parseExportFormat function
The Export for a --format value, or null (the mp4 default) for
null/empty/mp4.
A capture harness reads --format as a string (a --dart-define carries no
types), so the mapping lives here rather than in each harness — the CLI, the
Playground, and the example gallery all parse it the same way or they render
different files for the same flag.
Throws an ArgumentError naming the value when it is not a known format.
Implementation
Export? parseExportFormat(String? format) => switch (format) {
null || '' || 'mp4' => null,
'gif' => const Export.gif(),
'imageSequence' => const Export.imageSequence(),
'transparent' => const Export.transparent(),
_ => throw ArgumentError.value(format, 'format', 'unknown export format'),
};