diff options
Diffstat (limited to 'core/src/layout')
| -rw-r--r-- | core/src/layout/DRUID_LICENSE | 202 | ||||
| -rw-r--r-- | core/src/layout/flex.rs | 232 | ||||
| -rw-r--r-- | core/src/layout/limits.rs | 163 | ||||
| -rw-r--r-- | core/src/layout/node.rs | 91 |
4 files changed, 688 insertions, 0 deletions
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Distribute elements using a flex-based layout. +// This code is heavily inspired by the [`druid`] codebase. +// +// [`druid`]: https://github.com/xi-editor/druid +// +// Copyright 2018 The xi-editor Authors, Héctor Ramón +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +use crate::Element; + +use crate::layout::{Limits, Node}; +use crate::{Alignment, Padding, Point, Size}; + +/// The main axis of a flex layout. +#[derive(Debug)] +pub enum Axis { + /// The horizontal axis + Horizontal, + + /// The vertical axis + Vertical, +} + +impl Axis { + fn main(&self, size: Size) -> f32 { + match self { + Axis::Horizontal => size.width, + Axis::Vertical => size.height, + } + } + + fn cross(&self, size: Size) -> f32 { + match self { + Axis::Horizontal => size.height, + Axis::Vertical => size.width, + } + } + + fn pack(&self, main: f32, cross: f32) -> (f32, f32) { + match self { + Axis::Horizontal => (main, cross), + Axis::Vertical => (cross, main), + } + } +} + +/// Computes the flex layout with the given axis and limits, applying spacing, +/// padding and alignment to the items as needed. +/// +/// It returns a new layout [`Node`]. +pub fn resolve<Message, Renderer>( + axis: Axis, + renderer: &Renderer, + limits: &Limits, + padding: Padding, + spacing: f32, + align_items: Alignment, + items: &[Element<'_, Message, Renderer>], +) -> Node +where + Renderer: crate::Renderer, +{ + let limits = limits.pad(padding); + let total_spacing = spacing * items.len().saturating_sub(1) as f32; + let max_cross = axis.cross(limits.max()); + + let mut fill_sum = 0; + let mut cross = axis.cross(limits.min()).max(axis.cross(limits.fill())); + let mut available = axis.main(limits.max()) - total_spacing; + + let mut nodes: Vec<Node> = Vec::with_capacity(items.len()); + nodes.resize(items.len(), Node::default()); + + if align_items == Alignment::Fill { + let mut fill_cross = axis.cross(limits.min()); + + items.iter().for_each(|child| { + let cross_fill_factor = match axis { + Axis::Horizontal => child.as_widget().height(), + Axis::Vertical => child.as_widget().width(), + } + .fill_factor(); + + if cross_fill_factor == 0 { + let (max_width, max_height) = axis.pack(available, max_cross); + + let child_limits = + Limits::new(Size::ZERO, Size::new(max_width, max_height)); + + let layout = child.as_widget().layout(renderer, &child_limits); + let size = layout.size(); + + fill_cross = fill_cross.max(axis.cross(size)); + } + }); + + cross = fill_cross; + } + + for (i, child) in items.iter().enumerate() { + let fill_factor = match axis { + Axis::Horizontal => child.as_widget().width(), + Axis::Vertical => child.as_widget().height(), + } + .fill_factor(); + + if fill_factor == 0 { + let (min_width, min_height) = if align_items == Alignment::Fill { + axis.pack(0.0, cross) + } else { + axis.pack(0.0, 0.0) + }; + + let (max_width, max_height) = if align_items == Alignment::Fill { + axis.pack(available, cross) + } else { + axis.pack(available, max_cross) + }; + + let child_limits = Limits::new( + Size::new(min_width, min_height), + Size::new(max_width, max_height), + ); + + let layout = child.as_widget().layout(renderer, &child_limits); + let size = layout.size(); + + available -= axis.main(size); + + if align_items != Alignment::Fill { + cross = cross.max(axis.cross(size)); + } + + nodes[i] = layout; + } else { + fill_sum += fill_factor; + } + } + + let remaining = available.max(0.0); + + for (i, child) in items.iter().enumerate() { + let fill_factor = match axis { + Axis::Horizontal => child.as_widget().width(), + Axis::Vertical => child.as_widget().height(), + } + .fill_factor(); + + if fill_factor != 0 { + let max_main = remaining * fill_factor as f32 / fill_sum as f32; + let min_main = if max_main.is_infinite() { + 0.0 + } else { + max_main + }; + + let (min_width, min_height) = if align_items == Alignment::Fill { + axis.pack(min_main, cross) + } else { + axis.pack(min_main, axis.cross(limits.min())) + }; + + let (max_width, max_height) = if align_items == Alignment::Fill { + axis.pack(max_main, cross) + } else { + axis.pack(max_main, max_cross) + }; + + let child_limits = Limits::new( + Size::new(min_width, min_height), + Size::new(max_width, max_height), + ); + + let layout = child.as_widget().layout(renderer, &child_limits); + + if align_items != Alignment::Fill { + cross = cross.max(axis.cross(layout.size())); + } + + nodes[i] = layout; + } + } + + let pad = axis.pack(padding.left, padding.top); + let mut main = pad.0; + + for (i, node) in nodes.iter_mut().enumerate() { + if i > 0 { + main += spacing; + } + + let (x, y) = axis.pack(main, pad.1); + + node.move_to(Point::new(x, y)); + + match axis { + Axis::Horizontal => { + node.align( + Alignment::Start, + align_items, + Size::new(0.0, cross), + ); + } + Axis::Vertical => { + node.align( + align_items, + Alignment::Start, + Size::new(cross, 0.0), + ); + } + } + + let size = node.size(); + + main += axis.main(size); + } + + let (width, height) = axis.pack(main - pad.0, cross); + let size = limits.resolve(Size::new(width, height)); + + Node::with_children(size.pad(padding), nodes) +} diff --git a/core/src/layout/limits.rs b/core/src/layout/limits.rs new file mode 100644 index 00000000..5d3c1556 --- /dev/null +++ b/core/src/layout/limits.rs @@ -0,0 +1,163 @@ +#![allow(clippy::manual_clamp)] +use crate::{Length, Padding, Size}; + +/// A set of size constraints for layouting. +#[derive(Debug, Clone, Copy)] +pub struct Limits { + min: Size, + max: Size, + fill: Size, +} + +impl Limits { + /// No limits + pub const NONE: Limits = Limits { + min: Size::ZERO, + max: Size::INFINITY, + fill: Size::INFINITY, + }; + + /// Creates new [`Limits`] with the given minimum and maximum [`Size`]. + pub const fn new(min: Size, max: Size) -> Limits { + Limits { + min, + max, + fill: Size::INFINITY, + } + } + + /// Returns the minimum [`Size`] of the [`Limits`]. + pub fn min(&self) -> Size { + self.min + } + + /// Returns the maximum [`Size`] of the [`Limits`]. + pub fn max(&self) -> Size { + self.max + } + + /// Returns the fill [`Size`] of the [`Limits`]. + pub fn fill(&self) -> Size { + self.fill + } + + /// Applies a width constraint to the current [`Limits`]. + pub fn width(mut self, width: impl Into<Length>) -> Limits { + match width.into() { + Length::Shrink => { + self.fill.width = self.min.width; + } + Length::Fill | Length::FillPortion(_) => { + self.fill.width = self.fill.width.min(self.max.width); + } + Length::Fixed(amount) => { + let new_width = amount.min(self.max.width).max(self.min.width); + + self.min.width = new_width; + self.max.width = new_width; + self.fill.width = new_width; + } + } + + self + } + + /// Applies a height constraint to the current [`Limits`]. + pub fn height(mut self, height: impl Into<Length>) -> Limits { + match height.into() { + Length::Shrink => { + self.fill.height = self.min.height; + } + Length::Fill | Length::FillPortion(_) => { + self.fill.height = self.fill.height.min(self.max.height); + } + Length::Fixed(amount) => { + let new_height = + amount.min(self.max.height).max(self.min.height); + + self.min.height = new_height; + self.max.height = new_height; + self.fill.height = new_height; + } + } + + self + } + + /// Applies a minimum width constraint to the current [`Limits`]. + pub fn min_width(mut self, min_width: f32) -> Limits { + self.min.width = self.min.width.max(min_width).min(self.max.width); + + self + } + + /// Applies a maximum width constraint to the current [`Limits`]. + pub fn max_width(mut self, max_width: f32) -> Limits { + self.max.width = self.max.width.min(max_width).max(self.min.width); + + self + } + + /// Applies a minimum height constraint to the current [`Limits`]. + pub fn min_height(mut self, min_height: f32) -> Limits { + self.min.height = self.min.height.max(min_height).min(self.max.height); + + self + } + + /// Applies a maximum height constraint to the current [`Limits`]. + pub fn max_height(mut self, max_height: f32) -> Limits { + self.max.height = self.max.height.min(max_height).max(self.min.height); + + self + } + + /// Shrinks the current [`Limits`] to account for the given padding. + pub fn pad(&self, padding: Padding) -> Limits { + self.shrink(Size::new(padding.horizontal(), padding.vertical())) + } + + /// Shrinks the current [`Limits`] by the given [`Size`]. + pub fn shrink(&self, size: Size) -> Limits { + let min = Size::new( + (self.min().width - size.width).max(0.0), + (self.min().height - size.height).max(0.0), + ); + + let max = Size::new( + (self.max().width - size.width).max(0.0), + (self.max().height - size.height).max(0.0), + ); + + let fill = Size::new( + (self.fill.width - size.width).max(0.0), + (self.fill.height - size.height).max(0.0), + ); + + Limits { min, max, fill } + } + + /// Removes the minimum width constraint for the current [`Limits`]. + pub fn loose(&self) -> Limits { + Limits { + min: Size::ZERO, + max: self.max, + fill: self.fill, + } + } + + /// Computes the resulting [`Size`] that fits the [`Limits`] given the + /// intrinsic size of some content. + pub fn resolve(&self, intrinsic_size: Size) -> Size { + Size::new( + intrinsic_size + .width + .min(self.max.width) + .max(self.fill.width), + intrinsic_size + .height + .min(self.max.height) + .max(self.fill.height), + ) + } +} diff --git a/core/src/layout/node.rs b/core/src/layout/node.rs new file mode 100644 index 00000000..e0c7dcb2 --- /dev/null +++ b/core/src/layout/node.rs @@ -0,0 +1,91 @@ +use crate::{Alignment, Point, Rectangle, Size, Vector}; + +/// The bounds of an element and its children. +#[derive(Debug, Clone, Default)] +pub struct Node { + bounds: Rectangle, + children: Vec<Node>, +} + +impl Node { + /// Creates a new [`Node`] with the given [`Size`]. + pub const fn new(size: Size) -> Self { + Self::with_children(size, Vec::new()) + } + + /// Creates a new [`Node`] with the given [`Size`] and children. + pub const fn with_children(size: Size, children: Vec<Node>) -> Self { + Node { + bounds: Rectangle { + x: 0.0, + y: 0.0, + width: size.width, + height: size.height, + }, + children, + } + } + + /// Returns the [`Size`] of the [`Node`]. + pub fn size(&self) -> Size { + Size::new(self.bounds.width, self.bounds.height) + } + + /// Returns the bounds of the [`Node`]. + pub fn bounds(&self) -> Rectangle { + self.bounds + } + + /// Returns the children of the [`Node`]. + pub fn children(&self) -> &[Node] { + &self.children + } + + /// Aligns the [`Node`] in the given space. + pub fn align( + &mut self, + horizontal_alignment: Alignment, + vertical_alignment: Alignment, + space: Size, + ) { + match horizontal_alignment { + Alignment::Start => {} + Alignment::Center => { + self.bounds.x += (space.width - self.bounds.width) / 2.0; + } + Alignment::End => { + self.bounds.x += space.width - self.bounds.width; + } + Alignment::Fill => { + self.bounds.width = space.width; + } + } + + match vertical_alignment { + Alignment::Start => {} + Alignment::Center => { + self.bounds.y += (space.height - self.bounds.height) / 2.0; + } + Alignment::End => { + self.bounds.y += space.height - self.bounds.height; + } + Alignment::Fill => { + self.bounds.height = space.height; + } + } + } + + /// Moves the [`Node`] to the given position. + pub fn move_to(&mut self, position: Point) { + self.bounds.x = position.x; + self.bounds.y = position.y; + } + + /// Translates the [`Node`] by the given translation. + pub fn translate(self, translation: Vector) -> Self { + Self { + bounds: self.bounds + translation, + ..self + } + } +} |