Create `iced_widget` subcrate and re-organize the whole codebase

1 files changed, 122 insertions, 0 deletions

diff --git a/core/src/overlay.rs b/core/src/overlay.rs
new file mode 100644
index 00000000..b9f3c735
--- /dev/null
+++ b/core/src/overlay.rs
@@ -0,0 +1,122 @@
+//! Display interactive elements on top of other widgets.
+mod element;
+mod group;
+
+pub use element::Element;
+pub use group::Group;
+
+use crate::event::{self, Event};
+use crate::layout;
+use crate::mouse;
+use crate::renderer;
+use crate::widget;
+use crate::widget::Tree;
+use crate::{Clipboard, Layout, Point, Rectangle, Shell, Size};
+
+/// An interactive component that can be displayed on top of other widgets.
+pub trait Overlay<Message, Renderer>
+where
+    Renderer: crate::Renderer,
+{
+    /// Returns the layout [`Node`] of the [`Overlay`].
+    ///
+    /// This [`Node`] is used by the runtime to compute the [`Layout`] of the
+    /// user interface.
+    ///
+    /// [`Node`]: layout::Node
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        bounds: Size,
+        position: Point,
+    ) -> layout::Node;
+
+    /// Draws the [`Overlay`] using the associated `Renderer`.
+    fn draw(
+        &self,
+        renderer: &mut Renderer,
+        theme: &Renderer::Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    );
+
+    /// Applies a [`widget::Operation`] to the [`Overlay`].
+    fn operate(
+        &mut self,
+        _layout: Layout<'_>,
+        _renderer: &Renderer,
+        _operation: &mut dyn widget::Operation<Message>,
+    ) {
+    }
+
+    /// Processes a runtime [`Event`].
+    ///
+    /// It receives:
+    ///   * an [`Event`] describing user interaction
+    ///   * the computed [`Layout`] of the [`Overlay`]
+    ///   * the current cursor position
+    ///   * a mutable `Message` list, allowing the [`Overlay`] to produce
+    ///   new messages based on user interaction.
+    ///   * the `Renderer`
+    ///   * a [`Clipboard`], if available
+    ///
+    /// By default, it does nothing.
+    fn on_event(
+        &mut self,
+        _event: Event,
+        _layout: Layout<'_>,
+        _cursor_position: Point,
+        _renderer: &Renderer,
+        _clipboard: &mut dyn Clipboard,
+        _shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        event::Status::Ignored
+    }
+
+    /// Returns the current [`mouse::Interaction`] of the [`Overlay`].
+    ///
+    /// By default, it returns [`mouse::Interaction::Idle`].
+    fn mouse_interaction(
+        &self,
+        _layout: Layout<'_>,
+        _cursor_position: Point,
+        _viewport: &Rectangle,
+        _renderer: &Renderer,
+    ) -> mouse::Interaction {
+        mouse::Interaction::Idle
+    }
+
+    /// Returns true if the cursor is over the [`Overlay`].
+    ///
+    /// By default, it returns true if the bounds of the `layout` contain
+    /// the `cursor_position`.
+    fn is_over(&self, layout: Layout<'_>, cursor_position: Point) -> bool {
+        layout.bounds().contains(cursor_position)
+    }
+}
+
+/// Returns a [`Group`] of overlay [`Element`] children.
+///
+/// This method will generally only be used by advanced users that are
+/// implementing the [`Widget`](crate::Widget) trait.
+pub fn from_children<'a, Message, Renderer>(
+    children: &'a mut [crate::Element<'_, Message, Renderer>],
+    tree: &'a mut Tree,
+    layout: Layout<'_>,
+    renderer: &Renderer,
+) -> Option<Element<'a, Message, Renderer>>
+where
+    Renderer: crate::Renderer,
+{
+    let children = children
+        .iter_mut()
+        .zip(&mut tree.children)
+        .zip(layout.children())
+        .filter_map(|((child, state), layout)| {
+            child.as_widget_mut().overlay(state, layout, renderer)
+        })
+        .collect::<Vec<_>>();
+
+    (!children.is_empty()).then(|| Group::with_children(children).overlay())
+}