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

Stateless widgets

1 files changed, 163 insertions, 0 deletions

diff --git a/pure/src/element.rs b/pure/src/element.rs
new file mode 100644
index 00000000..3d5697fe
--- /dev/null
+++ b/pure/src/element.rs
@@ -0,0 +1,163 @@
+use crate::widget::tree::{self, Tree};
+use crate::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 Element<'a, Message, Renderer> {
+    widget: Box<dyn Widget<Message, Renderer> + 'a>,
+}
+
+impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
+    pub fn new(widget: impl Widget<Message, Renderer> + 'a) -> Self {
+        Self {
+            widget: Box::new(widget),
+        }
+    }
+
+    pub fn as_widget(&self) -> &dyn Widget<Message, Renderer> {
+        self.widget.as_ref()
+    }
+
+    pub fn as_widget_mut(&mut self) -> &mut dyn Widget<Message, Renderer> {
+        self.widget.as_mut()
+    }
+
+    pub fn map<B>(
+        self,
+        f: impl Fn(Message) -> B + 'a,
+    ) -> Element<'a, B, Renderer>
+    where
+        Message: 'a,
+        Renderer: iced_native::Renderer + 'a,
+        B: 'a,
+    {
+        Element::new(Map::new(self.widget, f))
+    }
+}
+
+struct Map<'a, A, B, Renderer> {
+    widget: Box<dyn Widget<A, Renderer> + 'a>,
+    mapper: Box<dyn Fn(A) -> B + 'a>,
+}
+
+impl<'a, A, B, Renderer> Map<'a, A, B, Renderer> {
+    pub fn new<F>(
+        widget: Box<dyn Widget<A, Renderer> + 'a>,
+        mapper: F,
+    ) -> Map<'a, A, B, Renderer>
+    where
+        F: 'a + Fn(A) -> B,
+    {
+        Map {
+            widget,
+            mapper: Box::new(mapper),
+        }
+    }
+}
+
+impl<'a, A, B, Renderer> Widget<B, Renderer> for Map<'a, A, B, Renderer>
+where
+    Renderer: iced_native::Renderer + 'a,
+    A: 'a,
+    B: 'a,
+{
+    fn tag(&self) -> tree::Tag {
+        self.widget.tag()
+    }
+
+    fn state(&self) -> tree::State {
+        self.widget.state()
+    }
+
+    fn children(&self) -> Vec<Tree> {
+        self.widget.children()
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        self.widget.diff(tree)
+    }
+
+    fn width(&self) -> Length {
+        self.widget.width()
+    }
+
+    fn height(&self) -> Length {
+        self.widget.height()
+    }
+
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        self.widget.layout(renderer, limits)
+    }
+
+    fn on_event(
+        &mut self,
+        tree: &mut Tree,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, B>,
+    ) -> event::Status {
+        let mut local_messages = Vec::new();
+        let mut local_shell = Shell::new(&mut local_messages);
+
+        let status = self.widget.on_event(
+            tree,
+            event,
+            layout,
+            cursor_position,
+            renderer,
+            clipboard,
+            &mut local_shell,
+        );
+
+        shell.merge(local_shell, &self.mapper);
+
+        status
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+    ) {
+        self.widget.draw(
+            tree,
+            renderer,
+            style,
+            layout,
+            cursor_position,
+            viewport,
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.widget.mouse_interaction(
+            tree,
+            layout,
+            cursor_position,
+            viewport,
+            renderer,
+        )
+    }
+}