Less usage of QgsProject::instance

Author: m-kuhn

src/core/qgscoordinateutils.cpp

@@ -24,15 +24,17 @@
 #include "qgscoordinateformatter.h"
 ///@cond NOT_STABLE_API
 
-int QgsCoordinateUtils::calculateCoordinatePrecision( double mapUnitsPerPixel, const QgsCoordinateReferenceSystem &mapCrs )
+int QgsCoordinateUtils::calculateCoordinatePrecision( double mapUnitsPerPixel, const QgsCoordinateReferenceSystem &mapCrs, QgsProject *project )
 {
+  if ( !project )
+    project = QgsProject::instance();
   // Get the display precision from the project settings
-  bool automatic = QgsProject::instance()->readBoolEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/Automatic" ) );
+  bool automatic = project->readBoolEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/Automatic" ) );
   int dp = 0;
 
   if ( automatic )
   {
-    QString format = QgsProject::instance()->readEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/DegreeFormat" ), QStringLiteral( "MU" ) );
+    QString format = project->readEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/DegreeFormat" ), QStringLiteral( "MU" ) );
     bool formatGeographic = ( format == QLatin1String( "DM" ) || format == QLatin1String( "DMS" ) || format == QLatin1String( "D" ) );
 
     // we can only calculate an automatic precision if one of these is true:
@@ -49,11 +51,14 @@ int QgsCoordinateUtils::calculateCoordinatePrecision( double mapUnitsPerPixel, c
     }
     else
     {
-      dp = format == QLatin1String( "D" ) ? 4 : 2; //guess sensible fallback
+      if ( format == QLatin1String( "D" ) )
+        dp = 4;
+      else
+        dp = 2;
     }
   }
   else
-    dp = QgsProject::instance()->readNumEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/DecimalPlaces" ) );
+    dp = project->readNumEntry( QStringLiteral( "PositionPrecision" ), QStringLiteral( "/DecimalPlaces" ) );
 
   // Keep dp sensible
   if ( dp < 0 )

src/core/qgscoordinateutils.h

@@ -45,17 +45,20 @@ class CORE_EXPORT QgsCoordinateUtils
   public:
 
     /**
-     * Returns the precision to use for displaying coordinates to the user, respecting
-     * the user's project settings. If the user has set the project to use "automatic"
-     * precision, this function tries to calculate an optimal coordinate precision for a given
-     * map units per pixel by calculating the number of decimal places for the coordinates
-     * with the aim of always having enough decimal places to show the difference in position
-     * between adjacent pixels.
-     * \param mapUnitsPerPixel number of map units per pixel
-     * \param mapCrs CRS of map
-     * \returns optimal number of decimal places for coordinates
+     * Returns the precision to use for displaying coordinates in \a mapCrs to the user.
+     * It respects the user's \a project settings.
+     * If the user has set the project to use "automatic" precision, this function tries
+     * to calculate an optimal coordinate precision for a given \a mapUnitsPerPixel by
+     * calculating the number of decimal places for the coordinates with the aim of always
+     * having enough decimal places to show the difference in position between adjacent
+     * pixels.
+     *
+     * \since QGIS 3.6 a new \a project parameter is available. Using the method without this
+     *        a \a project paramter is deprecated and will be removed with QGIS 4.
+     *        For backward compatibility, QgsProject.instance() will be used if the \a project
+     *        parameter is not specified.
      */
-    Q_INVOKABLE static int calculateCoordinatePrecision( double mapUnitsPerPixel, const QgsCoordinateReferenceSystem &mapCrs );
+    Q_INVOKABLE static int calculateCoordinatePrecision( double mapUnitsPerPixel, const QgsCoordinateReferenceSystem &mapCrs, QgsProject *project = nullptr );
 
     /**
      * Formats a \a point coordinate for use with the specified \a project, respecting the project's