMPInfoHeader to the passed in values
nsresult
nsBMPEncoder::InitInfoHeader(Version aVersion, uint16_t aBPP, uint32_t aWidth,
                             uint32_t aHeight)
{
  memset(&mBMPInfoHeader, 0, sizeof(mBMPInfoHeader));
  if (aVersion == VERSION_3) {
    mBMPInfoHeader.bihsize = InfoHeaderLength::WIN_V3;
  } else {
    MOZ_ASSERT(aVersion == VERSION_5);
    mBMPInfoHeader.bihsize = InfoHeaderLength::WIN_V5;
  }

  CheckedInt32 width(aWidth);
  CheckedInt32 height(aHeight);
  if (MOZ_UNLIKELY(!width.isValid() || !height.isValid())) {
    return NS_ERROR_INVALID_ARG;
  }
  mBMPInfoHeader.width = width.value();
  mBMPInfoHeader.height = height.value();

  mBMPInfoHeader.planes = 1;
  mBMPInfoHeader.bpp = aBPP;
  mBMPInfoHeader.compression = 0;
  mBMPInfoHeader.colors = 0;
  mBMPInfoHeader.important_colors = 0;

  CheckedUint32 check = CheckedUint32(aWidth) * BytesPerPixel(aBPP);
  if (MOZ_UNLIKELY(!check.isValid())) {
    return NS_ERROR_INVALID_ARG;
  }

  if (aBPP <= 8) {
    CheckedUint32 imagesize = CheckedUint32(aWidth) * aHeight;
    if (MOZ_UNLIKELY(!imagesize.isValid())) {
      return NS_ERROR_INVALID_ARG;
    }
    mBMPInfoHeader.image_size = imagesize.value();
  } else {
    CheckedUint32 imagesize =
      (CheckedUint32(aWidth) * BytesPerPixel(aBPP) + PaddingBytes(aBPP, aWidth)) * CheckedUint32(aHeight);
    if (MOZ_UNLIKELY(!imagesize.isValid())) {
      return NS_ERROR_INVALID_ARG;
    }
    mBMPInfoHeader.image_size = imagesize.value();
  }
  mBMPInfoHeader.xppm = 0;
  mBMPInfoHeader.yppm = 0;
  if (aVersion >= VERSION_5) {
      mBMPInfoHeader.red_mask   = 0x000000FF;
      mBMPInfoHeader.green_mask = 0x0000FF00;
      mBMPInfoHeader.blue_mask  = 0x00FF0000;
      mBMPInfoHeader.alpha_mask = 0xFF000000;
      mBMPInfoHeader.color_space = V5InfoHeader::COLOR_SPACE_LCS_SRGB;
      mBMPInfoHeader.white_point.r.x = 0;
      mBMPInfoHeader.white_point.r.y = 0;
      mBMPInfoHeader.white_point.r.z = 0;
      mBMPInfoHeader.white_point.g.x = 0;
      mBMPInfoHeader.white_point.g.y = 0;
      mBMPInfoHeader.white_point.g.z = 0;
      mBMPInfoHeader.white_point.b.x = 0;
      mBMPInfoHeader.white_point.b.y = 0;
      mBMPInfoHeader.white_point.b.z = 0;
      mBMPInfoHeader.gamma_red = 0;
      mBMPInfoHeader.gamma_green = 0;
      mBMPInfoHeader.gamma_blue = 0;
      mBMPInfoHeader.intent = 0;
      mBMPInfoHeader.profile_offset = 0;
      mBMPInfoHeader.profile_size = 0;
      mBMPInfoHeader.reserved = 0;
  }

  return NS_OK;
}

// Encodes the BMP file header mBMPFileHeader
void
nsBMPEncoder::EncodeFileHeader()
{
  FileHeader littleEndianBFH = mBMPFileHeader;
  NativeEndian::swapToLittleEndianInPlace(&littleEndianBFH.filesize, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianBFH.reserved, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianBFH.dataoffset, 1);

  ENCODE(&mImageBufferCurr, littleEndianBFH.signature);
  ENCODE(&mImageBufferCurr, littleEndianBFH.filesize);
  ENCODE(&mImageBufferCurr, littleEndianBFH.reserved);
  ENCODE(&mImageBufferCurr, littleEndianBFH.dataoffset);
}

// Encodes the BMP infor header mBMPInfoHeader
void
nsBMPEncoder::EncodeInfoHeader()
{
  V5InfoHeader littleEndianmBIH = mBMPInfoHeader;
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.bihsize, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.width, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.height, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.planes, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.bpp, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.compression, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.image_size, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.xppm, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.yppm, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.colors, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.important_colors,
                                          1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.red_mask, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.green_mask, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.blue_mask, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.alpha_mask, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.color_space, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.r.x, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.r.y, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.r.z, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.g.x, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.g.y, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.g.z, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.b.x, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.b.y, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.b.z, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.gamma_red, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.gamma_green, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.gamma_blue, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.intent, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.profile_offset, 1);
  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.profile_size, 1);

  ENCODE(&mImageBufferCurr, littleEndianmBIH.bihsize);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.width);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.height);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.planes);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.bpp);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.compression);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.image_size);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.xppm);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.yppm);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.colors);
  ENCODE(&mImageBufferCurr, littleEndianmBIH.important_colors);

  if (mBMPInfoHeader.bihsize > InfoHeaderLength::WIN_V3) {
    ENCODE(&mImageBufferCurr, littleEndianmBIH.red_mask);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.green_mask);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.blue_mask);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.alpha_mask);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.color_space);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.r.x);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.r.y);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.r.z);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.g.x);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.g.y);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.g.z);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.b.x);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.b.y);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.b.z);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.gamma_red);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.gamma_green);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.gamma_blue);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.intent);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.profile_offset);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.profile_size);
    ENCODE(&mImageBufferCurr, littleEndianmBIH.reserved);
  }
}

// Sets a pixel in the image buffer that doesn't have alpha data
static inline void
SetPixel24(uint8_t*& imageBufferCurr, uint8_t aRed, uint8_t aGreen,
  uint8_t aBlue)
{
  *imageBufferCurr = aBlue;
  *(imageBufferCurr + 1) = aGreen;
  *(imageBufferCurr + 2) = aRed;
}

// Sets a pixel in the image buffer with alpha data
static inline void
SetPixel32(uint8_t*& imageBufferCurr, uint8_t aRed, uint8_t aGreen,
           uint8_t aBlue, uint8_t aAlpha = 0xFF)
{
  *imageBufferCurr = aBlue;
  *(imageBufferCurr + 1) = aGreen;
  *(imageBufferCurr + 2) = aRed;
  *(imageBufferCurr + 3) = aAlpha;
}

// Encodes a row of image data which does not have alpha data
void
nsBMPEncoder::EncodeImageDataRow24(const uint8_t* aData)
{
  for (int32_t x = 0; x < mBMPInfoHeader.width; x++) {
    uint32_t pos = x * BytesPerPixel(mBMPInfoHeader.bpp);
    SetPixel24(mImageBufferCurr, aData[pos], aData[pos + 1], aData[pos + 2]);
    mImageBufferCurr += BytesPerPixel(mBMPInfoHeader.bpp);
  }

  for (uint32_t x = 0; x < PaddingBytes(mBMPInfoHeader.bpp,
                                        mBMPInfoHeader.width); x++) {
    *mImageBufferCurr++ = 0;
  }
}

// Encodes a row of image data which does have alpha data
void
nsBMPEncoder::EncodeImageDataRow32(const uint8_t* aData)
{
  for (int32_t x = 0; x < mBMPInfoHeader.width; x++) {
    uint32_t pos = x * BytesPerPixel(mBMPInfoHeader.bpp);
    SetPixel32(mImageBufferCurr, aData[pos], aData[pos + 1],
               aData[pos + 2], aData[pos + 3]);
    mImageBufferCurr += 4;
  }

  for (uint32_t x = 0; x < PaddingBytes(mBMPInfoHeader.bpp,
                                        mBMPInfoHeader.width); x++) {
    *mImageBufferCurr++ = 0;
  }
}