make white bins appear in the output SiStripTkMaps

DQM/TrackerRemapper/src/SiStripTkMaps.cc

@@ -56,9 +56,15 @@ void SiStripTkMaps::bookMap(const std::string mapTitle, const std::string zAxisT
   m_trackerMap->GetZaxis()->SetTitle(m_zAxisTitle.c_str());
   m_trackerMap->GetZaxis()->CenterTitle();
 
+  // Add all bins
   for (const auto& pair : m_bins) {
     m_trackerMap->AddBin(pair.second->Clone());
   }
+
+  // Initialize all bins with zero values
+  for (const auto& pair : m_bins) {
+    m_trackerMap->Fill(pair.first, 0.0);
+  }
 }
 
 //============================================================================
@@ -79,6 +85,24 @@ void SiStripTkMaps::drawMap(TCanvas& canvas, std::string option) {
   static constexpr int wH_ = 3000;
   static constexpr int hH_ = 700;
 
+  // Define a special value for "empty" bins
+  static constexpr double emptyBinValue = -9999;
+
+  // Ensure all bins are drawn, including empty ones
+  for (int i = 1; i <= m_trackerMap->GetNumberOfBins(); ++i) {
+    if (m_trackerMap->GetBinContent(i) == 0) {
+      m_trackerMap->SetBinContent(i, emptyBinValue);
+    }
+  }
+
+  // Adjust the color palette
+  double minValue = *std::min_element(m_values.begin(), m_values.end());
+  double maxValue = *std::max_element(m_values.begin(), m_values.end());
+
+  // Setting a palette that skips the color for the emptyBinValue
+  m_trackerMap->SetMinimum(minValue);  // Set min to the smallest valid value
+  m_trackerMap->SetMaximum(maxValue);  // Set max to the largest valid value
+
   canvas.cd();
   adjustCanvasMargins(canvas.cd(), tmargin_, bmargin_, lmargin_, rmargin_);
   canvas.Update();
@@ -90,6 +114,14 @@ void SiStripTkMaps::drawMap(TCanvas& canvas, std::string option) {
     m_trackerMap->Draw();
   }
 
+  // Set the "empty" bins color to white
+  for (int i = 1; i <= m_trackerMap->GetNumberOfBins(); ++i) {
+    if (m_trackerMap->GetBinContent(i) == emptyBinValue) {
+      m_trackerMap->SetBinContent(i, emptyBinValue);
+      m_trackerMap->SetMarkerColor(kWhite);
+    }
+  }
+
   canvas.SetFrameLineColor(0);
   gPad->Update();
   TPaletteAxis* palette = (TPaletteAxis*)m_trackerMap->GetListOfFunctions()->FindObject("palette");