[Common] add functions for accessing the reference comparator plots from the canvas

Add to the ReferenceUtils.h header file the functions that allow to access
the current, reference and ratio plots from the TCanvas created by the
ReferenceComparartorPlot class.

This will allow for example custom checkers to access the plots.

Author: aferrero2707

Framework/include/QualityControl/ReferenceUtils.h

@@ -25,6 +25,9 @@
 #include "QualityControl/QcInfoLogger.h"
 #include "QualityControl/RepoPathUtils.h"
 
+#include <TH1.h>
+#include <TCanvas.h>
+
 namespace o2::quality_control::checker
 {
 
@@ -42,6 +45,70 @@ static std::shared_ptr<quality_control::core::MonitorObject> getReferencePlot(qu
   return qcdb->retrieveMO(path, name, repository::DatabaseInterface::Timestamp::Latest, referenceActivity);
 }
 
+//_________________________________________________________________________________________
+//
+// Get the current and reference histograms from the container canvas.
+// The two histograms are returned as a std::pair
+
+static std::pair<TH1*, TH1*> getPlotsFromCanvas(TCanvas* canvas, std::string& message)
+{
+  // Get the pad containing the current histogram, as well as the reference one in the case of 1-D plots
+  TPad* padHist = (TPad*)canvas->GetPrimitive(TString::Format("%s_PadHist", canvas->GetName()));
+  if (!padHist) {
+    message = "missing PadHist";
+    return { nullptr, nullptr };
+  }
+  // Get the pad containing the reference histogram.
+  // This pad is only present for 2-D histograms.
+  // 1-D histograms are drawn superimposed in the same pad
+  TPad* padHistRef = (TPad*)canvas->GetPrimitive(TString::Format("%s_PadHistRef", canvas->GetName()));
+
+  // Get the current histogram
+  TH1* hist = dynamic_cast<TH1*>(padHist->GetPrimitive(TString::Format("%s_hist", canvas->GetName())));
+  if (!hist) {
+    message = "missing histogram";
+    return { nullptr, nullptr };
+  }
+
+  // Get the reference histogram, trying both pads
+  TH1* histRef = nullptr;
+  if (padHistRef) {
+    histRef = dynamic_cast<TH1*>(padHistRef->GetPrimitive(TString::Format("%s_hist_ref", canvas->GetName())));
+  } else {
+    histRef = dynamic_cast<TH1*>(padHist->GetPrimitive(TString::Format("%s_hist_ref", canvas->GetName())));
+  }
+
+  if (!histRef) {
+    message = "missing reference histogram";
+    return { nullptr, nullptr };
+  }
+
+  // return a pair with the two histograms
+  return { hist, histRef };
+}
+
+//_________________________________________________________________________________________
+//
+// Get the ratio histogram from the container canvas
+
+static TH1* getRatioPlotFromCanvas(TCanvas* canvas)
+{
+  // Get the pad containing the current histogram, as well as the reference one in the case of 1-D plots
+  TPad* padHistRatio = (TPad*)canvas->GetPrimitive(TString::Format("%s_PadHistRatio", canvas->GetName()));
+  if (!padHistRatio) {
+    return nullptr;
+  }
+
+  // Get the current histogram
+  TH1* histRatio = dynamic_cast<TH1*>(padHistRatio->GetPrimitive(TString::Format("%s_hist_ratio", canvas->GetName())));
+  if (!histRatio) {
+    return nullptr;
+  }
+
+  // return a pair with the two histograms
+  return histRatio;
+}
+
 } // namespace o2::quality_control::checker
 
 #endif // QUALITYCONTROL_ReferenceUtils_H

Modules/Common/src/ReferenceComparatorCheck.cxx

@@ -75,72 +75,10 @@ void ReferenceComparatorCheck::endOfActivity(const Activity& activity)
 {
 }
 
-//_________________________________________________________________________________________
-//
-// Get the current and reference histograms from the canvas.
-// The two histograms are returned as a std::pair
-static std::pair<TH1*, TH1*> getPlotsFromCanvas(TCanvas* canvas, std::string& message)
-{
-  // Get the pad containing the current histogram, as well as the reference one in the case of 1-D plots
-  TPad* padHist = (TPad*)canvas->GetPrimitive(TString::Format("%s_PadHist", canvas->GetName()));
-  if (!padHist) {
-    message = "missing PadHist";
-    return { nullptr, nullptr };
-  }
-  // Get the pad containing the reference histogram.
-  // This pad is only present for 2-D histograms.
-  // 1-D histograms are drawn superimposed in the same pad
-  TPad* padHistRef = (TPad*)canvas->GetPrimitive(TString::Format("%s_PadHistRef", canvas->GetName()));
-
-  // Get the current histogram
-  TH1* hist = dynamic_cast<TH1*>(padHist->GetPrimitive(TString::Format("%s_hist", canvas->GetName())));
-  if (!hist) {
-    message = "missing histogram";
-    return { nullptr, nullptr };
-  }
-
-  // Get the reference histogram, trying both pads
-  TH1* histRef = nullptr;
-  if (padHistRef) {
-    histRef = dynamic_cast<TH1*>(padHistRef->GetPrimitive(TString::Format("%s_hist_ref", canvas->GetName())));
-  } else {
-    histRef = dynamic_cast<TH1*>(padHist->GetPrimitive(TString::Format("%s_hist_ref", canvas->GetName())));
-  }
-
-  if (!histRef) {
-    message = "missing reference histogram";
-    return { nullptr, nullptr };
-  }
-
-  // return a pair with the two histograms
-  return { hist, histRef };
-}
-
 static std::pair<TH1*, TH1*> getPlotsFromCanvas(TCanvas* canvas)
 {
   std::string dummyMessage;
-  return getPlotsFromCanvas(canvas, dummyMessage);
-}
-
-//_________________________________________________________________________________________
-//
-// Get the ratio histograms from the canvas
-static TH1* getRatioPlotFromCanvas(TCanvas* canvas)
-{
-  // Get the pad containing the current histogram, as well as the reference one in the case of 1-D plots
-  TPad* padHistRatio = (TPad*)canvas->GetPrimitive(TString::Format("%s_PadHistRatio", canvas->GetName()));
-  if (!padHistRatio) {
-    return nullptr;
-  }
-
-  // Get the current histogram
-  TH1* histRatio = dynamic_cast<TH1*>(padHistRatio->GetPrimitive(TString::Format("%s_hist_ratio", canvas->GetName())));
-  if (!histRatio) {
-    return nullptr;
-  }
-
-  // return a pair with the two histograms
-  return histRatio;
+  return o2::quality_control::checker::getPlotsFromCanvas(canvas, dummyMessage);
 }
 
 // Get the current and reference histograms from the canvas, and compare them using the comparator object passed as parameter
@@ -156,7 +94,7 @@ static Quality compare(TCanvas* canvas, ObjectComparatorInterface* comparator, s
   }
 
   // extract the histograms from the canvas
-  auto plots = getPlotsFromCanvas(canvas, message);
+  auto plots = o2::quality_control::checker::getPlotsFromCanvas(canvas, message);
   if (!plots.first || !plots.second) {
     return Quality::Null;
   }
@@ -389,7 +327,7 @@ void ReferenceComparatorCheck::beautify(std::shared_ptr<MonitorObject> mo, Quali
     setQualityLabel(canvas, quality);
 
     // draw a double-arrow indicating the horizontal range for the check, if it is set
-    beautifyRatioPlot(moName, getRatioPlotFromCanvas(canvas), quality);
+    beautifyRatioPlot(moName, o2::quality_control::checker::getRatioPlotFromCanvas(canvas), quality);
   } else {
     // draw the quality label directly on the plot if the MO is an histogram
     auto* th1 = dynamic_cast<TH1*>(mo->getObject());