embedded-graphics-core 0.1.0

Core traits and functionality for embedded-graphics
Documentation 
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//! `Drawable` trait and helpers
use crate::{draw_target::DrawTarget, geometry::Point, pixelcolor::PixelColor};

/// Marks an object as "drawable". Must be implemented for all graphics objects
///
/// The `Drawable` trait describes how a particular graphical object is drawn. A `Drawable` object
/// can define its `draw` method as a collection of graphical primitives or as an iterator
/// over pixels being rendered with [`DrawTarget`]'s [`draw_iter`] method.
///
/// ```rust
/// use embedded_graphics::{
///     fonts::{Font6x8, Text},
///     pixelcolor::{BinaryColor, PixelColor, Rgb888},
///     prelude::*,
///     primitives::Rectangle,
///     style::{MonoTextStyle, PrimitiveStyle},
/// };
///
/// struct Button<'a, C: PixelColor> {
///     top_left: Point,
///     size: Size,
///     bg_color: C,
///     fg_color: C,
///     text: &'a str,
/// }
///
/// impl<C> Drawable for Button<'_, C>
/// where
///     C: PixelColor + From<BinaryColor>,
/// {
///     type Color = C;
///
///     fn draw<D>(&self, display: &mut D) -> Result<(), D::Error>
///     where
///         D: DrawTarget<Color = C>,
///     {
///         Rectangle::new(self.top_left, self.size)
///             .into_styled(PrimitiveStyle::with_fill(self.bg_color))
///             .draw(display)?;
///
///         Text::new(self.text, Point::new(6, 6))
///             .into_styled(MonoTextStyle::new(Font6x8, self.fg_color))
///             .draw(display)
///     }
/// }
///
/// let mut button = Button {
///     top_left: Point::zero(),
///     size: Size::new(60, 20),
///     bg_color: Rgb888::RED,
///     fg_color: Rgb888::BLUE,
///     text: "Click me!",
/// };
///
/// # use embedded_graphics::mock_display::MockDisplay;
/// # let mut display = MockDisplay::default();
/// # display.set_allow_overdraw(true);
/// button.draw(&mut display)?;
/// # Ok::<(), core::convert::Infallible>(())
/// ```
///
/// [`DrawTarget`]: draw_target/trait.DrawTarget.html
/// [`draw_iter`]: draw_target/trait.DrawTarget.html#tymethod.draw_iter
pub trait Drawable {
    /// The pixel color type.
    type Color: PixelColor;

    /// Draw the graphics object using the supplied DrawTarget.
    fn draw<D>(&self, display: &mut D) -> Result<(), D::Error>
    where
        D: DrawTarget<Color = Self::Color>;
}

/// A single pixel.
///
/// `Pixel` objects are used to specify the position and color of drawn pixels.
///
/// # Examples
///
/// The [`Drawable`] trait is implemented for `Pixel` which allows single pixels
/// to be drawn to a [`DrawTarget`]:
/// ```
/// use embedded_graphics::{pixelcolor::BinaryColor, prelude::*};
/// # use embedded_graphics::mock_display::MockDisplay;
/// # let mut display = MockDisplay::new();
///
/// Pixel(Point::new(1, 2), BinaryColor::On).draw(&mut display)?;
/// # Ok::<(), core::convert::Infallible>(())
/// ```
///
/// Iterators with `Pixel` items can also be drawn:
///
/// ```
/// use embedded_graphics::{pixelcolor::BinaryColor, prelude::*};
/// # use embedded_graphics::mock_display::MockDisplay;
/// # let mut display = MockDisplay::new();
///
/// (0..32)
///     .map(|i| Pixel(Point::new(i, i * 2), BinaryColor::On))
///     .draw(&mut display)?;
/// # Ok::<(), core::convert::Infallible>(())
/// ```
///
/// [`Drawable`]: trait.Drawable.html
/// [`DrawTarget`]: draw_target/trait.DrawTarget.html
#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Default)]
pub struct Pixel<C>(pub Point, pub C)
where
    C: PixelColor;

impl<C> Drawable for Pixel<C>
where
    C: PixelColor,
{
    type Color = C;

    fn draw<D>(&self, display: &mut D) -> Result<(), D::Error>
    where
        D: DrawTarget<Color = C>,
    {
        display.draw_iter(core::iter::once(*self))
    }
}

#[cfg(test)]
mod tests {
    // NOTE: `crate` cannot be used here due to circular dependency resolution behaviour.
    use embedded_graphics::{
        geometry::Point, mock_display::MockDisplay, pixelcolor::BinaryColor, Drawable, Pixel,
    };

    #[test]
    fn draw_pixel() -> Result<(), core::convert::Infallible> {
        let mut display = MockDisplay::new();
        Pixel(Point::new(0, 0), BinaryColor::On).draw(&mut display)?;
        Pixel(Point::new(2, 1), BinaryColor::On).draw(&mut display)?;
        Pixel(Point::new(1, 2), BinaryColor::On).draw(&mut display)?;

        #[rustfmt::skip]
        assert_eq!(
            MockDisplay::from_pattern(&[
                "#  ",
                "  #",
                " # ",
            ]),
            display
        );

        Ok(())
    }
}