The Tor Browser: image/encoders/jpeg/nsJPEGEncoder.cpp@6474c204b198 (annotated)

image/encoders/jpeg/nsJPEGEncoder.cpp@6474c204b198 (annotated)

image/encoders/jpeg/nsJPEGEncoder.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- 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 <setjmp.h>
 #include "jerror.h"
 using namespace mozilla;
 NS_IMPL_ISUPPORTS(nsJPEGEncoder, imgIEncoder, nsIInputStream, nsIAsyncInputStream)
 // 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) {
     moz_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(NS_LITERAL_STRING("quality="));
     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 = 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 = initDestination;
   destmgr.empty_output_buffer = emptyOutputBuffer;
   destmgr.term_destination = 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) {
     uint8_t* row = new uint8_t[aWidth * 3];
     while (cinfo.next_scanline < cinfo.image_height) {
       ConvertRGBARow(&aData[cinfo.next_scanline * aStride], row, aWidth);
       jpeg_write_scanlines(&cinfo, &row, 1);
     }
     delete[] row;
   } else if (aInputFormat == INPUT_FORMAT_HOSTARGB) {
     uint8_t* row = new uint8_t[aWidth * 3];
     while (cinfo.next_scanline < cinfo.image_height) {
       ConvertHostARGBRow(&aData[cinfo.next_scanline * aStride], row, aWidth);
       jpeg_write_scanlines(&cinfo, &row, 1);
     }
     delete[] row;
   }
   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;
 }
 /* void close (); */
 NS_IMETHODIMP nsJPEGEncoder::Close()
 {
   if (mImageBuffer != nullptr) {
     moz_free(mImageBuffer);
     mImageBuffer = nullptr;
     mImageBufferSize = 0;
     mImageBufferUsed = 0;
     mImageBufferReadPoint = 0;
   }
   return NS_OK;
 }
 /* unsigned long available (); */
 NS_IMETHODIMP nsJPEGEncoder::Available(uint64_t *_retval)
 {
   if (!mImageBuffer)
     return NS_BASE_STREAM_CLOSED;
   *_retval = mImageBufferUsed - mImageBufferReadPoint;
   return NS_OK;
 }
 /* [noscript] unsigned long read (in charPtr aBuf, in unsigned long aCount); */
 NS_IMETHODIMP nsJPEGEncoder::Read(char * aBuf, uint32_t aCount,
                                   uint32_t *_retval)
 {
   return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
 }
 /* [noscript] unsigned long readSegments (in nsWriteSegmentFun aWriter, in voidPtr aClosure, in unsigned long aCount); */
 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),
 , 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;
 }
 /* boolean isNonBlocking (); */
 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);
   }
 }
 // nsJPEGEncoder::initDestination
 //
 //    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.
 void // static
 nsJPEGEncoder::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*)moz_malloc(that->mImageBufferSize);
   that->mImageBufferUsed = 0;
   cinfo->dest->next_output_byte = that->mImageBuffer;
   cinfo->dest->free_in_buffer = that->mImageBufferSize;
 }
 // nsJPEGEncoder::emptyOutputBuffer
 //
 //    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).
 boolean // static
 nsJPEGEncoder::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
   that->mImageBufferSize *= 2;
   uint8_t* newBuf = (uint8_t*)moz_realloc(that->mImageBuffer,
                                           that->mImageBufferSize);
   if (! newBuf) {
     // can't resize, just zero (this will keep us from writing more)
     moz_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;
 }
 // nsJPEGEncoder::termDestination
 //
 //    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.
 void // static
 nsJPEGEncoder::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();
 }
 // nsJPEGEncoder::errorExit
 //
 //    Override the standard error method in the IJG JPEG decoder code. This
 //    was mostly copied from nsJPEGDecoder.cpp
 void // static
 nsJPEGEncoder::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));
 }
 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(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);
   }
 }

The Tor Browser / annotate

image/encoders/jpeg/nsJPEGEncoder.cpp@6474c204b198 (annotated)

image/encoders/jpeg/nsJPEGEncoder.cpp