core: Move Letterbox to config module

core/src/config.rs

@@ -0,0 +1,30 @@
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+/// Controls whether the content is letterboxed or pillarboxed when the
+/// player's aspect ratio does not match the movie's aspect ratio.
+///
+/// When letterboxed, black bars will be rendered around the exterior
+/// margins of the content.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "serde", serde(rename = "letterbox"))]
+pub enum Letterbox {
+    /// The content will never be letterboxed.
+    #[cfg_attr(feature = "serde", serde(rename = "off"))]
+    Off,
+
+    /// The content will only be letterboxed if the content is running fullscreen.
+    #[cfg_attr(feature = "serde", serde(rename = "fullscreen"))]
+    Fullscreen,
+
+    /// The content will always be letterboxed.
+    #[cfg_attr(feature = "serde", serde(rename = "on"))]
+    On,
+}
+
+impl Default for Letterbox {
+    fn default() -> Self {
+        Letterbox::Fullscreen
+    }
+}