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

1 files changed, 991 insertions, 0 deletions

diff --git a/widget/src/pane_grid.rs b/widget/src/pane_grid.rs
new file mode 100644
index 00000000..a97cef60
--- /dev/null
+++ b/widget/src/pane_grid.rs
@@ -0,0 +1,991 @@
+//! Let your users split regions of your application and organize layout dynamically.
+//!
+//! [![Pane grid - Iced](https://thumbs.gfycat.com/MixedFlatJellyfish-small.gif)](https://gfycat.com/mixedflatjellyfish)
+//!
+//! # Example
+//! The [`pane_grid` example] showcases how to use a [`PaneGrid`] with resizing,
+//! drag and drop, and hotkey support.
+//!
+//! [`pane_grid` example]: https://github.com/iced-rs/iced/tree/0.8/examples/pane_grid
+mod axis;
+mod configuration;
+mod content;
+mod direction;
+mod draggable;
+mod node;
+mod pane;
+mod split;
+mod title_bar;
+
+pub mod state;
+
+pub use axis::Axis;
+pub use configuration::Configuration;
+pub use content::Content;
+pub use direction::Direction;
+pub use draggable::Draggable;
+pub use node::Node;
+pub use pane::Pane;
+pub use split::Split;
+pub use state::State;
+pub use title_bar::TitleBar;
+
+pub use crate::style::pane_grid::{Line, StyleSheet};
+
+use crate::container;
+use crate::core::event::{self, Event};
+use crate::core::layout;
+use crate::core::mouse;
+use crate::core::overlay::{self, Group};
+use crate::core::renderer;
+use crate::core::touch;
+use crate::core::widget;
+use crate::core::widget::tree::{self, Tree};
+use crate::core::{
+    Clipboard, Color, Element, Layout, Length, Pixels, Point, Rectangle, Shell,
+    Size, Vector, Widget,
+};
+
+/// A collection of panes distributed using either vertical or horizontal splits
+/// to completely fill the space available.
+///
+/// [![Pane grid - Iced](https://thumbs.gfycat.com/FrailFreshAiredaleterrier-small.gif)](https://gfycat.com/frailfreshairedaleterrier)
+///
+/// This distribution of space is common in tiling window managers (like
+/// [`awesome`](https://awesomewm.org/), [`i3`](https://i3wm.org/), or even
+/// [`tmux`](https://github.com/tmux/tmux)).
+///
+/// A [`PaneGrid`] supports:
+///
+/// * Vertical and horizontal splits
+/// * Tracking of the last active pane
+/// * Mouse-based resizing
+/// * Drag and drop to reorganize panes
+/// * Hotkey support
+/// * Configurable modifier keys
+/// * [`State`] API to perform actions programmatically (`split`, `swap`, `resize`, etc.)
+///
+/// ## Example
+///
+/// ```
+/// # use iced_widget::{pane_grid, text};
+/// #
+/// # type PaneGrid<'a, Message> =
+/// #     iced_widget::PaneGrid<'a, Message, iced_widget::renderer::Renderer<iced_widget::style::Theme>>;
+/// #
+/// enum PaneState {
+///     SomePane,
+///     AnotherKindOfPane,
+/// }
+///
+/// enum Message {
+///     PaneDragged(pane_grid::DragEvent),
+///     PaneResized(pane_grid::ResizeEvent),
+/// }
+///
+/// let (mut state, _) = pane_grid::State::new(PaneState::SomePane);
+///
+/// let pane_grid =
+///     PaneGrid::new(&state, |pane, state, is_maximized| {
+///         pane_grid::Content::new(match state {
+///             PaneState::SomePane => text("This is some pane"),
+///             PaneState::AnotherKindOfPane => text("This is another kind of pane"),
+///         })
+///     })
+///     .on_drag(Message::PaneDragged)
+///     .on_resize(10, Message::PaneResized);
+/// ```
+#[allow(missing_debug_implementations)]
+pub struct PaneGrid<'a, Message, Renderer = crate::Renderer>
+where
+    Renderer: crate::core::Renderer,
+    Renderer::Theme: StyleSheet + container::StyleSheet,
+{
+    contents: Contents<'a, Content<'a, Message, Renderer>>,
+    width: Length,
+    height: Length,
+    spacing: f32,
+    on_click: Option<Box<dyn Fn(Pane) -> Message + 'a>>,
+    on_drag: Option<Box<dyn Fn(DragEvent) -> Message + 'a>>,
+    on_resize: Option<(f32, Box<dyn Fn(ResizeEvent) -> Message + 'a>)>,
+    style: <Renderer::Theme as StyleSheet>::Style,
+}
+
+impl<'a, Message, Renderer> PaneGrid<'a, Message, Renderer>
+where
+    Renderer: crate::core::Renderer,
+    Renderer::Theme: StyleSheet + container::StyleSheet,
+{
+    /// Creates a [`PaneGrid`] with the given [`State`] and view function.
+    ///
+    /// The view function will be called to display each [`Pane`] present in the
+    /// [`State`]. [`bool`] is set if the pane is maximized.
+    pub fn new<T>(
+        state: &'a State<T>,
+        view: impl Fn(Pane, &'a T, bool) -> Content<'a, Message, Renderer>,
+    ) -> Self {
+        let contents = if let Some((pane, pane_state)) =
+            state.maximized.and_then(|pane| {
+                state.panes.get(&pane).map(|pane_state| (pane, pane_state))
+            }) {
+            Contents::Maximized(
+                pane,
+                view(pane, pane_state, true),
+                Node::Pane(pane),
+            )
+        } else {
+            Contents::All(
+                state
+                    .panes
+                    .iter()
+                    .map(|(pane, pane_state)| {
+                        (*pane, view(*pane, pane_state, false))
+                    })
+                    .collect(),
+                &state.internal,
+            )
+        };
+
+        Self {
+            contents,
+            width: Length::Fill,
+            height: Length::Fill,
+            spacing: 0.0,
+            on_click: None,
+            on_drag: None,
+            on_resize: None,
+            style: Default::default(),
+        }
+    }
+
+    /// Sets the width of the [`PaneGrid`].
+    pub fn width(mut self, width: impl Into<Length>) -> Self {
+        self.width = width.into();
+        self
+    }
+
+    /// Sets the height of the [`PaneGrid`].
+    pub fn height(mut self, height: impl Into<Length>) -> Self {
+        self.height = height.into();
+        self
+    }
+
+    /// Sets the spacing _between_ the panes of the [`PaneGrid`].
+    pub fn spacing(mut self, amount: impl Into<Pixels>) -> Self {
+        self.spacing = amount.into().0;
+        self
+    }
+
+    /// Sets the message that will be produced when a [`Pane`] of the
+    /// [`PaneGrid`] is clicked.
+    pub fn on_click<F>(mut self, f: F) -> Self
+    where
+        F: 'a + Fn(Pane) -> Message,
+    {
+        self.on_click = Some(Box::new(f));
+        self
+    }
+
+    /// Enables the drag and drop interactions of the [`PaneGrid`], which will
+    /// use the provided function to produce messages.
+    pub fn on_drag<F>(mut self, f: F) -> Self
+    where
+        F: 'a + Fn(DragEvent) -> Message,
+    {
+        self.on_drag = Some(Box::new(f));
+        self
+    }
+
+    /// Enables the resize interactions of the [`PaneGrid`], which will
+    /// use the provided function to produce messages.
+    ///
+    /// The `leeway` describes the amount of space around a split that can be
+    /// used to grab it.
+    ///
+    /// The grabbable area of a split will have a length of `spacing + leeway`,
+    /// properly centered. In other words, a length of
+    /// `(spacing + leeway) / 2.0` on either side of the split line.
+    pub fn on_resize<F>(mut self, leeway: impl Into<Pixels>, f: F) -> Self
+    where
+        F: 'a + Fn(ResizeEvent) -> Message,
+    {
+        self.on_resize = Some((leeway.into().0, Box::new(f)));
+        self
+    }
+
+    /// Sets the style of the [`PaneGrid`].
+    pub fn style(
+        mut self,
+        style: impl Into<<Renderer::Theme as StyleSheet>::Style>,
+    ) -> Self {
+        self.style = style.into();
+        self
+    }
+
+    fn drag_enabled(&self) -> bool {
+        (!self.contents.is_maximized())
+            .then(|| self.on_drag.is_some())
+            .unwrap_or_default()
+    }
+}
+
+impl<'a, Message, Renderer> Widget<Message, Renderer>
+    for PaneGrid<'a, Message, Renderer>
+where
+    Renderer: crate::core::Renderer,
+    Renderer::Theme: StyleSheet + container::StyleSheet,
+{
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<state::Action>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(state::Action::Idle)
+    }
+
+    fn children(&self) -> Vec<Tree> {
+        self.contents
+            .iter()
+            .map(|(_, content)| content.state())
+            .collect()
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        match &self.contents {
+            Contents::All(contents, _) => tree.diff_children_custom(
+                contents,
+                |state, (_, content)| content.diff(state),
+                |(_, content)| content.state(),
+            ),
+            Contents::Maximized(_, content, _) => tree.diff_children_custom(
+                &[content],
+                |state, content| content.diff(state),
+                |content| content.state(),
+            ),
+        }
+    }
+
+    fn width(&self) -> Length {
+        self.width
+    }
+
+    fn height(&self) -> Length {
+        self.height
+    }
+
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        layout(
+            renderer,
+            limits,
+            self.contents.layout(),
+            self.width,
+            self.height,
+            self.spacing,
+            self.contents.iter(),
+            |content, renderer, limits| content.layout(renderer, limits),
+        )
+    }
+
+    fn operate(
+        &self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+        operation: &mut dyn widget::Operation<Message>,
+    ) {
+        operation.container(None, &mut |operation| {
+            self.contents
+                .iter()
+                .zip(&mut tree.children)
+                .zip(layout.children())
+                .for_each(|(((_pane, content), state), layout)| {
+                    content.operate(state, layout, renderer, operation);
+                })
+        });
+    }
+
+    fn on_event(
+        &mut self,
+        tree: &mut Tree,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        let action = tree.state.downcast_mut::<state::Action>();
+
+        let on_drag = if self.drag_enabled() {
+            &self.on_drag
+        } else {
+            &None
+        };
+
+        let event_status = update(
+            action,
+            self.contents.layout(),
+            &event,
+            layout,
+            cursor_position,
+            shell,
+            self.spacing,
+            self.contents.iter(),
+            &self.on_click,
+            on_drag,
+            &self.on_resize,
+        );
+
+        let picked_pane = action.picked_pane().map(|(pane, _)| pane);
+
+        self.contents
+            .iter_mut()
+            .zip(&mut tree.children)
+            .zip(layout.children())
+            .map(|(((pane, content), tree), layout)| {
+                let is_picked = picked_pane == Some(pane);
+
+                content.on_event(
+                    tree,
+                    event.clone(),
+                    layout,
+                    cursor_position,
+                    renderer,
+                    clipboard,
+                    shell,
+                    is_picked,
+                )
+            })
+            .fold(event_status, event::Status::merge)
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        mouse_interaction(
+            tree.state.downcast_ref(),
+            self.contents.layout(),
+            layout,
+            cursor_position,
+            self.spacing,
+            self.on_resize.as_ref().map(|(leeway, _)| *leeway),
+        )
+        .unwrap_or_else(|| {
+            self.contents
+                .iter()
+                .zip(&tree.children)
+                .zip(layout.children())
+                .map(|(((_pane, content), tree), layout)| {
+                    content.mouse_interaction(
+                        tree,
+                        layout,
+                        cursor_position,
+                        viewport,
+                        renderer,
+                        self.drag_enabled(),
+                    )
+                })
+                .max()
+                .unwrap_or_default()
+        })
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        theme: &Renderer::Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+    ) {
+        draw(
+            tree.state.downcast_ref(),
+            self.contents.layout(),
+            layout,
+            cursor_position,
+            renderer,
+            theme,
+            style,
+            viewport,
+            self.spacing,
+            self.on_resize.as_ref().map(|(leeway, _)| *leeway),
+            &self.style,
+            self.contents
+                .iter()
+                .zip(&tree.children)
+                .map(|((pane, content), tree)| (pane, (content, tree))),
+            |(content, tree),
+             renderer,
+             style,
+             layout,
+             cursor_position,
+             rectangle| {
+                content.draw(
+                    tree,
+                    renderer,
+                    theme,
+                    style,
+                    layout,
+                    cursor_position,
+                    rectangle,
+                );
+            },
+        )
+    }
+
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+    ) -> Option<overlay::Element<'_, Message, Renderer>> {
+        let children = self
+            .contents
+            .iter_mut()
+            .zip(&mut tree.children)
+            .zip(layout.children())
+            .filter_map(|(((_, content), state), layout)| {
+                content.overlay(state, layout, renderer)
+            })
+            .collect::<Vec<_>>();
+
+        (!children.is_empty()).then(|| Group::with_children(children).overlay())
+    }
+}
+
+impl<'a, Message, Renderer> From<PaneGrid<'a, Message, Renderer>>
+    for Element<'a, Message, Renderer>
+where
+    Message: 'a,
+    Renderer: 'a + crate::core::Renderer,
+    Renderer::Theme: StyleSheet + container::StyleSheet,
+{
+    fn from(
+        pane_grid: PaneGrid<'a, Message, Renderer>,
+    ) -> Element<'a, Message, Renderer> {
+        Element::new(pane_grid)
+    }
+}
+
+/// Calculates the [`Layout`] of a [`PaneGrid`].
+pub fn layout<Renderer, T>(
+    renderer: &Renderer,
+    limits: &layout::Limits,
+    node: &Node,
+    width: Length,
+    height: Length,
+    spacing: f32,
+    contents: impl Iterator<Item = (Pane, T)>,
+    layout_content: impl Fn(T, &Renderer, &layout::Limits) -> layout::Node,
+) -> layout::Node {
+    let limits = limits.width(width).height(height);
+    let size = limits.resolve(Size::ZERO);
+
+    let regions = node.pane_regions(spacing, size);
+    let children = contents
+        .filter_map(|(pane, content)| {
+            let region = regions.get(&pane)?;
+            let size = Size::new(region.width, region.height);
+
+            let mut node = layout_content(
+                content,
+                renderer,
+                &layout::Limits::new(size, size),
+            );
+
+            node.move_to(Point::new(region.x, region.y));
+
+            Some(node)
+        })
+        .collect();
+
+    layout::Node::with_children(size, children)
+}
+
+/// Processes an [`Event`] and updates the [`state`] of a [`PaneGrid`]
+/// accordingly.
+pub fn update<'a, Message, T: Draggable>(
+    action: &mut state::Action,
+    node: &Node,
+    event: &Event,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    shell: &mut Shell<'_, Message>,
+    spacing: f32,
+    contents: impl Iterator<Item = (Pane, T)>,
+    on_click: &Option<Box<dyn Fn(Pane) -> Message + 'a>>,
+    on_drag: &Option<Box<dyn Fn(DragEvent) -> Message + 'a>>,
+    on_resize: &Option<(f32, Box<dyn Fn(ResizeEvent) -> Message + 'a>)>,
+) -> event::Status {
+    let mut event_status = event::Status::Ignored;
+
+    match event {
+        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerPressed { .. }) => {
+            let bounds = layout.bounds();
+
+            if bounds.contains(cursor_position) {
+                event_status = event::Status::Captured;
+
+                match on_resize {
+                    Some((leeway, _)) => {
+                        let relative_cursor = Point::new(
+                            cursor_position.x - bounds.x,
+                            cursor_position.y - bounds.y,
+                        );
+
+                        let splits = node.split_regions(
+                            spacing,
+                            Size::new(bounds.width, bounds.height),
+                        );
+
+                        let clicked_split = hovered_split(
+                            splits.iter(),
+                            spacing + leeway,
+                            relative_cursor,
+                        );
+
+                        if let Some((split, axis, _)) = clicked_split {
+                            if action.picked_pane().is_none() {
+                                *action =
+                                    state::Action::Resizing { split, axis };
+                            }
+                        } else {
+                            click_pane(
+                                action,
+                                layout,
+                                cursor_position,
+                                shell,
+                                contents,
+                                on_click,
+                                on_drag,
+                            );
+                        }
+                    }
+                    None => {
+                        click_pane(
+                            action,
+                            layout,
+                            cursor_position,
+                            shell,
+                            contents,
+                            on_click,
+                            on_drag,
+                        );
+                    }
+                }
+            }
+        }
+        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerLifted { .. })
+        | Event::Touch(touch::Event::FingerLost { .. }) => {
+            if let Some((pane, _)) = action.picked_pane() {
+                if let Some(on_drag) = on_drag {
+                    let mut dropped_region = contents
+                        .zip(layout.children())
+                        .filter(|(_, layout)| {
+                            layout.bounds().contains(cursor_position)
+                        });
+
+                    let event = match dropped_region.next() {
+                        Some(((target, _), _)) if pane != target => {
+                            DragEvent::Dropped { pane, target }
+                        }
+                        _ => DragEvent::Canceled { pane },
+                    };
+
+                    shell.publish(on_drag(event));
+                }
+
+                *action = state::Action::Idle;
+
+                event_status = event::Status::Captured;
+            } else if action.picked_split().is_some() {
+                *action = state::Action::Idle;
+
+                event_status = event::Status::Captured;
+            }
+        }
+        Event::Mouse(mouse::Event::CursorMoved { .. })
+        | Event::Touch(touch::Event::FingerMoved { .. }) => {
+            if let Some((_, on_resize)) = on_resize {
+                if let Some((split, _)) = action.picked_split() {
+                    let bounds = layout.bounds();
+
+                    let splits = node.split_regions(
+                        spacing,
+                        Size::new(bounds.width, bounds.height),
+                    );
+
+                    if let Some((axis, rectangle, _)) = splits.get(&split) {
+                        let ratio = match axis {
+                            Axis::Horizontal => {
+                                let position =
+                                    cursor_position.y - bounds.y - rectangle.y;
+
+                                (position / rectangle.height).clamp(0.1, 0.9)
+                            }
+                            Axis::Vertical => {
+                                let position =
+                                    cursor_position.x - bounds.x - rectangle.x;
+
+                                (position / rectangle.width).clamp(0.1, 0.9)
+                            }
+                        };
+
+                        shell.publish(on_resize(ResizeEvent { split, ratio }));
+
+                        event_status = event::Status::Captured;
+                    }
+                }
+            }
+        }
+        _ => {}
+    }
+
+    event_status
+}
+
+fn click_pane<'a, Message, T>(
+    action: &mut state::Action,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    shell: &mut Shell<'_, Message>,
+    contents: impl Iterator<Item = (Pane, T)>,
+    on_click: &Option<Box<dyn Fn(Pane) -> Message + 'a>>,
+    on_drag: &Option<Box<dyn Fn(DragEvent) -> Message + 'a>>,
+) where
+    T: Draggable,
+{
+    let mut clicked_region = contents
+        .zip(layout.children())
+        .filter(|(_, layout)| layout.bounds().contains(cursor_position));
+
+    if let Some(((pane, content), layout)) = clicked_region.next() {
+        if let Some(on_click) = &on_click {
+            shell.publish(on_click(pane));
+        }
+
+        if let Some(on_drag) = &on_drag {
+            if content.can_be_dragged_at(layout, cursor_position) {
+                let pane_position = layout.position();
+
+                let origin = cursor_position
+                    - Vector::new(pane_position.x, pane_position.y);
+
+                *action = state::Action::Dragging { pane, origin };
+
+                shell.publish(on_drag(DragEvent::Picked { pane }));
+            }
+        }
+    }
+}
+
+/// Returns the current [`mouse::Interaction`] of a [`PaneGrid`].
+pub fn mouse_interaction(
+    action: &state::Action,
+    node: &Node,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    spacing: f32,
+    resize_leeway: Option<f32>,
+) -> Option<mouse::Interaction> {
+    if action.picked_pane().is_some() {
+        return Some(mouse::Interaction::Grabbing);
+    }
+
+    let resize_axis =
+        action.picked_split().map(|(_, axis)| axis).or_else(|| {
+            resize_leeway.and_then(|leeway| {
+                let bounds = layout.bounds();
+
+                let splits = node.split_regions(spacing, bounds.size());
+
+                let relative_cursor = Point::new(
+                    cursor_position.x - bounds.x,
+                    cursor_position.y - bounds.y,
+                );
+
+                hovered_split(splits.iter(), spacing + leeway, relative_cursor)
+                    .map(|(_, axis, _)| axis)
+            })
+        });
+
+    if let Some(resize_axis) = resize_axis {
+        return Some(match resize_axis {
+            Axis::Horizontal => mouse::Interaction::ResizingVertically,
+            Axis::Vertical => mouse::Interaction::ResizingHorizontally,
+        });
+    }
+
+    None
+}
+
+/// Draws a [`PaneGrid`].
+pub fn draw<Renderer, T>(
+    action: &state::Action,
+    node: &Node,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    renderer: &mut Renderer,
+    theme: &Renderer::Theme,
+    default_style: &renderer::Style,
+    viewport: &Rectangle,
+    spacing: f32,
+    resize_leeway: Option<f32>,
+    style: &<Renderer::Theme as StyleSheet>::Style,
+    contents: impl Iterator<Item = (Pane, T)>,
+    draw_pane: impl Fn(
+        T,
+        &mut Renderer,
+        &renderer::Style,
+        Layout<'_>,
+        Point,
+        &Rectangle,
+    ),
+) where
+    Renderer: crate::core::Renderer,
+    Renderer::Theme: StyleSheet,
+{
+    let picked_pane = action.picked_pane();
+
+    let picked_split = action
+        .picked_split()
+        .and_then(|(split, axis)| {
+            let bounds = layout.bounds();
+
+            let splits = node.split_regions(spacing, bounds.size());
+
+            let (_axis, region, ratio) = splits.get(&split)?;
+
+            let region = axis.split_line_bounds(*region, *ratio, spacing);
+
+            Some((axis, region + Vector::new(bounds.x, bounds.y), true))
+        })
+        .or_else(|| match resize_leeway {
+            Some(leeway) => {
+                let bounds = layout.bounds();
+
+                let relative_cursor = Point::new(
+                    cursor_position.x - bounds.x,
+                    cursor_position.y - bounds.y,
+                );
+
+                let splits = node.split_regions(spacing, bounds.size());
+
+                let (_split, axis, region) = hovered_split(
+                    splits.iter(),
+                    spacing + leeway,
+                    relative_cursor,
+                )?;
+
+                Some((axis, region + Vector::new(bounds.x, bounds.y), false))
+            }
+            None => None,
+        });
+
+    let pane_cursor_position = if picked_pane.is_some() {
+        // TODO: Remove once cursor availability is encoded in the type
+        // system
+        Point::new(-1.0, -1.0)
+    } else {
+        cursor_position
+    };
+
+    let mut render_picked_pane = None;
+
+    for ((id, pane), layout) in contents.zip(layout.children()) {
+        match picked_pane {
+            Some((dragging, origin)) if id == dragging => {
+                render_picked_pane = Some((pane, origin, layout));
+            }
+            _ => {
+                draw_pane(
+                    pane,
+                    renderer,
+                    default_style,
+                    layout,
+                    pane_cursor_position,
+                    viewport,
+                );
+            }
+        }
+    }
+
+    // Render picked pane last
+    if let Some((pane, origin, layout)) = render_picked_pane {
+        let bounds = layout.bounds();
+
+        renderer.with_translation(
+            cursor_position
+                - Point::new(bounds.x + origin.x, bounds.y + origin.y),
+            |renderer| {
+                renderer.with_layer(bounds, |renderer| {
+                    draw_pane(
+                        pane,
+                        renderer,
+                        default_style,
+                        layout,
+                        pane_cursor_position,
+                        viewport,
+                    );
+                });
+            },
+        );
+    };
+
+    if let Some((axis, split_region, is_picked)) = picked_split {
+        let highlight = if is_picked {
+            theme.picked_split(style)
+        } else {
+            theme.hovered_split(style)
+        };
+
+        if let Some(highlight) = highlight {
+            renderer.fill_quad(
+                renderer::Quad {
+                    bounds: match axis {
+                        Axis::Horizontal => Rectangle {
+                            x: split_region.x,
+                            y: (split_region.y
+                                + (split_region.height - highlight.width)
+                                    / 2.0)
+                                .round(),
+                            width: split_region.width,
+                            height: highlight.width,
+                        },
+                        Axis::Vertical => Rectangle {
+                            x: (split_region.x
+                                + (split_region.width - highlight.width) / 2.0)
+                                .round(),
+                            y: split_region.y,
+                            width: highlight.width,
+                            height: split_region.height,
+                        },
+                    },
+                    border_radius: 0.0.into(),
+                    border_width: 0.0,
+                    border_color: Color::TRANSPARENT,
+                },
+                highlight.color,
+            );
+        }
+    }
+}
+
+/// An event produced during a drag and drop interaction of a [`PaneGrid`].
+#[derive(Debug, Clone, Copy)]
+pub enum DragEvent {
+    /// A [`Pane`] was picked for dragging.
+    Picked {
+        /// The picked [`Pane`].
+        pane: Pane,
+    },
+
+    /// A [`Pane`] was dropped on top of another [`Pane`].
+    Dropped {
+        /// The picked [`Pane`].
+        pane: Pane,
+
+        /// The [`Pane`] where the picked one was dropped on.
+        target: Pane,
+    },
+
+    /// A [`Pane`] was picked and then dropped outside of other [`Pane`]
+    /// boundaries.
+    Canceled {
+        /// The picked [`Pane`].
+        pane: Pane,
+    },
+}
+
+/// An event produced during a resize interaction of a [`PaneGrid`].
+#[derive(Debug, Clone, Copy)]
+pub struct ResizeEvent {
+    /// The [`Split`] that is being dragged for resizing.
+    pub split: Split,
+
+    /// The new ratio of the [`Split`].
+    ///
+    /// The ratio is a value in [0, 1], representing the exact position of a
+    /// [`Split`] between two panes.
+    pub ratio: f32,
+}
+
+/*
+ * Helpers
+ */
+fn hovered_split<'a>(
+    splits: impl Iterator<Item = (&'a Split, &'a (Axis, Rectangle, f32))>,
+    spacing: f32,
+    cursor_position: Point,
+) -> Option<(Split, Axis, Rectangle)> {
+    splits
+        .filter_map(|(split, (axis, region, ratio))| {
+            let bounds = axis.split_line_bounds(*region, *ratio, spacing);
+
+            if bounds.contains(cursor_position) {
+                Some((*split, *axis, bounds))
+            } else {
+                None
+            }
+        })
+        .next()
+}
+
+/// The visible contents of the [`PaneGrid`]
+#[derive(Debug)]
+pub enum Contents<'a, T> {
+    /// All panes are visible
+    All(Vec<(Pane, T)>, &'a state::Internal),
+    /// A maximized pane is visible
+    Maximized(Pane, T, Node),
+}
+
+impl<'a, T> Contents<'a, T> {
+    /// Returns the layout [`Node`] of the [`Contents`]
+    pub fn layout(&self) -> &Node {
+        match self {
+            Contents::All(_, state) => state.layout(),
+            Contents::Maximized(_, _, layout) => layout,
+        }
+    }
+
+    /// Returns an iterator over the values of the [`Contents`]
+    pub fn iter(&self) -> Box<dyn Iterator<Item = (Pane, &T)> + '_> {
+        match self {
+            Contents::All(contents, _) => Box::new(
+                contents.iter().map(|(pane, content)| (*pane, content)),
+            ),
+            Contents::Maximized(pane, content, _) => {
+                Box::new(std::iter::once((*pane, content)))
+            }
+        }
+    }
+
+    fn iter_mut(&mut self) -> Box<dyn Iterator<Item = (Pane, &mut T)> + '_> {
+        match self {
+            Contents::All(contents, _) => Box::new(
+                contents.iter_mut().map(|(pane, content)| (*pane, content)),
+            ),
+            Contents::Maximized(pane, content, _) => {
+                Box::new(std::iter::once((*pane, content)))
+            }
+        }
+    }
+
+    fn is_maximized(&self) -> bool {
+        matches!(self, Self::Maximized(..))
+    }
+}