Do not read Xft.dpi on platforms that shouldn't be using Xft settings

We only read this for desktop environments that have traditionally used
these to set settings for other toolkits.

Fixes: QTBUG-80323
Change-Id: Ifa8c2682301e69c2770d3734115080a0e6b4e85c
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index 8da299d491..7c60ca06f9 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -41,6 +41,7 @@
 #include "qxcbwindow.h"
 #include "qxcbcursor.h"
 #include "qxcbimage.h"
+#include "qxcbintegration.h"
 #include "qnamespace.h"
 #include "qxcbxsettings.h"
 
@@ -49,6 +50,7 @@
 #include <QDebug>
 #include <QtAlgorithms>
 
+#include <qpa/qplatformservices.h>
 #include <qpa/qwindowsysteminterface.h>
 #include <private/qmath_p.h>
 #include <QtGui/private/qhighdpiscaling_p.h>
@@ -356,6 +358,15 @@ static QFontEngine::SubpixelAntialiasingType parseXftRgba(const QByteArray& stri
 
 void QXcbVirtualDesktop::readXResources()
 {
+    const QPlatformServices *services = QXcbIntegration::instance()->services();
+    bool useXftConf = false;
+    if (services) {
+        const QList<QByteArray> desktopEnv = services->desktopEnvironment().split(':');
+        useXftConf = desktopEnv.contains("GNOME") || desktopEnv.contains("UNITY") || desktopEnv.contains("XFCE");
+    }
+    if (!useXftConf)
+        return;
+
     int offset = 0;
     QByteArray resources;
     while (true) {