Emit autolinks in QTextMarkdownWriter

When a markdown document contains a "naked" URL, or an angle-bracketed
<URL>, md4c recognizes it, and we set the AnchorHref charfmt property.
There's no need to expand it into the [text](url) form if the text is
the same as the url, there is no tooltip, and the url is valid.
QTextMarkdownWriter now writes a CommonMark "autolink" in that case:
https://spec.commonmark.org/0.30/#autolinks

[ChangeLog][QtGui][Text] QTextMarkdownWriter now writes an autolink
whenever a hyperlink has no custom text and no tooltip, including
when the document was parsed from Markdown containing a naked URL.

Pick-to: 6.4
Fixes: QTBUG-94713
Change-Id: I432db8499c62e1e0b1e913bfd8ef2147e3c2bb2a
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

3 files changed, 16 insertions, 8 deletions

diff --git a/src/gui/text/qtextmarkdownwriter.cpp b/src/gui/text/qtextmarkdownwriter.cpp
index 9f651a04fd..cda1f209ad 100644
--- a/src/gui/text/qtextmarkdownwriter.cpp
+++ b/src/gui/text/qtextmarkdownwriter.cpp
@@ -484,13 +484,19 @@ int QTextMarkdownWriter::writeBlock(const QTextBlock &block, bool wrap, bool ign
             m_stream << s;
             col += s.length();
         } else if (fmt.hasProperty(QTextFormat::AnchorHref)) {
-            QString s = u'[' + fragmentText + "]("_L1 +
-                    fmt.property(QTextFormat::AnchorHref).toString();
-            if (fmt.hasProperty(QTextFormat::TextToolTip)) {
-                s += Space;
-                s += createLinkTitle(fmt.property(QTextFormat::TextToolTip).toString());
+            const auto href = fmt.property(QTextFormat::AnchorHref).toString();
+            const bool hasToolTip = fmt.hasProperty(QTextFormat::TextToolTip);
+            QString s;
+            if (!hasToolTip && href == fragmentText && !QUrl(href, QUrl::StrictMode).scheme().isEmpty()) {
+                s = u'<' + href + u'>';
+            } else {
+                s = u'[' + fragmentText + "]("_L1 + href;
+                if (hasToolTip) {
+                    s += Space;
+                    s += createLinkTitle(fmt.property(QTextFormat::TextToolTip).toString());
+                }
+                s += u')';
             }
-            s += u')';
             if (wrap && col + s.length() > ColumnLimit) {
                 m_stream << Newline << wrapIndentString;
                 col = m_wrappedLineIndent;
diff --git a/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md b/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md
index b29b53651b..a021f15aba 100644
--- a/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md
+++ b/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md
@@ -13,8 +13,7 @@ MacFarlane writes:
 > > as readable as possible. The idea is that a Markdown-formatted document should
 > > be publishable as-is, as plain text, without looking like it's been marked up
 > > with tags or formatting instructions. ( 
-> > [http://daringfireball.net/projects/markdown/](http://daringfireball.net/projects/markdown/)
-> > )
+> > <http://daringfireball.net/projects/markdown/> )
 
 > The point can be illustrated by comparing a sample of AsciiDoc with an
 > equivalent sample of Markdown. Here is a sample of AsciiDoc from the AsciiDoc
diff --git a/tests/auto/gui/text/qtextmarkdownwriter/data/links.md b/tests/auto/gui/text/qtextmarkdownwriter/data/links.md
index 33cdb2b3ab..c9aae80c67 100644
--- a/tests/auto/gui/text/qtextmarkdownwriter/data/links.md
+++ b/tests/auto/gui/text/qtextmarkdownwriter/data/links.md
@@ -23,3 +23,6 @@ title")
 * [link](/url "title
 title title")
 * nonlink
+
+Qt has the <https://qt.io> site
+