Merge pull request #1284 from iced-rs/virtual-widgets

Stateless widgets

1 files changed, 157 insertions, 0 deletions

diff --git a/pure/src/lib.rs b/pure/src/lib.rs
new file mode 100644
index 00000000..ec2f29f8
--- /dev/null
+++ b/pure/src/lib.rs
@@ -0,0 +1,157 @@
+pub mod helpers;
+pub mod overlay;
+pub mod widget;
+
+pub(crate) mod flex;
+
+mod element;
+
+pub use element::Element;
+pub use helpers::*;
+pub use widget::Widget;
+
+use iced_native::event::{self, Event};
+use iced_native::layout::{self, Layout};
+use iced_native::mouse;
+use iced_native::renderer;
+use iced_native::{Clipboard, Length, Point, Rectangle, Shell};
+
+pub struct Pure<'a, Message, Renderer> {
+    state: &'a mut State,
+    element: Element<'a, Message, Renderer>,
+}
+
+impl<'a, Message, Renderer> Pure<'a, Message, Renderer>
+where
+    Message: 'static,
+    Renderer: iced_native::Renderer + 'static,
+{
+    pub fn new(
+        state: &'a mut State,
+        content: impl Into<Element<'a, Message, Renderer>>,
+    ) -> Self {
+        let element = content.into();
+        let _ = state.diff(&element);
+
+        Self { state, element }
+    }
+}
+
+pub struct State {
+    state_tree: widget::Tree,
+}
+
+impl State {
+    pub fn new() -> Self {
+        Self {
+            state_tree: widget::Tree::empty(),
+        }
+    }
+
+    fn diff<Message, Renderer>(
+        &mut self,
+        new_element: &Element<Message, Renderer>,
+    ) {
+        self.state_tree.diff(new_element);
+    }
+}
+
+impl<'a, Message, Renderer> iced_native::Widget<Message, Renderer>
+    for Pure<'a, Message, Renderer>
+where
+    Message: 'a,
+    Renderer: iced_native::Renderer + 'a,
+{
+    fn width(&self) -> Length {
+        self.element.as_widget().width()
+    }
+
+    fn height(&self) -> Length {
+        self.element.as_widget().height()
+    }
+
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        self.element.as_widget().layout(renderer, limits)
+    }
+
+    fn on_event(
+        &mut self,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        self.element.as_widget_mut().on_event(
+            &mut self.state.state_tree,
+            event,
+            layout,
+            cursor_position,
+            renderer,
+            clipboard,
+            shell,
+        )
+    }
+
+    fn draw(
+        &self,
+        renderer: &mut Renderer,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+    ) {
+        self.element.as_widget().draw(
+            &self.state.state_tree,
+            renderer,
+            style,
+            layout,
+            cursor_position,
+            viewport,
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.element.as_widget().mouse_interaction(
+            &self.state.state_tree,
+            layout,
+            cursor_position,
+            viewport,
+            renderer,
+        )
+    }
+
+    fn overlay(
+        &mut self,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+    ) -> Option<overlay::Element<'_, Message, Renderer>> {
+        self.element.as_widget_mut().overlay(
+            &mut self.state.state_tree,
+            layout,
+            renderer,
+        )
+    }
+}
+
+impl<'a, Message, Renderer> Into<iced_native::Element<'a, Message, Renderer>>
+    for Pure<'a, Message, Renderer>
+where
+    Message: 'a,
+    Renderer: iced_native::Renderer + 'a,
+{
+    fn into(self) -> iced_native::Element<'a, Message, Renderer> {
+        iced_native::Element::new(self)
+    }
+}