Add fullscreen monitor selection support on Linux (#235)

* Add fullscreen monitor support on Linux

* Add change file

* Remove todo on videomode

* Fix clippy

.changes/linux-monitor.md

@@ -0,0 +1,6 @@
+---
+"tao": patch
+---
+
+Add monitor selection when fullscreen on Linux and close possible way to create VideoMode on Linux since gtk doesn't acutally have such feature.
+

src/monitor.rs

@@ -152,6 +152,9 @@ impl MonitorHandle {
   }
 
   /// Returns all fullscreen video modes supported by this monitor.
+  ///
+  /// ## Platform-specific
+  /// - **Linux:** Unsupported. This will always return empty iterator.
   #[inline]
   pub fn video_modes(&self) -> impl Iterator<Item = VideoMode> {
     self.inner.video_modes()

src/platform_impl/linux/event_loop.rs

@@ -25,7 +25,7 @@ use crate::{
   menu::{MenuItem, MenuType},
   monitor::MonitorHandle as RootMonitorHandle,
   platform_impl::platform::{window::hit_test, DEVICE_ID},
-  window::{CursorIcon, WindowId as RootWindowId},
+  window::{CursorIcon, Fullscreen, WindowId as RootWindowId},
 };
 
 use super::{
@@ -245,7 +245,13 @@ impl<T: 'static> EventLoop<T> {
               }
             }
             WindowRequest::Fullscreen(fullscreen) => match fullscreen {
-              Some(_) => window.fullscreen(),
+              Some(f) => {
+                if let Fullscreen::Borderless(Some(monitor)) = f {
+                  let number = monitor.inner.number;
+                  let screen = window.display().default_screen();
+                  window.fullscreen_on_monitor(&screen, number);
+                }
+              }
               None => window.unfullscreen(),
             },
             WindowRequest::Decorations(decorations) => window.set_decorated(decorations),
@@ -838,14 +844,13 @@ impl<T: 'static> EventLoopProxy<T> {
 }
 
 fn assert_is_main_thread(suggested_method: &str) {
-  if !is_main_thread() {
-    panic!(
-      "Initializing the event loop outside of the main thread is a significant \
+  assert!(
+    is_main_thread(),
+    "Initializing the event loop outside of the main thread is a significant \
              cross-platform compatibility hazard. If you really, absolutely need to create an \
              EventLoop on a different thread, please use the `EventLoopExtUnix::{}` function.",
-      suggested_method
-    );
-  }
+    suggested_method
+  );
 }
 
 #[cfg(target_os = "linux")]

src/platform_impl/linux/monitor.rs

@@ -12,7 +12,7 @@ pub struct MonitorHandle {
   // We have to store the monitor number in GdkScreen despite
   // it's deprecated. Otherwise, there's no way to set it in
   // GtkWindow in Gtk3.
-  number: i32,
+  pub(crate) number: i32,
 }
 
 impl MonitorHandle {
@@ -51,7 +51,7 @@ impl MonitorHandle {
 
   #[inline]
   pub fn video_modes(&self) -> Box<dyn Iterator<Item = RootVideoMode>> {
-    todo!()
+    Box::new(Vec::new().into_iter())
   }
 }
 
@@ -64,21 +64,21 @@ pub struct VideoMode;
 impl VideoMode {
   #[inline]
   pub fn size(&self) -> PhysicalSize<u32> {
-    todo!()
+    panic!("VideoMode is unsupported on Linux.")
   }
 
   #[inline]
   pub fn bit_depth(&self) -> u16 {
-    todo!()
+    panic!("VideoMode is unsupported on Linux.")
   }
 
   #[inline]
   pub fn refresh_rate(&self) -> u16 {
-    todo!()
+    panic!("VideoMode is unsupported on Linux.")
   }
 
   #[inline]
   pub fn monitor(&self) -> RootMonitorHandle {
-    todo!()
+    panic!("VideoMode is unsupported on Linux.")
   }
 }

src/platform_impl/linux/window.rs

@@ -198,9 +198,10 @@ impl Window {
 
     // Rest attributes
     window.set_title(&attributes.title);
-    // TODO set it with Fullscreen enum
-    if attributes.fullscreen.is_some() {
-      window.fullscreen();
+    if let Some(Fullscreen::Borderless(Some(f))) = &attributes.fullscreen {
+      let number = f.inner.number;
+      let screen = window.display().default_screen();
+      window.fullscreen_on_monitor(&screen, number);
     }
     if attributes.maximized {
       window.maximize();