diff options
Diffstat (limited to 'src/layout/stack.rs')
| -rw-r--r-- | src/layout/stack.rs | 169 |
1 files changed, 126 insertions, 43 deletions
diff --git a/src/layout/stack.rs b/src/layout/stack.rs index 2e4f2d3a..369b1c81 100644 --- a/src/layout/stack.rs +++ b/src/layout/stack.rs @@ -70,13 +70,17 @@ impl StackLayouter { self.finish_space(true); } - // We want the new maximal alignment and since the layout's secondary - // alignment is at least the previous maximum, we just take it. - *self.secondary_alignment() = layout.alignment.secondary; - - // Add a cached soft space if there is one. - if let LastSpacing::Soft(spacing, _) = self.space.last_spacing { - self.add_spacing(spacing, SpacingKind::Hard); + if layout.alignment.secondary == *self.secondary_alignment() { + // Add a cached soft space if there is one and the alignment stayed + // the same. Soft spaces are discarded if the alignment changes. + if let LastSpacing::Soft(spacing, _) = self.space.last_spacing { + self.add_spacing(spacing, SpacingKind::Hard); + } + } else { + // We want the new maximal alignment and since the layout's + // secondary alignment is at least the previous maximum, we just + // take it. + *self.secondary_alignment() = layout.alignment.secondary; } // Find the first space that fits the layout. @@ -89,21 +93,7 @@ impl StackLayouter { self.finish_space(true); } - let axes = self.ctx.axes; - let dimensions = layout.dimensions.generalized(axes); - - let mut size = self.space.size.generalized(axes); - let mut extra = self.space.extra.generalized(axes); - - size.x += max(dimensions.x - extra.x, Size::ZERO); - size.y += max(dimensions.y - extra.y, Size::ZERO); - extra.x = max(extra.x, dimensions.x); - extra.y = max(extra.y - dimensions.y, Size::ZERO); - - self.space.size = size.specialized(axes); - self.space.extra = extra.specialized(axes); - - *self.space.usable.secondary_mut(axes) -= dimensions.y; + self.update_metrics(layout.dimensions.generalized(self.ctx.axes)); self.space.layouts.push((self.ctx.axes, layout)); self.space.last_spacing = LastSpacing::None; @@ -124,22 +114,24 @@ impl StackLayouter { /// Add secondary spacing to the stack. pub fn add_spacing(&mut self, mut spacing: Size, kind: SpacingKind) { match kind { - // A hard space is directly added to the sub's size. + // A hard space is simply an empty box. SpacingKind::Hard => { - // Reduce the spacing such that definitely fits. + // Reduce the spacing such that it definitely fits. spacing.min_eq(self.space.usable.secondary(self.ctx.axes)); + let dimensions = Size2D::with_y(spacing); + + self.update_metrics(dimensions); - self.add(Layout { - dimensions: Size2D::with_y(spacing).specialized(self.ctx.axes), - baseline: None, + self.space.layouts.push((self.ctx.axes, Layout { + dimensions: dimensions.specialized(self.ctx.axes), alignment: LayoutAlignment::default(), - actions: vec![], - }).expect("spacing should fit"); + actions: vec![] + })); self.space.last_spacing = LastSpacing::Hard; } - // A hard space is cached if it is not consumed by a hard space or + // A soft space is cached if it is not consumed by a hard space or // previous soft space with higher level. SpacingKind::Soft(level) => { let consumes = match self.space.last_spacing { @@ -155,11 +147,34 @@ impl StackLayouter { } } + /// Update the size metrics to reflect that a layout or spacing with the + /// given generalized dimensions has been added. + fn update_metrics(&mut self, dimensions: Size2D) { + let axes = self.ctx.axes; + + let mut size = self.space.size.generalized(axes); + let mut extra = self.space.extra.generalized(axes); + + size.x += max(dimensions.x - extra.x, Size::ZERO); + size.y += max(dimensions.y - extra.y, Size::ZERO); + extra.x = max(extra.x, dimensions.x); + extra.y = max(extra.y - dimensions.y, Size::ZERO); + + self.space.size = size.specialized(axes); + self.space.extra = extra.specialized(axes); + *self.space.usable.secondary_mut(axes) -= dimensions.y; + } + /// Change the layouting axes used by this layouter. /// /// This starts a new subspace (if the axes are actually different from the /// current ones). pub fn set_axes(&mut self, axes: LayoutAxes) { + // Forget the spacing because it is not relevant anymore. + if axes.secondary != self.ctx.axes.secondary { + self.space.last_spacing = LastSpacing::Hard; + } + self.ctx.axes = axes; } @@ -221,37 +236,105 @@ impl StackLayouter { pub fn finish_space(&mut self, hard: bool) { let space = self.ctx.spaces[self.space.index]; + // ------------------------------------------------------------------ // + // Step 1: Determine the full dimensions of the space. + // (Mostly done already while collecting the boxes, but here we + // expand if necessary.) + let usable = space.usable(); if space.expand.horizontal { self.space.size.x = usable.x; } if space.expand.vertical { self.space.size.y = usable.y; } let dimensions = self.space.size.padded(space.padding); + // ------------------------------------------------------------------ // + // 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 start = space.start(); + + let mut bounds = vec![]; + let mut bound = SizeBox { + left: start.x, + top: start.y, + right: start.x + self.space.size.x, + bottom: start.y + self.space.size.y, + }; + + for (axes, layout) in &self.space.layouts { + // First, we 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, we 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 it's origin by its + // extent along the secondary axis. + *bound.secondary_origin_mut(*axes) + += axes.secondary.factor() * layout.dimensions.secondary(*axes); + } + + // ------------------------------------------------------------------ // + // Step 3: Backward pass. Reduce the bounding boxes from the previous + // layouts by what is taken by the following ones. + + let mut extent = Size::ZERO; + + for (bound, entry) in bounds.iter_mut().zip(&self.space.layouts).rev() { + let (axes, layout) = entry; + + // We reduce the bounding box of this layout at it's end by the + // accumulated secondary extent of all layouts we have seen so far, + // which are the layouts after this one since we iterate reversed. + *bound.secondary_end_mut(*axes) -= axes.secondary.factor() * extent; + + // Then, we add this layout's secondary extent to the accumulator. + extent += layout.dimensions.secondary(*axes); + } + + // ------------------------------------------------------------------ // + // Step 4: Align each layout in its bounding box and collect everything + // into a single finished layout. + let mut actions = LayoutActions::new(); actions.add(LayoutAction::DebugBox(dimensions)); - let mut cursor = space.start(); - for (axes, layout) in std::mem::replace(&mut self.space.layouts, vec![]) { + let layouts = std::mem::replace(&mut self.space.layouts, vec![]); + + for ((axes, layout), bound) in layouts.into_iter().zip(bounds) { let LayoutAxes { primary, secondary } = axes; + let size = layout.dimensions.specialized(axes); - let alignment = layout.alignment.primary; + let alignment = layout.alignment; + + // The space in which this layout is aligned is given by it's + // corresponding bound box. + let usable = Size2D::new( + bound.right - bound.left, + bound.bottom - bound.top + ).generalized(axes); + + let offsets = Size2D { + x: usable.x.anchor(alignment.primary, primary.is_positive()) + - size.x.anchor(alignment.primary, primary.is_positive()), + y: usable.y.anchor(alignment.secondary, secondary.is_positive()) + - size.y.anchor(alignment.secondary, secondary.is_positive()), + }; - let primary_usable = self.space.size.primary(axes) - cursor.primary(axes); + let position = Size2D::new(bound.left, bound.top) + + offsets.specialized(axes); - let position = Size2D { - x: cursor.primary(axes) - + primary_usable.anchor(alignment, primary.is_positive()) - - size.x.anchor(alignment, primary.is_positive()), - y: cursor.secondary(axes), - }; + println!("pos: {}", position); + println!("usable: {}", usable); + println!("size: {}", size); - actions.add_layout(position.specialized(axes), layout); - *cursor.secondary_mut(axes) += size.y; + actions.add_layout(position, layout); } self.layouts.push(Layout { dimensions, - baseline: None, alignment: self.ctx.alignment, actions: actions.to_vec(), }); |