From 4fe821aabf979459ff15980598f19edfa7915d48 Mon Sep 17 00:00:00 2001
From: shun-iwasawa <shun.iwasawa@ghibli.jp>
Date: Jan 14 2021 23:19:12 +0000
Subject: fix redundant preview invocation


---

diff --git a/toonz/sources/common/tcore/tundo.cpp b/toonz/sources/common/tcore/tundo.cpp
index 4eb219a..bca63db 100644
--- a/toonz/sources/common/tcore/tundo.cpp
+++ b/toonz/sources/common/tcore/tundo.cpp
@@ -37,9 +37,10 @@ public:
   }
   int getUndoCount() const { return (int)m_undos.size(); }
   void setLast() {
-    for (UINT i                   = 1; i < m_undos.size(); i++)
-      m_undos[i]->m_isLastInBlock = false;
-    m_undos[0]->m_isLastInBlock   = true;
+    for (UINT i = 0; i < m_undos.size(); i++) {
+      m_undos[i]->m_isLastInBlock     = (i == 0);
+      m_undos[i]->m_isLastInRedoBlock = (i == m_undos.size() - 1);
+    }
   }
 
   void undo() const override {
@@ -65,7 +66,8 @@ public:
   //}
   void onAdd() override {}
   void add(TUndo *undo) {
-    undo->m_isLastInBlock = true;
+    undo->m_isLastInBlock     = true;
+    undo->m_isLastInRedoBlock = true;
     m_undos.push_back(undo);
   }
 
@@ -97,7 +99,7 @@ public:
       return m_undos.back()->getHistoryType();
   }
 };
-}
+}  // namespace
 
 typedef std::deque<TUndo *> UndoList;
 typedef UndoList::iterator UndoListIterator;
@@ -186,9 +188,8 @@ void TUndoManager::TUndoManagerImp::doAdd(TUndo *undo) {
   int i, memorySize = 0, count = m_undoList.size();
   for (i = 0; i < count; i++) memorySize += m_undoList[i]->getSize();
 
-  while (
-      count > 100 ||
-      (count != 0 && memorySize + undo->getSize() > m_undoMemorySize))  // 20MB
+  while (count > 100 || (count != 0 && memorySize + undo->getSize() >
+                                           m_undoMemorySize))  // 20MB
   {
     --count;
     TUndo *undo = m_undoList.front();
@@ -197,7 +198,8 @@ void TUndoManager::TUndoManagerImp::doAdd(TUndo *undo) {
     delete undo;
   }
 
-  undo->m_isLastInBlock = true;
+  undo->m_isLastInBlock     = true;
+  undo->m_isLastInRedoBlock = true;
   m_undoList.push_back(undo);
   m_current = m_undoList.end();
 }
diff --git a/toonz/sources/include/tundo.h b/toonz/sources/include/tundo.h
index 64a9800..25e34a9 100644
--- a/toonz/sources/include/tundo.h
+++ b/toonz/sources/include/tundo.h
@@ -28,7 +28,10 @@
 
 class DVAPI TUndo {
 public:
+  // To be called in the last of the block when undo
   bool m_isLastInBlock;
+  // To be called in the last of the block when redo
+  bool m_isLastInRedoBlock;
 
 public:
   TUndo() {}
diff --git a/toonz/sources/toonzlib/fxcommand.cpp b/toonz/sources/toonzlib/fxcommand.cpp
index f467e0f..2825851 100644
--- a/toonz/sources/toonzlib/fxcommand.cpp
+++ b/toonz/sources/toonzlib/fxcommand.cpp
@@ -1947,7 +1947,7 @@ void DeleteLinksUndo::redo() const {
       outputFx->getInputPort(index)->setFx(0);
   }
 
-  m_xshHandle->notifyXsheetChanged();
+  if (m_isLastInRedoBlock) m_xshHandle->notifyXsheetChanged();
 }
 
 //------------------------------------------------------
@@ -2012,7 +2012,7 @@ void DeleteLinksUndo::undo() const {
     }
   }
 
-  m_xshHandle->notifyXsheetChanged();
+  if (m_isLastInBlock) m_xshHandle->notifyXsheetChanged();
 }
 
 //------------------------------------------------------
@@ -2245,7 +2245,8 @@ void DeleteFxOrColumnUndo::redo() const {
   // Perform operation
   FxCommandUndo::removeFxOrColumn(xsh, m_fx.getPointer(), m_colIdx);
 
-  m_xshHandle->notifyXsheetChanged();  // Add the rest...
+  if (m_isLastInRedoBlock)
+    m_xshHandle->notifyXsheetChanged();  // Add the rest...
 }
 
 //-------------------------------------------------------------
@@ -2296,7 +2297,7 @@ void DeleteFxOrColumnUndo::undo() const {
 
     // Re-establish fx links
     DeleteLinksUndo::undo();
-  } else  // Already covered by DeleteLinksUndo::undo()
+  } else if (m_isLastInBlock)  // Already covered by DeleteLinksUndo::undo()
     m_xshHandle->notifyXsheetChanged();  // in the other branch
 }
 
@@ -2327,12 +2328,18 @@ static void deleteFxs(const std::list<TFxP> &fxs, TXsheetHandle *xshHandle,
     std::unique_ptr<FxCommandUndo> undo(
         new DeleteFxOrColumnUndo(*ft, xshHandle, fxHandle));
     if (undo->isConsistent()) {
+      // prevent emiting xsheetChanged signal for every undos which will cause
+      // multiple triggers of preview rendering
+      undo->m_isLastInRedoBlock = false;
       undo->redo();
       TUndoManager::manager()->add(undo.release());
     }
   }
 
   undoManager->endBlock();
+
+  // emit xsheetChanged once here
+  xshHandle->notifyXsheetChanged();
 }
 
 //**********************************************************************
@@ -2377,12 +2384,18 @@ static void deleteColumns(const std::list<int> &columns,
     std::unique_ptr<FxCommandUndo> undo(
         new DeleteFxOrColumnUndo(cols[c]->getIndex(), xshHandle, fxHandle));
     if (undo->isConsistent()) {
+      // prevent emiting xsheetChanged signal for every undos which will cause
+      // multiple triggers of preview rendering
+      undo->m_isLastInRedoBlock = false;
       undo->redo();
       undoManager->add(undo.release());
     }
   }
 
   undoManager->endBlock();
+
+  // emit xsheetChanged once here
+  xshHandle->notifyXsheetChanged();
 }
 
 //**********************************************************************
@@ -2407,9 +2420,9 @@ void TFxCommand::deleteSelection(const std::list<TFxP> &fxs,
   // Perform deletions
   TUndoManager::manager()->beginBlock();
 
-  deleteColumns(columns, xshHandle, fxHandle);
-  deleteFxs(filteredFxs, xshHandle, fxHandle);
-  deleteLinks(links, xshHandle);
+  if (!columns.empty()) deleteColumns(columns, xshHandle, fxHandle);
+  if (!filteredFxs.empty()) deleteFxs(filteredFxs, xshHandle, fxHandle);
+  if (!links.empty()) deleteLinks(links, xshHandle);
 
   TUndoManager::manager()->endBlock();
 }