Process events only when necessary

Additionally, this also fixes a bug where the old size was being used
for layouting after a resize.

1 files changed, 12 insertions, 6 deletions

diff --git a/winit/src/application.rs b/winit/src/application.rs
index 1042b412..fb40156a 100644
--- a/winit/src/application.rs
+++ b/winit/src/application.rs
@@ -110,7 +110,7 @@ pub trait Application: Sized {
 
         let dpi = window.hidpi_factor();
         let mut size = window.inner_size();
-        let mut new_size: Option<winit::dpi::LogicalSize> = None;
+        let mut resized = false;
 
         let mut renderer = Self::Renderer::new();
 
@@ -143,6 +143,11 @@ pub trait Application: Sized {
 
         event_loop.run(move |event, _, control_flow| match event {
             event::Event::MainEventsCleared => {
+                if events.is_empty() && external_messages.is_empty() && !resized
+                {
+                    return;
+                }
+
                 // TODO: We should be able to keep a user interface alive
                 // between events once we remove state references.
                 //
@@ -217,9 +222,9 @@ pub trait Application: Sized {
             event::Event::RedrawRequested(_) => {
                 debug.render_started();
 
-                if let Some(new_size) = new_size.take() {
+                if resized {
                     let dpi = window.hidpi_factor();
-                    let (width, height) = to_physical(new_size, dpi);
+                    let (width, height) = to_physical(size, dpi);
 
                     target.resize(
                         width,
@@ -228,7 +233,7 @@ pub trait Application: Sized {
                         &renderer,
                     );
 
-                    size = new_size;
+                    resized = false;
                 }
 
                 let new_mouse_cursor =
@@ -320,8 +325,9 @@ pub trait Application: Sized {
                 WindowEvent::CloseRequested => {
                     *control_flow = ControlFlow::Exit;
                 }
-                WindowEvent::Resized(size) => {
-                    new_size = Some(size.into());
+                WindowEvent::Resized(new_size) => {
+                    size = new_size;
+                    resized = true;
 
                     log::debug!("Resized: {:?}", new_size);
                 }