Add basic window control (#670)

This is the first merge-able part of #606.

It allows to implement custom CSDs via window management signals and a
new `WindowHandle` widget which is useful to implement a custom
titlebar.

masonry/src/contexts.rs

@@ -6,9 +6,11 @@
 use std::time::Duration;
 
 use accesskit::TreeUpdate;
+use dpi::LogicalPosition;
 use parley::{FontContext, LayoutContext};
 use tracing::{trace, warn};
 use vello::kurbo::Vec2;
+use winit::window::ResizeDirection;
 
 use crate::action::Action;
 use crate::passes::layout::run_layout_on;
@@ -606,6 +608,58 @@ impl_context_method!(
                 .emit_signal(RenderRootSignal::Action(action, self.widget_state.id));
         }
 
+        /// Start a window drag.
+        ///
+        /// Moves the window with the left mouse button until the button is released.
+        pub fn drag_window(&mut self) {
+            trace!("drag_window");
+            self.global_state
+                .signal_queue
+                .push_back(RenderRootSignal::DragWindow);
+        }
+
+        /// Start a window resize.
+        ///
+        /// Resizes the window with the left mouse button until the button is released.
+        pub fn drag_resize_window(&mut self, direction: ResizeDirection) {
+            trace!("drag_resize_window");
+            self.global_state
+                .signal_queue
+                .push_back(RenderRootSignal::DragResizeWindow(direction));
+        }
+
+        /// Toggle the maximized state of the window.
+        pub fn toggle_maximized(&mut self) {
+            trace!("toggle_maximized");
+            self.global_state
+                .signal_queue
+                .push_back(RenderRootSignal::ToggleMaximized);
+        }
+
+        /// Minimize the window.
+        pub fn minimize(&mut self) {
+            trace!("minimize");
+            self.global_state
+                .signal_queue
+                .push_back(RenderRootSignal::Minimize);
+        }
+
+        /// Exit the application.
+        pub fn exit(&mut self) {
+            trace!("exit");
+            self.global_state
+                .signal_queue
+                .push_back(RenderRootSignal::Exit);
+        }
+
+        /// Show the window menu at a specified position.
+        pub fn show_window_menu(&mut self, position: LogicalPosition<f64>) {
+            trace!("show_window_menu");
+            self.global_state
+                .signal_queue
+                .push_back(RenderRootSignal::ShowWindowMenu(position));
+        }
+
         /// Request a timer event.
         ///
         /// The return value is a token, which can be used to associate the

masonry/src/event_loop_runner.rs

@@ -649,7 +649,7 @@ impl MasonryState<'_> {
     pub fn handle_memory_warning(&mut self, _: &ActiveEventLoop) {}
 
     // --- MARK: SIGNALS ---
-    fn handle_signals(&mut self, _event_loop: &ActiveEventLoop, app_driver: &mut dyn AppDriver) {
+    fn handle_signals(&mut self, event_loop: &ActiveEventLoop, app_driver: &mut dyn AppDriver) {
         let WindowState::Rendering { window, .. } = &mut self.window else {
             tracing::warn!("Tried to handle a signal whilst suspended or before window created");
             return;
@@ -696,6 +696,26 @@ impl MasonryState<'_> {
                 render_root::RenderRootSignal::SetTitle(title) => {
                     window.set_title(&title);
                 }
+                render_root::RenderRootSignal::DragWindow => {
+                    // TODO - Handle return value?
+                    let _ = window.drag_window();
+                }
+                render_root::RenderRootSignal::DragResizeWindow(direction) => {
+                    // TODO - Handle return value?
+                    let _ = window.drag_resize_window(direction);
+                }
+                render_root::RenderRootSignal::ToggleMaximized => {
+                    window.set_maximized(!window.is_maximized());
+                }
+                render_root::RenderRootSignal::Minimize => {
+                    window.set_minimized(true);
+                }
+                render_root::RenderRootSignal::Exit => {
+                    event_loop.exit();
+                }
+                render_root::RenderRootSignal::ShowWindowMenu(position) => {
+                    window.show_window_menu(position);
+                }
             }
         }
 

masonry/src/render_root.rs

@@ -9,6 +9,7 @@ use parley::{FontContext, LayoutContext};
 use tracing::{info_span, warn};
 use vello::kurbo::{self, Rect};
 use vello::Scene;
+use winit::window::ResizeDirection;
 
 #[cfg(not(target_arch = "wasm32"))]
 use std::time::Instant;
@@ -123,6 +124,12 @@ pub enum RenderRootSignal {
     SetCursor(CursorIcon),
     SetSize(PhysicalSize<u32>),
     SetTitle(String),
+    DragWindow,
+    DragResizeWindow(ResizeDirection),
+    ToggleMaximized,
+    Minimize,
+    Exit,
+    ShowWindowMenu(LogicalPosition<f64>),
 }
 
 impl RenderRoot {

masonry/src/testing/harness.rs

@@ -264,6 +264,12 @@ impl TestHarness {
                 RenderRootSignal::SetTitle(title) => {
                     self.title = title;
                 }
+                RenderRootSignal::DragWindow => (),
+                RenderRootSignal::DragResizeWindow(_) => (),
+                RenderRootSignal::ToggleMaximized => (),
+                RenderRootSignal::Minimize => (),
+                RenderRootSignal::Exit => (),
+                RenderRootSignal::ShowWindowMenu(_) => (),
             }
         }
     }