#3470 snap: try to fix "no Qt platform plugin could be initialized" error

Signed-off-by: Patrizio Bekerle <patrizio@bekerle.com>

Author: pbek

build-systems/github/snap.qt6/snap/local/wrapper.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+arch="${SNAP_LAUNCHER_ARCH_TRIPLET:-x86_64-linux-gnu}"
+qt6_plugin_dir="$SNAP/usr/lib/$arch/qt6/plugins"
+qt6_qml_dir="$SNAP/usr/lib/$arch/qt6/qml"
+
+export QT_PLUGIN_PATH="$qt6_plugin_dir${QT_PLUGIN_PATH:+:$QT_PLUGIN_PATH}"
+export QT_QPA_PLATFORM_PLUGIN_PATH="$qt6_plugin_dir/platforms"
+export QML2_IMPORT_PATH="$qt6_qml_dir:$SNAP/lib/$arch${QML2_IMPORT_PATH:+:$QML2_IMPORT_PATH}"
+export QML_IMPORT_PATH="$qt6_qml_dir${QML_IMPORT_PATH:+:$QML_IMPORT_PATH}"
+
+exec "$SNAP/usr/bin/QOwnNotes" --snap "$@"

build-systems/github/snap.qt6/snapcraft.yaml

@@ -20,7 +20,9 @@ layout:
 
 apps:
   qownnotes:
-    command: bin/desktop-launch $SNAP/usr/bin/QOwnNotes --snap
+    # The desktop helper still configures Qt4/Qt5 plugin locations, so run a
+    # small wrapper after it to point Qt6 at the staged plugin and QML paths.
+    command: bin/desktop-launch $SNAP/wrapper.sh
     environment:
       DISABLE_WAYLAND: 1
       QT_QPA_PLATFORMTHEME: gtk3
@@ -107,8 +109,18 @@ parts:
       # libproxy1v5 ships libpxbackend-1.0.so in a private sub-directory;
       # the layout section above makes that path visible to the linker.
       - libproxy1v5
+      # Bundle the Wayland QPA plugins explicitly; libqt6gui6t64 ships xcb,
+      # but the Wayland backend lives in a separate package on Ubuntu 24.04.
+      - qt6-wayland
     stage:
       - -usr/share/pkgconfig
+    override-prime: |
+      craftctl default
+      arch_triplet="$(dpkg-architecture -q DEB_HOST_MULTIARCH)"
+      platform_dir="${CRAFT_PRIME}/usr/lib/${arch_triplet}/qt6/plugins/platforms"
+      test -f "${platform_dir}/libqxcb.so"
+      test -f "${platform_dir}/libqwayland-egl.so"
+      test -f "${platform_dir}/libqwayland-generic.so"
     after: [desktop-qt6]
 
   desktop-qt6:
@@ -165,3 +177,9 @@ parts:
     plugin: nil
     stage-packages:
       - qt6-gtk-platformtheme
+
+  scripts:
+    plugin: dump
+    source: snap/local
+    stage:
+      - wrapper.sh