[network/ruqola] src/widgets/misc: Make sure that emoji is drawing correctly in dpr

Git commit edcbb896dcd253a9596e089a1314dcdd08043799 by Laurent Montel.
Committed on 13/08/2026 at 20:41.
Pushed by mlaurent into branch 'master'.

Make sure that emoji is drawing correctly in dpr

M  +26   -16   src/widgets/misc/avatarcachemanager.cpp

https://invent.kde.org/network/ruqola/-/commit/edcbb896dcd253a9596e089a1314dcdd08043799

diff --git a/src/widgets/misc/avatarcachemanager.cpp b/src/widgets/misc/avatarcachemanager.cpp
index e07e903b80..455258b90f 100644
--- a/src/widgets/misc/avatarcachemanager.cpp
+++ b/src/widgets/misc/avatarcachemanager.cpp
@@ -68,24 +68,34 @@ QPixmap AvatarCacheManager::makeAvatarEmojiPixmap(const QString &emojiStr, const
     if (downScaled.isNull()) {
         auto *emojiManager = mRocketChatAccount->emojiManager();
         const TextEmoticonsCore::UnicodeEmoticon emoticon = emojiManager->unicodeEmoticonForEmoji(emojiStr);
-        if (emoticon.isValid()) {
-            const QFontMetrics fm(mEmojiFont);
-            const QSize size = fm.boundingRect(emoticon.unicode()).size();
-
-            // qDebug() << " size " << size << "emojiStr "<< emojiStr << " emoticon.unicode() " <<emoticon.unicode() <<
-            // fm.horizontalAdvance(emoticon.unicode()); boundingRect can return a width == 0 for existing character as :warning: emoji.
-            QPixmap fullScale(fm.horizontalAdvance(emoticon.unicode()), size.height());
-
-            fullScale.fill(Qt::white);
-            QPainter painter(&fullScale);
-            painter.setFont(mEmojiFont);
-            painter.drawText(fullScale.rect(), Qt::AlignCenter, emoticon.unicode());
-            downScaled = fullScale.scaledToHeight(maxHeight * dpr, Qt::SmoothTransformation);
-            downScaled.setDevicePixelRatio(dpr);
-            cache.insertCachedPixmap(emojiStr, downScaled);
-        } else {
+        if (!emoticon.isValid()) {
             return makeAvatarPixmap(widget, info, maxHeight);
         }
+        const int targetHeight = qMax(1, qRound(maxHeight * dpr));
+        // Draw the glyph at (roughly) its final device size: rendering at the font's natural size and
+        // upscaling afterwards made emoji avatars blurry on hidpi screens.
+        QFont emojiFont(mEmojiFont);
+        emojiFont.setPixelSize(targetHeight);
+        const QFontMetrics fm(emojiFont);
+        const QSize size = fm.boundingRect(emoticon.unicode()).size();
+
+        // qDebug() << " size " << size << "emojiStr "<< emojiStr << " emoticon.unicode() " <<emoticon.unicode() <<
+        // fm.horizontalAdvance(emoticon.unicode()); boundingRect can return a width == 0 for existing character as :warning: emoji.
+        QPixmap fullScale(fm.horizontalAdvance(emoticon.unicode()), size.height());
+
+        // The avatar is drawn over the view background, so the emoji must not carry an opaque
+        // rectangle of its own.
+        fullScale.fill(Qt::transparent);
+        QPainter painter(&fullScale);
+        painter.setFont(emojiFont);
+        // Emojis without a color glyph fall back to the pen color, which defaults to black: follow the
+        // palette so that they stay readable with a dark color scheme.
+        painter.setPen(widget->palette().color(QPalette::WindowText));
+        painter.drawText(fullScale.rect(), Qt::AlignCenter, emoticon.unicode());
+        painter.end();
+        downScaled = fullScale.scaledToHeight(targetHeight, Qt::SmoothTransformation);
+        downScaled.setDevicePixelRatio(dpr);
+        cache.insertCachedPixmap(emojiStr, downScaled);
     }
     return downScaled;
 }