Fix missing scrollbars in combo box for value map / relation

If a value map widget or value relation widget has a combo box with many options, the default behavior in Qt is not to add scrollbars, only arrows at the top/bottom of the list. That however makes it quite slow to scroll if the list of choices is long. This fixes the issue for both value map and value relation. If the list of choices is short that it fits the screen, no scrollbar gets shown.
qgis · Feb 13, 2022 · af58cc8 · af58cc8
1 parent fb57979
commit af58cc8
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diff --git a/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.cpp b/src/gui/editorwidgets/qgsvaluemapwidgetwrapper.cpp
@@ -62,6 +62,7 @@ void QgsValueMapWidgetWrapper::initWidget( QWidget *editor )
   if ( mComboBox )
   {
     QgsValueMapConfigDlg::populateComboBox( mComboBox, config(), false );
+    mComboBox->view()->setVerticalScrollBarPolicy( Qt::ScrollBarAsNeeded );
     connect( mComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ),
              this, static_cast<void ( QgsEditorWidgetWrapper::* )()>( &QgsEditorWidgetWrapper::emitValueChanged ) );
   }

diff --git a/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp b/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp
@@ -164,6 +164,7 @@ void QgsValueRelationWidgetWrapper::initWidget( QWidget *editor )
 
   if ( mComboBox )
   {
+    mComboBox->view()->setVerticalScrollBarPolicy( Qt::ScrollBarAsNeeded );
     connect( mComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ),
              this, static_cast<void ( QgsEditorWidgetWrapper::* )()>( &QgsEditorWidgetWrapper::emitValueChanged ), Qt::UniqueConnection );
   }