Trait BackendTextStyle

pub trait BackendTextStyle {
    type FontError: Error + Sync + Send + 'static;

    // Required methods
    fn family(&self) -> FontFamily<'_>;
    fn layout_box(
        &self,
        text: &str,
    ) -> Result<((i32, i32), (i32, i32)), Self::FontError>;
    fn draw<E, DrawFunc: FnMut(i32, i32, BackendColor) -> Result<(), E>>(
        &self,
        text: &str,
        pos: BackendCoord,
        draw: DrawFunc,
    ) -> Result<Result<(), E>, Self::FontError>;

    // Provided methods
    fn color(&self) -> BackendColor { ... }
    fn size(&self) -> f64 { ... }
    fn transform(&self) -> FontTransform { ... }
    fn style(&self) -> FontStyle { ... }
    fn anchor(&self) -> Pos { ... }
}

The trait that abstracts a style of a text.

This is used because the the backend crate have no knowledge about how the text handling is implemented in plotters.

But the backend still wants to know some information about the font, for the backend doesn’t handles text drawing, may want to call the draw method which is implemented by the plotters main crate. While for the backend that handles the text drawing, those font information provides instructions about how the text should be rendered: color, size, slant, anchor, font, etc.

This trait decouples the detailed implementation about the font and the backend code which wants to perform some operation on the font.

Required Associated Types

type FontError: Error + Sync + Send + 'static

The error type of this text style implementation

Required Methods

fn family(&self) -> FontFamily<'_>

fn layout_box( &self, text: &str, ) -> Result<((i32, i32), (i32, i32)), Self::FontError>

fn draw<E, DrawFunc: FnMut(i32, i32, BackendColor) -> Result<(), E>>( &self, text: &str, pos: BackendCoord, draw: DrawFunc, ) -> Result<Result<(), E>, Self::FontError>

Provided Methods

fn color(&self) -> BackendColor

fn size(&self) -> f64

fn transform(&self) -> FontTransform

fn style(&self) -> FontStyle

fn anchor(&self) -> Pos

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors