printing/image.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 PRINTING_IMAGE_H_
   6 #define PRINTING_IMAGE_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/logging.h"
  13 #include "printing/printing_export.h"
  14 #include "ui/gfx/size.h"
  15
  16 class FilePath;
  17
  18 namespace printing {
  19
  20 class Metafile;
  21
  22 // Lightweight raw-bitmap management. The image, once initialized, is immutable.
  23 // The main purpose is testing image contents.
  24 class PRINTING_EXPORT Image {
  25  public:
  26   // Creates the image from the given file on disk.  Uses extension to
  27   // defer file type. PNG and EMF (on Windows) currently supported.
  28   // If image loading fails size().IsEmpty() will be true.
  29   explicit Image(const FilePath& path);
  30
  31   // Creates the image from the metafile.  Deduces bounds based on bounds in
  32   // metafile.  If loading fails size().IsEmpty() will be true.
  33   explicit Image(const Metafile& metafile);
  34
  35   // Copy constructor.
  36   explicit Image(const Image& image);
  37
  38   ~Image();
  39
  40   const gfx::Size& size() const {
  41     return size_;
  42   }
  43
  44   // Return a checksum of the image (MD5 over the internal data structure).
  45   std::string checksum() const;
  46
  47   // Save image as PNG.
  48   bool SaveToPng(const FilePath& filepath) const;
  49
  50   // Returns % of pixels different
  51   double PercentageDifferent(const Image& rhs) const;
  52
  53   // Returns the 0x0RGB or 0xARGB value of the pixel at the given location.
  54   uint32 Color(uint32 color) const {
  55     if (ignore_alpha_)
  56       return color & 0xFFFFFF;  // Strip out A.
  57     else
  58       return color;
  59   }
  60
  61   uint32 pixel_at(int x, int y) const {
  62     DCHECK(x >= 0 && x < size_.width());
  63     DCHECK(y >= 0 && y < size_.height());
  64     const uint32* data = reinterpret_cast<const uint32*>(&*data_.begin());
  65     const uint32* data_row = data + y * row_length_ / sizeof(uint32);
  66     return Color(data_row[x]);
  67   }
  68
  69  private:
  70   // Construct from metafile.  This is kept internal since it's ambiguous what
  71   // kind of data is used (png, bmp, metafile etc).
  72   Image(const void* data, size_t size);
  73
  74   bool LoadPng(const std::string& compressed);
  75
  76   bool LoadMetafile(const std::string& data);
  77
  78   bool LoadMetafile(const Metafile& metafile);
  79
  80   // Pixel dimensions of the image.
  81   gfx::Size size_;
  82
  83   // Length of a line in bytes.
  84   int row_length_;
  85
  86   // Actual bitmap data in arrays of RGBAs (so when loaded as uint32, it's
  87   // 0xABGR).
  88   std::vector<unsigned char> data_;
  89
  90   // Flag to signal if the comparison functions should ignore the alpha channel.
  91   const bool ignore_alpha_;  // Currently always true.
  92
  93   // Prevent operator= (this function has no implementation)
  94   Image& operator=(const Image& image);
  95 };
  96
  97 }  // namespace printing
  98
  99 #endif  // PRINTING_IMAGE_H_