From c9f8337aa771c5cb48a5da8a54d946b2f9632616 Mon Sep 17 00:00:00 2001
From: IceSentry <c.giguere42@gmail.com>
Date: Sun, 20 Aug 2023 18:21:25 -0400
Subject: [PATCH] user controlled visibility

---
 crates/bevy_window/src/window.rs       | 13 ++++++++++++-
 crates/bevy_winit/src/system.rs        |  4 ++++
 crates/bevy_winit/src/winit_windows.rs |  4 ++--
 examples/window/window_settings.rs     | 13 +++++++++++++
 4 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/crates/bevy_window/src/window.rs b/crates/bevy_window/src/window.rs
index 301c1c4efe82a..d5d191d70d2ca 100644
--- a/crates/bevy_window/src/window.rs
+++ b/crates/bevy_window/src/window.rs
@@ -213,6 +213,16 @@ pub struct Window {
     ///
     /// - iOS / Android / Web: Unsupported.
     pub window_theme: Option<WindowTheme>,
+    /// Sets the window's visibility.
+    ///
+    /// If `false`, this will hide the window the window completely, it won't appear on the screen or in the task bar.
+    /// If `true`, this will show the window.
+    /// Note that this doesn't change its focused or minimized state.
+    ///
+    /// ## Platform-specific
+    ///
+    /// - **Android / Wayland / Web:** Unsupported.
+    pub visible: bool,
 }
 
 impl Default for Window {
@@ -239,6 +249,7 @@ impl Default for Window {
             prevent_default_event_handling: true,
             canvas: None,
             window_theme: None,
+            visible: true,
         }
     }
 }
@@ -1016,7 +1027,7 @@ pub enum WindowTheme {
 ///
 /// ## Platform-specific
 ///
-/// **`iOS`**, **`Android`**, and the **`Web`** do not have window control buttons.  
+/// **`iOS`**, **`Android`**, and the **`Web`** do not have window control buttons.
 ///
 /// On some **`Linux`** environments these values have no effect.
 #[derive(Debug, Copy, Clone, PartialEq, Reflect)]
diff --git a/crates/bevy_winit/src/system.rs b/crates/bevy_winit/src/system.rs
index af7f41e405ab1..0be99b24cc73e 100644
--- a/crates/bevy_winit/src/system.rs
+++ b/crates/bevy_winit/src/system.rs
@@ -308,6 +308,10 @@ pub(crate) fn changed_windows(
                 winit_window.set_theme(window.window_theme.map(convert_window_theme));
             }
 
+            if window.visible != cache.window.visible {
+                winit_window.set_visible(window.visible);
+            }
+
             cache.window = window.clone();
         }
     }
diff --git a/crates/bevy_winit/src/winit_windows.rs b/crates/bevy_winit/src/winit_windows.rs
index e38203b819945..4c7f30df6fa82 100644
--- a/crates/bevy_winit/src/winit_windows.rs
+++ b/crates/bevy_winit/src/winit_windows.rs
@@ -96,7 +96,8 @@ impl WinitWindows {
             .with_resizable(window.resizable)
             .with_enabled_buttons(convert_enabled_buttons(window.enabled_buttons))
             .with_decorations(window.decorations)
-            .with_transparent(window.transparent);
+            .with_transparent(window.transparent)
+            .with_visible(window.visible);
 
         let constraints = window.resize_constraints.check_constraints();
         let min_inner_size = LogicalSize {
@@ -167,7 +168,6 @@ impl WinitWindows {
         );
         adapters.insert(entity, adapter);
         handlers.insert(entity, handler);
-        winit_window.set_visible(true);
 
         // Do not set the grab mode on window creation if it's none. It can fail on mobile.
         if window.cursor.grab_mode != CursorGrabMode::None {
diff --git a/examples/window/window_settings.rs b/examples/window/window_settings.rs
index 3a7687ee92155..4623c45308c8a 100644
--- a/examples/window/window_settings.rs
+++ b/examples/window/window_settings.rs
@@ -6,6 +6,7 @@ use bevy::{
     prelude::*,
     window::{CursorGrabMode, PresentMode, WindowLevel, WindowTheme},
 };
+use bevy_internal::window::PrimaryWindow;
 
 fn main() {
     App::new()
@@ -24,6 +25,10 @@ fn main() {
                         maximize: false,
                         ..Default::default()
                     },
+                    // This will spawn an invisible window
+                    // The window will be made visible in the setup() function
+                    // This is useful when you want to avoid the white window that shows up before the GPU is ready to render the app.
+                    visible: false,
                     ..default()
                 }),
                 ..default()
@@ -31,6 +36,7 @@ fn main() {
             LogDiagnosticsPlugin::default(),
             FrameTimeDiagnosticsPlugin,
         ))
+        .add_systems(Startup, setup)
         .add_systems(
             Update,
             (
@@ -46,6 +52,13 @@ fn main() {
         .run();
 }
 
+fn setup(mut primary_window: Query<&mut Window, With<PrimaryWindow>>) {
+    // At this point the gpu is ready to show the app so we can make the window visible
+    // There might still be a white frame when doing it in startup.
+    // Alternatively, you could have a system that waits a few seconds before making the window visible.
+    primary_window.single_mut().visible = true;
+}
+
 /// This system toggles the vsync mode when pressing the button V.
 /// You'll see fps increase displayed in the console.
 fn toggle_vsync(input: Res<Input<KeyCode>>, mut windows: Query<&mut Window>) {