Add flatpak packaging

command to build:
flatpak-builder --force-clean --user --install-deps-from=flathub --repo=repo --install builddir flatpak/me.gapixels.Megapixels.yml

flatpak/me.gapixels.Megapixels.yml

@@ -0,0 +1,176 @@
+---
+app-id: me.gapixels.Megapixels
+runtime: org.gnome.Platform
+runtime-version: "46"
+sdk: org.gnome.Sdk
+command: megapixels
+finish-args:
+  # access /dev/media* and /dev/video*
+  - --device=all
+  # access /sys/firmware/devicetree/base/compatible
+  - --filesystem=/sys
+
+  # X11 + XShm access
+  - --socket=fallback-x11
+  - --share=ipc
+
+  # wayland access
+  - --socket=wayland
+
+  # GPU acceleration
+  - --device=dri
+
+  # Needs to save file locally
+  - --filesystem=xdg-pictures
+
+  # camera shutter feedback
+  - --talk-name=org.sigxcpu.Feedback
+
+modules:
+  - name: megapixels
+    buildsystem: meson
+    run-tests: false
+    sources:
+      - type: dir
+        path: ../
+    post-install:
+      # meson should probably be doing this
+      - glib-compile-schemas --strict /app/share/glib-2.0/schemas
+
+    modules:
+      - name: libmegapixels
+        buildsystem: meson
+        sources:
+          - type: git
+            url: https://gitlab.com/megapixels-org/libmegapixels
+            tag: 0.2.0
+        modules:
+          - name: libconfig
+            sources:
+              - type: archive
+                url: https://hyperrealm.github.io/libconfig/dist/libconfig-1.7.2.tar.gz
+                sha256: 7c3c7a9c73ff3302084386e96f903eb62ce06953bb1666235fac74363a16fad9
+            cleanup:
+              - "/include"
+              - "*.la"
+              - "*.a"
+              - "/lib/pkgconfig"
+      - name: libfeedback
+        buildsystem: meson
+        config-opts:
+          - -Dtests=false
+          - -Ddaemon=false
+        sources:
+          - type: git
+            url: https://source.puri.sm/Librem5/feedbackd.git
+            tag: v0.7.0
+      - name: zbar
+        config-opts:
+          - --disable-doc
+          - --disable-video
+          - --enable-codes=qrcode
+          - --without-dbus
+          - --without-directshow
+          - --without-gir
+          - --without-graphicsmagick
+          - --without-gtk
+          - --without-imagemagick
+          - --without-jpeg
+          - --without-java
+          - --without-npapi
+          - --without-python
+          - --without-qt
+          - --without-qt5
+          - --without-xshm
+          - --without-xv
+        sources:
+          - type: git
+            url: https://github.com/mchehab/zbar
+            tag: 0.23.93
+          - type: script
+            dest-filename: autogen.sh
+            commands:
+              - autoreconf -vfi -W none
+      - name: libdng
+        buildsystem: meson
+        sources:
+          - type: git
+            url: https://gitlab.com/megapixels-org/libdng
+            tag: 0.2.1
+  - name: postprocessd
+    buildsystem: meson
+    sources:
+      - type: git
+        url: https://gitlab.com/megapixels-org/postprocessd
+        commit: 6264c9bfa71c961fd0868a2c4976845699760ed7
+    modules:
+      - name: libraw
+        builddir: true
+        sources:
+          - type: git
+            url: https://github.com/LibRaw/LibRaw
+            tag: 0.21.3
+          - type: shell
+            commands:
+              - autoreconf -vfi
+      - name: opencv
+        buildsystem: cmake-ninja
+        builddir: true
+        config-opts:
+          - -DCMAKE_BUILD_TYPE=Release
+          - -DOPENCV_GENERATE_PKGCONFIG=ON
+          - -DBUILD_LIST=core,imgproc,tracking,imgcodecs,videostab
+        sources:
+          - type: archive
+            url: https://github.com/opencv/opencv/archive/4.11.0.tar.gz
+            sha256: 9a7c11f924eff5f8d8070e297b322ee68b9227e003fd600d4b8122198091665f
+          - type: archive
+            url: https://github.com/opencv/opencv_contrib/archive/4.11.0.tar.gz
+            sha256: 2dfc5957201de2aa785064711125af6abb2e80a64e2dc246aca4119b19687041
+      - name: lensfun
+        buildsystem: cmake-ninja
+        config-opts:
+          - -DCMAKE_BUILD_TYPE=RelWithDebInfo
+        cleanup:
+          - /bin
+          - '/lib/python3.*'
+        sources:
+          - type: git
+            url: https://github.com/lensfun/lensfun.git
+            tag: v0.3.4
+  - name: ImageMagick
+    config-opts:
+      - --disable-static
+      - --disable-docs
+      - --with-hdri
+      - --with-pic
+    sources:
+      - type: git
+        url: https://github.com/ImageMagick/ImageMagick
+        tag: 7.1.1-43
+  - name: exiftool
+    buildsystem: simple
+    build-commands:
+      - perl Makefile.PL
+      - make install
+    cleanup:
+      - '*.pod'
+    sources:
+      - type: git
+        url: https://github.com/exiftool/exiftool.git
+        tag: "13.21"
+    modules:
+      - name: perl
+        buildsystem: simple
+        build-commands:
+          - ./Configure -des -Dprefix=$FLATPAK_DEST -Dman1dir=none -Dman3dir=none
+          - make
+          - make install
+        sources:
+          - type: git
+            url: https://github.com/Perl/perl5.git
+            tag: v5.40.1
+            disable-fsckobjects: true
+        post-install:
+          # Fix permissions
+          - chmod -R u+w $FLATPAK_DEST/lib/perl5