Add developer option to enable the Wine Wayland backend

The current situation is still (unfortunately...) rough, but it could be
useful to enable in some cases. Once it improves enough we can make
it the default.

launcher/config.kcfg

@@ -54,5 +54,8 @@ SPDX-License-Identifier: CC0-1.0
     <entry name="GithubApi" type="String">
       <default>api.github.com</default>
     </entry>
+    <entry name="EnableWayland" type="bool">
+      <default>false</default>
+    </entry>
   </group>
 </kcfg>

launcher/src/gamerunner.cpp

@@ -13,6 +13,7 @@
 #include "utility.h"
 
 #include <KProcessList>
+#include <QGuiApplication>
 
 using namespace Qt::StringLiterals;
 
@@ -340,6 +341,12 @@ void GameRunner::launchExecutable(const Profile &profile, QProcess *process, con
     const QString logDir = dataDir.absoluteFilePath(QStringLiteral("log"));
 
     env.insert(QStringLiteral("DXVK_LOG_PATH"), logDir);
+
+    // Enable the Wayland backend if we detect we're running on Wayland, otherwise fallback to X11.
+    if (QGuiApplication::platformName() == QStringLiteral("wayland") && m_launcher.config()->enableWayland()) {
+        // We have to unset the DISPLAY variable for Wine to pick it up.
+        env.remove(QStringLiteral("DISPLAY"));
+    }
 #endif
 
 #if defined(Q_OS_MAC) || defined(Q_OS_LINUX)

launcher/ui/Settings/DeveloperSettings.qml

@@ -85,6 +85,23 @@ FormCard.FormCardPage {
                 LauncherCore.config.save();
             }
         }
+
+        FormCard.FormDelegateSeparator {
+            above: renderDocCaptureDelegate
+            below: enableWaylandDelegate
+        }
+
+        FormCard.FormCheckDelegate {
+            id: enableWaylandDelegate
+
+            text: i18n("Run Game on Wayland")
+            description: i18n("Use the native Wine Wayland driver instead of going through XWayland.")
+            checked: LauncherCore.config.enableWayland
+            onCheckedChanged: {
+                LauncherCore.config.enableWayland = checked;
+                LauncherCore.config.save();
+            }
+        }
     }
 
     FormCard.FormHeader {