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102 lines
4.0 KiB
C++
102 lines
4.0 KiB
C++
/***************************************************************************
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qgscoordinateutils.cpp
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----------------------
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begin : February 2016
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copyright : (C) 2016 by Nyall Dawson
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email : nyall dot dawson at gmail dot com
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***************************************************************************/
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/***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#include "qgscoordinateutils.h"
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#include "qgscoordinatereferencesystem.h"
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#include "qgscoordinatetransform.h"
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#include "qgsproject.h"
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#include "qgis.h"
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#include "qgsexception.h"
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///@cond NOT_STABLE_API
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int QgsCoordinateUtils::calculateCoordinatePrecision( double mapUnitsPerPixel, const QgsCoordinateReferenceSystem &mapCrs )
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{
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// Get the display precision from the project settings
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bool automatic = QgsProject::instance()->readBoolEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/Automatic" ) );
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int dp = 0;
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if ( automatic )
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{
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QString format = QgsProject::instance()->readEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/DegreeFormat" ), QStringLiteral( "MU" ) );
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bool formatGeographic = ( format == QLatin1String( "DM" ) || format == QLatin1String( "DMS" ) || format == QLatin1String( "D" ) );
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// we can only calculate an automatic precision if one of these is true:
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// - both map CRS and format are geographic
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// - both map CRS and format are not geographic
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// - map CRS is geographic but format is not geographic (i.e. map units)
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if ( mapCrs.isGeographic() || !formatGeographic )
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{
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// Work out a suitable number of decimal places for the coordinates with the aim of always
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// having enough decimal places to show the difference in position between adjacent pixels.
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// Also avoid taking the log of 0.
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if ( !qgsDoubleNear( mapUnitsPerPixel, 0.0 ) )
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dp = static_cast<int>( std::ceil( -1.0 * std::log10( mapUnitsPerPixel ) ) );
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}
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else
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{
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dp = format == QLatin1String( "D" ) ? 4 : 2; //guess sensible fallback
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}
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}
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else
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dp = QgsProject::instance()->readNumEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/DecimalPlaces" ) );
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// Keep dp sensible
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if ( dp < 0 )
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dp = 0;
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return dp;
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}
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QString QgsCoordinateUtils::formatCoordinateForProject( const QgsPointXY &point, const QgsCoordinateReferenceSystem &destCrs, int precision )
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{
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QString format = QgsProject::instance()->readEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/DegreeFormat" ), QStringLiteral( "MU" ) );
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QgsPointXY geo = point;
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if ( format == QLatin1String( "DM" ) || format == QLatin1String( "DMS" ) || format == QLatin1String( "D" ) )
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{
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// degrees
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if ( destCrs.isValid() && !destCrs.isGeographic() )
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{
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// need to transform to geographic coordinates
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QgsCoordinateTransform ct( destCrs, QgsCoordinateReferenceSystem( GEOSRID ) );
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try
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{
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geo = ct.transform( point );
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}
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catch ( QgsCsException & )
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{
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return QString();
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}
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}
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if ( format == QLatin1String( "DM" ) )
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return geo.toDegreesMinutes( precision, true, true );
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else if ( format == QLatin1String( "DMS" ) )
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return geo.toDegreesMinutesSeconds( precision, true, true );
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else
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return geo.toString( precision );
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}
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else
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{
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// coordinates in map units
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return point.toString( precision );
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}
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}
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///@endcond
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