Allow users to create viewports larger than monitor on Windows & macOS

crates/eframe/src/native/epi_integration.rs

@@ -20,14 +20,22 @@ pub fn viewport_builder<E>(
 
     let mut viewport_builder = native_options.viewport.clone();
 
+    // Allow users to create windows larger than monitor on windows & macos
+    let with_constraint: bool = !cfg!(any(target_os = "windows", target_os = "macos"))
+        || viewport_builder.clamp_size_to_monitor_size.unwrap_or(true);
+
     // Always use the default window size / position on iOS. Trying to restore the previous position
     // causes the window to be shown too small.
     #[cfg(not(target_os = "ios"))]
     let inner_size_points = if let Some(mut window_settings) = window_settings {
         // Restore pos/size from previous session
 
-        window_settings
-            .clamp_size_to_sane_values(largest_monitor_point_size(egui_zoom_factor, event_loop));
+        if with_constraint {
+            window_settings.clamp_size_to_sane_values(largest_monitor_point_size(
+                egui_zoom_factor,
+                event_loop,
+            ));
+        }
         window_settings.clamp_position_to_monitors(egui_zoom_factor, event_loop);
 
         viewport_builder = window_settings.initialize_viewport_builder(viewport_builder);
@@ -37,10 +45,12 @@ pub fn viewport_builder<E>(
             viewport_builder = viewport_builder.with_position(pos);
         }
 
-        if let Some(initial_window_size) = viewport_builder.inner_size {
-            let initial_window_size = initial_window_size
-                .at_most(largest_monitor_point_size(egui_zoom_factor, event_loop));
-            viewport_builder = viewport_builder.with_inner_size(initial_window_size);
+        if with_constraint {
+            if let Some(initial_window_size) = viewport_builder.inner_size {
+                let initial_window_size = initial_window_size
+                    .at_most(largest_monitor_point_size(egui_zoom_factor, event_loop));
+                viewport_builder = viewport_builder.with_inner_size(initial_window_size);
+            }
         }
 
         viewport_builder.inner_size

crates/egui-winit/src/lib.rs

@@ -1563,6 +1563,7 @@ pub fn create_winit_window_builder<T>(
         window_type: _window_type,
 
         mouse_passthrough: _, // handled in `apply_viewport_builder_to_window`
+        ..
     } = viewport_builder;
 
     let mut window_builder = winit::window::WindowBuilder::new()

crates/egui/src/viewport.rs

@@ -275,6 +275,9 @@ pub struct ViewportBuilder {
     pub min_inner_size: Option<Vec2>,
     pub max_inner_size: Option<Vec2>,
 
+    /// Whether clamp the window's size to monitor's size. Default to `true`
+    pub clamp_size_to_monitor_size: Option<bool>,
+
     pub fullscreen: Option<bool>,
     pub maximized: Option<bool>,
     pub resizable: Option<bool>,
@@ -493,6 +496,17 @@ impl ViewportBuilder {
         self
     }
 
+    /// Sets whether clamp the window's size to monitor's size.
+    ///
+    /// This only works on windows & macos, otherwise will be dismissed.
+    ///
+    /// Default to `true`
+    #[inline]
+    pub fn with_clamp_size_to_monitor_size(mut self, value: bool) -> Self {
+        self.clamp_size_to_monitor_size = Some(value);
+        self
+    }
+
     /// Does not work on X11.
     #[inline]
     pub fn with_close_button(mut self, value: bool) -> Self {
@@ -606,6 +620,7 @@ impl ViewportBuilder {
             inner_size: new_inner_size,
             min_inner_size: new_min_inner_size,
             max_inner_size: new_max_inner_size,
+            clamp_size_to_monitor_size: new_clamp_size_to_monitor_size,
             fullscreen: new_fullscreen,
             maximized: new_maximized,
             resizable: new_resizable,
@@ -740,6 +755,13 @@ impl ViewportBuilder {
 
         let mut recreate_window = false;
 
+        if new_clamp_size_to_monitor_size.is_some()
+            && self.clamp_size_to_monitor_size != new_clamp_size_to_monitor_size
+        {
+            self.clamp_size_to_monitor_size = new_clamp_size_to_monitor_size;
+            recreate_window = true;
+        }
+
         if new_active.is_some() && self.active != new_active {
             self.active = new_active;
             recreate_window = true;