euv_chart/backend/common/
trait.rs

1use super::*;
2
3/// A rendering backend for the chart.
4///
5/// The three backends — WebGPU, WebGL2, and Canvas2D — all replay the
6/// same display list, so the chart model never has to know which one is
7/// in use. That is what keeps the public API identical across backends.
8pub trait ChartBackend {
9    /// Returns the kind of the backend.
10    ///
11    /// # Returns
12    ///
13    /// - `BackendKind` - A `BackendKind` value.
14    fn kind(&self) -> BackendKind;
15
16    /// Prepares the backend for a canvas of the given CSS size, at the
17    /// given device pixel ratio.
18    ///
19    /// The backends size their drawing buffer to `width * dpr` by
20    /// `height * dpr` physical pixels and scale their coordinate system
21    /// accordingly, so the model always works in CSS pixels.
22    ///
23    /// # Arguments
24    ///
25    /// - `f64` - A 64-bit float (`f64`).
26    fn resize(&mut self, width: f64, height: f64, dpr: f64);
27
28    /// Replays the display list onto the canvas.
29    ///
30    /// The backend is free to cache whatever it can: the display list is
31    /// retained between frames, so a chart that has not changed should
32    /// cost close to nothing to draw.
33    ///
34    /// # Arguments
35    ///
36    /// - `&DisplayList` - Shared reference to a `DisplayList`.
37    /// - `&mut TextShaper` - Mutable reference to a `TextShaper` (mutated in place).
38    fn render(&mut self, list: &DisplayList, shaper: &mut TextShaper);
39
40    /// Releases the resources the backend holds.
41    ///
42    /// Called when the chart is disposed. The backend must stay usable
43    /// afterwards — it will simply re-acquire its resources on the next
44    /// render.
45    fn dispose(&mut self);
46}
euv_chart/backend/common/trait.rs

euv_chart/backend/common/
trait.rs
