Add support for building with meson and add flatpak template

src/config.rs

@@ -0,0 +1,8 @@
+pub const APP_ID: &str = "com.lemmy-gtk.lemoa";
+pub const GETTEXT_PACKAGE: &str = ;
+pub const LOCALEDIR: &str = ;
+pub const PKGDATADIR: &str = "/usr/local/share/lemoa";
+pub const PROFILE: &str = ;
+pub const RESOURCES_FILE: &str = concat!("/usr/local/share/lemoa", "/resources.gresource");
+pub const VERSION: &str = "0.1.0";
+

src/config.rs.in

@@ -0,0 +1,8 @@
+pub const APP_ID: &str = @APP_ID@;
+pub const GETTEXT_PACKAGE: &str = @GETTEXT_PACKAGE@;
+pub const LOCALEDIR: &str = @LOCALEDIR@;
+pub const PKGDATADIR: &str = @PKGDATADIR@;
+pub const PROFILE: &str = @PROFILE@;
+pub const RESOURCES_FILE: &str = concat!(@PKGDATADIR@, "/resources.gresource");
+pub const VERSION: &str = @VERSION@;
+

src/meson.build

@@ -0,0 +1,44 @@
+# Configuration file
+conf = configuration_data()
+conf.set_quoted('APP_ID', application_id)
+conf.set_quoted('PKGDATADIR', pkgdatadir)
+conf.set_quoted('VERSION', version)
+
+configure_file(
+    input: 'config.rs.in',
+    output: 'config.rs',
+    configuration: conf
+)
+
+run_command(
+  'cp',
+  join_paths(meson.project_build_root(), 'src', 'config.rs'),
+  join_paths(meson.project_source_root(), 'src', 'config.rs'),
+  check: true
+)
+
+# Setup cargo
+cargo = find_program('cargo')
+cargo_env = [ 'CARGO_HOME=' + meson.project_build_root() / 'cargo-home' ]
+cargo_options = [ '--manifest-path', meson.project_source_root() / 'Cargo.toml' ]
+cargo_options += [ '--target-dir', meson.project_build_root() / 'target' ]
+cargo_options += [ '--release' ]
+
+cargo_release = custom_target(
+  'cargo-build',
+  build_by_default: true,
+  build_always_stale: true,
+  output: meson.project_name(),
+  console: true,
+  install: true,
+  install_dir: bindir,
+  command: [
+    'env',
+    cargo_env,
+    cargo, 'build',
+    cargo_options,
+    '&&',
+    'cp', 'target' / 'release' / meson.project_name(), '@OUTPUT@',
+  ]
+)
+