Maintain correct order of legend items when inserting pie chart items

Rewrite QLegendPrivate::handleCountChanged() so that the order
of the markers is preserved. Split out helper functions for
insertion/removal that leave the m_markers list untouched and
add helpers for finding markers by series and related objects.
In QLegendPrivate::handleCountChanged(), remove the markers
of the series from m_markers and replace the existing ones
in the createdMarkers. Finally re-insert createdMarkers into
m_markers, preserving the order.

Task-number: QTBUG-62082
Change-Id: I03c81dcf5dfd5a5883377630cad16c943503a1be
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

1 files changed, 11 insertions, 1 deletions

diff --git a/tests/auto/qpieslice/tst_qpieslice.cpp b/tests/auto/qpieslice/tst_qpieslice.cpp
index 19d838f5..977ed35b 100644
--- a/tests/auto/qpieslice/tst_qpieslice.cpp
+++ b/tests/auto/qpieslice/tst_qpieslice.cpp
@@ -31,6 +31,8 @@
 #include <tst_definitions.h>
 #include <QtCharts/QChartView>
 #include <QtCharts/QChart>
+#include <QtCharts/QLegend>
+#include <QtCharts/QLegendMarker>
 #include <QtCharts/QPieSlice>
 #include <QtCharts/QPieSeries>
 
@@ -217,12 +219,20 @@ void tst_qpieslice::customize()
     QCOMPARE(s1->labelFont(), f1);
 
     // insert a slice
-    series->insert(0, new QPieSlice("slice 5", 5));
+    series->insert(0, new QPieSlice("slice 0", 5));
     QCOMPARE(s1->pen(), p1);
     QCOMPARE(s1->brush(), b1);
     QCOMPARE(s1->labelBrush(), b1);
     QCOMPARE(s1->labelFont(), f1);
 
+    // QTBUG-62082, verify correct insertion at 0.
+    const QStringList expectedLabels{"slice 0", "slice 1", "slice 3", "slice 4"};
+    const auto legendMarkers = view.chart()->legend()->markers();
+    const int legendMarkersSize = legendMarkers.size();
+    QCOMPARE(legendMarkersSize, expectedLabels.size());
+    for (int m = 0; m < legendMarkersSize; ++m)
+        QCOMPARE(legendMarkers.at(m)->label(), expectedLabels.at(m));
+
     // change theme
     // theme will overwrite customizations
     view.chart()->setTheme(QChart::ChartThemeHighContrast);