/* 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/. */
//! Gecko's restyle damage computation (aka change hints, aka `nsChangeHint`).
use crate::gecko_bindings::bindings;
use crate::gecko_bindings::structs;
use crate::gecko_bindings::structs::nsChangeHint;
use crate::matching::{StyleChange, StyleDifference};
use crate::properties::ComputedValues;
use std::ops::{BitAnd, BitOr, BitOrAssign, Not};
/// The representation of Gecko's restyle damage is just a wrapper over
/// `nsChangeHint`.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct GeckoRestyleDamage(nsChangeHint);
impl GeckoRestyleDamage {
/// Trivially construct a new `GeckoRestyleDamage`.
#[inline]
pub fn new(raw: nsChangeHint) -> Self {
GeckoRestyleDamage(raw)
}
/// Get the inner change hint for this damage.
#[inline]
pub fn as_change_hint(&self) -> nsChangeHint {
self.0
}
/// Get an empty change hint, that is (`nsChangeHint(0)`).
#[inline]
pub fn empty() -> Self {
GeckoRestyleDamage(nsChangeHint(0))
}
/// Returns whether this restyle damage represents the empty damage.
#[inline]
pub fn is_empty(&self) -> bool {
self.0 == nsChangeHint(0)
}
/// Computes the `StyleDifference` (including the appropriate change hint)
/// given an old and a new style.
pub fn compute_style_difference(
old_style: &ComputedValues,
new_style: &ComputedValues,
) -> StyleDifference {
let mut any_style_changed = false;
let mut reset_only = false;
let hint = unsafe {
bindings::Gecko_CalcStyleDifference(
old_style.as_gecko_computed_style(),
new_style.as_gecko_computed_style(),
&mut any_style_changed,
&mut reset_only,
)
};
if reset_only && !old_style.custom_properties_equal(new_style) {
// The Gecko_CalcStyleDifference call only checks the non-custom
// property structs, so we check the custom properties here. Since
// they generate no damage themselves, we can skip this check if we
// already know we had some inherited (regular) property
// differences.
any_style_changed = true;
reset_only = false;
}
let change = if any_style_changed {
StyleChange::Changed { reset_only }
} else {
StyleChange::Unchanged
};
let damage = GeckoRestyleDamage(nsChangeHint(hint));
StyleDifference { damage, change }
}
/// Returns true if this restyle damage contains all the damage of |other|.
pub fn contains(self, other: Self) -> bool {
self & other == other
}
/// Gets restyle damage to reconstruct the entire frame, subsuming all
/// other damage.
pub fn reconstruct() -> Self {
GeckoRestyleDamage(structs::nsChangeHint::nsChangeHint_ReconstructFrame)
}
}
impl Default for GeckoRestyleDamage {
fn default() -> Self {
Self::empty()
}
}
impl BitOr for GeckoRestyleDamage {
type Output = Self;
fn bitor(self, other: Self) -> Self {
GeckoRestyleDamage(self.0 | other.0)
}
}
impl BitOrAssign for GeckoRestyleDamage {
fn bitor_assign(&mut self, other: Self) {
*self = *self | other;
}
}
impl BitAnd for GeckoRestyleDamage {
type Output = Self;
fn bitand(self, other: Self) -> Self {
GeckoRestyleDamage(nsChangeHint((self.0).0 & (other.0).0))
}
}
impl Not for GeckoRestyleDamage {
type Output = Self;
fn not(self) -> Self {
GeckoRestyleDamage(nsChangeHint(!(self.0).0))
}
}
