Copy formatting attributes when cloning an empty QTextDocument

When cloning a QTextDocument, the text fragment of the original document
is copied into the new one, which results into copying also the
formatting attributes. However, when the text document is empty, the
corresponding text fragment is also empty, so nothing is copied.

If we want to transfer the formatting attributes for an empty document,
we need to set them explicitly.

Fixes: QTBUG-80399
Change-Id: I382cd0821723436120af47c06ec7bfa849636307
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

2 files changed, 40 insertions, 1 deletions

diff --git a/src/gui/text/qtextdocument.cpp b/src/gui/text/qtextdocument.cpp
index e94f635651..4b35509ace 100644
--- a/src/gui/text/qtextdocument.cpp
+++ b/src/gui/text/qtextdocument.cpp
@@ -347,7 +347,19 @@ QTextDocument *QTextDocument::clone(QObject *parent) const
 {
     Q_D(const QTextDocument);
     QTextDocument *doc = new QTextDocument(parent);
-    QTextCursor(doc).insertFragment(QTextDocumentFragment(this));
+    if (isEmpty()) {
+        const QTextCursor thisCursor(const_cast<QTextDocument *>(this));
+
+        const auto blockFormat = thisCursor.blockFormat();
+        if (blockFormat.isValid() && !blockFormat.isEmpty())
+            QTextCursor(doc).setBlockFormat(blockFormat);
+
+        const auto blockCharFormat = thisCursor.blockCharFormat();
+        if (blockCharFormat.isValid() && !blockCharFormat.isEmpty())
+            QTextCursor(doc).setBlockCharFormat(blockCharFormat);
+    } else {
+        QTextCursor(doc).insertFragment(QTextDocumentFragment(this));
+    }
     doc->rootFrame()->setFrameFormat(rootFrame()->frameFormat());
     QTextDocumentPrivate *priv = doc->d_func();
     priv->title = d->title;
diff --git a/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp b/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp
index 52e56feb5a..33d4976b2a 100644
--- a/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp
+++ b/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp
@@ -125,6 +125,7 @@ private slots:
     void clonePreservesResources();
     void clonePreservesUserStates();
     void clonePreservesIndentWidth();
+    void clonePreservesFormatsWhenEmpty();
     void blockCount();
     void defaultStyleSheet();
 
@@ -2342,6 +2343,32 @@ void tst_QTextDocument::clonePreservesIndentWidth()
     delete clone;
 }
 
+void tst_QTextDocument::clonePreservesFormatsWhenEmpty()
+{
+    QTextDocument document;
+    QTextCursor cursor(&document);
+
+    // Change a few char format attributes
+    QTextCharFormat charFormat;
+    charFormat.setFontPointSize(charFormat.fontPointSize() + 1);
+    charFormat.setFontWeight(charFormat.fontWeight() + 1);
+    cursor.setBlockCharFormat(charFormat);
+
+    // Change a few block format attributes
+    QTextBlockFormat blockFormat;
+    blockFormat.setAlignment(Qt::AlignRight); // The default is Qt::AlignLeft
+    blockFormat.setIndent(blockFormat.indent() + 1);
+    cursor.setBlockFormat(blockFormat);
+
+    auto clone = document.clone();
+    QTextCursor cloneCursor(clone);
+
+    QCOMPARE(cloneCursor.blockCharFormat().fontPointSize(), charFormat.fontPointSize());
+    QCOMPARE(cloneCursor.blockCharFormat().fontWeight(), charFormat.fontWeight());
+    QCOMPARE(cloneCursor.blockFormat().alignment(), blockFormat.alignment());
+    QCOMPARE(cloneCursor.blockFormat().indent(), blockFormat.indent());
+}
+
 void tst_QTextDocument::blockCount()
 {
     QCOMPARE(doc->blockCount(), 1);