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      1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef UI_GFX_CODEC_JPEG_CODEC_H_
      6 #define UI_GFX_CODEC_JPEG_CODEC_H_
      7 
      8 #include <stddef.h>
      9 #include <vector>
     10 
     11 #include "ui/gfx/gfx_export.h"
     12 
     13 class SkBitmap;
     14 
     15 namespace gfx {
     16 
     17 // Interface for encoding/decoding JPEG data. This is a wrapper around libjpeg,
     18 // which has an inconvenient interface for callers. This is only used for UI
     19 // elements, WebKit has its own more complicated JPEG decoder which handles,
     20 // among other things, partially downloaded data.
     21 class GFX_EXPORT JPEGCodec {
     22  public:
     23   enum ColorFormat {
     24     // 3 bytes per pixel (packed), in RGB order regardless of endianness.
     25     // This is the native JPEG format.
     26     FORMAT_RGB,
     27 
     28     // 4 bytes per pixel, in RGBA order in mem regardless of endianness.
     29     FORMAT_RGBA,
     30 
     31     // 4 bytes per pixel, in BGRA order in mem regardless of endianness.
     32     // This is the default Windows DIB order.
     33     FORMAT_BGRA,
     34 
     35     // 4 bytes per pixel, it can be either RGBA or BGRA. It depends on the bit
     36     // order in kARGB_8888_Config skia bitmap.
     37     FORMAT_SkBitmap
     38   };
     39 
     40   enum LibraryVariant {
     41     SYSTEM_LIBJPEG = 0,
     42     LIBJPEG_TURBO,
     43     IJG_LIBJPEG,
     44   };
     45 
     46   // This method helps identify at run time which library chromium is using.
     47   static LibraryVariant JpegLibraryVariant();
     48 
     49   // Encodes the given raw 'input' data, with each pixel being represented as
     50   // given in 'format'. The encoded JPEG data will be written into the supplied
     51   // vector and true will be returned on success. On failure (false), the
     52   // contents of the output buffer are undefined.
     53   //
     54   // w, h: dimensions of the image
     55   // row_byte_width: the width in bytes of each row. This may be greater than
     56   //   w * bytes_per_pixel if there is extra padding at the end of each row
     57   //   (often, each row is padded to the next machine word).
     58   // quality: an integer in the range 0-100, where 100 is the highest quality.
     59   static bool Encode(const unsigned char* input, ColorFormat format,
     60                      int w, int h, int row_byte_width,
     61                      int quality, std::vector<unsigned char>* output);
     62 
     63   // Decodes the JPEG data contained in input of length input_size. The
     64   // decoded data will be placed in *output with the dimensions in *w and *h
     65   // on success (returns true). This data will be written in the'format'
     66   // format. On failure, the values of these output variables is undefined.
     67   static bool Decode(const unsigned char* input, size_t input_size,
     68                      ColorFormat format, std::vector<unsigned char>* output,
     69                      int* w, int* h);
     70 
     71   // Decodes the JPEG data contained in input of length input_size. If
     72   // successful, a SkBitmap is created and returned. It is up to the caller
     73   // to delete the returned bitmap.
     74   static SkBitmap* Decode(const unsigned char* input, size_t input_size);
     75 };
     76 
     77 }  // namespace gfx
     78 
     79 #endif  // UI_GFX_CODEC_JPEG_CODEC_H_
     80