mirror of
https://github.com/servo/servo.git
synced 2025-06-06 16:45:39 +00:00
250 lines
10 KiB
Rust
250 lines
10 KiB
Rust
/* 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/. */
|
||
|
||
use crate::replaced::IntrinsicSizes;
|
||
use euclid::{Size2D, Vector2D};
|
||
use style::computed_values::background_clip::single_value::T as Clip;
|
||
use style::computed_values::background_origin::single_value::T as Origin;
|
||
use style::values::computed::background::BackgroundSize as Size;
|
||
use style::values::computed::{Length, LengthPercentage};
|
||
use style::values::specified::background::BackgroundRepeat as RepeatXY;
|
||
use style::values::specified::background::BackgroundRepeatKeyword as Repeat;
|
||
use webrender_api::{self as wr, units};
|
||
|
||
pub(super) struct Layer {
|
||
pub common: wr::CommonItemProperties,
|
||
pub bounds: units::LayoutRect,
|
||
pub tile_size: units::LayoutSize,
|
||
pub tile_spacing: units::LayoutSize,
|
||
pub repeat: bool,
|
||
}
|
||
|
||
struct Layout1DResult {
|
||
repeat: bool,
|
||
bounds_origin: f32,
|
||
bounds_size: f32,
|
||
}
|
||
|
||
fn get_cyclic<T>(values: &[T], layer_index: usize) -> &T {
|
||
&values[layer_index % values.len()]
|
||
}
|
||
|
||
pub(super) fn painting_area<'a>(
|
||
fragment_builder: &'a super::BuilderForBoxFragment,
|
||
builder: &mut super::DisplayListBuilder,
|
||
layer_index: usize,
|
||
) -> (&'a units::LayoutRect, wr::CommonItemProperties) {
|
||
let fb = fragment_builder;
|
||
let b = fb.fragment.style.get_background();
|
||
let (painting_area, clip) = match get_cyclic(&b.background_clip.0, layer_index) {
|
||
Clip::ContentBox => (fb.content_rect(), fb.content_edge_clip(builder)),
|
||
Clip::PaddingBox => (fb.padding_rect(), fb.padding_edge_clip(builder)),
|
||
Clip::BorderBox => (&fb.border_rect, fb.border_edge_clip(builder)),
|
||
};
|
||
// The 'backgound-clip' property maps directly to `clip_rect` in `CommonItemProperties`:
|
||
let mut common = builder.common_properties(*painting_area);
|
||
if let Some(clip_id) = clip {
|
||
common.clip_id = clip_id
|
||
}
|
||
(painting_area, common)
|
||
}
|
||
|
||
pub(super) fn layout_layer(
|
||
fragment_builder: &mut super::BuilderForBoxFragment,
|
||
builder: &mut super::DisplayListBuilder,
|
||
layer_index: usize,
|
||
intrinsic: IntrinsicSizes,
|
||
) -> Option<Layer> {
|
||
let b = fragment_builder.fragment.style.get_background();
|
||
let (painting_area, common) = painting_area(fragment_builder, builder, layer_index);
|
||
|
||
let positioning_area = match get_cyclic(&b.background_origin.0, layer_index) {
|
||
Origin::ContentBox => fragment_builder.content_rect(),
|
||
Origin::PaddingBox => fragment_builder.padding_rect(),
|
||
Origin::BorderBox => &fragment_builder.border_rect,
|
||
};
|
||
|
||
// https://drafts.csswg.org/css-backgrounds/#background-size
|
||
enum ContainOrCover {
|
||
Contain,
|
||
Cover,
|
||
}
|
||
let size_contain_or_cover = |background_size| {
|
||
let mut tile_size = positioning_area.size;
|
||
if let Some(intrinsic_ratio) = intrinsic.ratio {
|
||
let positioning_ratio = positioning_area.size.width / positioning_area.size.height;
|
||
// Whether the tile width (as opposed to height)
|
||
// is scaled to that of the positioning area
|
||
let fit_width = match background_size {
|
||
ContainOrCover::Contain => positioning_ratio <= intrinsic_ratio,
|
||
ContainOrCover::Cover => positioning_ratio > intrinsic_ratio,
|
||
};
|
||
// The other dimension needs to be adjusted
|
||
if fit_width {
|
||
tile_size.height = tile_size.width / intrinsic_ratio
|
||
} else {
|
||
tile_size.width = tile_size.height * intrinsic_ratio
|
||
}
|
||
}
|
||
tile_size
|
||
};
|
||
let mut tile_size = match get_cyclic(&b.background_size.0, layer_index) {
|
||
Size::Contain => size_contain_or_cover(ContainOrCover::Contain),
|
||
Size::Cover => size_contain_or_cover(ContainOrCover::Cover),
|
||
Size::ExplicitSize { width, height } => {
|
||
let mut width = width.non_auto().map(|lp| {
|
||
lp.0.percentage_relative_to(Length::new(positioning_area.size.width))
|
||
});
|
||
let mut height = height.non_auto().map(|lp| {
|
||
lp.0.percentage_relative_to(Length::new(positioning_area.size.height))
|
||
});
|
||
|
||
if width.is_none() && height.is_none() {
|
||
// Both computed values are 'auto':
|
||
// use intrinsic sizes, treating missing width or height as 'auto'
|
||
width = intrinsic.width;
|
||
height = intrinsic.height;
|
||
}
|
||
|
||
match (width, height) {
|
||
(Some(w), Some(h)) => units::LayoutSize::new(w.px(), h.px()),
|
||
(Some(w), None) => {
|
||
let h = if let Some(intrinsic_ratio) = intrinsic.ratio {
|
||
w / intrinsic_ratio
|
||
} else if let Some(intrinsic_height) = intrinsic.height {
|
||
intrinsic_height
|
||
} else {
|
||
// Treated as 100%
|
||
Length::new(positioning_area.size.height)
|
||
};
|
||
units::LayoutSize::new(w.px(), h.px())
|
||
},
|
||
(None, Some(h)) => {
|
||
let w = if let Some(intrinsic_ratio) = intrinsic.ratio {
|
||
h * intrinsic_ratio
|
||
} else if let Some(intrinsic_width) = intrinsic.width {
|
||
intrinsic_width
|
||
} else {
|
||
// Treated as 100%
|
||
Length::new(positioning_area.size.width)
|
||
};
|
||
units::LayoutSize::new(w.px(), h.px())
|
||
},
|
||
// Both comptued values were 'auto', and neither intrinsic size is present
|
||
(None, None) => size_contain_or_cover(ContainOrCover::Contain),
|
||
}
|
||
},
|
||
};
|
||
|
||
if tile_size.width == 0.0 || tile_size.height == 0.0 {
|
||
return None;
|
||
}
|
||
|
||
let mut tile_spacing = units::LayoutSize::zero();
|
||
let RepeatXY(repeat_x, repeat_y) = *get_cyclic(&b.background_repeat.0, layer_index);
|
||
let result_x = layout_1d(
|
||
&mut tile_size.width,
|
||
&mut tile_spacing.width,
|
||
repeat_x,
|
||
get_cyclic(&b.background_position_x.0, layer_index),
|
||
painting_area.origin.x - positioning_area.origin.x,
|
||
painting_area.size.width,
|
||
positioning_area.size.width,
|
||
);
|
||
let result_y = layout_1d(
|
||
&mut tile_size.height,
|
||
&mut tile_spacing.height,
|
||
repeat_y,
|
||
get_cyclic(&b.background_position_y.0, layer_index),
|
||
painting_area.origin.y - positioning_area.origin.y,
|
||
painting_area.size.height,
|
||
positioning_area.size.height,
|
||
);
|
||
let bounds = units::LayoutRect::new(
|
||
positioning_area.origin + Vector2D::new(result_x.bounds_origin, result_y.bounds_origin),
|
||
Size2D::new(result_x.bounds_size, result_y.bounds_size),
|
||
);
|
||
|
||
Some(Layer {
|
||
common,
|
||
bounds,
|
||
tile_size,
|
||
tile_spacing,
|
||
repeat: result_x.repeat || result_y.repeat,
|
||
})
|
||
}
|
||
|
||
/// Abstract over the horizontal or vertical dimension
|
||
/// Coordinates (0, 0) for the purpose of this function are the positioning area’s origin.
|
||
fn layout_1d(
|
||
tile_size: &mut f32,
|
||
tile_spacing: &mut f32,
|
||
mut repeat: Repeat,
|
||
position: &LengthPercentage,
|
||
painting_area_origin: f32,
|
||
painting_area_size: f32,
|
||
positioning_area_size: f32,
|
||
) -> Layout1DResult {
|
||
// https://drafts.csswg.org/css-backgrounds/#background-repeat
|
||
if let Repeat::Round = repeat {
|
||
*tile_size = positioning_area_size / (positioning_area_size / *tile_size).round();
|
||
}
|
||
// https://drafts.csswg.org/css-backgrounds/#background-position
|
||
let mut position = position
|
||
.percentage_relative_to(Length::new(positioning_area_size - *tile_size))
|
||
.px();
|
||
// https://drafts.csswg.org/css-backgrounds/#background-repeat
|
||
if let Repeat::Space = repeat {
|
||
// The most entire tiles we can fit
|
||
let tile_count = (positioning_area_size / *tile_size).floor();
|
||
if tile_count >= 2.0 {
|
||
position = 0.0;
|
||
// Make the outsides of the first and last of that many tiles
|
||
// touch the edges of the positioning area:
|
||
let total_space = positioning_area_size - *tile_size * tile_count;
|
||
let spaces_count = tile_count - 1.0;
|
||
*tile_spacing = total_space / spaces_count;
|
||
} else {
|
||
repeat = Repeat::NoRepeat
|
||
}
|
||
}
|
||
match repeat {
|
||
Repeat::Repeat | Repeat::Round | Repeat::Space => {
|
||
// WebRender’s `RepeatingImageDisplayItem` contains a `bounds` rectangle and:
|
||
//
|
||
// * The tiling is clipped to the intersection of `clip_rect` and `bounds`
|
||
// * The origin (top-left corner) of `bounds` is the position
|
||
// of the “first” (top-left-most) tile.
|
||
//
|
||
// In the general case that first tile is not the one that is positioned by
|
||
// `background-position`.
|
||
// We want it to be the top-left-most tile that intersects with `clip_rect`.
|
||
// We find it by offsetting by a whole number of strides,
|
||
// then compute `bounds` such that:
|
||
//
|
||
// * Its bottom-right is the bottom-right of `clip_rect`
|
||
// * Its top-left is the top-left of first tile.
|
||
let tile_stride = *tile_size + *tile_spacing;
|
||
let offset = position - painting_area_origin;
|
||
let bounds_origin = position - tile_stride * (offset / tile_stride).ceil();
|
||
let bounds_size = painting_area_size - bounds_origin - painting_area_origin;
|
||
Layout1DResult {
|
||
repeat: true,
|
||
bounds_origin,
|
||
bounds_size,
|
||
}
|
||
},
|
||
Repeat::NoRepeat => {
|
||
// `RepeatingImageDisplayItem` always repeats in both dimension.
|
||
// When we want only one of the dimensions to repeat,
|
||
// we use the `bounds` rectangle to clip the tiling to one tile
|
||
// in that dimension.
|
||
Layout1DResult {
|
||
repeat: false,
|
||
bounds_origin: position,
|
||
bounds_size: *tile_size,
|
||
}
|
||
},
|
||
}
|
||
}
|