src/bmp.cc

   1 ///
   2 /// \file       bmp.cc
   3 ///             BMP conversion routines
   4 ///
   5
   6 /*
   7     Copyright (C) 2009-2010, Net Direct Inc. (http://www.netdirect.ca/)
   8     Copyright (C) 2008-2009, Nicolas VIVIEN
   9
  10     This program is free software; you can redistribute it and/or modify
  11     it under the terms of the GNU General Public License as published by
  12     the Free Software Foundation; either version 2 of the License, or
  13     (at your option) any later version.
  14
  15     This program is distributed in the hope that it will be useful,
  16     but WITHOUT ANY WARRANTY; without even the implied warranty of
  17     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  18
  19     See the GNU General Public License in the COPYING file at the
  20     root directory of this project for more details.
  21 */
  22
  23 #include "bmp.h"
  24 #include "bmp-internal.h"
  25 #include "error.h"
  26 #include "endian.h"
  27
  28 namespace Barry {
  29
  30 //
  31 // GetTotalBitmapSize
  32 //
  33 /// Returns the total number of bytes needed to convert a
  34 /// screenshot of the given dimensions into a bitmap,
  35 /// using the ScreenshotToBitmap() function.
  36 ///
  37 BXEXPORT size_t GetTotalBitmapSize(const JLScreenInfo &info)
  38 {
  39         return sizeof(bmp_file_header_t) +
  40                 sizeof(bmp_info_header_t) +
  41                 (info.width * info.height * 4); // 4 byte RGB per pixel
  42
  43 }
  44
  45 //
  46 // ScreenshotToBitmap
  47 //
  48 /// Converts screenshot data obtained via JavaLoader::GetScreenshot()
  49 /// into uncompressed bitmap format, suitable for writing BMP files.
  50 /// Arguments info and screenshot come from GetScreenshot() and the
  51 /// converted data is stored in bitmap.
  52 ///
  53 //
  54 // This function assumes that the btoh() converter functions match
  55 // the needs of the bitmap file format.  Namely: little endian.
  56 //
  57 BXEXPORT void ScreenshotToBitmap(const JLScreenInfo &info,
  58                                  const Data &screenshot,
  59                                  Data &bitmap)
  60 {
  61         // Read screen info
  62         size_t width = info.width;
  63         size_t height = info.height;
  64         size_t total_bitmap_size = GetTotalBitmapSize(info);
  65
  66         // make sure there is enough screeshot pixel data for the
  67         // given width and height
  68         if( screenshot.GetSize() < (width * height * 2) ) // 2 byte screenshot pixel data
  69                 throw Error("Screenshot data size is too small for given width+height");
  70
  71
  72         // setup write pointer
  73         unsigned char *write = bitmap.GetBuffer(total_bitmap_size);
  74
  75         //
  76         // Build header BMP file
  77         //
  78         bmp_file_header_t *fileheader = (bmp_file_header_t*) write;
  79         write += sizeof(bmp_file_header_t);
  80
  81         // BMP
  82         fileheader->bfType[0] = 'B';
  83         fileheader->bfType[1] = 'M';
  84
  85         // Size of file
  86         fileheader->bfSize = btohl(total_bitmap_size);
  87
  88         // Always 0x00
  89         fileheader->bfReserved1 = 0;
  90         fileheader->bfReserved2 = 0;
  91
  92         // Offset to find the data
  93         fileheader->bfOffBits = btohl(sizeof(bmp_file_header_t) + sizeof(bmp_info_header_t));
  94
  95
  96         //
  97         // Build info BMP file
  98         //
  99         bmp_info_header_t *infoheader = (bmp_info_header_t*) write;
 100         write += sizeof(bmp_info_header_t);
 101
 102         // Size of info section
 103         infoheader->biSize = btohl(sizeof(bmp_info_header_t));
 104
 105         // Width x Height
 106         infoheader->biWidth = btohl(width);
 107         infoheader->biHeight = btohl(height);
 108
 109         // Planes number
 110         infoheader->biPlanes = btohs(0x01);
 111
 112         // Bit count
 113         infoheader->biBitCount = btohs(0x20);
 114
 115         // Compression : No
 116         infoheader->biCompression = 0;
 117
 118         // Size of image
 119         infoheader->biSizeImage = btohl(4 * width * height);
 120
 121         // Pels Per Meter
 122         infoheader->biXPelsPerMeter = 0;
 123         infoheader->biYPelsPerMeter = 0;
 124
 125         // Color palette used : None
 126         infoheader->biClrUsed = 0;
 127
 128         // Color palette important : None
 129         infoheader->biClrImportant = 0;
 130
 131
 132         // I work with 2 bytes (see the pixel format)
 133         const uint16_t *data = (const uint16_t*) screenshot.GetData();
 134         size_t pixel_count = width * height;
 135
 136         // For each pixel... (note BMP format is up and backwards, hence
 137         // offset calculation for each pixel in for loop)
 138         for (size_t j=0; j<height; j++) {
 139                 for (size_t i=0; i<width; i++) {
 140                         // Read one pixel in the picture
 141                         short value = data[(pixel_count - 1) - ((width-1 - i) + (width * j))];
 142
 143                         // Pixel format used by the handheld is : 16 bits
 144                         // MSB < .... .... .... .... > LSB
 145                         //                    ^^^^^^ : Blue (between 0x00 and 0x1F)
 146                         //             ^^^^^^^ : Green (between 0x00 and 0x3F)
 147                         //       ^^^^^^ : Red (between 0x00 and 0x1F)
 148
 149                         write[3] = 0x00;                                        // alpha
 150                         write[2] = (((value >> 11) & 0x1F) * 0xFF) / 0x1F;      // red
 151                         write[1] = (((value >> 5) & 0x3F) * 0xFF) / 0x3F;       // green
 152                         write[0] = ((value & 0x1F) * 0xFF) / 0x1F;              // blue
 153
 154                         write += 4;
 155                 }
 156         }
 157
 158         bitmap.ReleaseBuffer(total_bitmap_size);
 159 }
 160
 161 } // namespace Barry
 162