demo app: add buttons to toggle window decorations on/off

eframe/CHANGELOG.md

@@ -3,6 +3,7 @@ All notable changes to the `eframe` crate.
 
 
 ## Unreleased
+* `Frame` now provides `set_decorations` to set whether to show window decorations.
 
 
 ## 0.14.0 - 2021-08-24

egui_demo_lib/src/backend_panel.rs

@@ -134,13 +134,24 @@ impl BackendPanel {
             }
         }
 
-        if !frame.is_web()
-            && ui
+        if !frame.is_web() {
+            ui.horizontal(|ui| {
+                ui.label("Window decorations:");
+                if ui.button("Show").clicked() {
+                    frame.set_decorations(true);
+                }
+                if ui.button("Hide").clicked() {
+                    frame.set_decorations(false);
+                }
+            });
+
+            if ui
                 .button("📱 Phone Size")
                 .on_hover_text("Resize the window to be small like a phone.")
                 .clicked()
-        {
-            frame.set_window_size(egui::Vec2::new(375.0, 812.0)); // iPhone 12 mini
+            {
+                frame.set_window_size(egui::Vec2::new(375.0, 812.0)); // iPhone 12 mini
+            }
         }
 
         ui.separator();

egui_glium/src/backend.rs

@@ -346,7 +346,15 @@ pub fn run(mut app: Box<dyn epi::App>, native_options: epi::NativeOptions) {
             }
 
             {
-                let epi::backend::AppOutput { quit, window_size } = app_output;
+                let epi::backend::AppOutput {
+                    quit,
+                    window_size,
+                    decorated,
+                } = app_output;
+
+                if let Some(decorated) = decorated {
+                    display.gl_window().window().set_decorations(decorated);
+                }
 
                 if let Some(window_size) = window_size {
                     display.gl_window().window().set_inner_size(

egui_web/src/backend.rs

@@ -266,6 +266,7 @@ impl AppRunner {
             let epi::backend::AppOutput {
                 quit: _,        // Can't quit a web page
                 window_size: _, // Can't resize a web page
+                decorated: _,   // Can't show decorations
             } = app_output;
         }
 

epi/src/lib.rs

@@ -251,6 +251,12 @@ impl<'a> Frame<'a> {
         self.0.output.window_size = Some(size);
     }
 
+    /// Set whether to show window decorations (i.e. a frame around you app).
+    /// If false it will be difficult to move and resize the app.
+    pub fn set_decorations(&mut self, decorated: bool) {
+        self.0.output.decorated = Some(decorated);
+    }
+
     /// If you need to request a repaint from another thread, clone this and send it to that other thread.
     pub fn repaint_signal(&self) -> std::sync::Arc<dyn RepaintSignal> {
         self.0.repaint_signal.clone()
@@ -504,5 +510,8 @@ pub mod backend {
 
         /// Set to some size to resize the outer window (e.g. glium window) to this size.
         pub window_size: Option<egui::Vec2>,
+
+        /// Set to some bool to change window decorations
+        pub decorated: Option<bool>,
     }
 }