[FEATURE][layouts] Allow expressions to be embedded inside legend ite…

…m text This feature allows for expressions to be embedded directly inside legend item text (e.g. group, subgroup and item text). The expressions are evaluated at render time, with full knowledge of the legend's expression context (so can utilise variables from the layout/layout item/ etc) There's no UI for this yet (that will come in 3.8), but expressions are entered using the standard [% 1 + 2 %] format. E.g. a legend item text of My layer (rendered at 1:[% @map_scale %]) will show in the output as My layer (renderer at 1:1000)
qgis · Jan 18, 2019 · d70b60d · d70b60d
1 parent b3d5f27
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diff --git a/python/core/auto_generated/qgslegendsettings.sip.in b/python/core/auto_generated/qgslegendsettings.sip.in
@@ -198,6 +198,16 @@ The ``scale`` value indicates the scale denominator, e.g. 1000.0 for a 1:1000 ma
     void setDpi( int dpi );
 
 
+
+    QStringList evaluateItemText( const QString &stringToSplt, const QgsExpressionContext &context ) const;
+%Docstring
+Returns the actual text to render for a legend item, split into separate lines.
+
+:param ctx: Context for rendering - may be null if only doing layout without actual rendering
+
+.. versionadded:: 3.6
+%End
+
     QStringList splitStringForWrapping( const QString &stringToSplt ) const;
 %Docstring
 Splits a string using the wrap char taking into account handling empty

diff --git a/src/core/layertree/qgslayertreemodellegendnode.cpp b/src/core/layertree/qgslayertreemodellegendnode.cpp
@@ -92,7 +92,9 @@ QSizeF QgsLayerTreeModelLegendNode::drawSymbolText( const QgsLegendSettings &set
   double textHeight = settings.fontHeightCharacterMM( symbolLabelFont, QChar( '0' ) );
   double textDescent = settings.fontDescentMillimeters( symbolLabelFont );
 
-  const QStringList lines = settings.splitStringForWrapping( data( Qt::DisplayRole ).toString() );
+  QgsExpressionContext tempContext;
+
+  const QStringList lines = settings.evaluateItemText( data( Qt::DisplayRole ).toString(), ctx && ctx->context ? ctx->context->expressionContext() : tempContext );
 
   labelSize.rheight() = lines.count() * textHeight + ( lines.count() - 1 ) * ( settings.lineSpacing() + textDescent );
 

diff --git a/src/core/layout/qgslayoutitemlegend.cpp b/src/core/layout/qgslayoutitemlegend.cpp
@@ -831,7 +831,6 @@ QgsExpressionContext QgsLayoutItemLegend::createExpressionContext() const
     context.appendScope( mMap->createExpressionContext().popScope() );
   }
 
-
   QgsExpressionContextScope *scope = new QgsExpressionContextScope( tr( "Legend Settings" ) );
 
   scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "legend_title" ), title(), true ) );

diff --git a/src/core/qgslegendrenderer.cpp b/src/core/qgslegendrenderer.cpp
@@ -566,7 +566,8 @@ QSizeF QgsLegendRenderer::drawLayerTitleInternal( QgsLayerTreeLayer *nodeLayer,
   QModelIndex idx = mLegendModel->node2index( nodeLayer );
 
   //Let the user omit the layer title item by having an empty layer title string
-  if ( mLegendModel->data( idx, Qt::DisplayRole ).toString().isEmpty() ) return size;
+  if ( mLegendModel->data( idx, Qt::DisplayRole ).toString().isEmpty() )
+    return size;
 
   double y = point.y();
 
@@ -577,8 +578,11 @@ QSizeF QgsLegendRenderer::drawLayerTitleInternal( QgsLayerTreeLayer *nodeLayer,
 
   QFont layerFont = mSettings.style( nodeLegendStyle( nodeLayer ) ).font();
 
-  QStringList lines = mSettings.splitStringForWrapping( mLegendModel->data( idx, Qt::DisplayRole ).toString() );
+  QgsExpressionContext tempContext;
-  for ( QStringList::Iterator layerItemPart = lines.begin(); layerItemPart != lines.end(); ++layerItemPart )
+
+  const QStringList lines = mSettings.evaluateItemText( mLegendModel->data( idx, Qt::DisplayRole ).toString(),
+                            context ? context->expressionContext() : tempContext );
+  for ( QStringList::ConstIterator layerItemPart = lines.constBegin(); layerItemPart != lines.constEnd(); ++layerItemPart )
   {
     y += mSettings.fontAscentMillimeters( layerFont );
     if ( context && context->painter() )
@@ -617,8 +621,11 @@ QSizeF QgsLegendRenderer::drawGroupTitleInternal( QgsLayerTreeGroup *nodeGroup,
 
   QFont groupFont = mSettings.style( nodeLegendStyle( nodeGroup ) ).font();
 
-  QStringList lines = mSettings.splitStringForWrapping( mLegendModel->data( idx, Qt::DisplayRole ).toString() );
+  QgsExpressionContext tempContext;
-  for ( QStringList::Iterator groupPart = lines.begin(); groupPart != lines.end(); ++groupPart )
+
+  const QStringList lines = mSettings.evaluateItemText( mLegendModel->data( idx, Qt::DisplayRole ).toString(),
+                            context ? context->expressionContext() : tempContext );
+  for ( QStringList::ConstIterator groupPart = lines.constBegin(); groupPart != lines.constEnd(); ++groupPart )
   {
     y += mSettings.fontAscentMillimeters( groupFont );
     if ( context && context->painter() )

diff --git a/src/core/qgslegendsettings.cpp b/src/core/qgslegendsettings.cpp
@@ -14,6 +14,8 @@
  ***************************************************************************/
 
 #include "qgslegendsettings.h"
+#include "qgsexpressioncontext.h"
+#include "qgsexpression.h"
 
 #include <QPainter>
 
@@ -35,6 +37,12 @@ QgsLegendSettings::QgsLegendSettings()
   rstyle( QgsLegendStyle::SymbolLabel ).rfont().setPointSizeF( 12.0 );
 }
 
+QStringList QgsLegendSettings::evaluateItemText( const QString &stringToSplt, const QgsExpressionContext &context ) const
+{
+  const QString textToRender = QgsExpression::replaceExpressionText( stringToSplt, &context );
+  return splitStringForWrapping( textToRender );
+}
+
 QStringList QgsLegendSettings::splitStringForWrapping( const QString &stringToSplt ) const
 {
   QStringList list;

diff --git a/src/core/qgslegendsettings.h b/src/core/qgslegendsettings.h
@@ -25,6 +25,7 @@ class QRectF;
 
 #include "qgslegendstyle.h"
 
+class QgsExpressionContext;
 
 /**
  * \ingroup core
@@ -182,6 +183,20 @@ class CORE_EXPORT QgsLegendSettings
 
     // utility functions
 
+    /**
+     * Splits a string using the wrap char taking into account handling empty
+     * wrap char which means no wrapping
+     */
+
+    /**
+     * Returns the actual text to render for a legend item, split into separate lines.
+     *
+     * \param ctx Context for rendering - may be null if only doing layout without actual rendering
+     *
+     * \since QGIS 3.6
+     */
+    QStringList evaluateItemText( const QString &stringToSplt, const QgsExpressionContext &context ) const;
+
     /**
      * Splits a string using the wrap char taking into account handling empty
      * wrap char which means no wrapping

diff --git a/tests/src/core/testqgslayertree.cpp b/tests/src/core/testqgslayertree.cpp
@@ -27,6 +27,7 @@
 #include <qgslayertreemodel.h>
 #include <qgslayertreemodellegendnode.h>
 #include <qgslayertreeutils.h>
+#include "qgslegendsettings.h"
 
 class TestQgsLayerTree : public QObject
 {
@@ -53,6 +54,7 @@ class TestQgsLayerTree : public QObject
     void testFindGroups();
     void testUtilsCollectMapLayers();
     void testUtilsCountMapLayers();
+    void testSymbolText();
 
   private:
 
@@ -707,6 +709,62 @@ void TestQgsLayerTree::testUtilsCountMapLayers()
   QCOMPARE( QgsLayerTreeUtils::countMapLayerInTree( &root, vl ), 2 );
 }
 
+void TestQgsLayerTree::testSymbolText()
+{
+  //new memory layer
+  QgsVectorLayer *vl = new QgsVectorLayer( QStringLiteral( "Point?field=col1:integer" ), QStringLiteral( "vl" ), QStringLiteral( "memory" ) );
+  QVERIFY( vl->isValid() );
+
+  QgsProject project;
+  project.addMapLayer( vl );
+
+  //create a categorized renderer for layer
+  QgsCategorizedSymbolRenderer *renderer = new QgsCategorizedSymbolRenderer();
+  renderer->setClassAttribute( QStringLiteral( "col1" ) );
+  renderer->setSourceSymbol( QgsSymbol::defaultSymbol( QgsWkbTypes::PointGeometry ) );
+  renderer->addCategory( QgsRendererCategory( "a", QgsSymbol::defaultSymbol( QgsWkbTypes::PointGeometry ), QStringLiteral( "a [% 1 + 2 %]" ) ) );
+  renderer->addCategory( QgsRendererCategory( "b", QgsSymbol::defaultSymbol( QgsWkbTypes::PointGeometry ), QStringLiteral( "b,c" ) ) );
+  renderer->addCategory( QgsRendererCategory( "c", QgsSymbol::defaultSymbol( QgsWkbTypes::PointGeometry ), QStringLiteral( "c" ) ) );
+  vl->setRenderer( renderer );
+
+  //create legend with symbology nodes for categorized renderer
+  QgsLayerTree *root = new QgsLayerTree();
+  QgsLayerTreeLayer *n = new QgsLayerTreeLayer( vl );
+  root->addChildNode( n );
+  QgsLayerTreeModel *m = new QgsLayerTreeModel( root, nullptr );
+  m->refreshLayerLegend( n );
+
+  QList<QgsLayerTreeModelLegendNode *> nodes = m->layerLegendNodes( n );
+  QCOMPARE( nodes.length(), 3 );
+
+  QgsLegendSettings settings;
+  settings.setWrapChar( QStringLiteral( "," ) );
+  QCOMPARE( nodes.at( 0 )->data( Qt::DisplayRole ).toString(), QStringLiteral( "a [% 1 + 2 %]" ) );
+  QCOMPARE( nodes.at( 1 )->data( Qt::DisplayRole ).toString(), QStringLiteral( "b,c" ) );
+  QCOMPARE( nodes.at( 2 )->data( Qt::DisplayRole ).toString(), QStringLiteral( "c" ) );
+  nodes.at( 2 )->setUserLabel( QStringLiteral( "[% 2+3 %] x [% 3+4 %]" ) );
+  QCOMPARE( nodes.at( 2 )->data( Qt::DisplayRole ).toString(), QStringLiteral( "[% 2+3 %] x [% 3+4 %]" ) );
+
+  QgsExpressionContext context;
+  QCOMPARE( settings.evaluateItemText( nodes.at( 0 )->data( Qt::DisplayRole ).toString(), context ), QStringList() << QStringLiteral( "a 3" ) );
+  QCOMPARE( settings.evaluateItemText( nodes.at( 1 )->data( Qt::DisplayRole ).toString(), context ), QStringList() << QStringLiteral( "b" ) << QStringLiteral( "c" ) );
+  QCOMPARE( settings.evaluateItemText( nodes.at( 2 )->data( Qt::DisplayRole ).toString(), context ), QStringList() << QStringLiteral( "5 x 7" ) );
+
+  // split string should happen after expression evaluation
+  QgsExpressionContextScope *scope = new QgsExpressionContextScope();
+  scope->setVariable( QStringLiteral( "bbbb" ), QStringLiteral( "aaaa,bbbb,cccc" ) );
+  context.appendScope( scope );
+  nodes.at( 2 )->setUserLabel( QStringLiteral( "[% @bbbb %],[% 3+4 %]" ) );
+  QCOMPARE( settings.evaluateItemText( nodes.at( 2 )->data( Qt::DisplayRole ).toString(), context ), QStringList() << QStringLiteral( "aaaa" )
+            << QStringLiteral( "bbbb" )
+            << QStringLiteral( "cccc" )
+            << QStringLiteral( "7" ) );
+
+  //cleanup
+  delete m;
+  delete root;
+}
+
 
 QGSTEST_MAIN( TestQgsLayerTree )
 #include "testqgslayertree.moc"
diff --git a/tests/src/python/test_qgslayoutlegend.py b/tests/src/python/test_qgslayoutlegend.py
@@ -15,7 +15,8 @@
 from qgis.PyQt.QtCore import QRectF
 from qgis.PyQt.QtGui import QColor
 
-from qgis.core import (QgsLayoutItemLegend,
+from qgis.core import (QgsPrintLayout,
+                       QgsLayoutItemLegend,
                        QgsLayoutItemMap,
                        QgsLayout,
                        QgsMapSettings,
@@ -30,7 +31,10 @@
                        QgsLayoutItem,
                        QgsLayoutPoint,
                        QgsLayoutSize,
-                       QgsExpression)
+                       QgsExpression,
+                       QgsMapLayerLegendUtils,
+                       QgsLegendStyle,
+                       QgsFontUtils)
 from qgis.testing import (start_app,
                           unittest
                           )
@@ -305,6 +309,64 @@ def testLegendScopeVariables(self):
         exp6 = QgsExpression("@map_scale")
         self.assertAlmostEqual(exp6.evaluate(expc2), 15000, 2)
 
+    def testExpressionInText(self):
+        """Test expressions embedded in legend node text"""
+
+        point_path = os.path.join(TEST_DATA_DIR, 'points.shp')
+        point_layer = QgsVectorLayer(point_path, 'points', 'ogr')
+
+        layout = QgsPrintLayout(QgsProject.instance())
+        layout.setName('LAYOUT')
+        layout.initializeDefaults()
+
+        map = QgsLayoutItemMap(layout)
+        map.attemptSetSceneRect(QRectF(20, 20, 80, 80))
+        map.setFrameEnabled(True)
+        map.setLayers([point_layer])
+        layout.addLayoutItem(map)
+        map.setExtent(point_layer.extent())
+
+        legend = QgsLayoutItemLegend(layout)
+        legend.setTitle("Legend")
+        legend.attemptSetSceneRect(QRectF(120, 20, 100, 100))
+        legend.setFrameEnabled(True)
+        legend.setFrameStrokeWidth(QgsLayoutMeasurement(2))
+        legend.setBackgroundColor(QColor(200, 200, 200))
+        legend.setTitle('')
+        legend.setLegendFilterByMapEnabled(False)
+        legend.setStyleFont(QgsLegendStyle.Title, QgsFontUtils.getStandardTestFont('Bold', 16))
+        legend.setStyleFont(QgsLegendStyle.Group, QgsFontUtils.getStandardTestFont('Bold', 16))
+        legend.setStyleFont(QgsLegendStyle.Subgroup, QgsFontUtils.getStandardTestFont('Bold', 16))
+        legend.setStyleFont(QgsLegendStyle.Symbol, QgsFontUtils.getStandardTestFont('Bold', 16))
+        legend.setStyleFont(QgsLegendStyle.SymbolLabel, QgsFontUtils.getStandardTestFont('Bold', 16))
+
+        # disable auto resizing
+        legend.setResizeToContents(False)
+        legend.setAutoUpdateModel(False)
+
+        QgsProject.instance().addMapLayers([point_layer])
+        s = QgsMapSettings()
+        s.setLayers([point_layer])
+
+        group = legend.model().rootGroup().addGroup("Group [% 1 + 5 %] [% @layout_name %]")
+        layer_tree_layer = group.addLayer(point_layer)
+        layer_tree_layer.setCustomProperty("legend/title-label", 'bbbb [% 1+2 %] xx [% @layout_name %]')
+        QgsMapLayerLegendUtils.setLegendNodeUserLabel(layer_tree_layer, 0, 'xxxx')
+        legend.model().refreshLayerLegend(layer_tree_layer)
+        legend.model().layerLegendNodes(layer_tree_layer)[0].setUserLabel('bbbb [% 1+2 %] xx [% @layout_name %]')
+
+        layout.addLayoutItem(legend)
+        legend.setLinkedMap(map)
+
+        map.setExtent(QgsRectangle(-102.51, 41.16, -102.36, 41.30))
+
+        checker = QgsLayoutChecker(
+            'composer_legend_expressions', layout)
+        checker.setControlPathPrefix("composer_legend")
+        result, message = checker.testLayout()
+        self.assertTrue(result, message)
+
+        QgsProject.instance().removeMapLayers([point_layer.id()])
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/...d/expected_composer_legend_expressions/expected_composer_legend_expressions.png b/...d/expected_composer_legend_expressions/expected_composer_legend_expressions.png