servo/components/style/gecko/values.rs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

#![allow(unsafe_code)]

//! Different kind of helpers to interact with Gecko values.

use crate::counter_style::{Symbol, Symbols};
use crate::gecko_bindings::structs::StyleGridTrackBreadth;
use crate::gecko_bindings::structs::{nsStyleCoord, CounterStylePtr};
use crate::gecko_bindings::sugar::ns_style_coord::{CoordData, CoordDataMut, CoordDataValue};
use crate::values::computed::{Angle, Length, LengthPercentage};
use crate::values::computed::{Number, NumberOrPercentage, Percentage};
use crate::values::generics::grid::{TrackBreadth, TrackKeyword};
use crate::values::generics::length::LengthPercentageOrAuto;
use crate::values::generics::{CounterStyleOrNone, NonNegative};
use crate::values::Either;
use crate::{Atom, Zero};
use app_units::Au;
use cssparser::RGBA;
use nsstring::{nsACString, nsCStr};
use std::cmp::max;

/// A trait that defines an interface to convert from and to `nsStyleCoord`s.
///
/// TODO(emilio): Almost everything that is in this file should be somehow
/// switched to cbindgen.
pub trait GeckoStyleCoordConvertible: Sized {
    /// Convert this to a `nsStyleCoord`.
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T);
    /// Given a `nsStyleCoord`, try to get a value of this type..
    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self>;
}

impl nsStyleCoord {
    #[inline]
    /// Set this `nsStyleCoord` value to `val`.
    pub fn set<T: GeckoStyleCoordConvertible>(&mut self, val: T) {
        val.to_gecko_style_coord(self);
    }
}

impl<Inner> GeckoStyleCoordConvertible for NonNegative<Inner>
where
    Inner: GeckoStyleCoordConvertible,
{
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        self.0.to_gecko_style_coord(coord)
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        Some(NonNegative(Inner::from_gecko_style_coord(coord)?))
    }
}

impl GeckoStyleCoordConvertible for Number {
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        coord.set_value(CoordDataValue::Factor(*self));
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        match coord.as_value() {
            CoordDataValue::Factor(f) => Some(f),
            _ => None,
        }
    }
}

impl GeckoStyleCoordConvertible for Percentage {
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        coord.set_value(CoordDataValue::Percent(self.0));
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        match coord.as_value() {
            CoordDataValue::Percent(p) => Some(Percentage(p)),
            _ => None,
        }
    }
}

impl GeckoStyleCoordConvertible for NumberOrPercentage {
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        match *self {
            NumberOrPercentage::Number(ref n) => n.to_gecko_style_coord(coord),
            NumberOrPercentage::Percentage(ref p) => p.to_gecko_style_coord(coord),
        }
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        match coord.as_value() {
            CoordDataValue::Factor(f) => Some(NumberOrPercentage::Number(f)),
            CoordDataValue::Percent(p) => Some(NumberOrPercentage::Percentage(Percentage(p))),
            _ => None,
        }
    }
}

impl GeckoStyleCoordConvertible for LengthPercentage {
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        if self.was_calc {
            return coord.set_value(CoordDataValue::Calc((*self).into()));
        }
        debug_assert!(!self.has_percentage || self.unclamped_length() == Length::zero());
        if self.has_percentage {
            return coord.set_value(CoordDataValue::Percent(self.percentage()));
        }
        coord.set_value(CoordDataValue::Coord(self.unclamped_length().to_i32_au()))
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        match coord.as_value() {
            CoordDataValue::Coord(coord) => Some(LengthPercentage::new(Au(coord).into(), None)),
            CoordDataValue::Percent(p) => {
                Some(LengthPercentage::new(Au(0).into(), Some(Percentage(p))))
            },
            CoordDataValue::Calc(calc) => Some(calc.into()),
            _ => None,
        }
    }
}

impl GeckoStyleCoordConvertible for Length {
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        coord.set_value(CoordDataValue::Coord(self.to_i32_au()));
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        match coord.as_value() {
            CoordDataValue::Coord(coord) => Some(Au(coord).into()),
            _ => None,
        }
    }
}

impl<LengthPercentage> GeckoStyleCoordConvertible for LengthPercentageOrAuto<LengthPercentage>
where
    LengthPercentage: GeckoStyleCoordConvertible,
{
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        match *self {
            LengthPercentageOrAuto::Auto => coord.set_value(CoordDataValue::Auto),
            LengthPercentageOrAuto::LengthPercentage(ref lp) => lp.to_gecko_style_coord(coord),
        }
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        match coord.as_value() {
            CoordDataValue::Auto => Some(LengthPercentageOrAuto::Auto),
            _ => LengthPercentage::from_gecko_style_coord(coord)
                .map(LengthPercentageOrAuto::LengthPercentage),
        }
    }
}

impl<L: GeckoStyleCoordConvertible> GeckoStyleCoordConvertible for TrackBreadth<L> {
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        match *self {
            TrackBreadth::Breadth(ref lp) => lp.to_gecko_style_coord(coord),
            TrackBreadth::Fr(fr) => coord.set_value(CoordDataValue::FlexFraction(fr)),
            TrackBreadth::Keyword(TrackKeyword::Auto) => coord.set_value(CoordDataValue::Auto),
            TrackBreadth::Keyword(TrackKeyword::MinContent) => coord.set_value(
                CoordDataValue::Enumerated(StyleGridTrackBreadth::MinContent as u32),
            ),
            TrackBreadth::Keyword(TrackKeyword::MaxContent) => coord.set_value(
                CoordDataValue::Enumerated(StyleGridTrackBreadth::MaxContent as u32),
            ),
        }
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        L::from_gecko_style_coord(coord)
            .map(TrackBreadth::Breadth)
            .or_else(|| match coord.as_value() {
                CoordDataValue::Enumerated(v) => {
                    if v == StyleGridTrackBreadth::MinContent as u32 {
                        Some(TrackBreadth::Keyword(TrackKeyword::MinContent))
                    } else if v == StyleGridTrackBreadth::MaxContent as u32 {
                        Some(TrackBreadth::Keyword(TrackKeyword::MaxContent))
                    } else {
                        None
                    }
                },
                CoordDataValue::FlexFraction(fr) => Some(TrackBreadth::Fr(fr)),
                CoordDataValue::Auto => Some(TrackBreadth::Keyword(TrackKeyword::Auto)),
                _ => L::from_gecko_style_coord(coord).map(TrackBreadth::Breadth),
            })
    }
}

impl<T: GeckoStyleCoordConvertible> GeckoStyleCoordConvertible for Option<T> {
    fn to_gecko_style_coord<U: CoordDataMut>(&self, coord: &mut U) {
        if let Some(ref me) = *self {
            me.to_gecko_style_coord(coord);
        } else {
            coord.set_value(CoordDataValue::None);
        }
    }

    fn from_gecko_style_coord<U: CoordData>(coord: &U) -> Option<Self> {
        Some(T::from_gecko_style_coord(coord))
    }
}

impl GeckoStyleCoordConvertible for Angle {
    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
        coord.set_value(CoordDataValue::from(*self));
    }

    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
        match coord.as_value() {
            CoordDataValue::Degree(val) => Some(Angle::from_degrees(val)),
            _ => None,
        }
    }
}

/// Convert a given RGBA value to `nscolor`.
pub fn convert_rgba_to_nscolor(rgba: &RGBA) -> u32 {
    ((rgba.alpha as u32) << 24) |
        ((rgba.blue as u32) << 16) |
        ((rgba.green as u32) << 8) |
        (rgba.red as u32)
}

/// Convert a given `nscolor` to a Servo RGBA value.
pub fn convert_nscolor_to_rgba(color: u32) -> RGBA {
    RGBA::new(
        (color & 0xff) as u8,
        (color >> 8 & 0xff) as u8,
        (color >> 16 & 0xff) as u8,
        (color >> 24 & 0xff) as u8,
    )
}

/// Round `width` down to the nearest device pixel, but any non-zero value that
/// would round down to zero is clamped to 1 device pixel.  Used for storing
/// computed values of border-*-width and outline-width.
#[inline]
pub fn round_border_to_device_pixels(width: Au, au_per_device_px: Au) -> Au {
    if width == Au(0) {
        Au(0)
    } else {
        max(
            au_per_device_px,
            Au(width.0 / au_per_device_px.0 * au_per_device_px.0),
        )
    }
}

impl CounterStyleOrNone {
    /// Convert this counter style to a Gecko CounterStylePtr.
    pub fn to_gecko_value(self, gecko_value: &mut CounterStylePtr) {
        use crate::gecko_bindings::bindings::Gecko_SetCounterStyleToName as set_name;
        use crate::gecko_bindings::bindings::Gecko_SetCounterStyleToSymbols as set_symbols;
        match self {
            CounterStyleOrNone::None => unsafe {
                set_name(gecko_value, atom!("none").into_addrefed());
            },
            CounterStyleOrNone::Name(name) => unsafe {
                set_name(gecko_value, name.0.into_addrefed());
            },
            CounterStyleOrNone::Symbols(symbols_type, symbols) => {
                let symbols: Vec<_> = symbols
                    .0
                    .iter()
                    .map(|symbol| match *symbol {
                        Symbol::String(ref s) => nsCStr::from(&**s),
                        Symbol::Ident(_) => unreachable!("Should not have identifier in symbols()"),
                    })
                    .collect();
                let symbols: Vec<_> = symbols
                    .iter()
                    .map(|symbol| symbol as &nsACString as *const _)
                    .collect();
                unsafe {
                    set_symbols(
                        gecko_value,
                        symbols_type.to_gecko_keyword(),
                        symbols.as_ptr(),
                        symbols.len() as u32,
                    )
                };
            },
        }
    }

    /// Convert Gecko CounterStylePtr to CounterStyleOrNone or String.
    pub fn from_gecko_value(gecko_value: &CounterStylePtr) -> Either<Self, String> {
        use crate::gecko_bindings::bindings;
        use crate::values::generics::SymbolsType;
        use crate::values::CustomIdent;

        let name = unsafe { bindings::Gecko_CounterStyle_GetName(gecko_value) };
        if !name.is_null() {
            let name = unsafe { Atom::from_raw(name) };
            if name == atom!("none") {
                Either::First(CounterStyleOrNone::None)
            } else {
                Either::First(CounterStyleOrNone::Name(CustomIdent(name)))
            }
        } else {
            let anonymous =
                unsafe { bindings::Gecko_CounterStyle_GetAnonymous(gecko_value).as_ref() }.unwrap();
            let symbols = &anonymous.mSymbols;
            if anonymous.mSingleString {
                debug_assert_eq!(symbols.len(), 1);
                Either::Second(symbols[0].to_string())
            } else {
                let symbol_type = SymbolsType::from_gecko_keyword(anonymous.mSystem as u32);
                let symbols = symbols
                    .iter()
                    .map(|gecko_symbol| Symbol::String(gecko_symbol.to_string().into()))
                    .collect();
                Either::First(CounterStyleOrNone::Symbols(symbol_type, Symbols(symbols)))
            }
        }
    }
}