hUI/hui/src/draw/corner_radius.rs

use std::num::NonZeroU16;
use crate::rect::Corners;

//TODO uneven corners (separate width/height for each corner)

/// Calculate the number of points based on the maximum corner radius
fn point_count(corners: Corners<f32>) -> NonZeroU16 {
  //Increase for higher quality
  const VTX_PER_CORER_RADIUS_PIXEL: f32 = 0.5;
  NonZeroU16::new(
    (corners.max_f32() * VTX_PER_CORER_RADIUS_PIXEL).round() as u16 + 2
  ).unwrap()
}

/// Low-level options for rendering rounded corners
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct RoundedCorners {
  /// Corner radius of each corner
  pub radius: Corners<f32>,

  /// Number of points to use for each corner
  ///
  /// This value affects all corners, regardless of their individual radius
  pub point_count: NonZeroU16,
}

impl From<Corners<f32>> for RoundedCorners {
  /// Create a new `RoundedCorners` from [`Corners<f32>`](crate::rect::Corners)
  ///
  /// Point count will be calculated automatically based on the maximum radius
  fn from(radius: Corners<f32>) -> Self {
    Self::from_radius(radius)
  }
}

impl RoundedCorners {
  /// Create a new `RoundedCorners` from [`Corners<f32>`](crate::rect::Corners)
  ///
  /// Point count will be calculated automatically based on the maximum radius
  pub fn from_radius(radius: Corners<f32>) -> Self {
    Self {
      radius,
      point_count: point_count(radius),
    }
  }
}

impl Default for RoundedCorners {
  fn default() -> Self {
    Self {
      radius: Corners::default(),
      point_count: NonZeroU16::new(8).unwrap(),
    }
  }
}