[categorized renderer] When color ramp is set to random, randomize color

of appended categories to pre-existing list when hitting the classify button (fixes #31579)
qgis · Sep 16, 2019 · 6db7e9e · 6db7e9e
1 parent 7413335
commit 6db7e9e
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/src/gui/symbology/qgscategorizedsymbolrendererwidget.cpp b/src/gui/symbology/qgscategorizedsymbolrendererwidget.cpp
@@ -739,6 +739,9 @@ void QgsCategorizedSymbolRendererWidget::addCategories()
   {
     QgsCategoryList prevCats = mRenderer->categories();
     keepExistingColors = !prevCats.isEmpty();
+    QgsRandomColorRamp randomColors;
+    if ( keepExistingColors && btnColorRamp->isRandomColorRamp() )
+      randomColors.setTotalColorCount( cats.size() );
     for ( int i = 0; i < cats.size(); ++i )
     {
       bool contains = false;
@@ -753,7 +756,14 @@ void QgsCategorizedSymbolRendererWidget::addCategories()
       }
 
       if ( !contains )
+      {
+        if ( keepExistingColors && btnColorRamp->isRandomColorRamp() )
+        {
+          // insure that append symbols have random colors
+          cats.at( i ).symbol()->setColor( randomColors.color( i ) );
+        }
         prevCats.append( cats.at( i ) );
+      }
     }
     cats = prevCats;
   }