From a2ca9a079ecc8926f6ddf7a72803340a4944e7cf Mon Sep 17 00:00:00 2001
From: Eric Larson <larson.eric.d@gmail.com>
Date: Tue, 11 Oct 2022 12:12:38 -0400
Subject: [PATCH] BUG: Fix bug with vtkPlotBar.GetLookupTable()

Also remove old nullptr assignments as they are unnecessary
when using vtkSmartPointer.
---
 .../Core/Testing/Cxx/TestPlotBarRangeHandlesItem.cxx   |  2 ++
 Charts/Core/vtkPlotBar.cxx                             | 10 +++++++---
 .../release/dev/fix-vtkPlotBar-GetLookupTable.md       |  4 ++++
 3 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/release/dev/fix-vtkPlotBar-GetLookupTable.md

diff --git a/Charts/Core/Testing/Cxx/TestPlotBarRangeHandlesItem.cxx b/Charts/Core/Testing/Cxx/TestPlotBarRangeHandlesItem.cxx
index 2d0ed46b128..919319a6b4d 100644
--- a/Charts/Core/Testing/Cxx/TestPlotBarRangeHandlesItem.cxx
+++ b/Charts/Core/Testing/Cxx/TestPlotBarRangeHandlesItem.cxx
@@ -88,6 +88,8 @@ int TestPlotBarRangeHandlesItem(int, char*[])
 
   // Add bar plot and handles
   vtkPlotBar* barPlot = vtkPlotBar::SafeDownCast(chart->AddPlot(vtkChart::BAR));
+  // smoke test for https://gitlab.kitware.com/vtk/vtk/-/issues/18682#note_1258974
+  barPlot->GetLookupTable();
   barPlot->SetInputData(table, "Months", "Books");
   chart->SetBarWidthFraction(1.0);
 
diff --git a/Charts/Core/vtkPlotBar.cxx b/Charts/Core/vtkPlotBar.cxx
index a68a26c0ecd..220e8199d02 100644
--- a/Charts/Core/vtkPlotBar.cxx
+++ b/Charts/Core/vtkPlotBar.cxx
@@ -535,12 +535,11 @@ vtkStandardNewMacro(vtkPlotBar);
 vtkPlotBar::vtkPlotBar()
 {
   this->Private = new vtkPlotBarPrivate(this);
+  // Points is not a vtkSmartPointer, so set it explicitly to nullptr
   this->Points = nullptr;
-  this->AutoLabels = nullptr;
   this->Width = 1.0;
   this->Pen->SetWidth(1.0);
   this->Offset = 1.0;
-  this->ColorSeries = nullptr;
   this->Orientation = vtkPlotBar::VERTICAL;
   this->ScalarVisibility = false;
   this->EnableOpacityMapping = true;
@@ -612,6 +611,10 @@ void vtkPlotBar::GetBounds(double bounds[4], bool unscaled)
 
   // Get the x and y arrays (index 0 and 1 respectively)
   vtkTable* table = this->Data->GetInput();
+  if (!table)
+  {
+    return;
+  }
   vtkDataArray* x =
     this->UseIndexForXSeries ? nullptr : this->Data->GetInputArrayToProcess(0, table);
   vtkDataArray* y = this->Data->GetInputArrayToProcess(1, table);
@@ -945,7 +948,8 @@ void vtkPlotBar::CreateDefaultLookupTable()
   // rainbow - blue to red
   lut->SetHueRange(0.6667, 0.0);
   lut->Build();
-  double bounds[4];
+  // set reasonable defaults in case no data has been set
+  double bounds[4] = { 0.0, 1.0, 0.0, 1.0 };
   this->GetBounds(bounds);
   lut->SetRange(bounds[0], bounds[1]);
   this->LookupTable = lut;
diff --git a/Documentation/release/dev/fix-vtkPlotBar-GetLookupTable.md b/Documentation/release/dev/fix-vtkPlotBar-GetLookupTable.md
new file mode 100644
index 00000000000..ba6a96753ac
--- /dev/null
+++ b/Documentation/release/dev/fix-vtkPlotBar-GetLookupTable.md
@@ -0,0 +1,4 @@
+## Fixes for vtkPlotBar.GetLookupTable
+
+Fixes a bug where calling vtkPlotBar.GetLookupTable caused a segmentation
+fault in the case where no data had been plotted yet.
-- 
GitLab