added merging of TCanvas to mergers

Author: Michal Tichák

Utilities/Mergers/CMakeLists.txt

@@ -15,7 +15,7 @@ o2_add_library(Mergers
                SOURCES src/FullHistoryMerger.cxx src/IntegratingMerger.cxx src/Mergeable.cxx
                        src/MergerAlgorithm.cxx src/MergerBuilder.cxx src/MergerInfrastructureBuilder.cxx
                        src/ObjectStore.cxx
-               PUBLIC_LINK_LIBRARIES O2::Framework AliceO2::InfoLogger)
+               PUBLIC_LINK_LIBRARIES O2::Framework AliceO2::InfoLogger ROOT::Gpad)
 
 o2_target_root_dictionary(
   Mergers

Utilities/Mergers/src/MergerAlgorithm.cxx

@@ -16,7 +16,6 @@
 
 #include "Mergers/MergerAlgorithm.h"
 
-#include "Framework/Logger.h"
 #include "Mergers/MergeInterface.h"
 #include "Mergers/ObjectStore.h"
 
@@ -29,6 +28,10 @@
 #include <THnSparse.h>
 #include <TObjArray.h>
 #include <TTree.h>
+#include <TPad.h>
+#include <TCanvas.h>
+#include <algorithm>
+#include <stdexcept>
 
 namespace o2::mergers::algorithm
 {
@@ -43,6 +46,51 @@ size_t estimateTreeSize(TTree* tree)
   return totalSize;
 }
 
+// Mergeable objects are kept as primitives in TCanvas object in underlying TPad.
+// TPad is a linked list of primitives of any type (https://root.cern.ch/doc/master/classTPad.html)
+// including other TPads. So in order to collect all mergeable objects from TCanvas
+// we need to recursively transverse whole TPad structure.
+auto collectUnderlyingObjects(TCanvas* canvas) -> std::vector<TObject*>
+{
+  auto collectFromTPad = [](TPad* pad, std::vector<TObject*>& objects, auto&& collectFromTPad) {
+    if (!pad) {
+      return;
+    }
+    auto* primitives = pad->GetListOfPrimitives();
+    for (int i = 0; i < primitives->GetSize(); ++i) {
+      auto* primitive = primitives->At(i);
+      if (auto* primitivePad = dynamic_cast<TPad*>(primitive)) {
+        collectFromTPad(primitivePad, objects, collectFromTPad);
+      } else {
+        objects.push_back(primitive);
+      }
+    }
+  };
+
+  std::vector<TObject*> collectedObjects;
+  collectFromTPad(canvas, collectedObjects, collectFromTPad);
+
+  return collectedObjects;
+}
+
+struct MatchedCollectedObjects {
+  TObject* target;
+  TObject* other;
+};
+
+auto matchCollectedToPairs(const std::vector<TObject*>& targetObjects, const std::vector<TObject*> otherObjects) -> std::vector<MatchedCollectedObjects>
+{
+  std::vector<MatchedCollectedObjects> matchedObjects;
+  matchedObjects.reserve(std::max(targetObjects.size(), otherObjects.size()));
+  for (const auto& targetObject : targetObjects) {
+    if (const auto found_it = std::ranges::find_if(otherObjects, [&targetObject](TObject* obj) { return std::string_view(targetObject->GetName()) == std::string_view(obj->GetName()); });
+        found_it != otherObjects.end()) {
+      matchedObjects.emplace_back(targetObject, *found_it);
+    }
+  }
+  return matchedObjects;
+}
+
 void merge(TObject* const target, TObject* const other)
 {
   if (target == nullptr) {
@@ -82,6 +130,29 @@ void merge(TObject* const target, TObject* const other)
       }
     }
     delete otherIterator;
+  } else if (auto targetCanvas = dynamic_cast<TCanvas*>(target)) {
+
+    auto otherCanvas = dynamic_cast<TCanvas*>(other);
+    if (otherCanvas == nullptr) {
+      throw std::runtime_error(std::string("The target object '") + target->GetName() +
+                               "' is a TCanvas, while the other object '" + other->GetName() + "' is not.");
+    }
+
+    const auto targetObjects = collectUnderlyingObjects(targetCanvas);
+    const auto otherObjects = collectUnderlyingObjects(otherCanvas);
+    if (targetObjects.size() != otherObjects.size()) {
+      throw std::runtime_error(std::string("Trying to merge canvas: ") + targetCanvas->GetName() + " and canvas " + otherObjects.size() + "but contents are not the same");
+    }
+
+    const auto matched = matchCollectedToPairs(targetObjects, otherObjects);
+    if (targetObjects.size() != matched.size()) {
+      throw std::runtime_error(std::string("Trying to merge canvas: ") + targetCanvas->GetName() + " and canvas " + otherObjects.size() + "but contents are not the same");
+    }
+
+    for (const auto& [targetObject, otherObject] : matched) {
+      merge(targetObject, otherObject);
+    }
+
   } else {
     Long64_t errorCode = 0;
     TObjArray otherCollection;
@@ -169,4 +240,4 @@ void deleteTCollections(TObject* obj)
   }
 }
 
-} // namespace o2::mergers::algorithm
+} // namespace o2::mergers::algorithm

Utilities/Mergers/test/test_Algorithm.cxx

@@ -14,9 +14,12 @@
 ///
 /// \author Piotr Konopka, piotr.jan.konopka@cern.ch
 
+#include <boost/mpl/pair.hpp>
 #include <boost/test/tools/interface.hpp>
+#include <boost/test/tools/old/interface.hpp>
 #include <gsl/span>
 #include <memory>
+#include <stdexcept>
 #define BOOST_TEST_MODULE Test Utilities MergerAlgorithm
 #define BOOST_TEST_MAIN
 #define BOOST_TEST_DYN_LINK
@@ -39,6 +42,7 @@
 #include <TF1.h>
 #include <TGraph.h>
 #include <TProfile.h>
+#include <TCanvas.h>
 
 // using namespace o2::framework;
 using namespace o2::mergers;
@@ -305,6 +309,120 @@ BOOST_AUTO_TEST_CASE(MergerCollection)
   delete target;
 }
 
+TCanvas* createCanvas(std::string name, std::string title, std::vector<std::shared_ptr<TH1I>>& histograms)
+{
+  auto canvas = new TCanvas(name.c_str(), title.c_str(), 100, 100);
+  canvas->Divide(histograms.size(), 1);
+  for (size_t i = 1; const auto& hist : histograms) {
+    canvas->cd(i);
+    hist->Draw();
+    ++i;
+  }
+  return canvas;
+}
+
+auto collectUnderlyingObjects(TCanvas* canvas) -> std::vector<TObject*>
+{
+  if (!canvas) {
+    return {};
+  }
+
+  auto collectFromTPad = []<class TPadOrTCanvas>
+    requires std::same_as<TPadOrTCanvas, TPad> || std::same_as<TPadOrTCanvas, TCanvas>
+  (TPadOrTCanvas * pad, std::vector<TObject*> & objects, auto&& collectFromTPad) -> void {
+    auto* primitives = pad->GetListOfPrimitives();
+    for (int i = 0; i < primitives->GetSize(); ++i) {
+      auto* primitive = primitives->At(i);
+      if (auto* primitivePad = dynamic_cast<TPad*>(primitive)) {
+        collectFromTPad(primitivePad, objects, collectFromTPad);
+      } else {
+        objects.push_back(primitive);
+      }
+    }
+  };
+
+  std::vector<TObject*> collectedObjects;
+  collectFromTPad(canvas, collectedObjects, collectFromTPad);
+
+  return collectedObjects;
+}
+
+BOOST_AUTO_TEST_CASE(MergerTCanvas)
+{
+  // working example
+  {
+    std::vector<std::shared_ptr<TH1I>> histsC1{
+      std::make_shared<TH1I>("th1", "obj1", bins, min, max),
+      std::make_shared<TH1I>("th2", "obj2", bins, min, max),
+    };
+    histsC1[0]->Fill(5);
+    histsC1[1]->Fill(2);
+    BOOST_CHECK_EQUAL(histsC1[0]->GetBinContent(histsC1[0]->FindBin(5)), 1);
+    BOOST_CHECK_EQUAL(histsC1[1]->GetBinContent(histsC1[1]->FindBin(2)), 1);
+
+    std::vector<std::shared_ptr<TH1I>> histsC2{
+      std::make_shared<TH1I>("th1", "obj1", bins, min, max),
+      std::make_shared<TH1I>("th2", "obj2", bins, min, max),
+    };
+
+    histsC2[0]->Fill(5);
+    histsC2[1]->Fill(2);
+    BOOST_CHECK_EQUAL(histsC2[0]->GetBinContent(histsC2[0]->FindBin(5)), 1);
+    BOOST_CHECK_EQUAL(histsC2[1]->GetBinContent(histsC2[1]->FindBin(2)), 1);
+
+    auto targetCanvas = createCanvas("c1", "test title 1", histsC1);
+    auto otherCanvas = createCanvas("c2", "test title 2", histsC2);
+
+    algorithm::merge(targetCanvas, otherCanvas);
+
+    auto targetObjects = collectUnderlyingObjects(targetCanvas);
+
+    BOOST_CHECK_EQUAL(targetObjects.size(), 2);
+    for (const auto& object : targetObjects) {
+      auto th = static_cast<TH1*>(object);
+      if (std::string(th->GetName()) == "th1") {
+        BOOST_CHECK_EQUAL(th->GetBinContent(th->FindBin(5)), 2);
+      }
+      if (std::string(th->GetName()) == "th2") {
+        BOOST_CHECK_EQUAL(th->GetBinContent(th->FindBin(2)), 2);
+      }
+    }
+  }
+
+  // throw because we try to merge canvases with different number of underlying items
+  {
+    std::vector<std::shared_ptr<TH1I>> histsC1{
+      std::make_shared<TH1I>("th1", "obj1", bins, min, max),
+      std::make_shared<TH1I>("th2", "obj2", bins, min, max),
+    };
+
+    std::vector<std::shared_ptr<TH1I>> histsC2{
+      std::make_shared<TH1I>("th1", "obj1", bins, min, max),
+    };
+
+    auto targetCanvas = createCanvas("c1", "test title 1", histsC1);
+    auto otherCanvas = createCanvas("c2", "test title 2", histsC2);
+
+    BOOST_CHECK_THROW(algorithm::merge(targetCanvas, otherCanvas), std::runtime_error);
+  }
+
+  // throw because we try to merge canvases with different underlying items
+  {
+    std::vector<std::shared_ptr<TH1I>> histsC1{
+      std::make_shared<TH1I>("th1", "obj1", bins, min, max),
+    };
+
+    std::vector<std::shared_ptr<TH1I>> histsC2{
+      std::make_shared<TH1I>("th2", "obj2", bins, min, max),
+    };
+
+    auto targetCanvas = createCanvas("c1", "test title 1", histsC1);
+    auto otherCanvas = createCanvas("c2", "test title 2", histsC2);
+
+    BOOST_CHECK_THROW(algorithm::merge(targetCanvas, otherCanvas), std::runtime_error);
+  }
+}
+
 BOOST_AUTO_TEST_CASE(Deleting)
 {
   TObjArray* main = new TObjArray();