KiCad PCB EDA Suite
convert_to_biu.h
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1 /*
2  * This program source code file is part of KiCad, a free EDA CAD application.
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4  * Copyright (C) 2012-2016 Jean-Pierre Charras, jp.charras at wanadoo.fr
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23  */
24 
25 #pragma once
26 
27 
28 /* Note about internal units and max size for boards and items
29 
30  The largest distance that we (and Kicad) can support is INT_MAX, since it represents
31  distance often in a wxCoord or wxSize. As a scalar, a distance is always
32  positive. Because int is 32 bits and INT_MAX is
33  2147483647. The most difficult distance for a virtual (world) cartesian
34  space is the hypotenuse, or diagonal measurement at a 45 degree angle. This
35  puts the most stress on the distance magnitude within the bounded virtual
36  space. So if we allow this distance to be our constraint of <= INT_MAX, this
37  constraint then propagates to the maximum distance in X and in Y that can be
38  supported on each axis. Remember that the hypotenuse of a 1x1 square is
39  sqrt( 1x1 + 1x1 ) = sqrt(2) = 1.41421356.
40 
41  hypotenuse of any square = sqrt(2) * deltaX;
42 
43  Let maximum supported hypotenuse be INT_MAX, then:
44 
45  MAX_AXIS = INT_MAX / sqrt(2) = 2147483647 / 1.41421356 = 1518500251
46 
47  The next choice is what to use for internal units (IU), sometimes called
48  world units. If nanometers, then the virtual space must be limited to
49  about 1.5 x 1.5 meters square. This is 1518500251 divided by 1e9 nm/meter.
50 
51  The maximum zoom factor then depends on the client window size. If we ask
52  wx to handle something outside INT_MIN to INT_MAX, there are unreported
53  problems in the non-Debug build because wxRound() goes silent.
54 
55  Pcbnew uses nanometers because we need to convert coordinates and size between
56  millimeters and inches. using a iu = 1 nm avoid rounding issues
57 
58  Gerbview uses iu = 10 nm because we can have coordinates far from origin, and
59  1 nm is too small to avoid int overflow.
60  (Conversions between millimeters and inches are not critical)
61 */
62 
69 constexpr double GERB_IU_PER_MM = 1e5; // Gerbview IU is 10 nanometers.
70 constexpr double PCB_IU_PER_MM = 1e6; // Pcbnew IU is 1 nanometer.
71 constexpr double PL_IU_PER_MM = 1e3; // internal units in micron (should be enough)
72 constexpr double SCH_IU_PER_MM = 1e4; // Schematic internal units 1=100nm
73 
75 #if defined(PCBNEW) || defined(CVPCB)
76 constexpr double IU_PER_MM = PCB_IU_PER_MM;
77 #elif defined(GERBVIEW)
78 constexpr double IU_PER_MM = GERB_IU_PER_MM;
79 #elif defined(PL_EDITOR)
80 constexpr double IU_PER_MM = PL_IU_PER_MM;
81 #elif defined(EESCHEMA)
82 constexpr double IU_PER_MM = SCH_IU_PER_MM;
83 #else
84 #define UNKNOWN_IU
85 #endif
86 
87 #ifndef UNKNOWN_IU
88 constexpr double IU_PER_MILS = (IU_PER_MM * 0.0254);
89 
90 constexpr inline int Mils2iu( int mils )
91 {
92  double x = mils * IU_PER_MILS;
93  return int( x < 0 ? x - 0.5 : x + 0.5 );
94 }
95 
96 #if defined(EESCHEMA)
97 constexpr inline int Iu2Mils( int iu )
98 {
99  double mils = iu / IU_PER_MILS;
100 
101  return static_cast< int >( mils < 0 ? mils - 0.5 : mils + 0.5 );
102 }
103 #else
104 constexpr inline double Iu2Mils( int iu )
105 {
106  double mils = iu / IU_PER_MILS;
107 
108  return static_cast< int >( mils < 0 ? mils - 0.5 : mils + 0.5 );
109 }
110 #endif
111 
112 // Other definitions used in a few files
113 constexpr double MM_PER_IU = ( 1 / IU_PER_MM );
114 
116 constexpr inline int Millimeter2iu( double mm )
117 {
118  return (int) ( mm < 0 ? mm * IU_PER_MM - 0.5 : mm * IU_PER_MM + 0.5 );
119 }
120 
122 constexpr inline double Iu2Millimeter( int iu )
123 {
124  return iu / IU_PER_MM;
125 }
126 
128 // constexpr inline double Iu2Mils( int iu )
129 // {
130 // return iu / IU_PER_MILS;
131 // }
132 
133 // The max error is the distance between the middle of a segment, and the circle
134 // for circle/arc to segment approximation.
135 // Warning: too small values can create very long calculation time in zone filling
136 // 0.05 to 0.005 mm are reasonable values
137 
138 constexpr int ARC_LOW_DEF = Millimeter2iu( 0.02 );
139 constexpr int ARC_HIGH_DEF = Millimeter2iu( 0.005 );
140 
141 #else
142 constexpr double PCB_IU_PER_MILS = (PCB_IU_PER_MM * 0.0254);
143 constexpr double SCH_IU_PER_MILS = (SCH_IU_PER_MM * 0.0254);
144 
145 constexpr inline int SchMils2iu( int mils )
146 {
147  double x = mils * SCH_IU_PER_MILS;
148  return int( x < 0 ? x - 0.5 : x + 0.5 );
149 }
150 constexpr inline double SchIu2Mils( int iu )
151 {
152  return iu / SCH_IU_PER_MILS;
153 }
154 
155 constexpr inline int PcbMillimeter2iu( double mm )
156 {
157  return (int) ( mm < 0 ? mm * PCB_IU_PER_MM - 0.5 : mm * PCB_IU_PER_MM + 0.5 );
158 }
159 constexpr inline double PcbIu2Millimeter( int iu )
160 {
161  return iu / PCB_IU_PER_MM;
162 }
163 
164 #endif
constexpr double PCB_IU_PER_MILS
static constexpr double IU_PER_MM
Mock up a conversion function.
constexpr double PcbIu2Millimeter(int iu)
constexpr int PcbMillimeter2iu(double mm)
constexpr double PCB_IU_PER_MM
constexpr double SchIu2Mils(int iu)
constexpr double SCH_IU_PER_MM
constexpr double SCH_IU_PER_MILS
constexpr double PL_IU_PER_MM
constexpr double GERB_IU_PER_MM
some define and functions to convert a value in mils, decimils or mm to the internal unit used in pcb...
#define IU_PER_MILS
Definition: plotter.cpp:137
constexpr int SchMils2iu(int mils)
static constexpr int Millimeter2iu(double mm)