patches/qtbase_5_12_8/0005-spellcheck-underline-from-chrome.patch

diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index b70b29e54e..9519894076 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -6245,6 +6245,91 @@ static QPixmap generateWavyPixmap(qreal maxRadius, const QPen &pen)
     return pixmap;
 }
 
+// Patch: Improved underline with SpellCheck style for macOS and Windows.
+// Added implementation of underline drawing from Chrome.
+static QPixmap generateChromeSpellcheckPixmap(qreal descent, qreal factor, const QPen &pen) {
+    QString key = QLatin1String("ChromeUnderline-")
+        % pen.color().name()
+        % HexString<qreal>(factor)
+        % HexString<qreal>(pen.widthF());
+
+    QPixmap pixmap;
+    if (QPixmapCache::find(key, pixmap)) {
+        return pixmap;
+    }
+    // https://chromium.googlesource.com/chromium/src/+/refs/heads/master/third_party/blink/renderer/core/paint/document_marker_painter.cc
+
+#ifdef Q_OS_MAC
+
+    constexpr qreal kMarkerHeight = 3;
+
+    const qreal height = kMarkerHeight * factor;
+    const qreal width = height * 2;
+
+    pixmap = QPixmap(qCeil(width), qFloor(height) * 2);
+    pixmap.setDevicePixelRatio(qApp->devicePixelRatio());
+    pixmap.fill(Qt::transparent);
+    {
+        QPainter imgPainter(&pixmap);
+        imgPainter.setPen(Qt::NoPen);
+        imgPainter.setBrush(pen.color());
+        imgPainter.setRenderHints(
+            QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
+        imgPainter.drawEllipse(0, 0, qFloor(height), qFloor(height));
+    }
+
+#else
+
+    constexpr qreal kMarkerWidth = 4;
+    constexpr qreal kMarkerHeight = 2;
+
+    const auto x1 = (kMarkerWidth * -3 / 8) * factor;
+    const auto y1 = (kMarkerHeight * 3 / 4) * factor;
+
+    const auto cY = (kMarkerHeight * 1 / 4) * factor;
+
+    const auto c1X1 = (kMarkerWidth * -1 / 8) * factor;
+    const auto c1X2 = (kMarkerWidth * 3 / 8) * factor;
+    const auto c1X3 = (kMarkerWidth * 7 / 8) * factor;
+
+    const auto c2X1 = (kMarkerWidth * 1 / 8) * factor;
+    const auto c2X2 = (kMarkerWidth * 5 / 8) * factor;
+    const auto c2X3 = (kMarkerWidth * 9 / 8) * factor;
+
+    QPainterPath path;
+    path.moveTo(x1, y1);
+    path.cubicTo(c1X1, y1,
+        c1X1, cY,
+        c2X1, cY);
+    path.cubicTo(c1X2, cY,
+        c1X2, y1,
+        c2X2, y1);
+    path.cubicTo(c1X3, y1,
+        c1X3, cY,
+        c2X3, cY);
+
+    pixmap = QPixmap(kMarkerWidth * factor, kMarkerHeight * factor * 2);
+    pixmap.fill(Qt::transparent);
+    {
+        QPen wavePen = pen;
+        wavePen.setCapStyle(Qt::RoundCap);
+        wavePen.setJoinStyle(Qt::RoundJoin);
+        wavePen.setWidthF(1 * factor);
+
+        QPainter imgPainter(&pixmap);
+        imgPainter.setPen(std::move(wavePen));
+        imgPainter.setRenderHint(QPainter::Antialiasing);
+        imgPainter.translate(0, descent - (kMarkerHeight * factor));
+        imgPainter.drawPath(std::move(path));
+    }
+
+#endif
+
+    QPixmapCache::insert(std::move(key), pixmap);
+
+    return pixmap;
+}
+
 static void drawTextItemDecoration(QPainter *painter, const QPointF &pos, const QFontEngine *fe, QTextEngine *textEngine,
                                    QTextCharFormat::UnderlineStyle underlineStyle,
                                    QTextItem::RenderFlags flags, qreal width,
@@ -6262,7 +6347,9 @@ static void drawTextItemDecoration(QPainter *painter, const QPointF &pos, const
     pen.setWidthF(fe->lineThickness().toReal());
     pen.setCapStyle(Qt::FlatCap);
 
-    QLineF line(qFloor(pos.x()), pos.y(), qFloor(pos.x() + width), pos.y());
+    // Patch: Improved underline with SpellCheck style for macOS and Windows.
+    // Slightly move the beginning of the underline to the right.
+    QLineF line(qFloor(pos.x() + 1), pos.y(), qFloor(pos.x() + width), pos.y());
 
     bool wasCompatiblePainting = painter->renderHints()
             & QPainter::Qt4CompatiblePainting;
@@ -6273,13 +6360,29 @@ static void drawTextItemDecoration(QPainter *painter, const QPointF &pos, const
     const qreal underlineOffset = fe->underlinePosition().toReal();
 
     if (underlineStyle == QTextCharFormat::SpellCheckUnderline) {
-        QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme();
-        if (theme)
-            underlineStyle = QTextCharFormat::UnderlineStyle(theme->themeHint(QPlatformTheme::SpellCheckUnderlineStyle).toInt());
-        if (underlineStyle == QTextCharFormat::SpellCheckUnderline) // still not resolved
-            underlineStyle = QTextCharFormat::WaveUnderline;
-    }
+        const qreal fontFactor = qreal(charFormat.font().pixelSize()) / qreal(10.);
+        painter->save();
+        painter->translate(0, pos.y() + 1);
+        const qreal maxHeight = fe->descent().toReal() - qreal(1);
+
+        QColor uc = charFormat.underlineColor();
+        if (uc.isValid())
+            pen.setColor(uc);
 
+        const QPixmap wave = generateChromeSpellcheckPixmap(maxHeight, fontFactor, pen);
+        const int descent = qFloor(maxHeight);
+
+        painter->setBrushOrigin(painter->brushOrigin().x(), 0);
+#ifdef Q_OS_MAC
+        const auto h = wave.height() / 2;
+        painter->drawTiledPixmap(
+            QRectF(pos.x(), (descent - h) / 2., qCeil(width), h),
+            wave);
+#else
+        painter->fillRect(pos.x(), 0, qCeil(width), descent, wave);
+#endif
+        painter->restore();
+    } else
     if (underlineStyle == QTextCharFormat::WaveUnderline) {
         painter->save();
         painter->translate(0, pos.y() + 1);