ui/gfx/image/image_util.h

   1 // Copyright (c) 2012 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_IMAGE_IMAGE_UTIL_H_
   6 #define UI_GFX_IMAGE_IMAGE_UTIL_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "ui/gfx/gfx_export.h"
  12
  13 namespace gfx {
  14 class Image;
  15 class ImageSkia;
  16 }
  17
  18 namespace gfx {
  19
  20 // Creates an image from the given JPEG-encoded input. If there was an error
  21 // creating the image, returns an IsEmpty() Image.
  22 GFX_EXPORT Image ImageFrom1xJPEGEncodedData(const unsigned char* input,
  23                                             size_t input_size);
  24
  25 // Fills the |dst| vector with JPEG-encoded bytes of the 1x representation of
  26 // the given image.
  27 // Returns true if the image has a 1x representation and the 1x representation
  28 // was encoded successfully.
  29 // |quality| determines the compression level, 0 == lowest, 100 == highest.
  30 // Returns true if the Image was encoded successfully.
  31 GFX_EXPORT bool JPEG1xEncodedDataFromImage(const Image& image,
  32                                            int quality,
  33                                            std::vector<unsigned char>* dst);
  34
  35 // Returns the visible (non-transparent) width of the 1x rep of the given
  36 // image. If the image has no transparency, the leading value will be 0 and
  37 // the trailing will be the image width. Return values are in the 1x width
  38 // pixel units. Margins are given in 0-based column format. So if the image
  39 // has only transparent pixels in columns 0, 1, 2, 3, then the leading value
  40 // will be 4. Similarly, if there are all transparent pixels in column
  41 // width-2, width-1, then the trailing margin value will be width-3.
  42 // Returns true if the value is computed from opacity, false if it is a
  43 // default value because of null image, missing Rep, etc.
  44 // This method is only suitable for fairly small images (i.e. 16x16).
  45 // The margins for a completely transparent image will be w/2-1, w/2, but this
  46 // will be an expensive operation: it isn't expected that it will be frequently
  47 // calculated.
  48 GFX_EXPORT bool VisibleMargins(const ImageSkia& image,
  49                                int* leading, int* trailing);
  50
  51 }  // namespace gfx
  52
  53 #endif  // UI_GFX_IMAGE_IMAGE_UTIL_H_