Improve QgsScaleCalculator unit support, use standard unit conversion…

… methods
qgis · Apr 6, 2023 · 28b1159 · 28b1159
1 parent 693f744
commit 28b1159
Showing 1 changed file with 18 additions and 8 deletions.
diff --git a/src/core/qgsscalecalculator.cpp b/src/core/qgsscalecalculator.cpp
@@ -20,6 +20,7 @@
 #include "qgslogger.h"
 #include "qgsscalecalculator.h"
 #include "qgsrectangle.h"
+#include "qgsunittypes.h"
 #include <QSizeF>
 
 QgsScaleCalculator::QgsScaleCalculator( double dpi, Qgis::DistanceUnit mapUnits )
@@ -89,20 +90,29 @@ QSizeF QgsScaleCalculator::calculateImageSize( const QgsRectangle &mapExtent, do
 void QgsScaleCalculator::calculateMetrics( const QgsRectangle &mapExtent, double &delta, double &conversionFactor ) const
 {
   delta = mapExtent.xMaximum() - mapExtent.xMinimum();
+
   switch ( mMapUnits )
   {
-    case Qgis::DistanceUnit::Meters:
-      // convert meters to inches
-      conversionFactor = 39.3700787;
+    case Qgis::DistanceUnit::Inches:
+      conversionFactor = 1;
       break;
+
+    case Qgis::DistanceUnit::Meters:
+    case Qgis::DistanceUnit::Kilometers:
     case Qgis::DistanceUnit::Feet:
-      conversionFactor = 12.0;
-      break;
+    case Qgis::DistanceUnit::Yards:
+    case Qgis::DistanceUnit::Millimeters:
+    case Qgis::DistanceUnit::Centimeters:
+    case Qgis::DistanceUnit::Miles:
     case Qgis::DistanceUnit::NauticalMiles:
-      // convert nautical miles to inches
-      conversionFactor = 72913.4;
+      // convert to inches
+      conversionFactor = QgsUnitTypes::fromUnitToUnitFactor( mMapUnits, Qgis::DistanceUnit::Inches );
       break;
-    default:
+
+    case Qgis::DistanceUnit::Unknown:
+      // assume degrees to maintain old API
+      FALLTHROUGH
+
     case Qgis::DistanceUnit::Degrees:
       // degrees require conversion to meters first
       conversionFactor = 39.3700787;