src/bmp.cc

   1 ///
   2 /// \file       bmp.cc
   3 ///             BMP conversion routines
   4 ///
   5
   6 /*
   7     Copyright (C) 2009-2011, 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 #include "data.h"
  28 #include "m_javaloader.h"
  29
  30 namespace Barry {
  31
  32 //
  33 // GetTotalBitmapSize
  34 //
  35 /// Returns the total number of bytes needed to convert a
  36 /// screenshot of the given dimensions into a bitmap,
  37 /// using the ScreenshotToBitmap() function.
  38 ///
  39 BXEXPORT size_t GetTotalBitmapSize(const JLScreenInfo &info)
  40 {
  41         return sizeof(bmp_file_header_t) +
  42                 sizeof(bmp_info_header_t) +
  43                 (info.width * info.height * 4); // 4 byte RGB per pixel
  44
  45 }
  46
  47 //
  48 // ScreenshotToBitmap
  49 //
  50 /// Converts screenshot data obtained via JavaLoader::GetScreenshot()
  51 /// into uncompressed bitmap format, suitable for writing BMP files.
  52 /// Arguments info and screenshot come from GetScreenshot() and the
  53 /// converted data is stored in bitmap.
  54 ///
  55 //
  56 // This function assumes that the btoh() converter functions match
  57 // the needs of the bitmap file format.  Namely: little endian.
  58 //
  59 BXEXPORT void ScreenshotToBitmap(const JLScreenInfo &info,
  60                                  const Data &screenshot,
  61                                  Data &bitmap)
  62 {
  63         // Read screen info
  64         size_t width = info.width;
  65         size_t height = info.height;
  66         size_t total_bitmap_size = GetTotalBitmapSize(info);
  67
  68         // make sure there is enough screeshot pixel data for the
  69         // given width and height
  70         if( screenshot.GetSize() < (width * height * 2) ) // 2 byte screenshot pixel data
  71                 throw Error("Screenshot data size is too small for given width+height");
  72
  73
  74         // setup write pointer
  75         unsigned char *write = bitmap.GetBuffer(total_bitmap_size);
  76
  77         //
  78         // Build header BMP file
  79         //
  80         bmp_file_header_t *fileheader = (bmp_file_header_t*) write;
  81         write += sizeof(bmp_file_header_t);
  82
  83         // BMP
  84         fileheader->bfType[0] = 'B';
  85         fileheader->bfType[1] = 'M';
  86
  87         // Size of file
  88         fileheader->bfSize = btohl(total_bitmap_size);
  89
  90         // Always 0x00
  91         fileheader->bfReserved1 = 0;
  92         fileheader->bfReserved2 = 0;
  93
  94         // Offset to find the data
  95         fileheader->bfOffBits = btohl(sizeof(bmp_file_header_t) + sizeof(bmp_info_header_t));
  96
  97
  98         //
  99         // Build info BMP file
 100         //
 101         bmp_info_header_t *infoheader = (bmp_info_header_t*) write;
 102         write += sizeof(bmp_info_header_t);
 103
 104         // Size of info section
 105         infoheader->biSize = btohl(sizeof(bmp_info_header_t));
 106
 107         // Width x Height
 108         infoheader->biWidth = btohl(width);
 109         infoheader->biHeight = btohl(height);
 110
 111         // Planes number
 112         infoheader->biPlanes = btohs(0x01);
 113
 114         // Bit count
 115         infoheader->biBitCount = btohs(0x20);
 116
 117         // Compression : No
 118         infoheader->biCompression = 0;
 119
 120         // Size of image
 121         infoheader->biSizeImage = btohl(4 * width * height);
 122
 123         // Pels Per Meter
 124         infoheader->biXPelsPerMeter = 0;
 125         infoheader->biYPelsPerMeter = 0;
 126
 127         // Color palette used : None
 128         infoheader->biClrUsed = 0;
 129
 130         // Color palette important : None
 131         infoheader->biClrImportant = 0;
 132
 133
 134         // I work with 2 bytes (see the pixel format)
 135         const uint16_t *data = (const uint16_t*) screenshot.GetData();
 136         size_t pixel_count = width * height;
 137
 138         // For each pixel... (note BMP format is up and backwards, hence
 139         // offset calculation for each pixel in for loop)
 140         for (size_t j=0; j<height; j++) {
 141                 for (size_t i=0; i<width; i++) {
 142                         // Read one pixel in the picture
 143                         short value = data[(pixel_count - 1) - ((width-1 - i) + (width * j))];
 144
 145                         // Pixel format used by the handheld is : 16 bits
 146                         // MSB < .... .... .... .... > LSB
 147                         //                    ^^^^^^ : Blue (between 0x00 and 0x1F)
 148                         //             ^^^^^^^ : Green (between 0x00 and 0x3F)
 149                         //       ^^^^^^ : Red (between 0x00 and 0x1F)
 150
 151                         write[3] = 0x00;                                        // alpha
 152                         write[2] = (((value >> 11) & 0x1F) * 0xFF) / 0x1F;      // red
 153                         write[1] = (((value >> 5) & 0x3F) * 0xFF) / 0x3F;       // green
 154                         write[0] = ((value & 0x1F) * 0xFF) / 0x1F;              // blue
 155
 156                         write += 4;
 157                 }
 158         }
 159
 160         bitmap.ReleaseBuffer(total_bitmap_size);
 161 }
 162
 163 } // namespace Barry
 164