rlvgl_core/
widget.rs

1//! Basic widget traits and geometry types.
2
3use crate::event::Event;
4use crate::renderer::Renderer;
5
6/// Rectangle bounds of a widget.
7///
8/// Coordinates are relative to the parent widget. Width and height are signed
9/// integers to simplify layout calculations.
10///
11/// Used by [`Widget`] implementations to describe layout and passed to
12/// [`Renderer::fill_rect`] when drawing.
13#[derive(Debug, Clone, Copy, PartialEq, Eq)]
14pub struct Rect {
15    /// X coordinate relative to the parent widget.
16    pub x: i32,
17    /// Y coordinate relative to the parent widget.
18    pub y: i32,
19    /// Width in pixels.
20    pub width: i32,
21    /// Height in pixels.
22    pub height: i32,
23}
24
25/// RGBA color used by the renderer.
26#[derive(Debug, Clone, Copy, PartialEq, Eq)]
27pub struct Color(
28    /// Red component in the range `0..=255`.
29    pub u8,
30    /// Green component in the range `0..=255`.
31    pub u8,
32    /// Blue component in the range `0..=255`.
33    pub u8,
34    /// Alpha component in the range `0..=255`.
35    ///
36    /// A value of `255` is fully opaque and `0` is fully transparent.
37    pub u8,
38);
39
40impl Color {
41    /// Convert this color to a packed ARGB8888 integer.
42    ///
43    /// Used by display backends in the
44    /// [`rlvgl-platform`](https://docs.rs/rlvgl-platform) crate.
45    pub fn to_argb8888(self) -> u32 {
46        ((self.3 as u32) << 24) | ((self.0 as u32) << 16) | ((self.1 as u32) << 8) | (self.2 as u32)
47    }
48
49    /// Return a copy with the alpha channel multiplied by `opacity`.
50    ///
51    /// Both the existing alpha and `opacity` are in `0..=255`.
52    pub fn with_alpha(self, opacity: u8) -> Color {
53        Color(
54            self.0,
55            self.1,
56            self.2,
57            ((self.3 as u16 * opacity as u16) / 255) as u8,
58        )
59    }
60}
61
62/// Base trait implemented by all widgets.
63///
64/// A widget is expected to provide its bounds, draw itself using a
65/// [`Renderer`], and optionally handle input [`Event`]s.
66pub trait Widget {
67    /// Return the area this widget occupies relative to its parent.
68    fn bounds(&self) -> Rect;
69    /// Render the widget using the provided [`Renderer`].
70    fn draw(&self, renderer: &mut dyn Renderer);
71    /// Handle an event and return `true` if it was consumed.
72    ///
73    /// The default implementation for most widgets will simply ignore the
74    /// event and return `false`.
75    fn handle_event(&mut self, event: &Event) -> bool;
76
77    /// Return a region (in draw/landscape coordinates) that should be
78    /// restored from the pristine background copy, or `None`.
79    ///
80    /// Called once per frame before drawing. Overlay widgets should return
81    /// their bounds when they have just become hidden and need their
82    /// screen region cleared. The compositor handles the actual restoration.
83    fn clear_region(&mut self) -> Option<Rect> {
84        None
85    }
86}
rlvgl_core/widget.rs

rlvgl_core/
widget.rs
