Add flag to disable hardware acceleration (#1681)

This is a fix for the behaviour on macOS platforms where any egui app would use the dedicated GPU and consume more power than needed. Not all apps might have dedicated GPU requirements.

eframe/src/native/epi_integration.rs

@@ -47,11 +47,12 @@ pub fn window_builder(
         max_window_size,
         resizable,
         transparent,
-        vsync: _,          // used in `fn create_display`
-        multisampling: _,  // used in `fn create_display`
-        depth_buffer: _,   // used in `fn create_display`
-        stencil_buffer: _, // used in `fn create_display`
-        renderer: _,       // used in `fn run_native`
+        vsync: _,                 // used in `fn create_display`
+        multisampling: _,         // used in `fn create_display`
+        depth_buffer: _,          // used in `fn create_display`
+        stencil_buffer: _,        // used in `fn create_display`
+        hardware_acceleration: _, // used in `fn create_display`
+        renderer: _,              // used in `fn run_native`
     } = native_options;
 
     let window_icon = icon_data.clone().and_then(load_icon);

eframe/src/native/run.rs

@@ -17,6 +17,7 @@ fn create_display(
     crate::profile_function!();
     let gl_window = unsafe {
         glutin::ContextBuilder::new()
+            .with_hardware_acceleration(native_options.hardware_acceleration)
             .with_depth_buffer(native_options.depth_buffer)
             .with_multisampling(native_options.multisampling)
             .with_srgb(true)