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Split layout/background.rs file
Have background, border and gradient modules for calculation functions. Use shorter names for functions that are qualified by the module name like `border::radii`. Use push_item and push_iter to add items to WebRender.
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Pyfisch
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2304f02123
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2ff330a5c9
7 changed files with 577 additions and 658 deletions
314
components/layout/display_list/gradient.rs
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314
components/layout/display_list/gradient.rs
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// FIXME(rust-lang/rust#26264): Remove GenericEndingShape and GenericGradientItem.
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use app_units::Au;
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use display_list::ToLayout;
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use euclid::{Point2D, Size2D, Vector2D};
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use style::properties::ComputedValues;
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use style::values::computed::{Angle, GradientItem, LengthOrPercentage, Percentage, Position};
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use style::values::computed::image::{EndingShape, LineDirection};
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use style::values::generics::image::{Circle, Ellipse, ShapeExtent};
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use style::values::generics::image::EndingShape as GenericEndingShape;
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use style::values::generics::image::GradientItem as GenericGradientItem;
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use style::values::specified::position::{X, Y};
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use webrender_api::{ExtendMode, Gradient, GradientBuilder, GradientStop, RadialGradient};
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/// A helper data structure for gradients.
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#[derive(Clone, Copy)]
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struct StopRun {
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start_offset: f32,
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end_offset: f32,
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start_index: usize,
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stop_count: usize,
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}
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/// Determines the radius of a circle if it was not explictly provided.
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/// <https://drafts.csswg.org/css-images-3/#typedef-size>
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fn circle_size_keyword(
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keyword: ShapeExtent,
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size: &Size2D<Au>,
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center: &Point2D<Au>,
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) -> Size2D<Au> {
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let radius = match keyword {
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ShapeExtent::ClosestSide | ShapeExtent::Contain => {
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let dist = distance_to_sides(size, center, ::std::cmp::min);
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::std::cmp::min(dist.width, dist.height)
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},
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ShapeExtent::FarthestSide => {
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let dist = distance_to_sides(size, center, ::std::cmp::max);
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::std::cmp::max(dist.width, dist.height)
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},
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ShapeExtent::ClosestCorner => distance_to_corner(size, center, ::std::cmp::min),
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ShapeExtent::FarthestCorner | ShapeExtent::Cover => {
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distance_to_corner(size, center, ::std::cmp::max)
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},
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};
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Size2D::new(radius, radius)
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}
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/// Returns the radius for an ellipse with the same ratio as if it was matched to the sides.
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fn ellipse_radius<F>(size: &Size2D<Au>, center: &Point2D<Au>, cmp: F) -> Size2D<Au>
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where
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F: Fn(Au, Au) -> Au,
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{
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let dist = distance_to_sides(size, center, cmp);
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Size2D::new(
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dist.width.scale_by(::std::f32::consts::FRAC_1_SQRT_2 * 2.0),
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dist.height
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.scale_by(::std::f32::consts::FRAC_1_SQRT_2 * 2.0),
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)
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}
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/// Determines the radius of an ellipse if it was not explictly provided.
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/// <https://drafts.csswg.org/css-images-3/#typedef-size>
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fn ellipse_size_keyword(
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keyword: ShapeExtent,
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size: &Size2D<Au>,
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center: &Point2D<Au>,
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) -> Size2D<Au> {
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match keyword {
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ShapeExtent::ClosestSide | ShapeExtent::Contain => {
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distance_to_sides(size, center, ::std::cmp::min)
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},
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ShapeExtent::FarthestSide => distance_to_sides(size, center, ::std::cmp::max),
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ShapeExtent::ClosestCorner => ellipse_radius(size, center, ::std::cmp::min),
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ShapeExtent::FarthestCorner | ShapeExtent::Cover => {
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ellipse_radius(size, center, ::std::cmp::max)
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},
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}
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}
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fn convert_gradient_stops(
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style: &ComputedValues,
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gradient_items: &[GradientItem],
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total_length: Au,
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) -> GradientBuilder {
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// Determine the position of each stop per CSS-IMAGES § 3.4.
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// Only keep the color stops, discard the color interpolation hints.
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let mut stop_items = gradient_items
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.iter()
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.filter_map(|item| match *item {
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GenericGradientItem::ColorStop(ref stop) => Some(*stop),
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_ => None,
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}).collect::<Vec<_>>();
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assert!(stop_items.len() >= 2);
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// Run the algorithm from
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// https://drafts.csswg.org/css-images-3/#color-stop-syntax
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// Step 1:
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// If the first color stop does not have a position, set its position to 0%.
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{
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let first = stop_items.first_mut().unwrap();
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if first.position.is_none() {
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first.position = Some(LengthOrPercentage::Percentage(Percentage(0.0)));
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}
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}
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// If the last color stop does not have a position, set its position to 100%.
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{
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let last = stop_items.last_mut().unwrap();
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if last.position.is_none() {
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last.position = Some(LengthOrPercentage::Percentage(Percentage(1.0)));
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}
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}
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// Step 2: Move any stops placed before earlier stops to the
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// same position as the preceding stop.
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let mut last_stop_position = stop_items.first().unwrap().position.unwrap();
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for stop in stop_items.iter_mut().skip(1) {
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if let Some(pos) = stop.position {
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if position_to_offset(last_stop_position, total_length) >
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position_to_offset(pos, total_length)
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{
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stop.position = Some(last_stop_position);
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}
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last_stop_position = stop.position.unwrap();
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}
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}
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// Step 3: Evenly space stops without position.
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let mut stops = GradientBuilder::new();
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let mut stop_run = None;
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for (i, stop) in stop_items.iter().enumerate() {
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let offset = match stop.position {
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None => {
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if stop_run.is_none() {
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// Initialize a new stop run.
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// `unwrap()` here should never fail because this is the beginning of
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// a stop run, which is always bounded by a length or percentage.
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let start_offset =
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position_to_offset(stop_items[i - 1].position.unwrap(), total_length);
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// `unwrap()` here should never fail because this is the end of
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// a stop run, which is always bounded by a length or percentage.
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let (end_index, end_stop) = stop_items[(i + 1)..]
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.iter()
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.enumerate()
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.find(|&(_, ref stop)| stop.position.is_some())
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.unwrap();
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let end_offset = position_to_offset(end_stop.position.unwrap(), total_length);
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stop_run = Some(StopRun {
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start_offset,
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end_offset,
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start_index: i - 1,
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stop_count: end_index,
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})
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}
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let stop_run = stop_run.unwrap();
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let stop_run_length = stop_run.end_offset - stop_run.start_offset;
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stop_run.start_offset +
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stop_run_length * (i - stop_run.start_index) as f32 /
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((2 + stop_run.stop_count) as f32)
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},
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Some(position) => {
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stop_run = None;
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position_to_offset(position, total_length)
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},
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};
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assert!(offset.is_finite());
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stops.push(GradientStop {
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offset: offset,
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color: style.resolve_color(stop.color).to_layout(),
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})
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}
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stops
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}
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fn extend_mode(repeating: bool) -> ExtendMode {
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if repeating {
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ExtendMode::Repeat
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} else {
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ExtendMode::Clamp
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}
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}
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/// Returns the the distance to the nearest or farthest corner depending on the comperator.
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fn distance_to_corner<F>(size: &Size2D<Au>, center: &Point2D<Au>, cmp: F) -> Au
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where
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F: Fn(Au, Au) -> Au,
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{
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let dist = distance_to_sides(size, center, cmp);
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Au::from_f32_px(dist.width.to_f32_px().hypot(dist.height.to_f32_px()))
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}
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/// Returns the distance to the nearest or farthest sides depending on the comparator.
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///
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/// The first return value is horizontal distance the second vertical distance.
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fn distance_to_sides<F>(size: &Size2D<Au>, center: &Point2D<Au>, cmp: F) -> Size2D<Au>
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where
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F: Fn(Au, Au) -> Au,
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{
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let top_side = center.y;
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let right_side = size.width - center.x;
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let bottom_side = size.height - center.y;
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let left_side = center.x;
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Size2D::new(cmp(left_side, right_side), cmp(top_side, bottom_side))
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}
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fn position_to_offset(position: LengthOrPercentage, total_length: Au) -> f32 {
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if total_length == Au(0) {
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return 0.0;
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}
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match position {
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LengthOrPercentage::Length(l) => l.to_i32_au() as f32 / total_length.0 as f32,
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LengthOrPercentage::Percentage(percentage) => percentage.0 as f32,
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LengthOrPercentage::Calc(calc) => {
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calc.to_used_value(Some(total_length)).unwrap().0 as f32 / total_length.0 as f32
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},
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}
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}
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pub fn linear(
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style: &ComputedValues,
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size: Size2D<Au>,
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stops: &[GradientItem],
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direction: LineDirection,
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repeating: bool,
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) -> (Gradient, Vec<GradientStop>) {
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let angle = match direction {
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LineDirection::Angle(angle) => angle.radians(),
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LineDirection::Horizontal(x) => match x {
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X::Left => Angle::from_degrees(270.).radians(),
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X::Right => Angle::from_degrees(90.).radians(),
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},
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LineDirection::Vertical(y) => match y {
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Y::Top => Angle::from_degrees(0.).radians(),
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Y::Bottom => Angle::from_degrees(180.).radians(),
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},
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LineDirection::Corner(horizontal, vertical) => {
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// This the angle for one of the diagonals of the box. Our angle
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// will either be this one, this one + PI, or one of the other
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// two perpendicular angles.
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let atan = (size.height.to_f32_px() / size.width.to_f32_px()).atan();
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match (horizontal, vertical) {
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(X::Right, Y::Bottom) => ::std::f32::consts::PI - atan,
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(X::Left, Y::Bottom) => ::std::f32::consts::PI + atan,
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(X::Right, Y::Top) => atan,
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(X::Left, Y::Top) => -atan,
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}
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},
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};
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// Get correct gradient line length, based on:
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// https://drafts.csswg.org/css-images-3/#linear-gradients
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let dir = Point2D::new(angle.sin(), -angle.cos());
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let line_length =
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(dir.x * size.width.to_f32_px()).abs() + (dir.y * size.height.to_f32_px()).abs();
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let inv_dir_length = 1.0 / (dir.x * dir.x + dir.y * dir.y).sqrt();
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// This is the vector between the center and the ending point; i.e. half
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// of the distance between the starting point and the ending point.
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let delta = Vector2D::new(
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Au::from_f32_px(dir.x * inv_dir_length * line_length / 2.0),
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Au::from_f32_px(dir.y * inv_dir_length * line_length / 2.0),
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);
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// This is the length of the gradient line.
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let length = Au::from_f32_px((delta.x.to_f32_px() * 2.0).hypot(delta.y.to_f32_px() * 2.0));
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let mut builder = convert_gradient_stops(style, stops, length);
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let center = Point2D::new(size.width / 2, size.height / 2);
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(
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builder.gradient((center - delta).to_layout(), (center + delta).to_layout(), extend_mode(repeating)),
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builder.stops().to_vec()
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)
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}
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pub fn radial(
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style: &ComputedValues,
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size: Size2D<Au>,
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stops: &[GradientItem],
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shape: EndingShape,
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center: Position,
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repeating: bool,
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) -> (RadialGradient, Vec<GradientStop>) {
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let center = Point2D::new(
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center.horizontal.to_used_value(size.width),
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center.vertical.to_used_value(size.height),
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);
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let radius = match shape {
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GenericEndingShape::Circle(Circle::Radius(length)) => {
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let length = Au::from(length);
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Size2D::new(length, length)
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},
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GenericEndingShape::Circle(Circle::Extent(extent)) => {
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circle_size_keyword(extent, &size, ¢er)
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},
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GenericEndingShape::Ellipse(Ellipse::Radii(x, y)) => {
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Size2D::new(x.to_used_value(size.width), y.to_used_value(size.height))
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},
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GenericEndingShape::Ellipse(Ellipse::Extent(extent)) => {
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ellipse_size_keyword(extent, &size, ¢er)
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},
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};
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let mut builder = convert_gradient_stops(style, stops, radius.width);
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(
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builder.radial_gradient(center.to_layout(), radius.to_layout(), extend_mode(repeating)),
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builder.stops().to_vec(),
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)
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}
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