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use crate::core::mouse;
use crate::core::Rectangle;
use crate::renderer::wgpu::Primitive;
use crate::shader::{self, Action};
/// The state and logic of a [`Shader`] widget.
///
/// A [`Program`] can mutate the internal state of a [`Shader`] widget
/// and produce messages for an application.
///
/// [`Shader`]: crate::Shader
pub trait Program<Message> {
/// The internal state of the [`Program`].
type State: Default + 'static;
/// The type of primitive this [`Program`] can draw.
type Primitive: Primitive + 'static;
/// Update the internal [`State`] of the [`Program`]. This can be used to reflect state changes
/// based on mouse & other events. You can return an [`Action`] to publish a message, request a
/// redraw, or capture the event.
///
/// By default, this method returns `None`.
///
/// [`State`]: Self::State
fn update(
&self,
_state: &mut Self::State,
_event: &shader::Event,
_bounds: Rectangle,
_cursor: mouse::Cursor,
) -> Option<Action<Message>> {
None
}
/// Draws the [`Primitive`].
///
/// [`Primitive`]: Self::Primitive
fn draw(
&self,
state: &Self::State,
cursor: mouse::Cursor,
bounds: Rectangle,
) -> Self::Primitive;
/// 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 [`Shader`]'s program.
///
/// [`Shader`]: crate::Shader
fn mouse_interaction(
&self,
_state: &Self::State,
_bounds: Rectangle,
_cursor: mouse::Cursor,
) -> mouse::Interaction {
mouse::Interaction::default()
}
}
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