ail/bmp.cpp

   1 #include <ail/bmp.hpp>
   2
   3 #include <cstring>
   4
   5 #include <ail/memory.hpp>
   6 #include <ail/file.hpp>
   7
   8 namespace ail
   9 {
  10         namespace
  11         {
  12                 std::size_t const
  13                         bmp_header_size = 54,
  14                         bytes_per_pixel = 3, //24-bit
  15                         bmp_padding = 4,
  16                         dword_size = 4;
  17         }
  18
  19         bmp::bmp():
  20                 buffer(0)
  21         {
  22         }
  23
  24         bmp::bmp(std::size_t width, std::size_t height):
  25                 buffer(0)
  26         {
  27                 initialise(width, height);
  28         }
  29
  30         bmp::~bmp()
  31         {
  32                 release();
  33         }
  34
  35         void bmp::initialise(std::size_t new_width, std::size_t new_height)
  36         {
  37                 release();
  38                 width = new_width;
  39                 height = new_height;
  40                 process_image_size(width, height);
  41                 buffer = new char[image_size];
  42                 write_header();
  43         }
  44
  45         std::size_t bmp::process_image_size(std::size_t width, std::size_t height)
  46         {
  47                 bytes_per_line = width * bytes_per_pixel;
  48                 std::size_t remainder = bytes_per_line % bmp_padding;
  49                 if(remainder != 0)
  50                         bytes_per_line += bmp_padding - remainder;
  51                 image_size = bmp_header_size + height * bytes_per_line;
  52                 return image_size;
  53         }
  54
  55         void bmp::set_pixel(std::size_t x, std::size_t y, long value)
  56         {
  57                 if(x < 0 || x >= width)
  58                         throw exception("Invalid x coordinate");
  59                 if(y < 0 || y >= height)
  60                         throw exception("Invalid y coordinate");
  61                 std::size_t offset = bmp_header_size + (height - y) * bytes_per_line + x * bytes_per_pixel;
  62                 write_little_endian(static_cast<ulong>(value), buffer + offset, bytes_per_pixel);
  63         }
  64
  65         bool bmp::write(std::string const & file_name)
  66         {
  67                 file bmp_file;
  68                 if(!bmp_file.open_create(file_name))
  69                         return false;
  70                 bmp_file.write(buffer, image_size);
  71                 bmp_file.close();
  72                 return true;
  73         }
  74
  75         void bmp::write_header()
  76         {
  77                 char * data =
  78                         "\x42\x4D\xF6\x00\x00\x00\x00\x00\x00\x00\x36\x00\x00\x00\x28\x00"
  79                         "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x18\x00\x00\x00"
  80                         "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
  81                         "\x00\x00\x00\x00\x00\x00";
  82
  83                 std::memcpy(buffer, data, bmp_header_size);
  84                 write_little_endian(static_cast<ulong>(width), buffer + 18, dword_size);
  85                 write_little_endian(static_cast<ulong>(height), buffer + 22, dword_size);
  86                 write_little_endian(static_cast<ulong>(image_size - bmp_header_size), buffer + 34, dword_size);
  87         }
  88
  89         void bmp::release()
  90         {
  91                 if(buffer != 0)
  92                 {
  93                         delete buffer;
  94                         buffer = 0;
  95                 }
  96         }
  97 }