From a5b89bfe5a8deeb70344390ecf551b326de8c72a Mon Sep 17 00:00:00 2001
From: Kirill Chibisov <contact@kchibisov.com>
Date: Wed, 20 Dec 2023 18:48:50 +0400
Subject: [PATCH] On Wayland, fix resize being sent on focus change

Fixes #3263.
---
 CHANGELOG.md                                  |  1 +
 src/platform_impl/linux/wayland/state.rs      |  6 ++-
 .../linux/wayland/window/state.rs             | 43 +++++++++++--------
 3 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index eb6ae1045..b62f88c96 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@ Unreleased` header.
 - On Wayland, disable Client Side Decorations when `wl_subcompositor` is not supported.
 - On X11, fix `Xft.dpi` detection from Xresources.
 - On Windows, fix consecutive calls to `window.set_fullscreen(Some(Fullscreen::Borderless(None)))` resulting in losing previous window state when eventually exiting fullscreen using `window.set_fullscreen(None)`.
+- On Wayland, fix resize being sent on focus change.
 
 # 0.29.4
 
diff --git a/src/platform_impl/linux/wayland/state.rs b/src/platform_impl/linux/wayland/state.rs
index 967ee93f1..8e81c59a1 100644
--- a/src/platform_impl/linux/wayland/state.rs
+++ b/src/platform_impl/linux/wayland/state.rs
@@ -299,7 +299,11 @@ impl WindowHandler for WinitState {
                 &mut self.events_sink,
             );
 
-        self.window_compositor_updates[pos].size = Some(new_size);
+        // NOTE: Only update when the value is `Some` to not override consequent configures with
+        // the same sizes.
+        if new_size.is_some() {
+            self.window_compositor_updates[pos].size = new_size;
+        }
     }
 }
 
diff --git a/src/platform_impl/linux/wayland/window/state.rs b/src/platform_impl/linux/wayland/window/state.rs
index 73c0c92c5..7161be891 100644
--- a/src/platform_impl/linux/wayland/window/state.rs
+++ b/src/platform_impl/linux/wayland/window/state.rs
@@ -256,7 +256,7 @@ impl WindowState {
         shm: &Shm,
         subcompositor: &Option<Arc<SubcompositorState>>,
         event_sink: &mut EventSink,
-    ) -> LogicalSize<u32> {
+    ) -> Option<LogicalSize<u32>> {
         // NOTE: when using fractional scaling or wl_compositor@v6 the scaling
         // should be delivered before the first configure, thus apply it to
         // properly scale the physical sizes provided by the users.
@@ -319,14 +319,9 @@ impl WindowState {
             match configure.new_size {
                 (Some(width), Some(height)) => {
                     let (width, height) = frame.subtract_borders(width, height);
-                    (
-                        (
-                            width.map(|w| w.get()).unwrap_or(1),
-                            height.map(|h| h.get()).unwrap_or(1),
-                        )
-                            .into(),
-                        false,
-                    )
+                    let width = width.map(|w| w.get()).unwrap_or(1);
+                    let height = height.map(|h| h.get()).unwrap_or(1);
+                    ((width, height).into(), false)
                 }
                 (_, _) if stateless => (self.stateless_size, true),
                 _ => (self.size, true),
@@ -352,13 +347,27 @@ impl WindowState {
                 .unwrap_or(new_size.height);
         }
 
-        // XXX Set the configure before doing a resize.
+        let new_state = configure.state;
+        let old_state = self
+            .last_configure
+            .as_ref()
+            .map(|configure| configure.state)
+            .unwrap_or(XdgWindowState::empty());
+
+        let state_change_requires_resize = !new_state
+            .symmetric_difference(old_state)
+            .difference(XdgWindowState::ACTIVATED | XdgWindowState::SUSPENDED)
+            .is_empty();
+
+        // NOTE: Set the configure before doing a resize, since we query it during it.
         self.last_configure = Some(configure);
 
-        // XXX Update the new size right away.
-        self.resize(new_size);
-
-        new_size
+        if state_change_requires_resize || new_size != self.inner_size() {
+            self.resize(new_size);
+            Some(new_size)
+        } else {
+            None
+        }
     }
 
     /// Compute the bounds for the inner size of the surface.
@@ -912,7 +921,7 @@ impl WindowState {
 
     /// Set the IME position.
     pub fn set_ime_cursor_area(&self, position: LogicalPosition<u32>, size: LogicalSize<u32>) {
-        // XXX This won't fly unless user will have a way to request IME window per seat, since
+        // FIXME: This won't fly unless user will have a way to request IME window per seat, since
         // the ime windows will be overlapping, but winit doesn't expose API to specify for
         // which seat we're setting IME position.
         let (x, y) = (position.x as i32, position.y as i32);
@@ -943,7 +952,7 @@ impl WindowState {
     pub fn set_scale_factor(&mut self, scale_factor: f64) {
         self.scale_factor = scale_factor;
 
-        // XXX when fractional scaling is not used update the buffer scale.
+        // NOTE: When fractional scaling is not used update the buffer scale.
         if self.fractional_scale.is_none() {
             let _ = self.window.set_buffer_scale(self.scale_factor as _);
         }
@@ -1091,7 +1100,7 @@ impl From<ResizeDirection> for XdgResizeEdge {
     }
 }
 
-// XXX rust doesn't allow from `Option`.
+// NOTE: Rust doesn't allow `From<Option<Theme>>`.
 #[cfg(feature = "sctk-adwaita")]
 fn into_sctk_adwaita_config(theme: Option<Theme>) -> sctk_adwaita::FrameConfig {
     match theme {