From 8719208acfb1011773e72a5b2be0e54a70cf9b28 Mon Sep 17 00:00:00 2001
From: jkriege2 <jan@jkrieger.de>
Date: Sat, 1 Jul 2023 14:49:56 +0200
Subject: [PATCH] iproved JKQTMathText::drawIntoPixmap() and drawIntoPicture():
 using ARGB32_Premultiplied for QPixmap + enabled
 QPainter::VerticalSubpixelPositioning when available

---
 lib/jkqtmathtext/jkqtmathtext.cpp | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/lib/jkqtmathtext/jkqtmathtext.cpp b/lib/jkqtmathtext/jkqtmathtext.cpp
index dfc4690461..eb9f5c6fc3 100644
--- a/lib/jkqtmathtext/jkqtmathtext.cpp
+++ b/lib/jkqtmathtext/jkqtmathtext.cpp
@@ -64,7 +64,7 @@ QString JKQTMathText::init_caligraphicFont="decorative";
 QString JKQTMathText::init_blackboardFont="blackboard";
 QString JKQTMathText::init_fracturFont="fraktur";
 bool JKQTMathText::s_firstStart=true;
-std::mutex JKQTMathText::s_mutex=std::mutex();
+std::mutex JKQTMathText::s_mutex;
 
 
 
@@ -1256,6 +1256,9 @@ QPixmap JKQTMathText::drawIntoPixmap(bool drawBoxes, QColor backgroundColor, int
         painter.setRenderHint(QPainter::Antialiasing);
         painter.setRenderHint(QPainter::TextAntialiasing);
         painter.setRenderHint(QPainter::SmoothPixmapTransform);
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 1, 0))
+        painter.setRenderHint(QPainter::VerticalSubpixelPositioning);
+#endif
         const JKQTMathTextNodeSize size=getSizeDetail(painter);
         const QSize pixsize=size.getIntSize()+QSize(2*sizeincrease,2*sizeincrease);
         painter.end();
@@ -1270,6 +1273,9 @@ QPixmap JKQTMathText::drawIntoPixmap(bool drawBoxes, QColor backgroundColor, int
         painter.setRenderHint(QPainter::Antialiasing);
         painter.setRenderHint(QPainter::TextAntialiasing);
         painter.setRenderHint(QPainter::SmoothPixmapTransform);
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 1, 0))
+        painter.setRenderHint(QPainter::VerticalSubpixelPositioning);
+#endif
         draw(painter, Qt::AlignVCenter|Qt::AlignHCenter, QRect(QPoint(0,0),pixsize), drawBoxes);
         painter.end();
     }
@@ -1281,7 +1287,7 @@ QImage JKQTMathText::drawIntoImage(bool drawBoxes, QColor backgroundColor, int s
     // 1. generate dummy QPixmap that is needed to use a QPainter
     //    we need the dummy, because we first need to determine the size of the render output
     //    for which we need a QPainter.
-    QImage img(1,1,QImage::Format_ARGB32);
+    QImage img(1,1,QImage::Format_ARGB32_Premultiplied);
     img.setDevicePixelRatio(devicePixelRatio);
     img.setDotsPerMeterX(resolution_dpi*(10000/254));
     img.setDotsPerMeterY(resolution_dpi*(10000/254));
@@ -1294,6 +1300,9 @@ QImage JKQTMathText::drawIntoImage(bool drawBoxes, QColor backgroundColor, int s
         painter.setRenderHint(QPainter::Antialiasing);
         painter.setRenderHint(QPainter::TextAntialiasing);
         painter.setRenderHint(QPainter::SmoothPixmapTransform);
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 1, 0))
+        painter.setRenderHint(QPainter::VerticalSubpixelPositioning);
+#endif
         const JKQTMathTextNodeSize size=getSizeDetail(painter);
         const QSize pixsize=size.getIntSize()+QSize(2*sizeincrease,2*sizeincrease);
         painter.end();
@@ -1301,7 +1310,7 @@ QImage JKQTMathText::drawIntoImage(bool drawBoxes, QColor backgroundColor, int s
         // 3. finally we can generate a QPixmap with the appropriate
         //    size to contain the full rendering. We fill it with the
         //    color white and finally paint the math markup/LaTeX string
-        img=QImage(pixsize*devicePixelRatio,QImage::Format_ARGB32);
+        img=QImage(pixsize*devicePixelRatio,QImage::Format_ARGB32_Premultiplied);
         img.setDevicePixelRatio(devicePixelRatio);
         img.setDotsPerMeterX(resolution_dpi*(10000/254));
         img.setDotsPerMeterY(resolution_dpi*(10000/254));
@@ -1310,6 +1319,9 @@ QImage JKQTMathText::drawIntoImage(bool drawBoxes, QColor backgroundColor, int s
         painter.setRenderHint(QPainter::Antialiasing);
         painter.setRenderHint(QPainter::TextAntialiasing);
         painter.setRenderHint(QPainter::SmoothPixmapTransform);
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 1, 0))
+        painter.setRenderHint(QPainter::VerticalSubpixelPositioning);
+#endif
         draw(painter, Qt::AlignVCenter|Qt::AlignHCenter, QRect(QPoint(0,0),pixsize), drawBoxes);
         painter.end();
     }
@@ -1331,6 +1343,9 @@ QPicture JKQTMathText::drawIntoPicture(bool drawBoxes)
         painter.setRenderHint(QPainter::Antialiasing);
         painter.setRenderHint(QPainter::TextAntialiasing);
         painter.setRenderHint(QPainter::SmoothPixmapTransform);
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 1, 0))
+        painter.setRenderHint(QPainter::VerticalSubpixelPositioning);
+#endif
         const JKQTMathTextNodeSize size=getSizeDetail(painter);
         painter.end();
 
@@ -1341,6 +1356,9 @@ QPicture JKQTMathText::drawIntoPicture(bool drawBoxes)
         painter.setRenderHint(QPainter::Antialiasing);
         painter.setRenderHint(QPainter::TextAntialiasing);
         painter.setRenderHint(QPainter::SmoothPixmapTransform);
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 1, 0))
+        painter.setRenderHint(QPainter::VerticalSubpixelPositioning);
+#endif
         draw(painter, 0, size.baselineHeight, drawBoxes);
         painter.end();
     }