Move port coloring into view

The controller still determines the ports media type, but instead of coloring
the port itself, the media type is passed to the constructor, which then colors the port.

src/view/port.rs

@@ -1,3 +1,7 @@
+use gtk::WidgetExt;
+
+use crate::controller::MediaType;
+
 /// Graphical representation of a pipewire port.
 pub struct Port {
     pub widget: gtk::Button,
@@ -6,9 +10,24 @@ pub struct Port {
 }
 
 impl Port {
-    pub fn new(id: u32, name: &str, direction: pipewire::port::Direction) -> Self {
+    pub fn new(
+        id: u32,
+        name: &str,
+        direction: pipewire::port::Direction,
+        media_type: Option<MediaType>,
+    ) -> Self {
+        let widget = gtk::Button::with_label(name);
+
+        // Color the port according to its media type.
+        match media_type {
+            Some(MediaType::Video) => widget.add_css_class("video"),
+            Some(MediaType::Audio) => widget.add_css_class("audio"),
+            Some(MediaType::Midi) => widget.add_css_class("midi"),
+            None => {}
+        }
+
         Self {
-            widget: gtk::Button::with_label(name),
+            widget,
             id,
             direction,
         }