Support listing available video modes for a monitor (#896)

* Support listing available video modes for a monitor

* Use derivative for Windows `MonitorHandle`

* Update FEATURES.md

* Fix multiline if statement

* Add documentation for `VideoMode` type

src/monitor.rs

@@ -44,6 +44,45 @@ impl Iterator for AvailableMonitorsIter {
     }
 }
 
+/// Describes a fullscreen video mode of a monitor.
+///
+/// Can be acquired with:
+/// - [`MonitorHandle::video_modes`][monitor_get].
+///
+/// [monitor_get]: ../monitor/struct.MonitorHandle.html#method.video_modes
+#[derive(Debug, Clone, Eq, PartialEq, Hash)]
+pub struct VideoMode {
+    pub(crate) dimensions: (u32, u32),
+    pub(crate) bit_depth: u16,
+    pub(crate) refresh_rate: u16,
+}
+
+impl VideoMode {
+    /// Returns the resolution of this video mode.
+    pub fn dimensions(&self) -> PhysicalSize {
+        self.dimensions.into()
+    }
+
+    /// Returns the bit depth of this video mode, as in how many bits you have
+    /// available per color. This is generally 24 bits or 32 bits on modern
+    /// systems, depending on whether the alpha channel is counted or not.
+    ///
+    /// ## Platform-specific
+    ///
+    /// - **Wayland:** Always returns 32.
+    /// - **iOS:** Always returns 32.
+    pub fn bit_depth(&self) -> u16 {
+        self.bit_depth
+    }
+
+    /// Returns the refresh rate of this video mode. **Note**: the returned
+    /// refresh rate is an integer approximation, and you shouldn't rely on this
+    /// value to be exact.
+    pub fn refresh_rate(&self) -> u16 {
+        self.refresh_rate
+    }
+}
+
 /// Handle to a monitor.
 ///
 /// Allows you to retrieve information about a given monitor and can be used in [`Window`] creation.
@@ -88,4 +127,10 @@ impl MonitorHandle {
     pub fn hidpi_factor(&self) -> f64 {
         self.inner.hidpi_factor()
     }
+
+    /// Returns all fullscreen video modes supported by this monitor.
+    #[inline]
+    pub fn video_modes(&self) -> impl Iterator<Item = VideoMode> {
+        self.inner.video_modes()
+    }
 }