FileAssoc: Slice D — Linux: .desktop MimeType + XDG MIME XML + .deb postinstall + snap update

[fernandotonon]

Parent epic: #664
Depends on: Slice A (#665).

Goal

On a Linux install (deb or snap), file managers (Nautilus, Dolphin, Nemo) and xdg-open route the supported 3D formats to QtMeshEditor.

Scope

Shared assets (referenced by both deb and snap)

• packaging/linux/qtmesheditor.desktop (canonical file, copied into both deb and snap at build time):

  [Desktop Entry]
  Name=QtMeshEditor
  GenericName=3D Model Editor
  Comment=Free 3D asset tool — FBX/glTF/materials/MCP CLI
  Keywords=3D;mesh;FBX;glTF;model;material;animation;Ogre;editor;
  Exec=qtmesheditor %F
  TryExec=qtmesheditor
  Icon=qtmesheditor
  Terminal=false
  Type=Application
  Categories=Graphics;3DGraphics;Development;
  MimeType=model/gltf-binary;model/gltf+json;application/vnd.autodesk.fbx;model/obj;model/stl;application/vnd.ms-collada+xml;application/sla;model/x-ply;application/x-3ds;application/x-ogre-mesh;application/x-ogre-material;application/x-ps1-rsd;application/x-ps1-tmd;
  StartupWMClass=QtMeshEditor
  

  Note Exec=qtmesheditor %F (capital F = supports multi-file selection from "Open With" multi-select; deferred to Slice A's multi-file handling).

• packaging/linux/qtmesheditor.xml — XDG shared-mime-info entries declaring custom MIME types for formats without a registered IANA type:

  <?xml version="1.0" encoding="UTF-8"?>
  <mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
    <mime-type type="application/x-ogre-mesh">
      <comment>Ogre 3D Mesh</comment>
      <glob pattern="*.mesh"/>
      <icon name="qtmesheditor-mesh"/>
    </mime-type>
    <mime-type type="application/x-ogre-material">
      <comment>Ogre 3D Material Script</comment>
      <glob pattern="*.material"/>
      <icon name="qtmesheditor-material"/>
    </mime-type>
    <mime-type type="application/x-ps1-rsd">
      <comment>PlayStation Resource Database</comment>
      <glob pattern="*.rsd"/>
      <icon name="qtmesheditor-mesh"/>
    </mime-type>
    <mime-type type="application/x-ps1-tmd">
      <comment>PlayStation TMD Model</comment>
      <glob pattern="*.tmd"/>
      <icon name="qtmesheditor-mesh"/>
    </mime-type>
    <mime-type type="model/x-ply">
      <comment>Stanford Polygon Format</comment>
      <glob pattern="*.ply"/>
      <icon name="qtmesheditor-static"/>
    </mime-type>
    <!-- Other formats use their IANA-registered types so no entries needed here -->
  </mime-info>

.deb

• DEBIAN-control.in updated to declare:

  Provides: 3d-model-viewer
  

• New install-time files in the .deb:
  • /usr/share/applications/qtmesheditor.desktop (from the shared asset).
  • /usr/share/mime/packages/qtmesheditor.xml (from the shared asset).
  • /usr/share/icons/hicolor/<sizes>/apps/qtmesheditor.png — the app icon (probably already exists; verify).
  • /usr/share/icons/hicolor/<sizes>/mimetypes/qtmesheditor-mesh.png, qtmesheditor-material.png, qtmesheditor-static.png, qtmesheditor-animatable.png — the per-family icons mirroring Slices B and C.
• DEBIAN-postinst (new — currently the project has no postinst):

  #!/bin/sh
  set -e
  if command -v update-desktop-database >/dev/null 2>&1; then
      update-desktop-database -q /usr/share/applications || true
  fi
  if command -v update-mime-database >/dev/null 2>&1; then
      update-mime-database /usr/share/mime || true
  fi
  if command -v gtk-update-icon-cache >/dev/null 2>&1; then
      gtk-update-icon-cache --quiet /usr/share/icons/hicolor || true
  fi
  exit 0

• DEBIAN-postrm mirrors postinst for clean uninstall.
• These need wiring through the existing CMake / packaging path that produces the .deb. Verify the project's current packaging step (the workflow at .github/workflows/deploy.yml mentions deb) and extend it to copy the new files.

Snap

• snap/gui/qtmesheditor.desktop updated to add the MimeType= line (currently absent — see the existing file). Replace it with the canonical packaging/linux/qtmesheditor.desktop minus the ${SNAP}/meta/gui/icon.png rewrite that the snap toolchain currently does.
• snap/snapcraft.yaml updated to register the XDG MIME XML:

  apps:
    qtmesheditor:
      command: bin/qtmesheditor
      common-id: io.github.fernandotonon.QtMeshEditor
      desktop: meta/gui/qtmesheditor.desktop
      plugs:
        - home
        - removable-media
        - desktop
        - desktop-legacy
        - wayland
        - x11
        - opengl
  parts:
    qtmesheditor:
      # ... existing part definition ...
      override-prime: |
        snapcraftctl prime
        mkdir -p $SNAPCRAFT_PRIME/meta/mime
        cp $SNAPCRAFT_PROJECT_DIR/packaging/linux/qtmesheditor.xml $SNAPCRAFT_PRIME/meta/mime/qtmesheditor.xml

  Note: snap's MIME registration story is weaker than deb's — file managers may not pick up custom MIME types from a snap-confined app unless the snap is installed classic or with extra plugs. Document the limitation; for users who care, recommend the deb.

Verification

A new scripts/verify-linux-association.sh that uses xdg-mime query default model/gltf-binary and asserts QtMeshEditor is listed in the alternatives (xdg-mime query default returns one app; gio mime model/gltf-binary lists alternatives — use both).

Acceptance Criteria

• After apt install qtmesheditor*.deb, xdg-open model.fbx opens QtMeshEditor.
• File managers (Nautilus, Dolphin, Nemo) list QtMeshEditor in "Open With…" for all supported formats.
• Custom MIME types (.mesh, .rsd, .tmd, .material) get the right icon in file managers.
• update-mime-database, update-desktop-database, gtk-update-icon-cache run cleanly on postinst with no errors.
• Uninstall removes the .desktop and MIME registration cleanly (verified by verify-linux-association.sh post-uninstall).
• Snap registration works on at least Ubuntu (where snap is well-supported); document any limitations for confined snaps.
• CI's scan-assets-docker job (or a new verify-linux-association job) runs the verification script and fails the build if the registration is missing.

Effort

~5 days. Snap's MIME-registration quirks under confinement are the schedule risk.