Clamp eframe window size to at most the size of the largest monitor (#2445)

This can hopefully fix some reported bugs where

crates/eframe/src/epi.rs

@@ -255,10 +255,10 @@ pub struct NativeOptions {
     /// The initial inner size of the native window in points (logical pixels).
     pub initial_window_size: Option<egui::Vec2>,
 
-    /// The minimum inner window size
+    /// The minimum inner window size in points (logical pixels).
     pub min_window_size: Option<egui::Vec2>,
 
-    /// The maximum inner window size
+    /// The maximum inner window size in points (logical pixels).
     pub max_window_size: Option<egui::Vec2>,
 
     /// Should the app window be resizable?

crates/eframe/src/native/epi_integration.rs

@@ -5,6 +5,7 @@ use winit::platform::macos::WindowBuilderExtMacOS as _;
 
 #[cfg(feature = "accesskit")]
 use egui::accesskit;
+use egui::NumExt as _;
 #[cfg(feature = "accesskit")]
 use egui_winit::accesskit_winit;
 use egui_winit::{native_pixels_per_point, EventResponse, WindowSettings};
@@ -48,10 +49,11 @@ pub fn read_window_info(window: &winit::window::Window, pixels_per_point: f32) -
     }
 }
 
-pub fn window_builder(
+pub fn window_builder<E>(
+    event_loop: &EventLoopWindowTarget<E>,
     title: &str,
     native_options: &epi::NativeOptions,
-    window_settings: &Option<WindowSettings>,
+    window_settings: Option<WindowSettings>,
 ) -> winit::window::WindowBuilder {
     let epi::NativeOptions {
         always_on_top,
@@ -103,7 +105,9 @@ pub fn window_builder(
 
     window_builder = window_builder_drag_and_drop(window_builder, *drag_and_drop_support);
 
-    if let Some(window_settings) = window_settings {
+    if let Some(mut window_settings) = window_settings {
+        // Restore pos/size from previous session
+        window_settings.clamp_to_sane_values(largest_monitor_point_size(event_loop));
         window_builder = window_settings.initialize_window(window_builder);
     } else {
         if let Some(pos) = *initial_window_pos {
@@ -112,7 +116,10 @@ pub fn window_builder(
                 y: pos.y as f64,
             });
         }
+
         if let Some(initial_window_size) = *initial_window_size {
+            let initial_window_size =
+                initial_window_size.at_most(largest_monitor_point_size(event_loop));
             window_builder = window_builder.with_inner_size(points_to_size(initial_window_size));
         }
     }
@@ -120,6 +127,22 @@ pub fn window_builder(
     window_builder
 }
 
+fn largest_monitor_point_size<E>(event_loop: &EventLoopWindowTarget<E>) -> egui::Vec2 {
+    let mut max_size = egui::Vec2::ZERO;
+
+    for monitor in event_loop.available_monitors() {
+        let size = monitor.size().to_logical::<f32>(monitor.scale_factor());
+        let size = egui::vec2(size.width, size.height);
+        max_size = max_size.max(size);
+    }
+
+    if max_size == egui::Vec2::ZERO {
+        egui::Vec2::splat(16000.0)
+    } else {
+        max_size
+    }
+}
+
 fn load_icon(icon_data: epi::IconData) -> Option<winit::window::Icon> {
     winit::window::Icon::from_rgba(icon_data.rgba, icon_data.width, icon_data.height).ok()
 }
@@ -445,9 +468,7 @@ const STORAGE_WINDOW_KEY: &str = "window";
 pub fn load_window_settings(_storage: Option<&dyn epi::Storage>) -> Option<WindowSettings> {
     #[cfg(feature = "persistence")]
     {
-        let mut settings: WindowSettings = epi::get_value(_storage?, STORAGE_WINDOW_KEY)?;
+        epi::get_value(_storage?, STORAGE_WINDOW_KEY)
-        settings.clamp_to_sane_values();
-        Some(settings)
     }
     #[cfg(not(feature = "persistence"))]
     None

crates/eframe/src/native/run.rs

@@ -504,7 +504,7 @@ mod glow_integration {
             let window_settings = epi_integration::load_window_settings(storage);
 
             let winit_window =
-                epi_integration::window_builder(title, native_options, &window_settings)
+                epi_integration::window_builder(event_loop, title, native_options, window_settings)
                     .build(event_loop)?;
             // a lot of the code below has been lifted from glutin example in their repo.
             let glutin_window_context =
@@ -937,7 +937,7 @@ mod wgpu_integration {
         ) -> Result<winit::window::Window> {
             let window_settings = epi_integration::load_window_settings(storage);
             Ok(
-                epi_integration::window_builder(title, native_options, &window_settings)
+                epi_integration::window_builder(event_loop, title, native_options, window_settings)
                     .build(event_loop)?,
             )
         }

crates/egui-winit/src/window_settings.rs

@@ -76,11 +76,14 @@ impl WindowSettings {
         }
     }
 
-    pub fn clamp_to_sane_values(&mut self) {
+    pub fn clamp_to_sane_values(&mut self, max_size: egui::Vec2) {
+        use egui::NumExt as _;
+
         if let Some(size) = &mut self.inner_size_points {
             // Prevent ridiculously small windows
             let min_size = egui::Vec2::splat(64.0);
-            *size = size.max(min_size);
+            *size = size.at_least(min_size);
+            *size = size.at_most(max_size);
         }
     }
 }