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use crate::core::{Size, Transformation};

/// A viewing region for displaying computer graphics.
#[derive(Debug, Clone)]
pub struct Viewport {
    physical_size: Size<u32>,
    logical_size: Size<f32>,
    scale_factor: f64,
    projection: Transformation,
}

impl Viewport {
    /// Creates a new [`Viewport`] with the given logical dimensions and scale factor
    pub fn with_logical_size(size: Size<f32>, scale_factor: f64) -> Viewport {
        let physical_size = Size::new(
            (size.width as f64 * scale_factor).ceil() as u32,
            (size.height as f64 * scale_factor).ceil() as u32,
        );
        Viewport {
            physical_size,
            logical_size: size,
            scale_factor,
            projection: Transformation::orthographic(
                physical_size.width,
                physical_size.height,
            ),
        }
    }

    /// Creates a new [`Viewport`] with the given physical dimensions and scale
    /// factor.
    pub fn with_physical_size(size: Size<u32>, scale_factor: f64) -> Viewport {
        Viewport {
            physical_size: size,
            logical_size: Size::new(
                (size.width as f64 / scale_factor) as f32,
                (size.height as f64 / scale_factor) as f32,
            ),
            scale_factor,
            projection: Transformation::orthographic(size.width, size.height),
        }
    }

    /// Returns the physical size of the [`Viewport`].
    pub fn physical_size(&self) -> Size<u32> {
        self.physical_size
    }

    /// Returns the physical width of the [`Viewport`].
    pub fn physical_width(&self) -> u32 {
        self.physical_size.width
    }

    /// Returns the physical height of the [`Viewport`].
    pub fn physical_height(&self) -> u32 {
        self.physical_size.height
    }

    /// Returns the logical size of the [`Viewport`].
    pub fn logical_size(&self) -> Size<f32> {
        self.logical_size
    }

    /// Returns the scale factor of the [`Viewport`].
    pub fn scale_factor(&self) -> f64 {
        self.scale_factor
    }

    /// Returns the projection transformation of the [`Viewport`].
    pub fn projection(&self) -> Transformation {
        self.projection
    }
}