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// Copyright 2018 The xi-editor Authors. // // 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. //! A widget that arranges its children in a one-dimensional array. use crate::kurbo::common::FloatExt; use crate::kurbo::{Point, Rect, Size}; use crate::widget::SizedBox; use crate::{ BoxConstraints, Data, Env, Event, EventCtx, KeyOrValue, LayoutCtx, LifeCycle, LifeCycleCtx, PaintCtx, UpdateCtx, Widget, WidgetPod, }; /// A container with either horizontal or vertical layout. /// /// This widget is the foundation of most layouts, and is highly configurable. /// /// # Flex layout algorithm /// /// Children of a `Flex` container can have an optional `flex` parameter. /// Layout occurs in several passes. First we measure (calling their [`layout`] /// method) our non-flex children, providing them with unbounded space on the /// main axis. Next, the remaining space is divided between the flex children /// according to their flex factor, and they are measured. Unlike a non-flex /// child, a child with a non-zero flex factor has a maximum allowed size /// on the main axis; non-flex children are allowed to choose their size first, /// and freely. /// /// If you would like a child to be forced to use up all of the flex space /// passed to it, you can place it in a [`SizedBox`] set to `expand` in the /// appropriate axis. There are convenience methods for this available on /// [`WidgetExt`]: [`expand_width`] and [`expand_height`]. /// /// # Flex or non-flex? /// /// When should your children be flexible? With other things being equal, /// a flexible child has lower layout priority than a non-flexible child. /// Imagine, for instance, we have a row that is 30dp wide, and we have /// two children, both of which want to be 20dp wide. If child #1 is non-flex /// and child #2 is flex, the first widget will take up its 20dp, and the second /// widget will be constrained to 10dp. /// /// If, instead, both widgets are flex, they will each be given equal space, /// and both will end up taking up 15dp. /// /// If both are non-flex they will both take up 20dp, and will overflow the /// container. /// /// ```no_compile /// -------non-flex----- -flex----- /// | child #1 | child #2 | /// /// /// ----flex------- ----flex------- /// | child #1 | child #2 | /// /// ``` /// /// In general, if you are using widgets that are opinionated about their size /// (such as most control widgets, which are designed to lay out nicely together, /// or text widgets that are sized to fit their text) you should make them /// non-flexible. /// /// If you are trying to divide space evenly, or if you want a particular item /// to have access to all left over space, then you should make it flexible. /// /// **note**: by default, a widget will not necessarily use all the space that /// is available to it. For instance, the [`TextBox`] widget has a default /// width, and will choose this width if possible, even if more space is /// available to it. If you want to force a widget to use all available space, /// you should expand it, with [`expand_width`] or [`expand_height`]. /// /// /// # Options /// /// To experiment with these options, see the `flex` example in `druid/examples`. /// /// - [`CrossAxisAlignment`] determines how children are positioned on the /// cross or 'minor' axis. The default is `CrossAxisAlignment::Center`. /// /// - [`MainAxisAlignment`] determines how children are positioned on the main /// axis; this is only meaningful if the container has more space on the main /// axis than is taken up by its children. /// /// - [`must_fill_main_axis`] determines whether the container is obliged to /// be maximally large on the major axis, as determined by its own constraints. /// If this is `true`, then the container must fill the available space on that /// axis; otherwise it may be smaller if its children are smaller. /// /// Additional options can be set (or overridden) in the [`FlexParams`]. /// /// # Examples /// /// Construction with builder methods /// /// ``` /// use druid::widget::{Flex, FlexParams, Label, Slider, CrossAxisAlignment}; /// /// let my_row = Flex::row() /// .cross_axis_alignment(CrossAxisAlignment::Center) /// .must_fill_main_axis(true) /// .with_child(Label::new("hello")) /// .with_spacer(8.0) /// .with_flex_child(Slider::new(), 1.0); /// ``` /// /// Construction with mutating methods /// /// ``` /// use druid::widget::{Flex, FlexParams, Label, Slider, CrossAxisAlignment}; /// /// let mut my_row = Flex::row(); /// my_row.set_must_fill_main_axis(true); /// my_row.set_cross_axis_alignment(CrossAxisAlignment::Center); /// my_row.add_child(Label::new("hello")); /// my_row.add_spacer(8.0); /// my_row.add_flex_child(Slider::new(), 1.0); /// ``` /// /// [`layout`]: ../trait.Widget.html#tymethod.layout /// [`MainAxisAlignment`]: enum.MainAxisAlignment.html /// [`CrossAxisAlignment`]: enum.CrossAxisAlignment.html /// [`must_fill_main_axis`]: struct.Flex.html#method.must_fill_main_axis /// [`FlexParams`]: struct.FlexParams.html /// [`WidgetExt`]: ../trait.WidgetExt.html /// [`expand_height`]: ../trait.WidgetExt.html#method.expand_height /// [`expand_width`]: ../trait.WidgetExt.html#method.expand_width /// [`TextBox`]: struct.TextBox.html /// [`SizedBox`]: struct.SizedBox.html pub struct Flex<T> { direction: Axis, cross_alignment: CrossAxisAlignment, main_alignment: MainAxisAlignment, fill_major_axis: bool, children: Vec<ChildWidget<T>>, } struct ChildWidget<T> { widget: WidgetPod<T, Box<dyn Widget<T>>>, params: FlexParams, } /// A dummy widget we use to do spacing. struct Spacer { axis: Axis, len: KeyOrValue<f64>, } /// Optional parameters for an item in a [`Flex`] container (row or column). /// /// Generally, when you would like to add a flexible child to a container, /// you can simply call [`with_flex_child`] or [`add_flex_child`], passing the /// child and the desired flex factor as a `f64`, which has an impl of /// `Into<FlexParams>`. /// /// If you need to set additional paramaters, such as a custom [`CrossAxisAlignment`], /// you can construct `FlexParams` directly. By default, the child has the /// same `CrossAxisAlignment` as the container. /// /// For an overview of the flex layout algorithm, see the [`Flex`] docs. /// /// # Examples /// ``` /// use druid::widget::{FlexParams, Label, CrossAxisAlignment}; /// /// let mut row = druid::widget::Flex::<()>::row(); /// let child_1 = Label::new("I'm hungry"); /// let child_2 = Label::new("I'm scared"); /// // normally you just use a float: /// row.add_flex_child(child_1, 1.0); /// // you can construct FlexParams if needed: /// let params = FlexParams::new(2.0, CrossAxisAlignment::End); /// row.add_flex_child(child_2, params); /// ``` /// /// [`CrossAxisAlignment`]: enum.CrossAxisAlignment.html /// [`Flex`]: struct.Flex.html /// [`with_flex_child`]: struct.Flex.html#method.with_flex_child /// [`add_flex_child`]: struct.Flex.html#method.add_flex_child #[derive(Copy, Clone, Default)] pub struct FlexParams { flex: f64, alignment: Option<CrossAxisAlignment>, } #[derive(Clone, Copy)] pub(crate) enum Axis { Horizontal, Vertical, } /// The alignment of the widgets on the container's cross (or minor) axis. /// /// If a widget is smaller than the container on the minor axis, this determines /// where it is positioned. #[derive(Debug, Clone, Copy, PartialEq, Data)] pub enum CrossAxisAlignment { /// Top or leading. /// /// In a vertical container, widgets are top aligned. In a horiziontal /// container, their leading edges are aligned. Start, /// Widgets are centered in the container. Center, /// Bottom or trailing. /// /// In a vertical container, widgets are bottom aligned. In a horiziontal /// container, their trailing edges are aligned. End, } /// Arrangement of children on the main axis. /// /// If there is surplus space on the main axis after laying out children, this /// enum represents how children are laid out in this space. #[derive(Debug, Clone, Copy, PartialEq, Data)] pub enum MainAxisAlignment { /// Top or leading. /// /// Children are aligned with the top or leading edge, without padding. Start, /// Children are centered, without padding. Center, /// Bottom or trailing. /// /// Children are aligned with the bottom or trailing edge, without padding. End, /// Extra space is divided evenly between each child. SpaceBetween, /// Extra space is divided evenly between each child, as well as at the ends. SpaceEvenly, /// Space between each child, with less at the start and end. /// /// This divides space such that each child is separated by `n` units, /// and the start and end have `n/2` units of padding. SpaceAround, } impl FlexParams { /// Create custom `FlexParams` with a specific `flex_factor` and an optional /// [`CrossAxisAlignment`]. /// /// You likely only need to create these manually if you need to specify /// a custom alignment; if you only need to use a custom `flex_factor` you /// can pass an `f64` to any of the functions that take `FlexParams`. /// /// By default, the widget uses the alignment of its parent [`Flex`] container. /// /// /// [`Flex`]: struct.Flex.html /// [`CrossAxisAlignment`]: enum.CrossAxisAlignment.html pub fn new(flex: f64, alignment: impl Into<Option<CrossAxisAlignment>>) -> Self { FlexParams { flex, alignment: alignment.into(), } } } impl<T> ChildWidget<T> { fn new(child: impl Widget<T> + 'static, params: FlexParams) -> Self { ChildWidget { widget: WidgetPod::new(Box::new(child)), params, } } } impl Axis { pub(crate) fn major(self, coords: Size) -> f64 { match self { Axis::Horizontal => coords.width, Axis::Vertical => coords.height, } } pub(crate) fn minor(self, coords: Size) -> f64 { match self { Axis::Horizontal => coords.height, Axis::Vertical => coords.width, } } pub(crate) fn pack(self, major: f64, minor: f64) -> (f64, f64) { match self { Axis::Horizontal => (major, minor), Axis::Vertical => (minor, major), } } /// Generate constraints with new values on the major axis. fn constraints(self, bc: &BoxConstraints, min_major: f64, major: f64) -> BoxConstraints { match self { Axis::Horizontal => BoxConstraints::new( Size::new(min_major, bc.min().height), Size::new(major, bc.max().height), ), Axis::Vertical => BoxConstraints::new( Size::new(bc.min().width, min_major), Size::new(bc.max().width, major), ), } } } impl<T: Data> Flex<T> { /// Create a new horizontal stack. /// /// The child widgets are laid out horizontally, from left to right. pub fn row() -> Self { Flex { direction: Axis::Horizontal, children: Vec::new(), cross_alignment: CrossAxisAlignment::Center, main_alignment: MainAxisAlignment::Start, fill_major_axis: false, } } /// Create a new vertical stack. /// /// The child widgets are laid out vertically, from top to bottom. pub fn column() -> Self { Flex { direction: Axis::Vertical, children: Vec::new(), cross_alignment: CrossAxisAlignment::Center, main_alignment: MainAxisAlignment::Start, fill_major_axis: false, } } /// Builder-style method for specifying the childrens' [`CrossAxisAlignment`]. /// /// [`CrossAxisAlignment`]: enum.CrossAxisAlignment.html pub fn cross_axis_alignment(mut self, alignment: CrossAxisAlignment) -> Self { self.cross_alignment = alignment; self } /// Builder-style method for specifying the childrens' [`MainAxisAlignment`]. /// /// [`MainAxisAlignment`]: enum.MainAxisAlignment.html pub fn main_axis_alignment(mut self, alignment: MainAxisAlignment) -> Self { self.main_alignment = alignment; self } /// Builder-style method for setting whether the container must expand /// to fill the available space on its main axis. /// /// If any children have flex then this container will expand to fill all /// available space on its main axis; But if no children are flex, /// this flag determines whether or not the container should shrink to fit, /// or must expand to fill. /// /// If it expands, and there is extra space left over, that space is /// distributed in accordance with the [`MainAxisAlignment`]. /// /// The default value is `false`. /// /// [`MainAxisAlignment`]: enum.MainAxisAlignment.html pub fn must_fill_main_axis(mut self, fill: bool) -> Self { self.fill_major_axis = fill; self } /// Builder-style variant of `add_child`. /// /// Convenient for assembling a group of widgets in a single expression. pub fn with_child(mut self, child: impl Widget<T> + 'static) -> Self { self.add_flex_child(child, 0.0); self } /// Builder-style method to add a flexible child to the container. /// /// This method is used when you need more control over the behaviour /// of the widget you are adding. In the general case, this likely /// means giving that child a 'flex factor', but it could also mean /// giving the child a custom [`CrossAxisAlignment`], or a combination /// of the two. /// /// This function takes a child widget and [`FlexParams`]; importantly /// you can pass in a float as your [`FlexParams`] in most cases. /// /// For the non-builder varient, see [`add_flex_child`]. /// /// # Examples /// /// ``` /// use druid::widget::{Flex, FlexParams, Label, Slider, CrossAxisAlignment}; /// /// let my_row = Flex::row() /// .with_flex_child(Slider::new(), 1.0) /// .with_flex_child(Slider::new(), FlexParams::new(1.0, CrossAxisAlignment::End)); /// ``` /// /// [`FlexParams`]: struct.FlexParams.html /// [`add_flex_child`]: #method.add_flex_child /// [`CrossAxisAlignment`]: enum.CrossAxisAlignment.html pub fn with_flex_child( mut self, child: impl Widget<T> + 'static, params: impl Into<FlexParams>, ) -> Self { self.add_flex_child(child, params); self } /// Builder-style method for adding a fixed-size spacer to the container. pub fn with_spacer(mut self, len: impl Into<KeyOrValue<f64>>) -> Self { self.add_spacer(len); self } /// Builder-style method for adding a `flex` spacer to the container. pub fn with_flex_spacer(mut self, flex: f64) -> Self { self.add_flex_spacer(flex); self } /// Set the childrens' [`CrossAxisAlignment`]. /// /// [`CrossAxisAlignment`]: enum.CrossAxisAlignment.html pub fn set_cross_axis_alignment(&mut self, alignment: CrossAxisAlignment) { self.cross_alignment = alignment; } /// Set the childrens' [`MainAxisAlignment`]. /// /// [`MainAxisAlignment`]: enum.MainAxisAlignment.html pub fn set_main_axis_alignment(&mut self, alignment: MainAxisAlignment) { self.main_alignment = alignment; } /// Set whether the container must expand to fill the available space on /// its main axis. pub fn set_must_fill_main_axis(&mut self, fill: bool) { self.fill_major_axis = fill; } /// Add a non-flex child widget. /// /// See also [`with_child`]. /// /// [`with_child`]: #method.with_child pub fn add_child(&mut self, child: impl Widget<T> + 'static) { self.add_flex_child(child, 0.0); } /// Add a flexible child widget. /// /// This method is used when you need more control over the behaviour /// of the widget you are adding. In the general case, this likely /// means giving that child a 'flex factor', but it could also mean /// giving the child a custom [`CrossAxisAlignment`], or a combination /// of the two. /// /// This function takes a child widget and [`FlexParams`]; importantly /// you can pass in a float as your [`FlexParams`] in most cases. /// /// For the builder-style varient, see [`with_flex_child`]. /// /// # Examples /// /// ``` /// use druid::widget::{Flex, FlexParams, Label, Slider, CrossAxisAlignment}; /// /// let mut my_row = Flex::row(); /// my_row.add_flex_child(Slider::new(), 1.0); /// my_row.add_flex_child(Slider::new(), FlexParams::new(1.0, CrossAxisAlignment::End)); /// ``` /// /// [`FlexParams`]: struct.FlexParams.html /// [`with_flex_child`]: #method.with_flex_child pub fn add_flex_child( &mut self, child: impl Widget<T> + 'static, params: impl Into<FlexParams>, ) { let child = ChildWidget::new(child, params.into()); self.children.push(child); } /// Add an empty spacer widget with the given length. pub fn add_spacer(&mut self, len: impl Into<KeyOrValue<f64>>) { let spacer = Spacer { axis: self.direction, len: len.into(), }; self.add_flex_child(spacer, 0.0); } /// Add an empty spacer widget with a specific `flex` factor. pub fn add_flex_spacer(&mut self, flex: f64) { let child = match self.direction { Axis::Vertical => SizedBox::empty().expand_height(), Axis::Horizontal => SizedBox::empty().expand_width(), }; self.add_flex_child(child, flex); } } impl<T: Data> Widget<T> for Flex<T> { fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut T, env: &Env) { for child in &mut self.children { child.widget.event(ctx, event, data, env); } } fn lifecycle(&mut self, ctx: &mut LifeCycleCtx, event: &LifeCycle, data: &T, env: &Env) { for child in &mut self.children { child.widget.lifecycle(ctx, event, data, env); } } fn update(&mut self, ctx: &mut UpdateCtx, _old_data: &T, data: &T, env: &Env) { for child in &mut self.children { child.widget.update(ctx, data, env); } } fn layout(&mut self, ctx: &mut LayoutCtx, bc: &BoxConstraints, data: &T, env: &Env) -> Size { bc.debug_check("Flex"); // we loosen our constraints when passing to children. let loosened_bc = bc.loosen(); // Measure non-flex children. let mut major_non_flex = 0.0; let mut minor = self.direction.minor(bc.min()); for child in &mut self.children { if child.params.flex == 0.0 { let child_bc = self .direction .constraints(&loosened_bc, 0., std::f64::INFINITY); let child_size = child.widget.layout(ctx, &child_bc, data, env); if child_size.width.is_infinite() { log::warn!("A non-Flex child has an infinite width."); } if child_size.height.is_infinite() { log::warn!("A non-Flex child has an infinite height."); } major_non_flex += self.direction.major(child_size).expand(); minor = minor.max(self.direction.minor(child_size).expand()); // Stash size. let rect = Rect::from_origin_size(Point::ORIGIN, child_size); child.widget.set_layout_rect(ctx, data, env, rect); } } let total_major = self.direction.major(bc.max()); let remaining = (total_major - major_non_flex).max(0.0); let mut remainder: f64 = 0.0; let flex_sum: f64 = self.children.iter().map(|child| child.params.flex).sum(); let mut major_flex: f64 = 0.0; // Measure flex children. for child in &mut self.children { if child.params.flex != 0.0 { let desired_major = remaining * child.params.flex / flex_sum + remainder; let actual_major = desired_major.round(); remainder = desired_major - actual_major; let min_major = 0.0; let child_bc = self .direction .constraints(&loosened_bc, min_major, actual_major); let child_size = child.widget.layout(ctx, &child_bc, data, env); major_flex += self.direction.major(child_size).expand(); minor = minor.max(self.direction.minor(child_size).expand()); // Stash size. let rect = Rect::from_origin_size(Point::ORIGIN, child_size); child.widget.set_layout_rect(ctx, data, env, rect); } } // figure out if we have extra space on major axis, and if so how to use it let extra = if self.fill_major_axis { (remaining - major_flex).max(0.0) } else { // if we are *not* expected to fill our available space this usually // means we don't have any extra, unless dictated by our constraints. (self.direction.major(bc.min()) - (major_non_flex + major_flex)).max(0.0) }; let mut spacing = Spacing::new(self.main_alignment, extra, self.children.len()); // Finalize layout, assigning positions to each child. let mut major = spacing.next().unwrap_or(0.); let mut child_paint_rect = Rect::ZERO; for child in &mut self.children { let rect = child.widget.layout_rect(); let extra_minor = minor - self.direction.minor(rect.size()); let alignment = child.params.alignment.unwrap_or(self.cross_alignment); let align_minor = alignment.align(extra_minor); let pos: Point = self.direction.pack(major, align_minor).into(); child .widget .set_layout_rect(ctx, data, env, rect.with_origin(pos)); child_paint_rect = child_paint_rect.union(child.widget.paint_rect()); major += self.direction.major(rect.size()).expand(); major += spacing.next().unwrap_or(0.); } if flex_sum > 0.0 && total_major.is_infinite() { log::warn!("A child of Flex is flex, but Flex is unbounded.") } if flex_sum > 0.0 { major = total_major; } let my_size: Size = self.direction.pack(major, minor).into(); // if we don't have to fill the main axis, we loosen that axis before constraining let my_size = if !self.fill_major_axis { let max_major = self.direction.major(bc.max()); self.direction .constraints(bc, 0.0, max_major) .constrain(my_size) } else { bc.constrain(my_size) }; let my_bounds = Rect::ZERO.with_size(my_size); let insets = child_paint_rect - my_bounds; ctx.set_paint_insets(insets); my_size } fn paint(&mut self, ctx: &mut PaintCtx, data: &T, env: &Env) { for child in &mut self.children { child.widget.paint(ctx, data, env); } } } impl CrossAxisAlignment { /// Given the difference between the size of the container and the size /// of the child (on their minor axis) return the necessary offset for /// this alignment. fn align(self, val: f64) -> f64 { match self { CrossAxisAlignment::Start => 0.0, CrossAxisAlignment::Center => (val / 2.0).round(), CrossAxisAlignment::End => val, } } } struct Spacing { alignment: MainAxisAlignment, extra: f64, n_children: usize, index: usize, equal_space: f64, remainder: f64, } impl Spacing { /// Given the provided extra space and children count, /// this returns an iterator of `f64` spacing, /// where the first element is the spacing before any children /// and all subsequent elements are the spacing after children. fn new(alignment: MainAxisAlignment, extra: f64, n_children: usize) -> Spacing { let extra = if extra.is_finite() { extra } else { 0. }; let equal_space = if n_children > 0 { match alignment { MainAxisAlignment::Center => extra / 2., MainAxisAlignment::SpaceBetween => extra / (n_children - 1).max(1) as f64, MainAxisAlignment::SpaceEvenly => extra / (n_children + 1) as f64, MainAxisAlignment::SpaceAround => extra / (2 * n_children) as f64, _ => 0., } } else { 0. }; Spacing { alignment, extra, n_children, index: 0, equal_space, remainder: 0., } } fn next_space(&mut self) -> f64 { let desired_space = self.equal_space + self.remainder; let actual_space = desired_space.round(); self.remainder = desired_space - actual_space; actual_space } } impl Iterator for Spacing { type Item = f64; fn next(&mut self) -> Option<f64> { if self.index > self.n_children { return None; } let result = { if self.n_children == 0 { self.extra } else { #[allow(clippy::match_bool)] match self.alignment { MainAxisAlignment::Start => match self.index == self.n_children { true => self.extra, false => 0., }, MainAxisAlignment::End => match self.index == 0 { true => self.extra, false => 0., }, MainAxisAlignment::Center => match self.index { 0 => self.next_space(), i if i == self.n_children => self.next_space(), _ => 0., }, MainAxisAlignment::SpaceBetween => match self.index { 0 => 0., i if i != self.n_children => self.next_space(), _ => match self.n_children { 1 => self.next_space(), _ => 0., }, }, MainAxisAlignment::SpaceEvenly => self.next_space(), MainAxisAlignment::SpaceAround => { if self.index == 0 || self.index == self.n_children { self.next_space() } else { self.next_space() + self.next_space() } } } } }; self.index += 1; Some(result) } } impl<T: Data> Widget<T> for Spacer { fn event(&mut self, _: &mut EventCtx, _: &Event, _: &mut T, _: &Env) {} fn lifecycle(&mut self, _: &mut LifeCycleCtx, _: &LifeCycle, _: &T, _: &Env) {} fn update(&mut self, _: &mut UpdateCtx, _: &T, _: &T, _: &Env) {} fn layout(&mut self, _: &mut LayoutCtx, _: &BoxConstraints, _: &T, env: &Env) -> Size { let major = self.len.resolve(env); self.axis.pack(major, 0.0).into() } fn paint(&mut self, _: &mut PaintCtx, _: &T, _: &Env) {} } impl From<f64> for FlexParams { fn from(flex: f64) -> FlexParams { FlexParams { flex, alignment: None, } } } #[cfg(test)] mod tests { use super::*; #[test] #[allow(clippy::cognitive_complexity)] fn test_main_axis_alignment_spacing() { // The following alignment strategy is based on how // Chrome 80 handles it with CSS flex. let vec = |a, e, n| -> Vec<f64> { Spacing::new(a, e, n).collect() }; let a = MainAxisAlignment::Start; assert_eq!(vec(a, 10., 0), vec![10.]); assert_eq!(vec(a, 10., 1), vec![0., 10.]); assert_eq!(vec(a, 10., 2), vec![0., 0., 10.]); assert_eq!(vec(a, 10., 3), vec![0., 0., 0., 10.]); let a = MainAxisAlignment::End; assert_eq!(vec(a, 10., 0), vec![10.]); assert_eq!(vec(a, 10., 1), vec![10., 0.]); assert_eq!(vec(a, 10., 2), vec![10., 0., 0.]); assert_eq!(vec(a, 10., 3), vec![10., 0., 0., 0.]); let a = MainAxisAlignment::Center; assert_eq!(vec(a, 10., 0), vec![10.]); assert_eq!(vec(a, 10., 1), vec![5., 5.]); assert_eq!(vec(a, 10., 2), vec![5., 0., 5.]); assert_eq!(vec(a, 10., 3), vec![5., 0., 0., 5.]); assert_eq!(vec(a, 1., 0), vec![1.]); assert_eq!(vec(a, 3., 1), vec![2., 1.]); assert_eq!(vec(a, 5., 2), vec![3., 0., 2.]); assert_eq!(vec(a, 17., 3), vec![9., 0., 0., 8.]); let a = MainAxisAlignment::SpaceBetween; assert_eq!(vec(a, 10., 0), vec![10.]); assert_eq!(vec(a, 10., 1), vec![0., 10.]); assert_eq!(vec(a, 10., 2), vec![0., 10., 0.]); assert_eq!(vec(a, 10., 3), vec![0., 5., 5., 0.]); assert_eq!(vec(a, 33., 5), vec![0., 8., 9., 8., 8., 0.]); assert_eq!(vec(a, 34., 5), vec![0., 9., 8., 9., 8., 0.]); assert_eq!(vec(a, 35., 5), vec![0., 9., 9., 8., 9., 0.]); assert_eq!(vec(a, 36., 5), vec![0., 9., 9., 9., 9., 0.]); assert_eq!(vec(a, 37., 5), vec![0., 9., 10., 9., 9., 0.]); assert_eq!(vec(a, 38., 5), vec![0., 10., 9., 10., 9., 0.]); assert_eq!(vec(a, 39., 5), vec![0., 10., 10., 9., 10., 0.]); let a = MainAxisAlignment::SpaceEvenly; assert_eq!(vec(a, 10., 0), vec![10.]); assert_eq!(vec(a, 10., 1), vec![5., 5.]); assert_eq!(vec(a, 10., 2), vec![3., 4., 3.]); assert_eq!(vec(a, 10., 3), vec![3., 2., 3., 2.]); assert_eq!(vec(a, 33., 5), vec![6., 5., 6., 5., 6., 5.]); assert_eq!(vec(a, 34., 5), vec![6., 5., 6., 6., 5., 6.]); assert_eq!(vec(a, 35., 5), vec![6., 6., 5., 6., 6., 6.]); assert_eq!(vec(a, 36., 5), vec![6., 6., 6., 6., 6., 6.]); assert_eq!(vec(a, 37., 5), vec![6., 6., 7., 6., 6., 6.]); assert_eq!(vec(a, 38., 5), vec![6., 7., 6., 6., 7., 6.]); assert_eq!(vec(a, 39., 5), vec![7., 6., 7., 6., 7., 6.]); let a = MainAxisAlignment::SpaceAround; assert_eq!(vec(a, 10., 0), vec![10.]); assert_eq!(vec(a, 10., 1), vec![5., 5.]); assert_eq!(vec(a, 10., 2), vec![3., 5., 2.]); assert_eq!(vec(a, 10., 3), vec![2., 3., 3., 2.]); assert_eq!(vec(a, 33., 5), vec![3., 7., 6., 7., 7., 3.]); assert_eq!(vec(a, 34., 5), vec![3., 7., 7., 7., 7., 3.]); assert_eq!(vec(a, 35., 5), vec![4., 7., 7., 7., 7., 3.]); assert_eq!(vec(a, 36., 5), vec![4., 7., 7., 7., 7., 4.]); assert_eq!(vec(a, 37., 5), vec![4., 7., 8., 7., 7., 4.]); assert_eq!(vec(a, 38., 5), vec![4., 7., 8., 8., 7., 4.]); assert_eq!(vec(a, 39., 5), vec![4., 8., 7., 8., 8., 4.]); } }