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

3 files changed, 194 insertions, 0 deletions

diff --git a/widget/src/canvas/cursor.rs b/widget/src/canvas/cursor.rs
new file mode 100644
index 00000000..5a65e9a7
--- /dev/null
+++ b/widget/src/canvas/cursor.rs
@@ -0,0 +1,64 @@
+use crate::core::{Point, Rectangle};
+
+/// The mouse cursor state.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum Cursor {
+    /// The cursor has a defined position.
+    Available(Point),
+
+    /// The cursor is currently unavailable (i.e. out of bounds or busy).
+    Unavailable,
+}
+
+impl Cursor {
+    // TODO: Remove this once this type is used in `iced_native` to encode
+    // proper cursor availability
+    pub(crate) fn from_window_position(position: Point) -> Self {
+        if position.x < 0.0 || position.y < 0.0 {
+            Cursor::Unavailable
+        } else {
+            Cursor::Available(position)
+        }
+    }
+
+    /// Returns the absolute position of the [`Cursor`], if available.
+    pub fn position(&self) -> Option<Point> {
+        match self {
+            Cursor::Available(position) => Some(*position),
+            Cursor::Unavailable => None,
+        }
+    }
+
+    /// Returns the relative position of the [`Cursor`] inside the given bounds,
+    /// if available.
+    ///
+    /// If the [`Cursor`] is not over the provided bounds, this method will
+    /// return `None`.
+    pub fn position_in(&self, bounds: &Rectangle) -> Option<Point> {
+        if self.is_over(bounds) {
+            self.position_from(bounds.position())
+        } else {
+            None
+        }
+    }
+
+    /// Returns the relative position of the [`Cursor`] from the given origin,
+    /// if available.
+    pub fn position_from(&self, origin: Point) -> Option<Point> {
+        match self {
+            Cursor::Available(position) => {
+                Some(Point::new(position.x - origin.x, position.y - origin.y))
+            }
+            Cursor::Unavailable => None,
+        }
+    }
+
+    /// Returns whether the [`Cursor`] is currently over the provided bounds
+    /// or not.
+    pub fn is_over(&self, bounds: &Rectangle) -> bool {
+        match self {
+            Cursor::Available(position) => bounds.contains(*position),
+            Cursor::Unavailable => false,
+        }
+    }
+}
diff --git a/widget/src/canvas/event.rs b/widget/src/canvas/event.rs
new file mode 100644
index 00000000..4508c184
--- /dev/null
+++ b/widget/src/canvas/event.rs
@@ -0,0 +1,21 @@
+//! Handle events of a canvas.
+use crate::core::keyboard;
+use crate::core::mouse;
+use crate::core::touch;
+
+pub use crate::core::event::Status;
+
+/// A [`Canvas`] event.
+///
+/// [`Canvas`]: crate::widget::Canvas
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum Event {
+    /// A mouse event.
+    Mouse(mouse::Event),
+
+    /// A touch event.
+    Touch(touch::Event),
+
+    /// A keyboard event.
+    Keyboard(keyboard::Event),
+}
diff --git a/widget/src/canvas/program.rs b/widget/src/canvas/program.rs
new file mode 100644
index 00000000..efb33c56
--- /dev/null
+++ b/widget/src/canvas/program.rs
@@ -0,0 +1,109 @@
+use crate::canvas::event::{self, Event};
+use crate::canvas::mouse;
+use crate::canvas::Cursor;
+use crate::core::Rectangle;
+use crate::graphics::geometry;
+
+/// The state and logic of a [`Canvas`].
+///
+/// A [`Program`] can mutate internal state and produce messages for an
+/// application.
+///
+/// [`Canvas`]: crate::widget::Canvas
+pub trait Program<Message, Renderer = crate::Renderer>
+where
+    Renderer: geometry::Renderer,
+{
+    /// The internal state mutated by the [`Program`].
+    type State: Default + 'static;
+
+    /// Updates the [`State`](Self::State) of the [`Program`].
+    ///
+    /// When a [`Program`] is used in a [`Canvas`], the runtime will call this
+    /// method for each [`Event`].
+    ///
+    /// This method can optionally return a `Message` to notify an application
+    /// of any meaningful interactions.
+    ///
+    /// By default, this method does and returns nothing.
+    ///
+    /// [`Canvas`]: crate::widget::Canvas
+    fn update(
+        &self,
+        _state: &mut Self::State,
+        _event: Event,
+        _bounds: Rectangle,
+        _cursor: Cursor,
+    ) -> (event::Status, Option<Message>) {
+        (event::Status::Ignored, None)
+    }
+
+    /// Draws the state of the [`Program`], producing a bunch of [`Geometry`].
+    ///
+    /// [`Geometry`] can be easily generated with a [`Frame`] or stored in a
+    /// [`Cache`].
+    ///
+    /// [`Frame`]: crate::widget::canvas::Frame
+    /// [`Cache`]: crate::widget::canvas::Cache
+    fn draw(
+        &self,
+        state: &Self::State,
+        renderer: &Renderer,
+        theme: &Renderer::Theme,
+        bounds: Rectangle,
+        cursor: Cursor,
+    ) -> Vec<Renderer::Geometry>;
+
+    /// Returns the current mouse interaction of the [`Program`].
+    ///
+    /// The interaction returned will be in effect even if the cursor position
+    /// is out of bounds of the program's [`Canvas`].
+    ///
+    /// [`Canvas`]: crate::widget::Canvas
+    fn mouse_interaction(
+        &self,
+        _state: &Self::State,
+        _bounds: Rectangle,
+        _cursor: Cursor,
+    ) -> mouse::Interaction {
+        mouse::Interaction::default()
+    }
+}
+
+impl<Message, Renderer, T> Program<Message, Renderer> for &T
+where
+    Renderer: geometry::Renderer,
+    T: Program<Message, Renderer>,
+{
+    type State = T::State;
+
+    fn update(
+        &self,
+        state: &mut Self::State,
+        event: Event,
+        bounds: Rectangle,
+        cursor: Cursor,
+    ) -> (event::Status, Option<Message>) {
+        T::update(self, state, event, bounds, cursor)
+    }
+
+    fn draw(
+        &self,
+        state: &Self::State,
+        renderer: &Renderer,
+        theme: &Renderer::Theme,
+        bounds: Rectangle,
+        cursor: Cursor,
+    ) -> Vec<Renderer::Geometry> {
+        T::draw(self, state, renderer, theme, bounds, cursor)
+    }
+
+    fn mouse_interaction(
+        &self,
+        state: &Self::State,
+        bounds: Rectangle,
+        cursor: Cursor,
+    ) -> mouse::Interaction {
+        T::mouse_interaction(self, state, bounds, cursor)
+    }
+}