gecko-dev/image/encoders/jpeg/nsJPEGEncoder.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 "nsJPEGEncoder.h"
#include "prprf.h"
#include "nsString.h"
#include "nsStreamUtils.h"
#include "gfxColor.h"
#include "mozilla/CheckedInt.h"

extern "C" {
#include "jpeglib.h"
}

#include <setjmp.h>
#include "jerror.h"

using namespace mozilla;

NS_IMPL_ISUPPORTS(nsJPEGEncoder, imgIEncoder, nsIInputStream,
                  nsIAsyncInputStream)

class nsJPEGEncoderInternal {
  friend class nsJPEGEncoder;

 protected:
  /**
   * Initialize destination. This is called by jpeg_start_compress() before
   * any data is actually written. It must initialize next_output_byte and
   * free_in_buffer. free_in_buffer must be initialized to a positive value.
   */
  static void initDestination(jpeg_compress_struct* cinfo);

  /**
   * This is called whenever the buffer has filled (free_in_buffer reaches
   * zero).  In typical applications, it should write out the *entire* buffer
   * (use the saved start address and buffer length; ignore the current state
   * of next_output_byte and free_in_buffer).  Then reset the pointer & count
   * to the start of the buffer, and return TRUE indicating that the buffer
   * has been dumped.  free_in_buffer must be set to a positive value when
   * TRUE is returned.  A FALSE return should only be used when I/O suspension
   * is desired (this operating mode is discussed in the next section).
   */
  static boolean emptyOutputBuffer(jpeg_compress_struct* cinfo);

  /**
   * Terminate destination --- called by jpeg_finish_compress() after all data
   * has been written.  In most applications, this must flush any data
   * remaining in the buffer.  Use either next_output_byte or free_in_buffer
   * to determine how much data is in the buffer.
   */
  static void termDestination(jpeg_compress_struct* cinfo);

  /**
   * Override the standard error method in the IJG JPEG decoder code. This
   * was mostly copied from nsJPEGDecoder.cpp
   */
  static void errorExit(jpeg_common_struct* cinfo);
};

// used to pass error info through the JPEG library
struct encoder_error_mgr {
  jpeg_error_mgr pub;
  jmp_buf setjmp_buffer;
};

nsJPEGEncoder::nsJPEGEncoder()
    : mFinished(false),
      mImageBuffer(nullptr),
      mImageBufferSize(0),
      mImageBufferUsed(0),
      mImageBufferReadPoint(0),
      mCallback(nullptr),
      mCallbackTarget(nullptr),
      mNotifyThreshold(0),
      mReentrantMonitor("nsJPEGEncoder.mReentrantMonitor") {}

nsJPEGEncoder::~nsJPEGEncoder() {
  if (mImageBuffer) {
    free(mImageBuffer);
    mImageBuffer = nullptr;
  }
}

// nsJPEGEncoder::InitFromData
//
//    One output option is supported: "quality=X" where X is an integer in the
//    range 0-100. Higher values for X give better quality.
//
//    Transparency is always discarded.

NS_IMETHODIMP
nsJPEGEncoder::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) {
  NS_ENSURE_ARG(aData);

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

  // Stride is the padded width of each row, so it better be longer (I'm afraid
  // people will not understand what stride means, so check it well)
  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;
  }

  // can't initialize more than once
  if (mImageBuffer != nullptr) {
    return NS_ERROR_ALREADY_INITIALIZED;
  }

  // options: we only have one option so this is easy
  int quality = 92;
  if (aOutputOptions.Length() > 0) {
    // have options string
    const nsString qualityPrefix(u"quality="_ns);
    if (aOutputOptions.Length() > qualityPrefix.Length() &&
        StringBeginsWith(aOutputOptions, qualityPrefix)) {
      // have quality string
      nsCString value = NS_ConvertUTF16toUTF8(
          Substring(aOutputOptions, qualityPrefix.Length()));
      int newquality = -1;
      if (PR_sscanf(value.get(), "%d", &newquality) == 1) {
        if (newquality >= 0 && newquality <= 100) {
          quality = newquality;
        } else {
          NS_WARNING(
              "Quality value out of range, should be 0-100,"
              " using default");
        }
      } else {
        NS_WARNING(
            "Quality value invalid, should be integer 0-100,"
            " using default");
      }
    } else {
      return NS_ERROR_INVALID_ARG;
    }
  }

  jpeg_compress_struct cinfo;

  // We set up the normal JPEG error routines, then override error_exit.
  // This must be done before the call to create_compress
  encoder_error_mgr errmgr;
  cinfo.err = jpeg_std_error(&errmgr.pub);
  errmgr.pub.error_exit = nsJPEGEncoderInternal::errorExit;
  // Establish the setjmp return context for my_error_exit to use.
  if (setjmp(errmgr.setjmp_buffer)) {
    // If we get here, the JPEG code has signaled an error.
    // We need to clean up the JPEG object, close the input file, and return.
    return NS_ERROR_FAILURE;
  }

  jpeg_create_compress(&cinfo);
  cinfo.image_width = aWidth;
  cinfo.image_height = aHeight;
  cinfo.input_components = 3;
  cinfo.in_color_space = JCS_RGB;
  cinfo.data_precision = 8;

  jpeg_set_defaults(&cinfo);
  jpeg_set_quality(&cinfo, quality, 1);  // quality here is 0-100
  if (quality >= 90) {
    int i;
    for (i = 0; i < MAX_COMPONENTS; i++) {
      cinfo.comp_info[i].h_samp_factor = 1;
      cinfo.comp_info[i].v_samp_factor = 1;
    }
  }

  // set up the destination manager
  jpeg_destination_mgr destmgr;
  destmgr.init_destination = nsJPEGEncoderInternal::initDestination;
  destmgr.empty_output_buffer = nsJPEGEncoderInternal::emptyOutputBuffer;
  destmgr.term_destination = nsJPEGEncoderInternal::termDestination;
  cinfo.dest = &destmgr;
  cinfo.client_data = this;

  jpeg_start_compress(&cinfo, 1);

  // feed it the rows
  if (aInputFormat == INPUT_FORMAT_RGB) {
    while (cinfo.next_scanline < cinfo.image_height) {
      const uint8_t* row = &aData[cinfo.next_scanline * aStride];
      jpeg_write_scanlines(&cinfo, const_cast<uint8_t**>(&row), 1);
    }
  } else if (aInputFormat == INPUT_FORMAT_RGBA) {
    UniquePtr<uint8_t[]> rowptr = MakeUnique<uint8_t[]>(aWidth * 3);
    uint8_t* row = rowptr.get();
    while (cinfo.next_scanline < cinfo.image_height) {
      ConvertRGBARow(&aData[cinfo.next_scanline * aStride], row, aWidth);
      jpeg_write_scanlines(&cinfo, &row, 1);
    }
  } else if (aInputFormat == INPUT_FORMAT_HOSTARGB) {
    UniquePtr<uint8_t[]> rowptr = MakeUnique<uint8_t[]>(aWidth * 3);
    uint8_t* row = rowptr.get();
    while (cinfo.next_scanline < cinfo.image_height) {
      ConvertHostARGBRow(&aData[cinfo.next_scanline * aStride], row, aWidth);
      jpeg_write_scanlines(&cinfo, &row, 1);
    }
  }

  jpeg_finish_compress(&cinfo);
  jpeg_destroy_compress(&cinfo);

  mFinished = true;
  NotifyListener();

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

  return NS_OK;
}

NS_IMETHODIMP
nsJPEGEncoder::StartImageEncode(uint32_t aWidth, uint32_t aHeight,
                                uint32_t aInputFormat,
                                const nsAString& aOutputOptions) {
  return NS_ERROR_NOT_IMPLEMENTED;
}

// Returns the number of bytes in the image buffer used.
NS_IMETHODIMP
nsJPEGEncoder::GetImageBufferUsed(uint32_t* aOutputSize) {
  NS_ENSURE_ARG_POINTER(aOutputSize);
  *aOutputSize = mImageBufferUsed;
  return NS_OK;
}

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

NS_IMETHODIMP
nsJPEGEncoder::AddImageFrame(const uint8_t* aData, uint32_t aLength,
                             uint32_t aWidth, uint32_t aHeight,
                             uint32_t aStride, uint32_t aFrameFormat,
                             const nsAString& aFrameOptions) {
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsJPEGEncoder::EndImageEncode() { return NS_ERROR_NOT_IMPLEMENTED; }

NS_IMETHODIMP
nsJPEGEncoder::Close() {
  if (mImageBuffer != nullptr) {
    free(mImageBuffer);
    mImageBuffer = nullptr;
    mImageBufferSize = 0;
    mImageBufferUsed = 0;
    mImageBufferReadPoint = 0;
  }
  return NS_OK;
}

NS_IMETHODIMP
nsJPEGEncoder::Available(uint64_t* _retval) {
  if (!mImageBuffer) {
    return NS_BASE_STREAM_CLOSED;
  }

  *_retval = mImageBufferUsed - mImageBufferReadPoint;
  return NS_OK;
}

NS_IMETHODIMP
nsJPEGEncoder::Read(char* aBuf, uint32_t aCount, uint32_t* _retval) {
  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
}

NS_IMETHODIMP
nsJPEGEncoder::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
                            uint32_t aCount, uint32_t* _retval) {
  // Avoid another thread reallocing the buffer underneath us
  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);

  uint32_t maxCount = mImageBufferUsed - 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*>(mImageBuffer + 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
nsJPEGEncoder::IsNonBlocking(bool* _retval) {
  *_retval = true;
  return NS_OK;
}

NS_IMETHODIMP
nsJPEGEncoder::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;  // 1 KB seems good.  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
nsJPEGEncoder::CloseWithStatus(nsresult aStatus) { return Close(); }

// nsJPEGEncoder::ConvertHostARGBRow
//
//    Our colors are stored with premultiplied alphas, but we need
//    an output with no alpha in machine-independent byte order.
//
//    See gfx/cairo/cairo/src/cairo-png.c
void nsJPEGEncoder::ConvertHostARGBRow(const uint8_t* aSrc, uint8_t* aDest,
                                       uint32_t aPixelWidth) {
  for (uint32_t x = 0; x < aPixelWidth; x++) {
    const uint32_t& pixelIn = ((const uint32_t*)(aSrc))[x];
    uint8_t* pixelOut = &aDest[x * 3];

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

/**
 * nsJPEGEncoder::ConvertRGBARow
 *
 * Input is RGBA, output is RGB, so we should alpha-premultiply.
 */
void nsJPEGEncoder::ConvertRGBARow(const uint8_t* aSrc, uint8_t* aDest,
                                   uint32_t aPixelWidth) {
  for (uint32_t x = 0; x < aPixelWidth; x++) {
    const uint8_t* pixelIn = &aSrc[x * 4];
    uint8_t* pixelOut = &aDest[x * 3];

    uint8_t alpha = pixelIn[3];
    pixelOut[0] = gfxPreMultiply(pixelIn[0], alpha);
    pixelOut[1] = gfxPreMultiply(pixelIn[1], alpha);
    pixelOut[2] = gfxPreMultiply(pixelIn[2], alpha);
  }
}

void nsJPEGEncoder::NotifyListener() {
  // We might call this function on multiple threads (any threads that call
  // AsyncWait and any that do encoding) so we lock to avoid notifying the
  // listener twice about the same data (which generally leads to a truncated
  // image).
  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);

  if (mCallback &&
      (mImageBufferUsed - mImageBufferReadPoint >= mNotifyThreshold ||
       mFinished)) {
    nsCOMPtr<nsIInputStreamCallback> callback;
    if (mCallbackTarget) {
      callback = NS_NewInputStreamReadyEvent("nsJPEGEncoder::NotifyListener",
                                             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);
  }
}

/* static */
void nsJPEGEncoderInternal::initDestination(jpeg_compress_struct* cinfo) {
  nsJPEGEncoder* that = static_cast<nsJPEGEncoder*>(cinfo->client_data);
  NS_ASSERTION(!that->mImageBuffer, "Image buffer already initialized");

  that->mImageBufferSize = 8192;
  that->mImageBuffer = (uint8_t*)malloc(that->mImageBufferSize);
  that->mImageBufferUsed = 0;

  cinfo->dest->next_output_byte = that->mImageBuffer;
  cinfo->dest->free_in_buffer = that->mImageBufferSize;
}

/* static */
boolean nsJPEGEncoderInternal::emptyOutputBuffer(jpeg_compress_struct* cinfo) {
  nsJPEGEncoder* that = static_cast<nsJPEGEncoder*>(cinfo->client_data);
  NS_ASSERTION(that->mImageBuffer, "No buffer to empty!");

  // When we're reallocing the buffer we need to take the lock to ensure
  // that nobody is trying to read from the buffer we are destroying
  ReentrantMonitorAutoEnter autoEnter(that->mReentrantMonitor);

  that->mImageBufferUsed = that->mImageBufferSize;

  // expand buffer, just double size each time
  uint8_t* newBuf = nullptr;
  CheckedInt<uint32_t> bufSize =
      CheckedInt<uint32_t>(that->mImageBufferSize) * 2;
  if (bufSize.isValid()) {
    that->mImageBufferSize = bufSize.value();
    newBuf = (uint8_t*)realloc(that->mImageBuffer, that->mImageBufferSize);
  }

  if (!newBuf) {
    // can't resize, just zero (this will keep us from writing more)
    free(that->mImageBuffer);
    that->mImageBuffer = nullptr;
    that->mImageBufferSize = 0;
    that->mImageBufferUsed = 0;

    // This seems to be the only way to do errors through the JPEG library.  We
    // pass an nsresult masquerading as an int, which works because the
    // setjmp() caller casts it back.
    longjmp(((encoder_error_mgr*)(cinfo->err))->setjmp_buffer,
            static_cast<int>(NS_ERROR_OUT_OF_MEMORY));
  }
  that->mImageBuffer = newBuf;

  cinfo->dest->next_output_byte = &that->mImageBuffer[that->mImageBufferUsed];
  cinfo->dest->free_in_buffer = that->mImageBufferSize - that->mImageBufferUsed;
  return 1;
}

/* static */
void nsJPEGEncoderInternal::termDestination(jpeg_compress_struct* cinfo) {
  nsJPEGEncoder* that = static_cast<nsJPEGEncoder*>(cinfo->client_data);
  if (!that->mImageBuffer) {
    return;
  }
  that->mImageBufferUsed = cinfo->dest->next_output_byte - that->mImageBuffer;
  NS_ASSERTION(that->mImageBufferUsed < that->mImageBufferSize,
               "JPEG library busted, got a bad image buffer size");
  that->NotifyListener();
}

/* static */
void nsJPEGEncoderInternal::errorExit(jpeg_common_struct* cinfo) {
  nsresult error_code;
  encoder_error_mgr* err = (encoder_error_mgr*)cinfo->err;

  // Convert error to a browser error code
  switch (cinfo->err->msg_code) {
    case JERR_OUT_OF_MEMORY:
      error_code = NS_ERROR_OUT_OF_MEMORY;
      break;
    default:
      error_code = NS_ERROR_FAILURE;
  }

  // Return control to the setjmp point.  We pass an nsresult masquerading as
  // an int, which works because the setjmp() caller casts it back.
  longjmp(err->setjmp_buffer, static_cast<int>(error_code));
}