124 lines
4.9 KiB
C++
124 lines
4.9 KiB
C++
/*
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* This program source code file is part of KiCad, a free EDA CAD application.
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*
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* Copyright (C) 2012-2016 Jean-Pierre Charras, jp.charras at wanadoo.fr
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* Copyright (C) 1992-2022 KiCad Developers, see AUTHORS.txt for contributors.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you may find one here:
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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* or you may search the http://www.gnu.org website for the version 2 license,
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* or you may write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#ifndef _BASE_UNITS_H_
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#define _BASE_UNITS_H_
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/* Note about internal units and max size for boards and items
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The largest distance that we (and Kicad) can support is INT_MAX, since it represents
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distance often in a wxCoord or wxSize. As a scalar, a distance is always
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positive. Because int is 32 bits and INT_MAX is
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2147483647. The most difficult distance for a virtual (world) cartesian
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space is the hypotenuse, or diagonal measurement at a 45 degree angle. This
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puts the most stress on the distance magnitude within the bounded virtual
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space. So if we allow this distance to be our constraint of <= INT_MAX, this
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constraint then propagates to the maximum distance in X and in Y that can be
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supported on each axis. Remember that the hypotenuse of a 1x1 square is
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sqrt( 1x1 + 1x1 ) = sqrt(2) = 1.41421356.
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hypotenuse of any square = sqrt(2) * deltaX;
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Let maximum supported hypotenuse be INT_MAX, then:
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MAX_AXIS = INT_MAX / sqrt(2) = 2147483647 / 1.41421356 = 1518500251
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The next choice is what to use for internal units (IU), sometimes called
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world units. If nanometers, then the virtual space must be limited to
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about 1.5 x 1.5 meters square. This is 1518500251 divided by 1e9 nm/meter.
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The maximum zoom factor then depends on the client window size. If we ask
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wx to handle something outside INT_MIN to INT_MAX, there are unreported
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problems in the non-Debug build because wxRound() goes silent.
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Pcbnew uses nanometers because we need to convert coordinates and size between
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millimeters and inches. using a iu = 1 nm avoid rounding issues
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Gerbview uses iu = 10 nm because we can have coordinates far from origin, and
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1 nm is too small to avoid int overflow.
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(Conversions between millimeters and inches are not critical)
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*/
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/**
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* @brief some macros and functions to convert a value in mils, decimils or mm to the internal
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* unit used in pcbnew, cvpcb or gerbview (nanometer or deci-mil) depending on compile time option
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*/
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constexpr double GERB_IU_PER_MM = 1e5; // Gerbview IU is 10 nanometers.
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constexpr double PCB_IU_PER_MM = 1e6; // Pcbnew IU is 1 nanometer.
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constexpr double PL_IU_PER_MM = 1e3; // internal units in micron (should be enough)
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constexpr double SCH_IU_PER_MM = 1e4; // Schematic internal units 1=100nm
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struct EDA_IU_SCALE
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{
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const double IU_PER_MM;
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const double IU_PER_MILS;
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const double MM_PER_IU;
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constexpr EDA_IU_SCALE( double aIUPerMM ) :
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IU_PER_MM( aIUPerMM ), IU_PER_MILS( aIUPerMM * 0.0254 ), MM_PER_IU( 1 / IU_PER_MM )
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{
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}
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constexpr inline double IUTomm( int iu ) const { return iu / IU_PER_MM; }
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constexpr inline int mmToIU( double mm ) const
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{
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return (int) ( mm < 0 ? ( mm * IU_PER_MM - 0.5 ) : ( mm * IU_PER_MM + 0.5 ) );
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}
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constexpr inline int MilsToIU( int mils ) const
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{
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double x = mils * IU_PER_MILS;
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return int( x < 0 ? x - 0.5 : x + 0.5 );
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}
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constexpr inline int IUToMils( int iu ) const
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{
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double mils = iu / IU_PER_MILS;
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return static_cast<int>( mils < 0 ? mils - 0.5 : mils + 0.5 );
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}
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};
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constexpr EDA_IU_SCALE gerbIUScale = EDA_IU_SCALE( GERB_IU_PER_MM );
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constexpr EDA_IU_SCALE pcbIUScale = EDA_IU_SCALE( PCB_IU_PER_MM );
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constexpr EDA_IU_SCALE drawSheetIUScale = EDA_IU_SCALE( PL_IU_PER_MM );
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constexpr EDA_IU_SCALE schIUScale = EDA_IU_SCALE( SCH_IU_PER_MM );
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constexpr EDA_IU_SCALE unityScale = EDA_IU_SCALE( 1 );
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#ifndef SWIG
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// The max error is the distance between the middle of a segment, and the circle
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// for circle/arc to segment approximation.
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// Warning: too small values can create very long calculation time in zone filling
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// 0.05 to 0.005 mm are reasonable values
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constexpr int ARC_LOW_DEF = pcbIUScale.mmToIU( 0.02 );
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constexpr int ARC_HIGH_DEF = pcbIUScale.mmToIU( 0.005 );
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#endif
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#endif // _BASE_UNITS_H_
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