//! CSS length values.

//!

//! [`CssLength`] is the struct librsvg uses to represent CSS lengths.

//! See its documentation for examples of how to construct it.

//!

//! `CssLength` values need to know whether they will be normalized with respect to the width,

//! height, or both dimensions of the current viewport.  `CssLength` values can be signed or

//! unsigned.  So, a `CssLength` has two type parameters, [`Normalize`] and [`Validate`];

//! the full type is `CssLength<N: Normalize, V: Validate>`.  We provide [`Horizontal`],

//! [`Vertical`], and [`Both`] implementations of [`Normalize`]; these let length values know

//! how to normalize themselves with respect to the current viewport.  We also provide

//! [`Signed`] and [`Unsigned`] implementations of [`Validate`].

//!

//! For ease of use, we define two type aliases [`Length`] and [`ULength`] corresponding to

//! signed and unsigned.

//!

//! For example, the implementation of [`Circle`][crate::shapes::Circle] defines this

//! structure with fields for the `(center_x, center_y, radius)`:

//!

//! ```

//! # use rsvg::doctest_only::{Length,ULength,Horizontal,Vertical,Both};

//! pub struct Circle {

//!     cx: Length<Horizontal>,

//!     cy: Length<Vertical>,

//!     r: ULength<Both>,

//! }

//! ```

//!

//! This means that:

//!

//! * `cx` and `cy` define the center of the circle, they can be positive or negative, and

//! they will be normalized with respect to the current viewport's width and height,

//! respectively.  If the SVG document specified `<circle cx="50%" cy="30%">`, the values

//! would be normalized to be at 50% of the the viewport's width, and 30% of the viewport's

//! height.

//!

//! * `r` is non-negative and needs to be resolved against the [normalized diagonal][diag]

//! of the current viewport.

//!

//! The `N` type parameter of `CssLength<N, I>` is enough to know how to normalize a length

//! value; the [`CssLength::to_user`] method will handle it automatically.

//!

//! [diag]: https://www.w3.org/TR/SVG/coords.html#Units

use cssparser::{match_ignore_ascii_case, Parser, Token};

use std::f64::consts::*;

use std::fmt;

use std::marker::PhantomData;

use crate::dpi::Dpi;

use crate::drawing_ctx::Viewport;

use crate::error::*;

use crate::parsers::{finite_f32, Parse};

use crate::properties::{ComputedValues, FontSize, TextOrientation, WritingMode};

use crate::rect::Rect;

use crate::viewbox::ViewBox;

/// Units for length values.

// This needs to be kept in sync with `rsvg.h:RsvgUnit`.

#[non_exhaustive]

#[repr(C)]

pub enum LengthUnit {

    /// `1.0` means 100%

    Percent,

    /// Pixels, or the CSS default unit

    Px,

    /// Size of the current font

    Em,

    /// x-height of the current font

    Ex,

    /// Inches (25.4 mm)

    In,

    /// Centimeters

    Cm,

    /// Millimeters

    Mm,

    /// Points (1/72 inch)

    Pt,

    /// Picas (12 points)

    Pc,

    /// Advance measure of a '0' character (depends on the text orientation)

    Ch,

}

/// A CSS length value.

///

/// This is equivalent to [CSS lengths].

///

/// [CSS lengths]: https://www.w3.org/TR/CSS22/syndata.html#length-units

///

/// It is up to the calling application to convert lengths in non-pixel units (i.e. those

/// where the [`unit`][RsvgLength::unit] field is not [`LengthUnit::Px`]) into something

/// meaningful to the application.  For example, if your application knows the

/// dots-per-inch (DPI) it is using, it can convert lengths with [`unit`] in

/// [`LengthUnit::In`] or other physical units.

// Keep this in sync with rsvg.h:RsvgLength

#[repr(C)]

pub struct RsvgLength {

    /// Numeric part of the length

    /// Unit part of the length

}

impl RsvgLength {

    /// Constructs a CSS length value.

}

/// Used for the `N` type parameter of `CssLength<N: Normalize, V: Validate>`.

pub trait Normalize {

    /// Computes an orientation-based scaling factor.

    ///

    /// This is used in the [`CssLength::to_user`] method to resolve lengths with percentage

    /// units; they need to be resolved with respect to the width, height, or [normalized

    /// diagonal][diag] of the current viewport.

    ///

    /// [diag]: https://www.w3.org/TR/SVG/coords.html#Units

    fn normalize(x: f64, y: f64) -> f64;

}

/// Allows declaring `CssLength<Horizontal>`.

pub struct Horizontal;

/// Allows declaring `CssLength<Vertical>`.

pub struct Vertical;

/// Allows declaring `CssLength<Both>`.

pub struct Both;

impl Normalize for Horizontal {

    #[inline]

        x

}

impl Normalize for Vertical {

    #[inline]

        y

}

impl Normalize for Both {

    #[inline]

}

/// Used for the `V` type parameter of `CssLength<N: Normalize, V: Validate>`.

pub trait Validate {

    /// Checks if the specified value is acceptable

    ///

    /// This is used when parsing a length value

}

pub struct Signed;

impl Validate for Signed {}

pub struct Unsigned;

impl Validate for Unsigned {

        } else {

            ))

        }

}

/// A CSS length value.

///

/// This is equivalent to [CSS lengths].

///

/// [CSS lengths]: https://www.w3.org/TR/CSS22/syndata.html#length-units

///

/// `CssLength` implements the [`Parse`] trait, so it can be parsed out of a

/// [`cssparser::Parser`].

///

/// This type will be normally used through the type aliases [`Length`] and [`ULength`]

///

/// Examples of construction:

///

/// ```

/// # use rsvg::doctest_only::{Length,ULength,LengthUnit,Horizontal,Vertical,Both};

/// # use rsvg::doctest_only::Parse;

/// // Explicit type

/// let width: Length<Horizontal> = Length::new(42.0, LengthUnit::Cm);

///

/// // Inferred type

/// let height = Length::<Vertical>::new(42.0, LengthUnit::Cm);

///

/// // Parsed

/// let radius = ULength::<Both>::parse_str("5px").unwrap();

/// ```

///

/// During the rendering phase, a `CssLength` needs to be converted to user-space

/// coordinates with the [`CssLength::to_user`] method.

pub struct CssLength<N: Normalize, V: Validate> {

    /// Numeric part of the length

    /// Unit part of the length

    /// Dummy; used internally for the type parameter `N`

    /// Dummy; used internally for the type parameter `V`

}

impl<N: Normalize, V: Validate> From<CssLength<N, V>> for RsvgLength {

            length: l.length,

            unit: l.unit,

        }

}

impl<N: Normalize, V: Validate> Default for CssLength<N, V> {

}

pub const POINTS_PER_INCH: f64 = 72.0;

const CM_PER_INCH: f64 = 2.54;

const MM_PER_INCH: f64 = 25.4;

const PICA_PER_INCH: f64 = 6.0;

impl<N: Normalize, V: Validate> Parse for CssLength<N, V> {

        let l_unit;

            Token::Dimension {

            } => {

                    "px" => LengthUnit::Px,

                    "em" => LengthUnit::Em,

                    "ex" => LengthUnit::Ex,

                    "in" => LengthUnit::In,

                    "cm" => LengthUnit::Cm,

                    "mm" => LengthUnit::Mm,

                    "pt" => LengthUnit::Pt,

                    "pc" => LengthUnit::Pc,

                    "ch" => LengthUnit::Ch,

                    _ => return Err(parser.new_unexpected_token_error(token)),

                };

        }

}

/// Parameters for length normalization extracted from [`ComputedValues`].

///

/// This is a precursor to [`NormalizeParams::from_values`], for cases where it is inconvenient

/// to keep a [`ComputedValues`] around.

pub struct NormalizeValues {

    font_size: FontSize,

    is_vertical_text: bool,

}

impl NormalizeValues {

            (WritingMode::VerticalLr, TextOrientation::Upright)

                | (WritingMode::VerticalRl, TextOrientation::Upright)

        );

        }

}

/// Parameters to normalize [`Length`] values to user-space distances.

pub struct NormalizeParams {

    vbox: ViewBox,

    font_size: f64,

    dpi: Dpi,

    is_vertical_text: bool,

}

impl NormalizeParams {

    /// Extracts the information needed to normalize [`Length`] values from a set of

    /// [`ComputedValues`] and the viewport size in [`Viewport`].

        }

    /// Just used by rsvg-convert, where there is no font size nor viewport.

            font_size: 1.0,

            dpi,

            is_vertical_text: false,

        }

}

impl<N: Normalize, V: Validate> CssLength<N, V> {

    /// Creates a CssLength.

    ///

    /// The compiler needs to know the type parameters `N` and `V` which represents the

    /// length's orientation and validation.

    /// You can specify them explicitly, or call the parametrized method:

    ///

    /// ```

    /// # use rsvg::doctest_only::{Length,LengthUnit,Horizontal,Vertical};

    /// // Explicit type

    /// let width: Length<Horizontal> = Length::new(42.0, LengthUnit::Cm);

    ///

    /// // Inferred type

    /// let height = Length::<Vertical>::new(42.0, LengthUnit::Cm);

    /// ```

            length: l,

            unit,

            orientation: PhantomData,

            validation: PhantomData,

        }

    /// Convert a Length with units into user-space coordinates.

    ///

    /// Lengths may come with non-pixel units, and when rendering, they need to be normalized

    /// to pixels based on the current viewport (e.g. for lengths with percent units), and

    /// based on the current element's set of [`ComputedValues`] (e.g. for lengths with `Em`

    /// units that need to be resolved against the current font size).

    ///

    /// Those parameters can be obtained with [`NormalizeParams::new()`].

            LengthUnit::Percent => {

            // how far "0" advances the text, so it varies depending on orientation

            // we're using the 0.5em or 1.0em (based on orientation) fallback from the spec

            LengthUnit::Ch => {

                } else {

                }

            }

            LengthUnit::Cm => {

            }

            LengthUnit::Mm => {

            }

            LengthUnit::Pt => {

            }

            LengthUnit::Pc => {

            }

        }

    /// Converts a Length to points.  Pixels are taken to be respect with the DPI.

    ///

    /// # Panics

    ///

    /// Will panic if the length is in Percent, Em, or Ex units.

            LengthUnit::Px => {

            }

            LengthUnit::Percent => {

            }

            LengthUnit::Em => {

            }

            LengthUnit::Ex => {

            }

            LengthUnit::Ch => {

            }

        }

}

        LengthUnit::Percent => unreachable!("ComputedValues can't have a relative font size"),

        // The following implies that our default font size is 12, which

        // matches the default from the FontSize property.

        // FontSize always is a Both, per properties.rs

    }

    // https://www.w3.org/TR/SVG/coords.html#Units

    // "For any other length value expressed as a percentage of the viewport, the

    // percentage is calculated as the specified percentage of

    // sqrt((actual-width)**2 + (actual-height)**2))/sqrt(2)."

/// Alias for `CssLength` types that can have negative values

pub type Length<N> = CssLength<N, Signed>;

/// Alias for `CssLength` types that are non negative

pub type ULength<N> = CssLength<N, Unsigned>;

pub enum LengthOrAuto<N: Normalize> {

    #[default]

    Auto,

}

impl<N: Normalize> Parse for LengthOrAuto<N> {

        {

        } else {

        }

}

impl fmt::Display for LengthUnit {

        };

}

#[cfg(test)]

mod tests {

    use super::*;

    use crate::properties::{ParsedProperty, SpecifiedValue, SpecifiedValues};

    use crate::{assert_approx_eq_cairo, float_eq_cairo::ApproxEqCairo};

    #[test]

        );

        );

    #[test]

        );

    #[test]

        );

    #[test]

        );

    #[test]

        );

    #[test]

        );

        );

        );

        );

        );

    #[test]

        );

        );

    #[test]

    #[test]

    #[test]

            10.0

        );

    #[test]

            400.0

        );

            500.0

        );

            400.0 / CM_PER_INCH

        );

            400.0 / MM_PER_INCH

        );

            400.0 / POINTS_PER_INCH

        );

            400.0 / PICA_PER_INCH

        );

    #[test]

            5.0

        );

            10.0

        );

    #[test]

        // These correspond to the default size for the font-size

        // property and the way we compute Em/Ex from that.

            12.0

        );

            6.0

        );

            6.0

        );

        // check for vertical upright text

            TextOrientation::Upright,

        )));

            WritingMode::VerticalLr,

        )));

            12.0

        );

    #[test]

            2.0 * 72.0

        );

            2.0 * 72.0

        );

}