Fix rendering of markdown in QLabel

Since 65314b6ce88cdbb28a22be0cab9856ec9bc9604b there is a TextFormat
for MarkdownText, and QWidgetTextControl supports that, but QLabel
does it in its own way and sets plain text or rich text on the text
document itself. Add a code path for MarkdownText there.

[ChangeLog][QtWidgets][QLabel] Markdown is now a supported textFormat
for QLabel.

Fixes: QTBUG-79766
Change-Id: Ib9370ef300089af2c4d6070e545c5470f32833a8
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

2 files changed, 25 insertions, 14 deletions

diff --git a/src/widgets/widgets/qlabel.cpp b/src/widgets/widgets/qlabel.cpp
index a840bf4ee6..77d117775a 100644
--- a/src/widgets/widgets/qlabel.cpp
+++ b/src/widgets/widgets/qlabel.cpp
@@ -85,6 +85,7 @@ QLabelPrivate::QLabelPrivate()
       shortcutId(0),
 #endif
       textformat(Qt::AutoText),
+      effectiveTextFormat(Qt::PlainText),
       textInteractionFlags(Qt::LinksAccessibleByMouse),
       sizePolicy(),
       margin(0),
@@ -94,7 +95,6 @@ QLabelPrivate::QLabelPrivate()
       scaledcontents(false),
       textLayoutDirty(false),
       textDirty(false),
-      isRichText(false),
       isTextLabel(false),
       hasShortcut(/*???*/),
 #ifndef QT_NO_CURSOR
@@ -294,8 +294,14 @@ void QLabel::setText(const QString &text)
     d->text = text;
     d->isTextLabel = true;
     d->textDirty = true;
-    d->isRichText = d->textformat == Qt::RichText
-                    || (d->textformat == Qt::AutoText && Qt::mightBeRichText(d->text));
+    if (d->textformat == Qt::AutoText) {
+        if (Qt::mightBeRichText(d->text))
+            d->effectiveTextFormat = Qt::RichText;
+        else
+            d->effectiveTextFormat = Qt::PlainText;
+    } else {
+        d->effectiveTextFormat = d->textformat;
+    }
 
     d->control = oldControl;
 
@@ -306,7 +312,7 @@ void QLabel::setText(const QString &text)
         d->control = nullptr;
     }
 
-    if (d->isRichText) {
+    if (d->effectiveTextFormat != Qt::PlainText) {
         setMouseTracking(true);
     } else {
         // Note: mouse tracking not disabled intentionally
@@ -1478,14 +1484,19 @@ void QLabelPrivate::ensureTextPopulated() const
     if (control) {
         QTextDocument *doc = control->document();
         if (textDirty) {
-#ifndef QT_NO_TEXTHTMLPARSER
-            if (isRichText)
-                doc->setHtml(text);
-            else
+            if (effectiveTextFormat == Qt::PlainText) {
                 doc->setPlainText(text);
-#else
-            doc->setPlainText(text);
+#if QT_CONFIG(texthtmlparser)
+            } else if (effectiveTextFormat == Qt::RichText) {
+                doc->setHtml(text);
+#endif
+#if QT_CONFIG(textmarkdownreader)
+            } else if (effectiveTextFormat == Qt::MarkdownText) {
+                doc->setMarkdown(text);
 #endif
+            } else {
+                doc->setPlainText(text);
+            }
             doc->setUndoRedoEnabled(false);
 
 #ifndef QT_NO_SHORTCUT
@@ -1623,7 +1634,7 @@ QMenu *QLabelPrivate::createStandardContextMenu(const QPoint &pos)
 {
     QString linkToCopy;
     QPoint p;
-    if (control && isRichText) {
+    if (control && effectiveTextFormat != Qt::PlainText) {
         p = layoutPoint(pos);
         linkToCopy = control->document()->documentLayout()->anchorAt(p);
     }
diff --git a/src/widgets/widgets/qlabel_p.h b/src/widgets/widgets/qlabel_p.h
index 59188563a9..6b3fbc5f0c 100644
--- a/src/widgets/widgets/qlabel_p.h
+++ b/src/widgets/widgets/qlabel_p.h
@@ -93,8 +93,8 @@ public:
 #endif
     inline bool needTextControl() const {
         return isTextLabel
-               && (isRichText
-                   || (!isRichText && (textInteractionFlags & (Qt::TextSelectableByMouse | Qt::TextSelectableByKeyboard))));
+               && (effectiveTextFormat != Qt::PlainText
+                   || (textInteractionFlags & (Qt::TextSelectableByMouse | Qt::TextSelectableByKeyboard)));
     }
 
     void ensureTextPopulated() const;
@@ -134,6 +134,7 @@ public:
     int shortcutId;
 #endif
     Qt::TextFormat textformat;
+    Qt::TextFormat effectiveTextFormat;
     Qt::TextInteractionFlags textInteractionFlags;
     mutable QSizePolicy sizePolicy;
     int margin;
@@ -143,7 +144,6 @@ public:
     uint scaledcontents : 1;
     mutable uint textLayoutDirty : 1;
     mutable uint textDirty : 1;
-    mutable uint isRichText : 1;
     mutable uint isTextLabel : 1;
     mutable uint hasShortcut : 1;
 #ifndef QT_NO_CURSOR