From 53736ab808a35f4d4d7bfb3c2d79a546685e784a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=88=98=E7=9A=93?= <whiteaxe@tuta.io>
Date: Sat, 30 Mar 2024 12:14:58 -0400
Subject: [PATCH] Fix continuous repaint on Wayland when TextEdit is focused or
 IME output is not None (#4269)

* Closes #4254

Changes egui-winit so that it calls `window.set_ime_cursor_area` when
the IME rect changes or the user interacts with the application instead
of calling it every time the app is rendered. This works around a winit
bug that causes the app to continuously repaint under certain
circumstances on Wayland.

Tested on Wayland and on X11 using the text edit in the egui_demo_app -
no changes in IME functionality as far as I can tell. Untested on
non-Linux platforms.

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
---
 crates/egui-winit/src/lib.rs | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/crates/egui-winit/src/lib.rs b/crates/egui-winit/src/lib.rs
index 41db04952e5..3d8e9184fdc 100644
--- a/crates/egui-winit/src/lib.rs
+++ b/crates/egui-winit/src/lib.rs
@@ -99,6 +99,7 @@ pub struct State {
     accesskit: Option<accesskit_winit::Adapter>,
 
     allow_ime: bool,
+    ime_rect_px: Option<egui::Rect>,
 }
 
 impl State {
@@ -139,6 +140,7 @@ impl State {
             accesskit: None,
 
             allow_ime: false,
+            ime_rect_px: None,
         };
 
         slf.egui_input
@@ -817,19 +819,26 @@ impl State {
         }
 
         if let Some(ime) = ime {
-            let rect = ime.rect;
             let pixels_per_point = pixels_per_point(&self.egui_ctx, window);
-            crate::profile_scope!("set_ime_cursor_area");
-            window.set_ime_cursor_area(
-                winit::dpi::PhysicalPosition {
-                    x: pixels_per_point * rect.min.x,
-                    y: pixels_per_point * rect.min.y,
-                },
-                winit::dpi::PhysicalSize {
-                    width: pixels_per_point * rect.width(),
-                    height: pixels_per_point * rect.height(),
-                },
-            );
+            let ime_rect_px = pixels_per_point * ime.rect;
+            if self.ime_rect_px != Some(ime_rect_px)
+                || self.egui_ctx.input(|i| !i.events.is_empty())
+            {
+                self.ime_rect_px = Some(ime_rect_px);
+                crate::profile_scope!("set_ime_cursor_area");
+                window.set_ime_cursor_area(
+                    winit::dpi::PhysicalPosition {
+                        x: ime_rect_px.min.x,
+                        y: ime_rect_px.min.y,
+                    },
+                    winit::dpi::PhysicalSize {
+                        width: ime_rect_px.width(),
+                        height: ime_rect_px.height(),
+                    },
+                );
+            }
+        } else {
+            self.ime_rect_px = None;
         }
 
         #[cfg(feature = "accesskit")]