src/libs/icon/flat_icon/FlatIconFormat.cpp

   1 /*
   2  * Copyright 2006-2007, Haiku. All rights reserved.
   3  * Distributed under the terms of the MIT License.
   4  *
   5  * Authors:
   6  *              Stephan Aßmus <superstippi@gmx.de>
   7  */
   8
   9
  10 #include "FlatIconFormat.h"
  11
  12 #include "LittleEndianBuffer.h"
  13
  14
  15 _BEGIN_ICON_NAMESPACE
  16
  17
  18 const uint32 FLAT_ICON_MAGIC = 'ficn';
  19
  20 const char* kVectorAttrNodeName = "BEOS:ICON";
  21 const char* kVectorAttrMimeName = "META:ICON";
  22
  23
  24 // read_coord
  25 bool
  26 read_coord(LittleEndianBuffer& buffer, float& coord)
  27 {
  28         uint8 value;
  29         if (!buffer.Read(value))
  30                 return false;
  31
  32         if (value & 128) {
  33                 // high bit set, the next byte is part of the coord
  34                 uint8 lowValue;
  35                 if (!buffer.Read(lowValue))
  36                         return false;
  37                 value &= 127;
  38                 uint16 coordValue = (value << 8) | lowValue;
  39                 coord = (float)coordValue / 102.0 - 128.0;
  40         } else {
  41                 // simple coord
  42                 coord = (float)value - 32.0;
  43         }
  44         return true;
  45 }
  46
  47 // write_coord
  48 bool
  49 write_coord(LittleEndianBuffer& buffer, float coord)
  50 {
  51         // clamp coord
  52         if (coord < -128.0)
  53                 coord = -128.0;
  54         if (coord > 192.0)
  55                 coord = 192.0;
  56
  57         if (int(coord * 100.0) == (int)coord * 100
  58                 && coord >= - 32.0 && coord <= 95.0) {
  59                 // saving coord in 7 bit is sufficient
  60                 uint8 value = (uint8)(coord + 32.0);
  61                 return buffer.Write(value);
  62         } else {
  63                 // needing to save coord in 15 bits
  64                 uint16 value = (uint16)((coord + 128.0) * 102.0);
  65                 // set high bit to indicate there is only one byte
  66                 value |= 32768;
  67                 uint8 highValue = value >> 8;
  68                 uint8 lowValue = value & 255;
  69                 return buffer.Write(highValue) && buffer.Write(lowValue);
  70         }
  71 }
  72
  73 // read_float_24
  74 bool
  75 read_float_24(LittleEndianBuffer& buffer, float& _value)
  76 {
  77         uint8 bufferValue[3];
  78         if (!buffer.Read(bufferValue[0]) || !buffer.Read(bufferValue[1])
  79                 || !buffer.Read(bufferValue[2]))
  80                 return false;
  81
  82         int shortValue = (bufferValue[0] << 16)
  83                 | (bufferValue[1] << 8) | bufferValue[2];
  84
  85         int sign = (shortValue & 0x800000) >> 23;
  86         int exponent = ((shortValue & 0x7e0000) >> 17) - 32;
  87         int mantissa = (shortValue & 0x01ffff) << 6;
  88
  89         if (shortValue == 0)
  90                 _value = 0.0;
  91         else {
  92                 uint32 value = (sign << 31) | ((exponent + 127) << 23) | mantissa;
  93
  94                 _value = (float&)value;
  95         }
  96
  97         return true;
  98 }
  99
 100 // write_float_24
 101 bool
 102 write_float_24(LittleEndianBuffer& buffer, float _value)
 103 {
 104         // 1 bit sign
 105         // 6 bit exponent
 106         // 17 bit mantissa
 107         // TODO: fixme for non-IEEE 754 architectures
 108         uint32 value = (uint32&)_value;
 109
 110         int sign = (value & 0x80000000) >> 31;
 111         int exponent = ((value & 0x7f800000) >> 23) - 127;
 112         int mantissa = value & 0x007fffff;
 113
 114         if (exponent >= 32 || exponent < -32) {
 115                 uint8 zero = 0;
 116                 return buffer.Write(zero) && buffer.Write(zero)
 117                         && buffer.Write(zero);
 118         }
 119
 120         int shortValue = (sign << 23)
 121                                          | ((exponent + 32) << 17)
 122                                          | (mantissa >> 6);
 123
 124         return buffer.Write((uint8)(shortValue >> 16))
 125                 && buffer.Write((uint8)((shortValue >> 8) & 0xff))
 126                 && buffer.Write((uint8)(shortValue & 0xff));
 127 }
 128
 129
 130 _END_ICON_NAMESPACE