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/geometry/size.h"
  15
  16 namespace base {
  17 class FilePath;
  18 }
  19
  20 namespace printing {
  21
  22 class Metafile;
  23
  24 // Lightweight raw-bitmap management. The image, once initialized, is immutable.
  25 // The main purpose is testing image contents.
  26 class PRINTING_EXPORT Image {
  27  public:
  28   // Creates the image from the given file on disk.  Uses extension to
  29   // defer file type. PNG and EMF (on Windows) currently supported.
  30   // If image loading fails size().IsEmpty() will be true.
  31   explicit Image(const base::FilePath& path);
  32
  33   // Creates the image from the metafile.  Deduces bounds based on bounds in
  34   // metafile.  If loading fails size().IsEmpty() will be true.
  35   explicit Image(const Metafile& metafile);
  36
  37   // Copy constructor.
  38   explicit Image(const Image& image);
  39
  40   ~Image();
  41
  42   const gfx::Size& size() const {
  43     return size_;
  44   }
  45
  46   // Return a checksum of the image (MD5 over the internal data structure).
  47   std::string checksum() const;
  48
  49   // Save image as PNG.
  50   bool SaveToPng(const base::FilePath& filepath) const;
  51
  52   // Returns % of pixels different
  53   double PercentageDifferent(const Image& rhs) const;
  54
  55   // Returns the 0x0RGB or 0xARGB value of the pixel at the given location.
  56   uint32_t Color(uint32_t color) const {
  57     if (ignore_alpha_)
  58       return color & 0xFFFFFF;  // Strip out A.
  59     else
  60       return color;
  61   }
  62
  63   uint32_t pixel_at(int x, int y) const {
  64     DCHECK(x >= 0 && x < size_.width());
  65     DCHECK(y >= 0 && y < size_.height());
  66     const uint32_t* data = reinterpret_cast<const uint32_t*>(&*data_.begin());
  67     const uint32_t* data_row = data + y * row_length_ / sizeof(uint32_t);
  68     return Color(data_row[x]);
  69   }
  70
  71  private:
  72   // Construct from metafile.  This is kept internal since it's ambiguous what
  73   // kind of data is used (png, bmp, metafile etc).
  74   Image(const void* data, size_t size);
  75
  76   bool LoadPng(const std::string& compressed);
  77
  78   bool LoadMetafile(const std::string& data);
  79
  80   bool LoadMetafile(const Metafile& metafile);
  81
  82   // Pixel dimensions of the image.
  83   gfx::Size size_;
  84
  85   // Length of a line in bytes.
  86   int row_length_;
  87
  88   // Actual bitmap data in arrays of RGBAs (so when loaded as uint32_t, it's
  89   // 0xABGR).
  90   std::vector<unsigned char> data_;
  91
  92   // Flag to signal if the comparison functions should ignore the alpha channel.
  93   const bool ignore_alpha_;  // Currently always true.
  94
  95   // Prevent operator= (this function has no implementation)
  96   Image& operator=(const Image& image);
  97 };
  98
  99 }  // namespace printing
 100
 101 #endif  // PRINTING_IMAGE_H_