ui/gfx/codec/jpeg_codec.h

   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_