Setup API to get theme linked to map pushed to linked legends

(cherry picked from commit 406867d)
qgis · Apr 6, 2020 · 77927b4 · 77927b4
1 parent 8ad01a2
commit 77927b4
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Showing 4 changed files with 71 additions and 1 deletion.
diff --git a/python/core/auto_generated/layout/qgslayoutitemlegend.sip.in b/python/core/auto_generated/layout/qgslayoutitemlegend.sip.in
@@ -502,6 +502,15 @@ Sets the ``map`` to associate with the legend.
 Returns the associated map.
 
 .. seealso:: :py:func:`setLinkedMap`
+%End
+
+    QString themeName() const;
+%Docstring
+Returns the name of the theme currently linked to the legend.
+
+This usually equates to the theme rendered in the linkedMap().
+
+.. versionadded:: 3.14
 %End
 
     void updateLegend();

diff --git a/src/core/layout/qgslayoutitemlegend.cpp b/src/core/layout/qgslayoutitemlegend.cpp
@@ -678,13 +678,15 @@ void QgsLayoutItemLegend::setupMapConnections( QgsLayoutItemMap *map, bool conne
     disconnect( map, &QgsLayoutObject::changed, this, &QgsLayoutItemLegend::updateFilterByMapAndRedraw );
     disconnect( map, &QgsLayoutItemMap::extentChanged, this, &QgsLayoutItemLegend::updateFilterByMapAndRedraw );
     disconnect( map, &QgsLayoutItemMap::layerStyleOverridesChanged, this, &QgsLayoutItemLegend::mapLayerStyleOverridesChanged );
+    disconnect( map, &QgsLayoutItemMap::themeChanged, this, &QgsLayoutItemLegend::mapThemeChanged );
   }
   else
   {
     connect( map, &QObject::destroyed, this, &QgsLayoutItemLegend::invalidateCurrentMap );
     connect( map, &QgsLayoutObject::changed, this, &QgsLayoutItemLegend::updateFilterByMapAndRedraw );
     connect( map, &QgsLayoutItemMap::extentChanged, this, &QgsLayoutItemLegend::updateFilterByMapAndRedraw );
     connect( map, &QgsLayoutItemMap::layerStyleOverridesChanged, this, &QgsLayoutItemLegend::mapLayerStyleOverridesChanged );
+    connect( map, &QgsLayoutItemMap::themeChanged, this, &QgsLayoutItemLegend::mapThemeChanged );
   }
 }
 
@@ -700,10 +702,10 @@ void QgsLayoutItemLegend::setLinkedMap( QgsLayoutItemMap *map )
   if ( mMap )
   {
     setupMapConnections( mMap, true );
+    mThemeName = mMap->themeToRender( mMap->createExpressionContext() );
   }
 
   updateFilterByMap();
-
 }
 
 void QgsLayoutItemLegend::invalidateCurrentMap()
@@ -773,9 +775,15 @@ void QgsLayoutItemLegend::mapLayerStyleOverridesChanged()
   }
 
   adjustBoxSize();
+
   updateFilterByMap( false );
 }
 
+void QgsLayoutItemLegend::mapThemeChanged( const QString &theme )
+{
+  mThemeName = theme;
+}
+
 void QgsLayoutItemLegend::updateFilterByMap( bool redraw )
 {
   // ask for update
@@ -821,6 +829,11 @@ void QgsLayoutItemLegend::doUpdateFilterByMap()
   mForceResize = true;
 }
 
+QString QgsLayoutItemLegend::themeName() const
+{
+  return mThemeName;
+}
+
 void QgsLayoutItemLegend::setLegendFilterOutAtlas( bool doFilter )
 {
   mFilterOutAtlas = doFilter;

diff --git a/src/core/layout/qgslayoutitemlegend.h b/src/core/layout/qgslayoutitemlegend.h
@@ -476,6 +476,15 @@ class CORE_EXPORT QgsLayoutItemLegend : public QgsLayoutItem
      */
     QgsLayoutItemMap *linkedMap() const { return mMap; }
 
+    /**
+     * Returns the name of the theme currently linked to the legend.
+     *
+     * This usually equates to the theme rendered in the linkedMap().
+     *
+     * \since QGIS 3.14
+     */
+    QString themeName() const;
+
     /**
      * Updates the model and all legend entries.
      */
@@ -518,6 +527,8 @@ class CORE_EXPORT QgsLayoutItemLegend : public QgsLayoutItem
 
     //! update legend in case style of associated map has changed
     void mapLayerStyleOverridesChanged();
+    //! update legend in case theme of associated map has changed
+    void mapThemeChanged( const QString &theme );
 
     //! react to atlas
     void onAtlasEnded();
@@ -567,6 +578,9 @@ class CORE_EXPORT QgsLayoutItemLegend : public QgsLayoutItem
     //! Will be TRUE if the legend should be resized automatically to fit contents
     bool mSizeToContents = true;
 
+    //! Name of theme for legend -- usually the theme associated with the linked map.
+    QString mThemeName;
+
     friend class QgsCompositionConverter;
 
 };

diff --git a/tests/src/python/test_qgslayoutlegend.py b/tests/src/python/test_qgslayoutlegend.py
@@ -490,6 +490,40 @@ def testSymbolExpressionRender(self):
 
         QgsProject.instance().removeMapLayers([point_layer.id()])
 
+    def testThemes(self):
+        layout = QgsPrintLayout(QgsProject.instance())
+        layout.setName('LAYOUT')
+
+        map = QgsLayoutItemMap(layout)
+        layout.addLayoutItem(map)
+        legend = QgsLayoutItemLegend(layout)
+
+        self.assertFalse(legend.themeName())
+        legend.setLinkedMap(map)
+        self.assertFalse(legend.themeName())
+
+        map.setFollowVisibilityPresetName('theme1')
+        map.setFollowVisibilityPreset(True)
+        self.assertEqual(legend.themeName(), 'theme1')
+        map.setFollowVisibilityPresetName('theme2')
+        self.assertEqual(legend.themeName(), 'theme2')
+        map.setFollowVisibilityPreset(False)
+        self.assertFalse(legend.themeName())
+
+        # with theme set before linking map
+        map2 = QgsLayoutItemMap(layout)
+        map2.setFollowVisibilityPresetName('theme3')
+        map2.setFollowVisibilityPreset(True)
+        legend.setLinkedMap(map2)
+        self.assertEqual(legend.themeName(), 'theme3')
+        map2.setFollowVisibilityPresetName('theme2')
+        self.assertEqual(legend.themeName(), 'theme2')
+
+        # replace with map with no theme
+        map3 = QgsLayoutItemMap(layout)
+        legend.setLinkedMap(map3)
+        self.assertFalse(legend.themeName())
+
 
 if __name__ == '__main__':
     unittest.main()