From 04d2c2d1761151455a9fae0e4c8749fcd9adf1cc Mon Sep 17 00:00:00 2001
From: Miguel Medina Ballesteros <maximetinu@gmail.com>
Date: Tue, 23 Apr 2024 17:47:56 +0200
Subject: [PATCH] Avoid sending multiple redundant RequestRedraws

---
 src/lib.rs     |  7 +++++++
 src/systems.rs | 14 ++++++++------
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index f57e1b5b4..51687a97c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -288,6 +288,13 @@ pub struct EguiRenderOutput {
     pub textures_delta: egui::TexturesDelta,
 }
 
+impl EguiRenderOutput {
+    /// Returns `true` if the output has no Egui shapes and no textures delta
+    pub fn is_empty(&self) -> bool {
+        self.paint_jobs.is_empty() && self.textures_delta.is_empty()
+    }
+}
+
 /// Is used for storing Egui output.
 #[derive(Component, Clone, Default)]
 pub struct EguiOutput {
diff --git a/src/systems.rs b/src/systems.rs
index 641ee8973..c98e10819 100644
--- a/src/systems.rs
+++ b/src/systems.rs
@@ -490,6 +490,8 @@ pub fn process_output_system(
     mut event: EventWriter<RequestRedraw>,
     #[cfg(windows)] mut last_cursor_icon: Local<bevy::utils::HashMap<Entity, egui::CursorIcon>>,
 ) {
+    let mut should_request_redraw = false;
+
     for mut context in contexts.iter_mut() {
         let ctx = context.ctx.get_mut();
         let full_output = ctx.end_frame();
@@ -532,12 +534,8 @@ pub fn process_output_system(
         #[cfg(not(windows))]
         set_icon();
 
-        let needs_repaint = !context.render_output.paint_jobs.is_empty()
-            && !context.render_output.textures_delta.is_empty();
-
-        if ctx.has_requested_repaint() && needs_repaint {
-            event.send(RequestRedraw);
-        }
+        let needs_repaint = !context.render_output.is_empty();
+        should_request_redraw |= ctx.has_requested_repaint() && needs_repaint;
 
         #[cfg(feature = "open_url")]
         if let Some(egui::output::OpenUrl { url, new_tab }) = platform_output.open_url {
@@ -558,6 +556,10 @@ pub fn process_output_system(
             }
         }
     }
+
+    if should_request_redraw {
+        event.send(RequestRedraw);
+    }
 }
 
 fn egui_to_winit_cursor_icon(cursor_icon: egui::CursorIcon) -> Option<bevy::window::CursorIcon> {