Delphi: Быстрое (де)кодирование JPEG с помощью libjpeg-turbo

unit suJpegTurboUnit;   interface   uses   Windows, SysUtils,     FastDIB;   type   //Обработчик события которое возникает когда получен буфер с JPEG файлом   TOnEncodedJpegBuffer = reference to procedure(ABuffer: Pointer; ABufferSize: LongWord);     //Декодирование JPEG файла из буфера   function DecodeJpegTurbo(ABuffer: Pointer; ABufferLen: Integer; HQ: Boolean = True): TFastDIB;     //Кодирование JPEG   procedure EncodeJpegTurbo(Source: TFastDIB; Quality: Integer; OnEncodedBuffer: TOnEncodedJpegBuffer);   implementation   uses   suJpegTurboHeadersUnit,   suJpegTurboMemDestUnit;   var   _LibInitialized: LongBool = False;   //Обработчик критической ошибки procedure ErrorExit(cinfo: j_common_ptr); cdecl; var   Msg: AnsiString; begin   //Получаем текст ошибки   SetLength(Msg, JMSG_LENGTH_MAX);   cinfo^.err^.format_message(cinfo, PAnsiChar(Msg));     //Что бы обрезать мусор после #0 передаем Msg как PAnsiChar   raise Exception.CreateFmt('JPEG error #%d (%s)',     [cinfo^.err^.msg_code, PAnsiChar(Msg)]); end;   //Обработчик вывода текста ошибки на экран procedure OutputMessage(cinfo: j_common_ptr); cdecl; begin end;   //Инициализация библиотеки LibJpeg-Turbo procedure InitLib; begin   if _LibInitialized then     Exit;     //Пробуем инициалировать   if not init_libJPEG then     raise Exception.Create('initialization of libJPEG failed.');     //Запишем флаг что библиотека инициализированна   if InterlockedCompareExchange(Integer(_LibInitialized), Integer(True), Integer(False)) = Integer(True) then     //Если там уже записан этот флаг, значит другой поток инициализировал библиотеку     //выгрузим свой экземпляр     quit_libJPEG; end;   //Декодирование function DecodeJpegTurbo(ABuffer: pointer; ABufferLen: Integer; HQ: Boolean): TFastDIB; var   Loop: Integer;   JpegErr: jpeg_error_mgr;   Jpeg: jpeg_decompress_struct; begin   //Инициализация библиотеки   InitLib;     FillChar(Jpeg, SizeOf(Jpeg), 0);   FillChar(JpegErr, SizeOf(JpegErr), 0);     //Создаем структуру декомпрессора   jpeg_create_decompress(@Jpeg);   try     //Назначим дефолтный обработчик ошибок     Jpeg.err := jpeg_std_error(@JpegErr);       //Переопределим методы дефолтного обработчика. По умолчанию, при возникновении     //любой ошибки в LibJPEG происходит закрытие приложения, и вывод ошибки в MessageBox     JpegErr.error_exit := ErrorExit;     JpegErr.output_message := OutputMessage;       jpeg_mem_src(@Jpeg, ABuffer, ABufferLen);       //Прочитаем хедеры, дабы знать высоту и ширину картинки     jpeg_read_header(@jpeg, False);       //На выходе нужно получать пиксели BGR     jpeg.out_color_space := JCS_EXT_BGR;       //Настроим масштабирование - 1:1     jpeg.scale_num := 1;     jpeg.scale_denom := 1;       //Скорость или хорошее качество     If HQ then     begin       jpeg.do_block_smoothing := 1;       jpeg.do_fancy_upsampling := 1;       jpeg.dct_method := JDCT_ISLOW     end     else     begin       jpeg.do_block_smoothing := 0;       jpeg.do_fancy_upsampling := 0;       jpeg.dct_method := JDCT_IFAST;     end;       //Декодируем изображение     jpeg_start_decompress(@Jpeg);     try       Result := TFastDIB.Create(jpeg.output_width, jpeg.output_height, 24);       try         //Читаем строки         for Loop := 0 to jpeg.output_height - 1 do           jpeg_read_scanlines(@jpeg, @Result.Scanlines[Result.Height - 1 - Loop], 1);       except         FreeAndNil(Result);         raise;       end;     finally       //Заканчиваем декодирование       jpeg_finish_decompress(@Jpeg);     end;   finally     //Уничтожаем ненужные объекты     jpeg_destroy_decompress(@Jpeg);   end; end;     //Кодирование изображения procedure EncodeJpegTurbo(Source: TFastDIB; Quality: Integer; OnEncodedBuffer: TOnEncodedJpegBuffer); var   ScanLine: JSAMPROW;   CompressedBuff: Pointer;   CompressedSize: LongWord;   JpegErr: jpeg_error_mgr;   Jpeg: jpeg_compress_struct; begin   //Инициализация библиотеки   InitLib;     FillChar(Jpeg, SizeOf(Jpeg), 0);   FillChar(JpegErr, SizeOf(JpegErr), 0);     //Создаем структуру компрессора   jpeg_create_compress(@Jpeg);   try     //Назначим дефолтный обработчик ошибок     Jpeg.err := jpeg_std_error(@JpegErr);       //Переопределим методы дефолтного обработчика. По умолчанию, при возникновении     //любой ошибки в LibJPEG происходит закрытие приложения, и вывод ошибки в MessageBox     JpegErr.error_exit := ErrorExit;     JpegErr.output_message := OutputMessage;       CompressedSize := 0;     CompressedBuff := nil;       //Используем свою реализацию jpeg_mem_dest из-за утечек памяти в стандартной.     suJpegTurboMemDestUnit.jpeg_mem_dest(@Jpeg, @CompressedBuff, @CompressedSize);     try       jpeg.image_width := Source.Width;       jpeg.image_height := Source.Height;       jpeg.input_components := Source.Info.Header.BitCount div 8;       jpeg.in_color_space := JCS_EXT_BGR;         //Setting defaults       jpeg_set_defaults(@Jpeg);         //Качество сжатия       jpeg_set_quality(@Jpeg, Quality, True);         //Декодируем изображение       jpeg_start_compress(@Jpeg, True);       try         while Jpeg.next_scanline < Jpeg.image_height do         begin           ScanLine := JSAMPROW(Source.Scanlines[Jpeg.image_height - Jpeg.next_scanline - 1]);           jpeg_write_scanlines(@Jpeg, @ScanLine, 1);         end;       finally         //Заканчиваем кодирование         jpeg_finish_compress(@Jpeg);       end;         //Передаем буфер вызывающей процедуре       if Assigned(OnEncodedBuffer) then         OnEncodedBuffer(CompressedBuff, CompressedSize);     finally       //Освободим память       FreeMemory(CompressedBuff);     end;   finally     //Уничтожаем ненужные объекты     jpeg_destroy_compress(@Jpeg);   end; end;   initialization   finalization   //Выгружаем если была загружена   if _LibInitialized then     quit_libJPEG; end. 

{   Реализация аналога jpeg_mem_dest из JpegTurbo.     Так как стандартная реализация требует после кодирования изображения освободить   память RTL функцией Free (которая не экспортируется), к которой у нас нет доступа,   пришлось написать аналог, который выделяет/освобождает память с помощью   GetMemory/FreeMemory.     Соответвенно, используя jpeg_mem_dest из данного модуля освобождать память с   картинкой нужно стандартной FreeMemory.     Код портирован на Delphi из jdatadst.c } unit suJpegTurboMemDestUnit;   interface   uses   suJpegTurboHeadersUnit;     procedure jpeg_mem_dest(cinfo: j_compress_ptr; outbuffer: PPointer; outsize: PLongWord);   implementation   const   OUTPUT_BUF_SIZE  = 4096; //choose an efficiently fwrite'able size   type   my_mem_destination_mgr = record     pub: jpeg_destination_mgr;  //public fields     outbuffer: PPointer; //target buffer     outsize: PLongWord;     newbuffer: Pointer;   //newly allocated buffer     buffer: JOCTET_ptr; //start of buffer     bufsize: LongWord;   end;   my_mem_dest_ptr = ^my_mem_destination_mgr;   //Initialize destination --- called by jpeg_start_compress //before any data is actually written. procedure init_mem_destination(cinfo: j_compress_ptr); cdecl; begin   //no work necessary here end;   {  Empty the output buffer --- called whenever buffer fills up.    In typical applications, this should write the entire output buffer  (ignoring the current state of next_output_byte & free_in_buffer),  reset the pointer & count to the start of the buffer, and return TRUE  indicating that the buffer has been dumped.    In applications that need to be able to suspend compression due to output  overrun, a FALSE return indicates that the buffer cannot be emptied now.  In this situation, the compressor will return to its caller (possibly with  an indication that it has not accepted all the supplied scanlines).  The  application should resume compression after it has made more room in the  output buffer.  Note that there are substantial restrictions on the use of  suspension --- see the documentation.    When suspending, the compressor will back up to a convenient restart point  (typically the start of the current MCU). next_output_byte & free_in_buffer  indicate where the restart point will be if the current call returns FALSE.  Data beyond this point will be regenerated after resumption, so do not  write it out when emptying the buffer externally. } function empty_mem_output_buffer(cinfo: j_compress_ptr): Boolean; cdecl; var   nextsize: LongWord;   dest: my_mem_dest_ptr;   nextbuffer: JOCTET_ptr; begin   dest := my_mem_dest_ptr(cinfo^.dest);     //Try to allocate new buffer with double size   nextsize := dest^.bufsize * 2;   nextbuffer := GetMemory(nextsize);     if nextbuffer = nil then     ERREXIT1(j_common_ptr(cinfo), JERR_OUT_OF_MEMORY, 10);     Move(dest^.buffer^, nextbuffer^, dest^.bufsize);     if dest^.newbuffer <> nil then     FreeMemory(dest^.newbuffer);     dest^.newbuffer := nextbuffer;     dest^.pub.next_output_byte := JOCTET_ptr(PByte(nextbuffer) + dest^.bufsize);   dest^.pub.free_in_buffer := dest^.bufsize;     dest^.buffer := nextbuffer;   dest^.bufsize := nextsize;     Result := True; end;   procedure term_mem_destination(cinfo: j_compress_ptr); cdecl; var   dest: my_mem_dest_ptr; begin   dest := my_mem_dest_ptr(cinfo^.dest);   dest^.outbuffer^ := dest^.buffer;   dest^.outsize^ := dest^.bufsize - dest^.pub.free_in_buffer; end;   {   Prepare for output to a memory buffer.   The caller may supply an own initial buffer with appropriate size.   Otherwise, or when the actual data output exceeds the given size,   the library adapts the buffer size as necessary.   The standard library functions GetMemory/FreeMemory are used for allocating   larger memory, so the buffer is available to the application after   finishing compression, and then the application is responsible for   freeing the requested memory. } procedure jpeg_mem_dest(cinfo: j_compress_ptr; outbuffer: PPointer; outsize: PLongWord); var   dest: my_mem_dest_ptr; begin   if (outbuffer = nil) or (outsize = nil) then     ERREXIT(j_common_ptr(cinfo), JERR_BUFFER_SIZE);     if (cinfo^.dest = nil) then //first time for this JPEG object?     cinfo^.dest := cinfo^.mem.alloc_small(j_common_ptr(cinfo), JPOOL_PERMANENT,       SizeOf(my_mem_destination_mgr));     dest := my_mem_dest_ptr(cinfo^.dest);   dest^.pub.init_destination := init_mem_destination;   dest^.pub.empty_output_buffer := empty_mem_output_buffer;   dest^.pub.term_destination := term_mem_destination;   dest^.outbuffer := outbuffer;   dest^.outsize := outsize;   dest^.newbuffer := nil;     if (outbuffer^ = nil) or (outsize^ = 0) then   begin     //Allocate initial buffer     outbuffer^ := GetMemory(OUTPUT_BUF_SIZE);       dest^.newbuffer := outbuffer^;       if dest^.newbuffer = nil then       ERREXIT1(j_common_ptr(cinfo), JERR_OUT_OF_MEMORY, 10);       outsize^ := OUTPUT_BUF_SIZE;   end;     dest^.buffer := outbuffer^;   dest^.pub.next_output_byte := dest^.buffer;     dest^.bufsize := outsize^;   dest^.pub.free_in_buffer := dest^.bufsize; end;   end.

{ Known color spaces. }  J_COLOR_SPACE = (    JCS_UNKNOWN, { error/unspecified }   JCS_GRAYSCALE,  //* monochrome */   JCS_RGB,  //* red/green/blue as specified by the RGB_RED, RGB_GREEN,       //RGB_BLUE, and RGB_PIXELSIZE macros */   JCS_YCbCr,  //* Y/Cb/Cr (also known as YUV) */   JCS_CMYK,  //* C/M/Y/K */   JCS_YCCK,  //* Y/Cb/Cr/K */   JCS_EXT_RGB,  //* red/green/blue */   JCS_EXT_RGBX,  //* red/green/blue/x */   JCS_EXT_BGR,  //* blue/green/red */   JCS_EXT_BGRX,  //* blue/green/red/x */   JCS_EXT_XBGR,  //* x/blue/green/red */   JCS_EXT_XRGB,  //* x/red/green/blue */ //  When out_color_space it set to JCS_EXT_RGBX, JCS_EXT_BGRX, //    JCS_EXT_XBGR, or JCS_EXT_XRGB during decompression, the X byte is //    undefined, and in order to ensure the best performance, //    libjpeg-turbo can set that byte to whatever value it wishes.  Use //    the following colorspace constants to ensure that the X byte is set //    to 0xFF, so that it can be interpreted as an opaque alpha //    channel.   JCS_EXT_RGBA,  ///* red/green/blue/alpha */   JCS_EXT_BGRA,  //* blue/green/red/alpha */   JCS_EXT_ABGR,  //* alpha/blue/green/red */   JCS_EXT_ARGB  //* alpha/red/green/blue */    );   ...    { Standard data source and destination managers: stdio streams. }  { Caller is responsible for opening the file before and closing after. }  // jpeg_stdio_dest: procedure(cinfo: j_compress_ptr; FILE * outfile); cdecl;  // jpeg_stdio_src: procedure(cinfo: j_decompress_ptr; FILE * infile); cdecl;    jpeg_mem_src: procedure(cinfo: j_decompress_ptr; inbuffer: Pointer; insize: LongWord); cdecl;  jpeg_mem_dest: procedure(cinfo: j_decompress_ptr; outbuffer: Pointer; outsize: PLongWord); cdecl;   ... Function init_libJPEG(): boolean; ...      @jpeg_mem_src := GetProcAddress(libJPEG_Handle, 'jpeg_mem_src');      @jpeg_mem_dest := GetProcAddress(libJPEG_Handle, 'jpeg_mem_dest');   ...  {$DEFINE JPEG_LIB_VERSION = 62} //Version 6b type  J_MESSAGE_CODE = (    JMSG_NOMESSAGE,    {$IF Declared(JPEG_LIB_VERSION) and (JPEG_LIB_VERSION < 70)}    JERR_ARITH_NOTIMPL,    {$IFEND}    JERR_BAD_ALIGN_TYPE,    JERR_BAD_ALLOC_CHUNK,    JERR_BAD_BUFFER_MODE,    JERR_BAD_COMPONENT_ID,    {$IF Declared(JPEG_LIB_VERSION) and (JPEG_LIB_VERSION >= 70)}    JERR_BAD_CROP_SPEC,    {$IFEND}    JERR_BAD_DCT_COEF,    JERR_BAD_DCTSIZE,    {$IF Declared(JPEG_LIB_VERSION) and (JPEG_LIB_VERSION >= 70)}    JERR_BAD_DROP_SAMPLING,    {$IFEND}    JERR_BAD_HUFF_TABLE,    JERR_BAD_IN_COLORSPACE,    JERR_BAD_J_COLORSPACE,    JERR_BAD_LENGTH,    JERR_BAD_LIB_VERSION,    JERR_BAD_MCU_SIZE,    JERR_BAD_POOL_ID,    JERR_BAD_PRECISION,    JERR_BAD_PROGRESSION,    JERR_BAD_PROG_SCRIPT,    JERR_BAD_SAMPLING,    JERR_BAD_SCAN_SCRIPT,    JERR_BAD_STATE,    JERR_BAD_STRUCT_SIZE,    JERR_BAD_VIRTUAL_ACCESS,    JERR_BUFFER_SIZE,    JERR_CANT_SUSPEND,    JERR_CCIR601_NOTIMPL,    JERR_COMPONENT_COUNT,    JERR_CONVERSION_NOTIMPL,    JERR_DAC_INDEX,    JERR_DAC_VALUE,    JERR_DHT_INDEX,    JERR_DQT_INDEX,    JERR_EMPTY_IMAGE,    JERR_EMS_READ,    JERR_EMS_WRITE,    JERR_EOI_EXPECTED,    JERR_FILE_READ,    JERR_FILE_WRITE,    JERR_FRACT_SAMPLE_NOTIMPL,    JERR_HUFF_CLEN_OVERFLOW,    JERR_HUFF_MISSING_CODE,    JERR_IMAGE_TOO_BIG,    JERR_INPUT_EMPTY,    JERR_INPUT_EOF,    JERR_MISMATCHED_QUANT_TABLE,    JERR_MISSING_DATA,    JERR_MODE_CHANGE,    JERR_NOTIMPL,    JERR_NOT_COMPILED,    {$IF Declared(JPEG_LIB_VERSION) and (JPEG_LIB_VERSION >= 70)}    JERR_NO_ARITH_TABLE,    {$IFEND}    JERR_NO_BACKING_STORE,    JERR_NO_HUFF_TABLE,    JERR_NO_IMAGE,    JERR_NO_QUANT_TABLE,    JERR_NO_SOI,    JERR_OUT_OF_MEMORY,    JERR_QUANT_COMPONENTS,    JERR_QUANT_FEW_COLORS,    JERR_QUANT_MANY_COLORS,    JERR_SOF_DUPLICATE,    JERR_SOF_NO_SOS,    JERR_SOF_UNSUPPORTED,    JERR_SOI_DUPLICATE,    JERR_SOS_NO_SOF,    JERR_TFILE_CREATE,    JERR_TFILE_READ,    JERR_TFILE_SEEK,    JERR_TFILE_WRITE,    JERR_TOO_LITTLE_DATA,    JERR_UNKNOWN_MARKER,    JERR_VIRTUAL_BUG,    JERR_WIDTH_OVERFLOW,    JERR_XMS_READ,    JERR_XMS_WRITE  );   procedure ERREXIT(cinfo: j_common_ptr; code: J_MESSAGE_CODE); procedure ERREXIT1(cinfo: j_common_ptr; code: J_MESSAGE_CODE; p1: Integer);   ...   //Макрос из jerror.h //Fatal errors (print message and exit) procedure ERREXIT(cinfo: j_common_ptr; code: J_MESSAGE_CODE); begin  cinfo^.err^.msg_code := Ord(code);  cinfo^.err^.error_exit(j_common_ptr(cinfo)); end;   procedure ERREXIT1(cinfo: j_common_ptr; code: J_MESSAGE_CODE; p1: Integer); begin  cinfo^.err^.msg_code := Ord(code);  cinfo^.err^.msg_parm.i[0] := p1;  cinfo^.err^.error_exit(j_common_ptr(cinfo)); end;