From 5dcc0673c61cc75122bf5f812a45bbb15b778218 Mon Sep 17 00:00:00 2001
From: Alexander Volkov <avolkov@astralinux.ru>
Date: Mon, 27 Apr 2020 15:52:18 +0300
Subject: [PATCH] Add HiDPI support

* Backported to 1.8 branch
---
 src/Overview.cpp             |  6 ++++--
 src/directorymergewindow.cpp | 15 +++++++++------
 src/main.cpp                 |  1 +
 src/mergeresultwindow.cpp    |  7 +++++--
 4 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/src/Overview.cpp b/src/Overview.cpp
index ee1d73f..ac35e7e 100644
--- a/src/Overview.cpp
+++ b/src/Overview.cpp
@@ -271,7 +271,8 @@ void Overview::paintEvent(QPaintEvent*)
     int h = height() - 1;
     int w = width();
 
-    if(m_pixmap.size() != size())
+    const auto dpr = devicePixelRatioF();
+    if(m_pixmap.size() != size() * dpr)
     {
         if(m_pOptions->m_bWordWrap)
         {
@@ -287,7 +288,8 @@ void Overview::paintEvent(QPaintEvent*)
             m_nofLines = m_pDiff3LineList->size();
         }
 
-        m_pixmap = QPixmap(size());
+        m_pixmap = QPixmap(size() * dpr);
+        m_pixmap.setDevicePixelRatio(dpr);
 
         QPainter p(&m_pixmap);
         p.fillRect(rect(), m_pOptions->m_bgColor);
diff --git a/src/directorymergewindow.cpp b/src/directorymergewindow.cpp
index 31dbcaf..1cc62b4 100644
--- a/src/directorymergewindow.cpp
+++ b/src/directorymergewindow.cpp
@@ -584,7 +584,10 @@ class DirectoryMergeWindow::DirMergeItemDelegate : public QStyledItemDelegate
             //QPixmap icon = value.value<QPixmap>(); //pixmap(column);
             if(!icon.isNull())
             {
-                int yOffset = (sizeHint(option, index).height() - icon.height()) / 2;
+                const auto dpr = thePainter->device()->devicePixelRatioF();
+                const int w = qRound(icon.width() / dpr);
+                const int h = qRound(icon.height() / dpr);
+                int yOffset = (sizeHint(option, index).height() - h) / 2;
                 thePainter->drawPixmap(x + 2, y + yOffset, icon);
 
                 int i = index == d->m_selection1Index ? 1 : index == d->m_selection2Index ? 2 : index == d->m_selection3Index ? 3 : 0;
@@ -593,20 +596,20 @@ class DirectoryMergeWindow::DirMergeItemDelegate : public QStyledItemDelegate
                     Options* pOpts = d->m_pOptions;
                     QColor c(i == 1 ? pOpts->m_colorA : i == 2 ? pOpts->m_colorB : pOpts->m_colorC);
                     thePainter->setPen(c); // highlight() );
-                    thePainter->drawRect(x + 2, y + yOffset, icon.width(), icon.height());
+                    thePainter->drawRect(x + 2, y + yOffset, w, h);
                     thePainter->setPen(QPen(c, 0, Qt::DotLine));
-                    thePainter->drawRect(x + 1, y + yOffset - 1, icon.width() + 2, icon.height() + 2);
+                    thePainter->drawRect(x + 1, y + yOffset - 1, w + 2, h + 2);
                     thePainter->setPen(Qt::white);
                     QString s(QChar('A' + i - 1));
 
-                    thePainter->drawText(x + 2 + (icon.width() - Utils::getHorizontalAdvance(thePainter->fontMetrics(), s)) / 2,
-                                y + yOffset + (icon.height() + thePainter->fontMetrics().ascent()) / 2 - 1,
+                    thePainter->drawText(x + 2 + (w - Utils::getHorizontalAdvance(thePainter->fontMetrics(), s)) / 2,
+                                y + yOffset + (h + thePainter->fontMetrics().ascent()) / 2 - 1,
                                 s);
                 }
                 else
                 {
                     thePainter->setPen(m_pDMW->palette().window().color());
-                    thePainter->drawRect(x + 1, y + yOffset - 1, icon.width() + 2, icon.height() + 2);
+                    thePainter->drawRect(x + 1, y + yOffset - 1, w + 2, h + 2);
                 }
                 return;
             }
diff --git a/src/main.cpp b/src/main.cpp
index df06eab..c62aee3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -81,6 +81,7 @@ int main(int argc, char* argv[])
 {
     const QLatin1String appName("kdiff3");
 
+    QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
     QApplication app(argc, argv); // KAboutData and QCommandLineParser depend on this being setup.
     KLocalizedString::setApplicationDomain(appName.data());
 
diff --git a/src/mergeresultwindow.cpp b/src/mergeresultwindow.cpp
index 894bc44..29d16ae 100644
--- a/src/mergeresultwindow.cpp
+++ b/src/mergeresultwindow.cpp
@@ -1970,8 +1970,11 @@ void MergeResultWindow::paintEvent(QPaintEvent*)
     if(!m_bCursorUpdate) // Don't redraw everything for blinking cursor?
     {
         m_selection.bSelectionContainsData = false;
-        if(size() != m_pixmap.size())
-            m_pixmap = QPixmap(size());
+        const auto dpr = devicePixelRatioF();
+        if(size() * dpr != m_pixmap.size()) {
+            m_pixmap = QPixmap(size() * dpr);
+            m_pixmap.setDevicePixelRatio(dpr);
+        }
 
         RLPainter p(&m_pixmap, m_pOptions->m_bRightToLeftLanguage, width(), fontWidth);
         p.setFont(font());
-- 
2.27.0