devotee_backend/
lib.rs

1#![deny(missing_docs)]
2
3//! Backend stuff for the `devotee` engine.
4
5use std::num::NonZeroU32;
6
7use winit::dpi::PhysicalPosition;
8use winit::window::Window;
9
10pub use winit;
11
12/// Backend trait.
13/// It provides functions to:
14///
15/// - create new instance;
16/// - handle resize events;
17/// - to draw output;
18/// - recalculate pointer position to canvas space.
19pub trait Backend: Sized {
20    /// Create new backend instance.
21    fn new(window: &Window, resolution: (u32, u32), scale: u32) -> Option<Self>;
22
23    /// Handle resize event.
24    fn resize(&mut self, width: NonZeroU32, height: NonZeroU32) -> Option<()>;
25
26    /// Draw image on the backend.
27    fn draw_image<'a, P: 'a, I>(
28        &mut self,
29        image: &'a dyn BackendImage<'a, P, Iterator = I>,
30        converter: &dyn Converter<Palette = P>,
31        window: &Window,
32        background: u32,
33    ) -> Option<()>
34    where
35        I: Iterator<Item = &'a P>;
36
37    /// Recalculate pointer position to canvas space.
38    fn window_pos_to_inner(
39        &self,
40        position: PhysicalPosition<f64>,
41        window: &Window,
42        resolution: (u32, u32),
43    ) -> Result<(i32, i32), (i32, i32)>;
44}
45
46/// Converter from pallette value to `u32` value.
47pub trait Converter {
48    /// Palette to convert from.
49    type Palette;
50    /// Perform conversion.
51    /// The output is considered to be `0x00rrggbb`.
52    fn convert(&self, color: &Self::Palette) -> u32;
53}
54
55/// Trait to generalize images to be displayed on the backend.
56///
57/// Currently implemented for `Canvas` and `Sprite`.
58pub trait BackendImage<'a, P: 'a> {
59    /// Iterator to produce pixel values of the image, row-by-row.
60    type Iterator: Iterator<Item = &'a P>;
61
62    /// Get reference to specific pixel.
63    ///
64    /// # Safety
65    /// - `x` must be in bounds `[0; width)`;
66    /// - `y` must be in bounds `[0; height)`.
67    unsafe fn pixel_unsafe(&self, x: u32, y: u32) -> &P;
68
69    /// Get image width in pixels.
70    fn width(&self) -> u32;
71
72    /// Get image height in pixels.
73    fn height(&self) -> u32;
74
75    /// Get iterator over pixels.
76    ///
77    /// The iterator is considered to provide pixels row-by-row.
78    fn pixels(&'a self) -> Self::Iterator;
79}
devotee_backend/lib.rs

devotee_backend/
lib.rs
