Make @zoom_level and @vector_tile_zoom expression variables always

available, not just for vector tile layers These are generic properties related to the map scale only, so by moving them up to the map settings level we then make it possible to copy symbols from vector tiles to non-vector tile layers, without breaking any nice symbology rules which utilise tile zoom levels (such as those converted from mapbox styles)
qgis · Jan 24, 2022 · 6dfb467 · 6dfb467
1 parent 0480319
commit 6dfb467
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Showing 4 changed files with 20 additions and 3 deletions.
diff --git a/src/core/expression/qgsexpression.cpp b/src/core/expression/qgsexpression.cpp
@@ -805,8 +805,8 @@ void QgsExpression::initVariableHelp()
   sVariableHelpTexts()->insert( QStringLiteral( "animation_interval" ), QCoreApplication::translate( "variable_help", "Duration of the animation's overall temporal time range (as an interval value)" ) );
 
   // vector tile layer variables
-  sVariableHelpTexts()->insert( QStringLiteral( "zoom_level" ), QCoreApplication::translate( "variable_help", "Zoom level of the tile that is being rendered (derived from the current map scale). Normally in interval [0, 20]." ) );
-  sVariableHelpTexts()->insert( QStringLiteral( "vector_tile_zoom" ), QCoreApplication::translate( "variable_help", "Exact zoom level of the tile that is being rendered (derived from the current map scale). Normally in interval [0, 20]. Unlike @zoom_level, this variable is a floating point value which can be used to interpolated values between two integer zoom levels." ) );
+  sVariableHelpTexts()->insert( QStringLiteral( "zoom_level" ), QCoreApplication::translate( "variable_help", "Vector tile zoom level of the map that is being rendered (derived from the current map scale). Normally in interval [0, 20]." ) );
+  sVariableHelpTexts()->insert( QStringLiteral( "vector_tile_zoom" ), QCoreApplication::translate( "variable_help", "Exact vector tile zoom level of the map that is being rendered (derived from the current map scale). Normally in interval [0, 20]. Unlike @zoom_level, this variable is a floating point value which can be used to interpolated values between two integer zoom levels." ) );
 
   sVariableHelpTexts()->insert( QStringLiteral( "row_number" ), QCoreApplication::translate( "variable_help", "Stores the number of the current row." ) );
   sVariableHelpTexts()->insert( QStringLiteral( "grid_number" ), QCoreApplication::translate( "variable_help", "Current grid annotation value." ) );

diff --git a/src/core/expression/qgsexpressioncontextutils.cpp b/src/core/expression/qgsexpressioncontextutils.cpp
@@ -35,6 +35,7 @@
 #include "qgsprojoperation.h"
 #include "qgsmarkersymbol.h"
 #include "qgstriangularmesh.h"
+#include "qgsvectortileutils.h"
 
 QgsExpressionContextScope *QgsExpressionContextUtils::globalScope()
 {
@@ -437,6 +438,9 @@ QgsExpressionContextScope *QgsExpressionContextUtils::mapSettingsScope( const Qg
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_rotation" ), mapSettings.rotation(), true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_scale" ), mapSettings.scale(), true ) );
 
+  scope->setVariable( QStringLiteral( "zoom_level" ), QgsVectorTileUtils::scaleToZoomLevel( mapSettings.scale(), 0, 99999 ), true );
+  scope->setVariable( QStringLiteral( "vector_tile_zoom" ), QgsVectorTileUtils::scaleToZoom( mapSettings.scale() ), true );
+
   // IMPORTANT: ANY CHANGES HERE ALSO NEED TO BE MADE TO QgsLayoutItemMap::createExpressionContext()
   // (rationale is described in QgsLayoutItemMap::createExpressionContext() )
 

diff --git a/src/core/layout/qgslayoutitemmap.cpp b/src/core/layout/qgslayoutitemmap.cpp
@@ -37,6 +37,7 @@
 #include "qgscoordinatereferencesystemregistry.h"
 #include "qgsprojoperation.h"
 #include "qgslabelingresults.h"
+#include "qgsvectortileutils.h"
 
 #include <QPainter>
 #include <QStyleOptionGraphicsItem>
@@ -1670,7 +1671,11 @@ QgsExpressionContext QgsLayoutItemMap::createExpressionContext() const
 
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_id" ), id(), true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_rotation" ), mMapRotation, true ) );
-  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_scale" ), scale(), true ) );
+  const double mapScale = scale();
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_scale" ), mapScale, true ) );
+
+  scope->setVariable( QStringLiteral( "zoom_level" ), QgsVectorTileUtils::scaleToZoomLevel( mapScale, 0, 99999 ), true );
+  scope->setVariable( QStringLiteral( "vector_tile_zoom" ), QgsVectorTileUtils::scaleToZoom( mapScale ), true );
 
   QgsRectangle currentExtent( extent() );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "map_extent" ), QVariant::fromValue( QgsGeometry::fromRect( currentExtent ) ), true ) );

diff --git a/tests/src/core/testqgsmapsettings.cpp b/tests/src/core/testqgsmapsettings.cpp
@@ -492,6 +492,14 @@ void TestQgsMapSettings::testExpressionContext()
   r = e.evaluate( &c );
   QGSCOMPARENEAR( r.toDouble(), 247990, 10.0 );
 
+  e = QgsExpression( QStringLiteral( "@zoom_level" ) );
+  r = e.evaluate( &c );
+  QCOMPARE( r.toDouble(), 10.0 );
+
+  e = QgsExpression( QStringLiteral( "@vector_tile_zoom" ) );
+  r = e.evaluate( &c );
+  QGSCOMPARENEAR( r.toDouble(), 10.1385606747, 0.0001 );
+
   // The old $scale function should silently map to @map_scale, so that older projects work without change
   e = QgsExpression( QStringLiteral( "$scale" ) );
   r = e.evaluate( &c );