TextEditor: add convenience function to clear additional highlights

Change-Id: Ie3cf6e7f9fb37f3e2270abaf5fca412e7a4a40da
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/cppeditor/cppeditordocument.cpp

@@ -180,8 +180,7 @@ void CppEditorDocument::applyFontSettings()
         // Clear all additional formats since they may have changed
         QTextBlock b = document()->firstBlock();
         while (b.isValid()) {
-            QVector<QTextLayout::FormatRange> noFormats;
+            highlighter->clearExtraFormats(b);
-            highlighter->setExtraFormats(b, noFormats);
             b = b.next();
         }
     }

src/plugins/texteditor/semantichighlighter.cpp

@@ -86,8 +86,7 @@ void SemanticHighlighter::incrementalApplyExtraAdditionalFormats(
 
         // clear formats of blocks until blockNumber
         while (currentBlockNumber < blockNumber) {
-            QVector<QTextLayout::FormatRange> noFormats;
+            highlighter->clearExtraFormats(b);
-            highlighter->setExtraFormats(b, noFormats);
             b = b.next();
             ++currentBlockNumber;
         }
@@ -142,8 +141,7 @@ void SemanticHighlighter::clearExtraAdditionalFormatsUntilEnd(
     QTextBlock b = doc->findBlockByNumber(firstBlockToClear);
 
     while (b.isValid()) {
-        QVector<QTextLayout::FormatRange> noFormats;
+        highlighter->clearExtraFormats(b);
-        highlighter->setExtraFormats(b, noFormats);
         b = b.next();
     }
 }

src/plugins/texteditor/syntaxhighlighter.cpp

@@ -701,6 +701,26 @@ void SyntaxHighlighter::setExtraFormats(const QTextBlock &block,
     d->inReformatBlocks = wasInReformatBlocks;
 }
 
+void SyntaxHighlighter::clearExtraFormats(const QTextBlock &block)
+{
+    Q_D(SyntaxHighlighter);
+
+    const int blockLength = block.length();
+    if (block.layout() == nullptr || blockLength == 0)
+        return;
+
+    const QVector<QTextLayout::FormatRange> formatsToApply
+        = Utils::filtered(block.layout()->formats(), [](const QTextLayout::FormatRange &r) {
+              return !r.format.hasProperty(QTextFormat::UserProperty);
+          });
+
+    bool wasInReformatBlocks = d->inReformatBlocks;
+    d->inReformatBlocks = true;
+    block.layout()->setFormats(formatsToApply);
+    document()->markContentsDirty(block.position(), blockLength - 1);
+    d->inReformatBlocks = wasInReformatBlocks;
+}
+
 /* Generate at least n different colors for highlighting, excluding background
  * color. */
 

src/plugins/texteditor/syntaxhighlighter.h

@@ -64,6 +64,7 @@ public:
     QTextDocument *document() const;
 
     void setExtraFormats(const QTextBlock &block, QVector<QTextLayout::FormatRange> &formats);
+    void clearExtraFormats(const QTextBlock &block);
 
     static QList<QColor> generateColors(int n, const QColor &background);