diff options
Diffstat (limited to 'src/layout/nodes/stack.rs')
| -rw-r--r-- | src/layout/nodes/stack.rs | 372 |
1 files changed, 122 insertions, 250 deletions
diff --git a/src/layout/nodes/stack.rs b/src/layout/nodes/stack.rs index 343f4461..cca64e62 100644 --- a/src/layout/nodes/stack.rs +++ b/src/layout/nodes/stack.rs @@ -37,298 +37,170 @@ impl Layout for Stack { ctx: &mut LayoutContext, constraints: LayoutConstraints, ) -> Vec<LayoutItem> { - let mut layouter = StackLayouter::new(StackContext { - dirs: self.dirs, - spaces: constraints.spaces, - repeat: constraints.repeat, - expand: self.expand, - }); + let mut items = vec![]; - for child in &self.children { - let items = child - .layout(ctx, LayoutConstraints { - spaces: layouter.remaining(), - repeat: constraints.repeat, - }) - .await; + let size = constraints.spaces[0].size; + let mut space = StackSpace::new(self.dirs, self.expand, size); + let mut i = 0; - for item in items { + for child in &self.children { + let child_constraints = LayoutConstraints { + spaces: { + let mut remaining = vec![LayoutSpace { + base: space.full_size, + size: space.usable, + }]; + let next = (i + 1).min(constraints.spaces.len() - 1); + remaining.extend(&constraints.spaces[next ..]); + remaining + }, + repeat: constraints.repeat, + }; + + for item in child.layout(ctx, child_constraints).await { match item { - LayoutItem::Spacing(amount) => layouter.push_spacing(amount), - LayoutItem::Box(boxed, aligns) => layouter.push_box(boxed, aligns), + LayoutItem::Spacing(spacing) => space.push_spacing(spacing), + LayoutItem::Box(mut boxed, aligns) => { + let mut last = false; + while let Err(back) = space.push_box(boxed, aligns) { + boxed = back; + if last { + break; + } + + items.push(LayoutItem::Box(space.finish(), self.aligns)); + + if i + 1 < constraints.spaces.len() { + i += 1; + } else { + last = true; + } + + let size = constraints.spaces[i].size; + space = StackSpace::new(self.dirs, self.expand, size); + } + } } } } - layouter - .finish() - .into_iter() - .map(|boxed| LayoutItem::Box(boxed, self.aligns)) - .collect() - } -} - -impl From<Stack> for LayoutNode { - fn from(stack: Stack) -> Self { - Self::dynamic(stack) + items.push(LayoutItem::Box(space.finish(), self.aligns)); + items } } -/// Performs the stack layouting. -pub(super) struct StackLayouter { - /// The context used for stack layouting. - pub ctx: StackContext, - /// The finished layouts. - pub layouts: Vec<BoxLayout>, - /// The in-progress space. - pub space: Space, -} - -/// The context for stack layouting. -#[derive(Debug, Clone)] -pub(super) struct StackContext { - /// The layouting directions. - pub dirs: Gen2<Dir>, - /// The spaces to layout into. - pub spaces: Vec<LayoutSpace>, - /// Whether to spill over into copies of the last space or finish layouting - /// when the last space is used up. - pub repeat: bool, - /// Whether to expand the size of the resulting layout to the full size of - /// this space or to shrink it to fit the content. - pub expand: Spec2<bool>, +struct StackSpace { + dirs: Gen2<Dir>, + expand: Spec2<bool>, + boxes: Vec<(BoxLayout, Gen2<GenAlign>)>, + full_size: Size, + usable: Size, + used: Size, + ruler: GenAlign, } -impl StackLayouter { - /// Create a new stack layouter. - pub fn new(ctx: StackContext) -> Self { - let space = ctx.spaces[0]; +impl StackSpace { + fn new(dirs: Gen2<Dir>, expand: Spec2<bool>, size: Size) -> Self { Self { - ctx, - layouts: vec![], - space: Space::new(0, true, space.size), + dirs, + expand, + boxes: vec![], + full_size: size, + usable: size, + used: Size::ZERO, + ruler: GenAlign::Start, } } - /// Add a layout to the stack. - pub fn push_box(&mut self, layout: BoxLayout, aligns: Gen2<GenAlign>) { - // If the alignment cannot be fitted in this space, finish it. - // - // TODO: Issue warning for non-fitting alignment in non-repeating - // context. - if aligns.main < self.space.allowed_align && self.ctx.repeat { - self.finish_space(true); - } - - // TODO: Issue warning about overflow if there is overflow in a - // non-repeating context. - if !self.space.usable.fits(layout.size) && self.ctx.repeat { - self.skip_to_fitting_space(layout.size); + fn push_box( + &mut self, + boxed: BoxLayout, + aligns: Gen2<GenAlign>, + ) -> Result<(), BoxLayout> { + let main = self.dirs.main.axis(); + let cross = self.dirs.cross.axis(); + if aligns.main < self.ruler || !self.usable.fits(boxed.size) { + return Err(boxed); } - // Change the usable space and size of the space. - self.update_metrics(layout.size.switch(self.ctx.dirs)); + let size = boxed.size.switch(self.dirs); + *self.used.get_mut(cross) = self.used.get(cross).max(size.cross); + *self.used.get_mut(main) += size.main; + *self.usable.get_mut(main) -= size.main; + self.boxes.push((boxed, aligns)); + self.ruler = aligns.main; - // Add the box to the vector and remember that spacings are allowed - // again. - self.space.layouts.push((layout, aligns)); - self.space.allowed_align = aligns.main; + Ok(()) } - /// Add spacing to the stack. - pub fn push_spacing(&mut self, mut spacing: f64) { - // Reduce the spacing such that it definitely fits. - let axis = self.ctx.dirs.main.axis(); - spacing = spacing.min(self.space.usable.get(axis)); + fn push_spacing(&mut self, spacing: f64) { + let main = self.dirs.main.axis(); + let max = self.usable.get(main); + let trimmed = spacing.min(max); + *self.used.get_mut(main) += trimmed; + *self.usable.get_mut(main) -= trimmed; - let size = Gen2::new(spacing, 0.0); - self.update_metrics(size); - self.space.layouts.push(( - BoxLayout::new(size.switch(self.ctx.dirs).to_size()), - Gen2::default(), - )); + let size = Gen2::new(trimmed, 0.0).switch(self.dirs); + self.boxes.push((BoxLayout::new(size.to_size()), Gen2::default())); } - fn update_metrics(&mut self, added: Gen2<f64>) { - let mut used = self.space.used.switch(self.ctx.dirs); - used.cross = used.cross.max(added.cross); - used.main += added.main; - self.space.used = used.switch(self.ctx.dirs).to_size(); - *self.space.usable.get_mut(self.ctx.dirs.main.axis()) -= added.main; - } + fn finish(mut self) -> BoxLayout { + let dirs = self.dirs; + let main = dirs.main.axis(); - /// Move to the first space that can fit the given size or do nothing - /// if no space is capable of that. - pub fn skip_to_fitting_space(&mut self, size: Size) { - let start = self.next_space(); - for (index, space) in self.ctx.spaces[start ..].iter().enumerate() { - if space.size.fits(size) { - self.finish_space(true); - self.start_space(start + index, true); - break; - } + if self.expand.horizontal { + self.used.width = self.full_size.width; } - } - - /// The remaining inner spaces. If something is laid out into these spaces, - /// it will fit into this stack. - pub fn remaining(&self) -> Vec<LayoutSpace> { - let mut spaces = vec![LayoutSpace { - base: self.space.size, - size: self.space.usable, - }]; - - spaces.extend(&self.ctx.spaces[self.next_space() ..]); - spaces - } - - /// The remaining usable size. - pub fn usable(&self) -> Size { - self.space.usable - } - - /// Whether the current layout space is empty. - pub fn space_is_empty(&self) -> bool { - self.space.used == Size::ZERO && self.space.layouts.is_empty() - } - /// Finish everything up and return the final collection of boxes. - pub fn finish(mut self) -> Vec<BoxLayout> { - if self.space.hard || !self.space_is_empty() { - self.finish_space(false); + if self.expand.vertical { + self.used.height = self.full_size.height; } - self.layouts - } - - /// Finish active current space and start a new one. - pub fn finish_space(&mut self, hard: bool) { - let dirs = self.ctx.dirs; - - // ------------------------------------------------------------------ // - // Step 1: Determine the full size of the space. - // (Mostly done already while collecting the boxes, but here we - // expand if necessary.) - - let space = self.ctx.spaces[self.space.index]; - let layout_size = { - let mut used_size = self.space.used; - if self.ctx.expand.horizontal { - used_size.width = space.size.width; - } - if self.ctx.expand.vertical { - used_size.height = space.size.height; - } - used_size - }; - - let mut layout = BoxLayout::new(layout_size); - // ------------------------------------------------------------------ // - // Step 2: Forward pass. Create a bounding box for each layout in which - // it will be aligned. Then, go forwards through the boxes and remove - // what is taken by previous layouts from the following layouts. + let mut sum = 0.0; + let mut sums = Vec::with_capacity(self.boxes.len() + 1); - let mut bounds = vec![]; - let mut bound = Rect { - x0: 0.0, - y0: 0.0, - x1: layout_size.width, - y1: layout_size.height, - }; - - for (layout, _) in &self.space.layouts { - // First, store the bounds calculated so far (which were reduced - // by the predecessors of this layout) as the initial bounding box - // of this layout. - bounds.push(bound); - - // Then, reduce the bounding box for the following layouts. This - // layout uses up space from the origin to the end. Thus, it reduces - // the usable space for following layouts at its origin by its - // main-axis extent. - *bound.get_mut(dirs.main.start()) += - dirs.main.factor() * layout.size.get(dirs.main.axis()); + for (boxed, _) in &self.boxes { + sums.push(sum); + sum += boxed.size.get(main); } - // ------------------------------------------------------------------ // - // Step 3: Backward pass. Reduce the bounding boxes from the previous - // layouts by what is taken by the following ones. + sums.push(sum); - let mut main_extent = 0.0; - for (child, bound) in self.space.layouts.iter().zip(&mut bounds).rev() { - let (layout, _) = child; + let mut layout = BoxLayout::new(self.used); + let used = self.used.switch(dirs); - // Reduce the bounding box of this layout by the following one's - // main-axis extents. - *bound.get_mut(dirs.main.end()) -= dirs.main.factor() * main_extent; + for (i, (boxed, aligns)) in self.boxes.into_iter().enumerate() { + let size = boxed.size.switch(dirs); - // And then, include this layout's main-axis extent. - main_extent += layout.size.get(dirs.main.axis()); - } + let before = sums[i]; + let after = sum - sums[i + 1]; + let main_len = used.main - size.main; + let main_range = if dirs.main.is_positive() { + before .. main_len - after + } else { + main_len - before .. after + }; - // ------------------------------------------------------------------ // - // Step 4: Align each layout in its bounding box and collect everything - // into a single finished layout. + let cross_len = used.cross - size.cross; + let cross_range = if dirs.cross.is_positive() { + 0.0 .. cross_len + } else { + cross_len .. 0.0 + }; - let children = std::mem::take(&mut self.space.layouts); - for ((child, aligns), bound) in children.into_iter().zip(bounds) { - // Align the child in its own bounds. - let local = - bound.size().anchor(dirs, aligns) - child.size.anchor(dirs, aligns); + let main = aligns.main.apply(main_range); + let cross = aligns.cross.apply(cross_range); + let pos = Gen2::new(main, cross).switch(dirs).to_point(); - // Make the local position in the bounds global. - let pos = bound.origin() + local; - layout.push_layout(pos, child); + layout.push_layout(pos, boxed); } - self.layouts.push(layout); - - // ------------------------------------------------------------------ // - // Step 5: Start the next space. - - self.start_space(self.next_space(), hard) - } - - fn start_space(&mut self, index: usize, hard: bool) { - let space = self.ctx.spaces[index]; - self.space = Space::new(index, hard, space.size); - } - - fn next_space(&self) -> usize { - (self.space.index + 1).min(self.ctx.spaces.len() - 1) + layout } } -/// A layout space composed of subspaces which can have different directions and -/// alignments. -#[derive(Debug)] -pub(super) struct Space { - /// The index of this space in `ctx.spaces`. - index: usize, - /// Whether to include a layout for this space even if it would be empty. - hard: bool, - /// The so-far accumulated layouts. - layouts: Vec<(BoxLayout, Gen2<GenAlign>)>, - /// The full size of this space. - size: Size, - /// The used size of this space. - used: Size, - /// The remaining space. - usable: Size, - /// Which alignments for new boxes are still allowed. - pub(super) allowed_align: GenAlign, -} - -impl Space { - fn new(index: usize, hard: bool, size: Size) -> Self { - Self { - index, - hard, - layouts: vec![], - size, - used: Size::ZERO, - usable: size, - allowed_align: GenAlign::Start, - } +impl From<Stack> for LayoutNode { + fn from(stack: Stack) -> Self { + Self::dynamic(stack) } } |