Editor: cache folded state in editor widgetHEADmaster

Iterating over all blocks is not cheap for huge documents. And the
saveState function is called multiple times per edit to save the cursor
position in the history.

Change-Id: I48c516347ecd458f2210010844f9cf8f7c34682c
Reviewed-by: Christian Stenger <[email protected]>

1 files changed, 32 insertions, 15 deletions

diff --git a/src/plugins/texteditor/texteditor.cpp b/src/plugins/texteditor/texteditor.cpp
index ab2415880d8..b27ee67a8fe 100644
--- a/src/plugins/texteditor/texteditor.cpp
+++ b/src/plugins/texteditor/texteditor.cpp
@@ -836,6 +836,7 @@ public:
     void transformSelection(TransformationMethod method);
 
     void slotUpdateExtraAreaWidth(std::optional<int> width = {});
+    void slotUpdateBlockCount();
     void slotUpdateRequest(const QRect &r, int dy);
     void slotUpdateBlockNotify(const QTextBlock &);
     void updateTabStops();
@@ -850,6 +851,7 @@ public:
     void setupScrollBar();
     void highlightSearchResultsInScrollBar();
     void scheduleUpdateHighlightScrollBar();
+    void slotFoldChanged(const int blockNumber, bool folded);
     void updateHighlightScrollBarNow();
     struct SearchResult {
         int start;
@@ -953,6 +955,7 @@ public:
     TextEditorOverlay *m_selectionHighlightOverlay = nullptr;
     bool snippetCheckCursor(const QTextCursor &cursor);
     void snippetTabOrBacktab(bool forward);
+    QSet<int> m_foldedBlockCache;
 
     struct AnnotationRect
     {
@@ -1275,7 +1278,8 @@ TextEditorWidgetPrivate::TextEditorWidgetPrivate(TextEditorWidget *parent)
     connect(&m_codeAssistant, &CodeAssistant::finished,
             q, &TextEditorWidget::assistFinished);
 
-    connect(q, &PlainTextEdit::blockCountChanged, this, [this] { slotUpdateExtraAreaWidth(); });
+    connect(q, &PlainTextEdit::blockCountChanged,
+            this, &TextEditorWidgetPrivate::slotUpdateBlockCount);
 
     connect(q, &PlainTextEdit::modificationChanged,
             m_extraArea, QOverload<>::of(&QWidget::update));
@@ -1546,6 +1550,11 @@ void TextEditorWidgetPrivate::setDocument(const QSharedPointer<TextDocument> &do
                                      m_extraArea,
                                      QOverload<>::of(&QWidget::update));
 
+    m_documentConnections << connect(documentLayout,
+                                     &TextDocumentLayout::foldChanged,
+                                     this,
+                                     &TextEditorWidgetPrivate::slotFoldChanged);
+
     m_documentConnections << connect(q,
                                      &TextEditorWidget::requestBlockUpdate,
                                      documentLayout,
@@ -3755,19 +3764,7 @@ QByteArray TextEditorWidget::saveState() const
     convertPosition(textCursor().position(), &line, &column);
     stream << line;
     stream << column;
-
-    // store code folding state
-    QList<int> foldedBlocks;
-    QTextBlock block = document()->firstBlock();
-    while (block.isValid()) {
-        if (TextBlockUserData::isFolded(block)) {
-            int number = block.blockNumber();
-            foldedBlocks += number;
-        }
-        block = block.next();
-    }
-    stream << foldedBlocks;
-
+    stream << d->m_foldedBlockCache;
     stream << firstVisibleBlockNumber();
     stream << lastVisibleBlockNumber();
 
@@ -3817,7 +3814,7 @@ void TextEditorWidget::restoreState(const QByteArray &state)
     stream >> columnVal;
 
     if (version >= 1) {
-        QList<int> collapsedBlocks;
+        QSet<int> collapsedBlocks;
         stream >> collapsedBlocks;
         auto foldingRestore = [this, collapsedBlocks] {
             QTextDocument *doc = document();
@@ -6612,6 +6609,18 @@ void TextEditorWidgetPrivate::slotUpdateExtraAreaWidth(std::optional<int> width)
         q->setViewportMargins(margins);
 }
 
+void TextEditorWidgetPrivate::slotUpdateBlockCount()
+{
+    slotUpdateExtraAreaWidth();
+    m_foldedBlockCache.clear();
+    QTextBlock block = q->document()->firstBlock();
+    while (block.isValid()) {
+        if (TextBlockUserData::isFolded(block))
+            m_foldedBlockCache += block.blockNumber();
+        block = block.next();
+    }
+}
+
 struct Internal::ExtraAreaPaintEventData
 {
     ExtraAreaPaintEventData(const TextEditorWidget *editor, TextEditorWidgetPrivate *d)
@@ -8278,6 +8287,14 @@ void TextEditorWidgetPrivate::scheduleUpdateHighlightScrollBar()
                               Qt::QueuedConnection);
 }
 
+void TextEditorWidgetPrivate::slotFoldChanged(const int blockNumber, bool folded)
+{
+    if (folded)
+        m_foldedBlockCache.insert(blockNumber);
+    else
+        m_foldedBlockCache.remove(blockNumber);
+}
+
 Highlight::Priority textMarkPrioToScrollBarPrio(const TextMark::Priority &prio)
 {
     switch (prio) {