slint/sixtyfps_runtime/corelib/layout.rs
2020-08-28 15:06:14 +02:00

387 lines
12 KiB
Rust

/* LICENSE BEGIN
This file is part of the SixtyFPS Project -- https://sixtyfps.io
Copyright (c) 2020 Olivier Goffart <olivier.goffart@sixtyfps.io>
Copyright (c) 2020 Simon Hausmann <simon.hausmann@sixtyfps.io>
SPDX-License-Identifier: GPL-3.0-only
This file is also available under commercial licensing terms.
Please contact info@sixtyfps.io for more information.
LICENSE END */
//! Runtime support for layouting.
//!
//! Currently this is a very basic implementation
use crate::{slice::Slice, Property};
type Coord = f32;
/// The constraint that applies to an item
#[repr(C)]
#[derive(Clone, Debug)]
pub struct LayoutInfo {
/// The minimum width for the item.
pub min_width: f32,
/// The maximum width for the item.
pub max_width: f32,
/// The minimum height for the item.
pub min_height: f32,
/// The maximum height for the item.
pub max_height: f32,
}
impl Default for LayoutInfo {
fn default() -> Self {
LayoutInfo { min_width: 0., max_width: f32::MAX, min_height: 0., max_height: f32::MAX }
}
}
impl LayoutInfo {
// Note: This "logic" is duplicated in the cpp generator's generated code for merging layout infos.
pub fn merge(&self, other: &LayoutInfo) -> Self {
Self {
min_width: self.min_width.max(other.min_width),
max_width: self.max_width.min(other.max_width),
min_height: self.min_height.max(other.min_height),
max_height: self.max_height.min(other.max_height),
}
}
}
mod internal {
use super::*;
#[derive(Debug, Clone)]
pub struct LayoutData {
// inputs
pub min: Coord,
pub max: Coord,
pub pref: Coord,
pub stretch: f32,
// outputs
pub pos: Coord,
pub size: Coord,
}
impl Default for LayoutData {
fn default() -> Self {
LayoutData { min: 0., max: Coord::MAX, pref: 0., stretch: 1., pos: 0., size: 0. }
}
}
/// Layout the items within a specified size
///
/// This is quite a simple implementation for now
pub fn layout_items(data: &mut [LayoutData], start_pos: Coord, size: Coord, spacing: Coord) {
let (min, _max, perf, mut s) =
data.iter().fold((0., 0., 0., 0.), |(min, max, pref, s), it| {
(min + it.min, max + it.max, pref + it.pref, s + it.stretch)
});
//let total_spacing = spacing * (data.len() - 1) as Coord;
let size_without_spacing = size - spacing * (data.len() - 1) as Coord;
if size_without_spacing >= perf {
// bigger than the prefered size
// distribute each item its prefered size
let mut pos = start_pos;
for it in data.iter_mut() {
it.size = it.pref;
it.pos = pos;
pos += it.size;
}
// Allocate the space according to the stretch. Until all space is distributed, or all item
// have reached their maximum size
let mut extra_space = size_without_spacing - perf;
while s > 0. && extra_space > 0. {
let extra_per_stretch = extra_space / s;
s = 0.;
let mut pos = start_pos;
for it in data.iter_mut() {
let give = (extra_per_stretch * it.stretch).min(it.max - it.size);
it.size += give;
extra_space -= give;
if give > 0. {
s += it.stretch;
}
it.pos = pos;
pos += it.size + spacing;
}
}
} else
/*if size < min*/
{
// We have less than the minimum size
// distribute the difference proportional to the size (TODO: and stretch)
let ratio = size_without_spacing / min;
let mut pos = start_pos;
for it in data {
it.size = it.min * ratio;
it.pos = pos;
pos += it.size + spacing;
}
}
}
#[test]
fn test_layout_items() {
let my_items = &mut [
LayoutData { min: 100., max: 200., pref: 100., stretch: 1., ..Default::default() },
LayoutData { min: 50., max: 300., pref: 100., stretch: 1., ..Default::default() },
LayoutData { min: 50., max: 150., pref: 100., stretch: 1., ..Default::default() },
];
layout_items(my_items, 100., 650., 0.);
assert_eq!(my_items[0].size, 200.);
assert_eq!(my_items[1].size, 300.);
assert_eq!(my_items[2].size, 150.);
layout_items(my_items, 100., 200., 0.);
assert_eq!(my_items[0].size, 100.);
assert_eq!(my_items[1].size, 50.);
assert_eq!(my_items[2].size, 50.);
layout_items(my_items, 100., 300., 0.);
assert_eq!(my_items[0].size, 100.);
assert_eq!(my_items[1].size, 100.);
assert_eq!(my_items[2].size, 100.);
}
}
#[repr(C)]
pub struct Constraint {
pub min: Coord,
pub max: Coord,
}
impl Default for Constraint {
fn default() -> Self {
Constraint { min: 0., max: Coord::MAX }
}
}
#[repr(C)]
#[derive(Debug, Default)]
pub struct Padding {
pub left: Coord,
pub right: Coord,
pub top: Coord,
pub bottom: Coord,
}
#[repr(C)]
#[derive(Debug)]
pub struct GridLayoutData<'a> {
pub width: Coord,
pub height: Coord,
pub x: Coord,
pub y: Coord,
pub spacing: Coord,
pub padding: &'a Padding,
pub cells: Slice<'a, GridLayoutCellData<'a>>,
}
#[repr(C)]
#[derive(Default, Debug)]
pub struct GridLayoutCellData<'a> {
pub col: u16,
pub row: u16,
pub colspan: u16,
pub rowspan: u16,
pub constraint: LayoutInfo,
pub x: Option<&'a Property<Coord>>,
pub y: Option<&'a Property<Coord>>,
pub width: Option<&'a Property<Coord>>,
pub height: Option<&'a Property<Coord>>,
}
/// FIXME: rename with sixstyfps prefix
#[no_mangle]
pub extern "C" fn solve_grid_layout(data: &GridLayoutData) {
let (mut num_col, mut num_row) = (0, 0);
for cell in data.cells.iter() {
num_row = num_row.max(cell.row + cell.rowspan);
num_col = num_col.max(cell.col + cell.colspan);
}
if num_col < 1 || num_row < 1 {
return;
}
let mut row_layout_data = vec![internal::LayoutData::default(); num_row as usize];
let mut col_layout_data = vec![internal::LayoutData::default(); num_col as usize];
for cell in data.cells.iter() {
let rdata = &mut row_layout_data[cell.row as usize];
let cdata = &mut col_layout_data[cell.col as usize];
rdata.max = rdata.max.min(cell.constraint.max_height);
cdata.max = cdata.max.min(cell.constraint.max_width);
rdata.min = rdata.min.max(cell.constraint.min_height);
cdata.min = cdata.min.max(cell.constraint.min_width);
rdata.pref = rdata.pref.max(cell.constraint.min_height);
cdata.pref = cdata.pref.max(cell.constraint.min_width);
}
internal::layout_items(
&mut row_layout_data,
data.y + data.padding.top,
data.height - (data.padding.top + data.padding.bottom),
data.spacing,
);
internal::layout_items(
&mut col_layout_data,
data.x + data.padding.left,
data.width - (data.padding.left + data.padding.right),
data.spacing,
);
for cell in data.cells.iter() {
let rdata = &row_layout_data[cell.row as usize];
let cdata = &col_layout_data[cell.col as usize];
cell.x.map(|p| p.set(cdata.pos));
cell.width.map(|p| p.set(cdata.size));
cell.y.map(|p| p.set(rdata.pos));
cell.height.map(|p| p.set(rdata.size));
}
}
#[no_mangle]
pub extern "C" fn grid_layout_info<'a>(
cells: &Slice<'a, GridLayoutCellData<'a>>,
spacing: Coord,
padding: &Padding,
) -> LayoutInfo {
let (mut num_col, mut num_row) = (0, 0);
for cell in cells.iter() {
num_row = num_row.max(cell.row + cell.rowspan);
num_col = num_col.max(cell.col + cell.colspan);
}
if num_col < 1 || num_row < 1 {
return LayoutInfo { min_width: 0., max_width: 0., min_height: 0., max_height: 0. };
};
let mut row_layout_data = vec![internal::LayoutData::default(); num_row as usize];
let mut col_layout_data = vec![internal::LayoutData::default(); num_col as usize];
for cell in cells.iter() {
let rdata = &mut row_layout_data[cell.row as usize];
let cdata = &mut col_layout_data[cell.col as usize];
rdata.max = rdata.max.min(cell.constraint.max_height);
cdata.max = cdata.max.min(cell.constraint.max_width);
rdata.min = rdata.min.max(cell.constraint.min_height);
cdata.min = cdata.min.max(cell.constraint.min_width);
rdata.pref = rdata.pref.max(cell.constraint.min_height);
cdata.pref = cdata.pref.max(cell.constraint.min_width);
}
let spacing_h = spacing * (num_row - 1) as Coord;
let spacing_w = spacing * (num_col - 1) as Coord;
let min_height = row_layout_data.iter().map(|data| data.min).sum::<Coord>()
+ spacing_h
+ padding.left
+ padding.right;
let max_height = row_layout_data.iter().map(|data| data.max).sum::<Coord>()
+ spacing_h
+ padding.top
+ padding.bottom;
let min_width = col_layout_data.iter().map(|data| data.min).sum::<Coord>()
+ spacing_w
+ padding.left
+ padding.right;
let max_width = col_layout_data.iter().map(|data| data.max).sum::<Coord>()
+ spacing_w
+ padding.top
+ padding.bottom;
LayoutInfo { min_width, max_width, min_height, max_height }
}
#[repr(C)]
pub struct PathLayoutData<'a> {
pub elements: &'a crate::graphics::PathData,
pub items: Slice<'a, PathLayoutItemData<'a>>,
pub x: Coord,
pub y: Coord,
pub width: Coord,
pub height: Coord,
pub offset: f32,
}
#[repr(C)]
#[derive(Default)]
pub struct PathLayoutItemData<'a> {
pub x: Option<&'a Property<Coord>>,
pub y: Option<&'a Property<Coord>>,
pub width: Coord,
pub height: Coord,
}
/// FIXME: rename with sixstyfps prefix
#[no_mangle]
pub extern "C" fn solve_path_layout(data: &PathLayoutData) {
use lyon::geom::*;
use lyon::path::iterator::PathIterator;
if data.items.is_empty() {
return;
}
let path_iter = data.elements.iter_fitted(data.width, data.height);
let tolerance = lyon::tessellation::StrokeOptions::DEFAULT_TOLERANCE;
let segment_lengths: Vec<Coord> = path_iter
.iter()
.bezier_segments()
.map(|segment| match segment {
BezierSegment::Linear(line_segment) => line_segment.length(),
BezierSegment::Quadratic(quadratic_segment) => {
quadratic_segment.approximate_length(tolerance)
}
BezierSegment::Cubic(cubic_segment) => cubic_segment.approximate_length(tolerance),
})
.collect();
let path_length: Coord = segment_lengths.iter().sum();
// the max(2) is there to put the item in the middle when there is a single item
let item_distance = 1. / ((data.items.len() - 1) as f32).max(2.);
let mut i = 0;
let mut next_t: f32 = data.offset;
if data.items.len() == 1 {
next_t += item_distance;
}
'main_loop: while i < data.items.len() {
let mut current_length: f32 = 0.;
next_t %= 1.;
for (seg_idx, segment) in path_iter.iter().bezier_segments().enumerate() {
let seg_len = segment_lengths[seg_idx];
let seg_start = current_length;
current_length += seg_len;
let seg_end_t = (seg_start + seg_len) / path_length;
while next_t <= seg_end_t {
let local_t = ((next_t * path_length) - seg_start) / seg_len;
let item_pos = segment.sample(local_t);
let center_x_offset = data.items[i].width / 2.;
let center_y_offset = data.items[i].height / 2.;
data.items[i].x.map(|prop| prop.set(item_pos.x - center_x_offset + data.x));
data.items[i].y.map(|prop| prop.set(item_pos.y - center_y_offset + data.y));
i += 1;
next_t += item_distance;
if i >= data.items.len() {
break 'main_loop;
}
}
if next_t > 1. {
break;
}
}
}
}