feat(widget): add ContextDrawer widget

src/widget/context_drawer/overlay.rs

@@ -0,0 +1,119 @@
+// Copyright 2023 System76 <info@system76.com>
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::Element;
+
+use iced::advanced::layout::{self, Layout};
+use iced::advanced::widget::{self, Operation, OperationOutputWrapper};
+use iced::advanced::{overlay, renderer};
+use iced::advanced::{Clipboard, Shell};
+use iced::{event, mouse, Event, Point, Rectangle, Size};
+use iced_core::Widget;
+
+pub(super) struct Overlay<'a, 'b, Message> {
+    pub(super) content: &'b mut Element<'a, Message>,
+    pub(super) tree: &'b mut widget::Tree,
+    pub(super) width: f32,
+}
+
+impl<'a, 'b, Message> overlay::Overlay<Message, crate::Renderer> for Overlay<'a, 'b, Message>
+where
+    Message: Clone,
+{
+    fn layout(&self, renderer: &crate::Renderer, bounds: Size, position: Point) -> layout::Node {
+        let limits = layout::Limits::new(Size::ZERO, bounds)
+            .width(self.width)
+            .height(bounds.height - 8.0 - position.y);
+
+        let mut node = self.content.as_widget().layout(renderer, &limits);
+        let node_size = node.size();
+
+        node.move_to(Point {
+            x: if bounds.width > node_size.width - 8.0 {
+                bounds.width - node_size.width - 8.0
+            } else {
+                0.0
+            },
+            y: if bounds.height > node_size.height - 8.0 {
+                bounds.height - node_size.height - 8.0
+            } else {
+                0.0
+            },
+        });
+
+        node
+    }
+
+    fn on_event(
+        &mut self,
+        event: Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &crate::Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        self.content.as_widget_mut().on_event(
+            self.tree,
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            &layout.bounds(),
+        )
+    }
+
+    fn draw(
+        &self,
+        renderer: &mut crate::Renderer,
+        theme: &crate::Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+    ) {
+        self.content.draw(
+            self.tree,
+            renderer,
+            theme,
+            style,
+            layout,
+            cursor,
+            &layout.bounds(),
+        );
+    }
+
+    fn operate(
+        &mut self,
+        layout: Layout<'_>,
+        renderer: &crate::Renderer,
+        operation: &mut dyn Operation<OperationOutputWrapper<Message>>,
+    ) {
+        self.content
+            .as_widget_mut()
+            .operate(self.tree, layout, renderer, operation);
+    }
+
+    fn mouse_interaction(
+        &self,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &crate::Renderer,
+    ) -> mouse::Interaction {
+        self.content
+            .as_widget()
+            .mouse_interaction(self.tree, layout, cursor, viewport, renderer)
+    }
+
+    fn overlay<'c>(
+        &'c mut self,
+        layout: Layout<'_>,
+        renderer: &crate::Renderer,
+    ) -> Option<overlay::Element<'c, Message, crate::Renderer>> {
+        self.content
+            .as_widget_mut()
+            .overlay(self.tree, layout, renderer)
+    }
+}